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Compliments of
SEWERAGE AND WATER BOARD
OF NEW ORLEANS, LA.
Please acknowledge receipt on
attached slip and exchange with any
reports or other published matter of
interest on Sewerage, Water or
Drainage Works under your direc-
tion.
New Orleans, La.,
602 Carondelet Street.
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SEWERAGE AND WATER BOARD,
]^,EW ORLEANS, LA.
RE^PORT
ON
Water Purification Investigation
PI^ANS PROPOSED
FOR
se^werage:
\VAXER-WORKS SYSTEMS
N
JANUARY ist, 1903.
NKW ORI^EANS :
A. W. Hyatt Stationery Manufacturing Co., lytd., 407 Camp Street.
1903
r
170649
^^^^.
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\N
SWF
Table of Contents.
Ivist of Plates ix
Ivist of Tables '. x
Membership and officers of the Sewerage and Water Board 1
Regular force employed by Sewerage and Water Board 2
Introduction by Geo. G. Barl, General Superintendent 3
WATER PURIFICATION INVESTIGATION,
by R. S. Weston, Resident Expert, chapters I to VIII, inclusive.
INTRODUCTORY CHAPTER.
Object of work 7
General description of water purification station '. 8
Modifications of water purification station 8
Period of investigation 9
Amount of analytical work 9
Force employed 10
Consultations 10
Cost of investigation .•. 11
Brief outline of report 11
I/ist of chapters 11
CHAPTER I.
Composition and Character of MiSvSissippi River Water.
Most characteristic features of the Mississippi River water 12
Variations in turbidity at same cross section of stream 12
Description of water shed 15
Area of river basins 16
Annual rainfall in principal basins 16
Relative stream discharges, area and rainfall for various basins 17
Differences in analytical character of tributaries 17
Urban population of the great divisions of the Mississippi Basin 18
Population of neighboring cities discharging sewage into the Mississippi
River above New Orleans 18
Rainfall 19
Stage of river 20
Floods 20
Comparative absence of sudden rises 22
Entrance of gulf water during low stages of river 22
Effect of wind storms 23
Relation of suspended matter to stage of river ...:.... 23
Synopsis of leading features of the Mississippi River water 24
Summary of constituents found in Mississippi River water 24
f
IV TABLE OF CONTENTS
.PAGE
Analytical description of the Mississippi River water 24-
Plan of analytical work 25
Sampling..... 25
Methods of analysis, physical 25
chemical 2a
bacterial .... 29
Physical character of Mississippi River water 30
Average amount of suspended matter 31
Daily normal amount of silica turbidity 34
Absorption of coagulant by suspended matter 35
Chemical character of Mississippi River water 36
Explanation of tables 37
List of tables 38
Tables 38-46
Biological character of Mississippi River water 47 ,
Species of bacteria isolated 48
Microscopical flora and fauna 49
Relative purity of Mississippi River at New Orleans 49
Classification of water 50-
CHAPTER II.
Description of Water Purification Station.
Location 52.
General arrangement of plant 53
Intake and pumps 54
Subsiding basins 54
Rearrangement of subsiding basins 55
Coagulating basins 56-
Devices for preparing and distributing the chemical solutions to the points
of application 59
Filters 60
English filters 60
Mechanical analyses of gravels 62
Modified English Filter 63
American Filter No. 3 63
Mechanical analyses of gravels 66
Losses of head in American Filter No. 3 67
American Filter No. 4 68
Sands used ; 70-
Mineralogical composition of sands 72
Maximum rates of filtration of sands in American Filters No. 3 and No. 4. 72
Analyses of sands used 74
Controllers 75
Controller boxes 75
Tower tank 75
Boiler house 76
Laboratory '. .' 76
TABLK OF CONTENTS V
CHAPTER III.
Manner of Operation of the Pi^in Subsiding Basins, and the Efficiency
OF P1.AIN Subsidence for Various Periods in the CtARiFicATioN and
Purification of the River Water.
PAGE
General plan of operation 77
Later modifications 77
Description of tables showing results of operation of subsiding basins ' 78
Tabulated list of tables 79
Tables 80-%
Interpretation of tables 97
Average amounts of silica turbidity and suspended matter remaining in
the Mississippi River water after various periods of plain subsidence... 101
Character of sediment 102
Decomposition of organic matter • 102
Algae growths in basins s.... 102
Removal of bacteria by plain subsidence 103
CHAPTER IV.
Description and Resui^ts of the Operation of the Engi^ish Fii^ter No. 1
and Discussion of the Leading Features Associated Therewith.
Description of regular operation of English Filter No. 1 104
Continuous plan 104
Regulation of rates 104
Loss of head ^ 104
Collection of samples 104
Head utilized 104
Scrapings 104
Filling from below 105
Resumption of filtration » 105
Initial data ' 105
Scraping samples 106
Significant results of operation of English Filter No. 1 109
Penetration of clay 110
Failure of system .* Ill
CHAPTER V. '
Description of the Operation of the Modified Engwsh System of
Water Purification and Discussion of the Leading Factors Asso-
ciated Therewith.
Comparison with English system , 113
Initial data 113
Operation of coagulating basin No. 2 114
Operation began 114
Operation with unsubsided river water 114
Coagulation 114
Chemical used as coagulant 114
Composition of coagulant 115
Action when applied to water 115
Description of tables XLVII-XLIX 116
Tables 117
VI TABLE OF CONTENTS
PAGB
Results of operation of Modified English Filter No. 2 122
Leading features of the operation of the Modified English Filter and the
significance of the results obtained 125
Penetration of clay, etc., into sand layer 128
Amount of coagulant required for water of different turbidities 129
Economical limit of plain subsidence , 131
Filter construction 132
Cost of purification by this method 133
Conclusion 134
CHAPTER VI.
Description of the Operation of the American System, and Discussion
OF THE Leading Features Associated Therewith.
Description of the American system of water purification 135
Initial data 136
Operation of chemical devices 136
Operation of coagulating and supplementary subsiding basins 136
Operation of filters 137
Outline of leading conditions of actual operation of the American system, 138
Division of periods of Filter No. 3 . 139
Division of periods of Filter No. 4 140
Description of tables LVII and LVIII 141
Tables LVII and LVIII, results of operation of American filters 142-169
Leading features associated with the efficiency and cost of operation of
the American system of purification, receiving plain subsided water,
based upon the results of these investigations 170
Importance of economical clarification, and the comparative unimport-
ance, from a hygienic standpoint, of the consideration of the bacterial
efficiency and the removal of organic matter by the American system. 170
Suspended matter in other water supplies 171
Leading points in the discussion of the American system of purification... 172
Preparation of the water for filtration .172
Limit of turbidity for filtration 172
Relation between turbidity and cost of wash water, etc 173
Character of water after various periods of subsidence 174
Coagulant required with different periods of plain subsidence 174
Comparison of factors of cost for different periods of subsidence, etc 176
Economical limit of plain subsidence 177
Notes on the special factors related to the preparation of the river water
for filtration 177
Discussion of factors from the standpoint of construction 178
a. — Construction of sand layer 178
b. — Employment of gravel layers in the filter 182
c. — ^Distance of sand surface from overflow 182
d. — ^Distribution of wash water 182
e. — Agitation of the sand layer 182
Effect of agitation on the leading results of operation 184
Available head 185
Considerations which affect the economical limit of loss of head in Ameri-
can filters 185
Rate of filtration ; 185
/
TABLE OF CONTENTS Vll
PAGE
Special factors associated with the operation of the American filters 185
Relation of proper supervision aud attendance to the operation of filters... 186
Cost of American filters 187
Conclusion 187
CHAPTER VII. .
Final Resume and Conclusions.
Character of the Mississsippi River water 188
Freedom from pollution.. 188
Complete clarification a concomitant of successful water purification at
New Orleans .'.. 188
, Methods of purification 188
Plain subsidence 189
Relative fineness of suspended matter 189
Plain subsidence inadequate to prepare water for filtration at all times 189
English filters and plain subsidence 189
Supplementary subsidence with the aid of coagulant 189
Necessity for coagulant 189
Diflficulty of renjoval of the last traces of turbidity by coagulant alone.... 190
Method of filtration 190
Applicability of both systems 191
Selection of best system 191
Necessity for careful supervision.. 191
CHAPTER VIII.
Tables of conversions and equivalents 192
Brief report on other sources of water supply, with analyses 192
Chemical analyses of efiiuents of Filters 1, 2, 3 and 4 196-199
Average, maximum and minimum of chemical analyses of Mississippi
River water, from September 1st, 1901, to September 1st, 1902 200
Special chlorine tests Mississippi River during low water, 1901 200
Bacterial tests Summer, 1902 202
CHAPTER IX.
Summary and Review of the Water Purification Question, by Messrs.
Hering& Fuller 204
OUTLINE OF PLANS PROPOSED FOR SEWERAGE AND
WATERWORKS SYSTEMS.
CHAPTER X.
The Proposed Sewerage System.
Causes which have prevented the sewering of New Orleans 210
Existing conditions as to sewerage 210
Funds available for present construction limited 210
Area to be sewered / 211
Method of sewage disposal 211
Character of ground 212
Population '. 214
Amount of sewage 215
Topography * 216
Depth of sewers 217
r
VIU TABLE OF CONTENTS
PAGB
Grades and velocities in sewers 217
Size and shape of sewers 218
Flushing 219.
Extensions 219
Sewage collection 220
Lateral transportation or main collection system 221
Pumping stations 222
Underground obstructions to sewerage construction 223
System designed for definite area and population 224
CHAPTER XI.
Waterworks Plans.
Existing conditions as to water supply 225
Topography of country about New Orleans 225
Possible source of supply 226
Assumed per capita water consumption 228
Filter and clear water reservoir capacity 229
Provision for future growth to be made ^n present construction 229
General Description of System Proposed and Reasons Governing
Design.
Location of purification and pumping plant 230
Area and condition of ground to be acquired 231
Relation of location chosen to distribution system 231
Working head to be used 232
Direct pressure system adopted 233
Hydraulic gradients 233
Reworkings of design for distribution system 233
Labor-saving devices used in design * 233
Hydrant, valve and minor pipe arrangement 233
Intake Pumping and Purification Station.
Location of intake 236
Main suction line and raw water pumps 238
Sedimentation reservoir system 238
Coagulation ,.,., 239
Operation of pumps and clear water reservoirs : 240
Method of constructing reservoirs 241
Plan for filters 241
Handling of coagulant 242
Cleaning system for reservoirs 243
Provision for extension at purification station 243
Separate plant required for Algiers 243
Present status of water purification design 244
CHAPTER XII.
Cost of Plans, Construction, Extensions and Operation.
Expenditures by Sewerage and Water Board for plans, etc., to January
1st, 1903 245
Future extensions of sewerage and waterworks system 246
Precautions essential to the successful construction and operation of sewer-
age and waterworks systems 247
List of Plates.
Water Purification Investigation.
DESCRIPTION
FACING PAGE
I . General view of Purification Station ^ —
II. Hydrograph and turbidity curves '
III. Sketch showing general location of Purification Plant ,
IV. General Plan of Water Purification Station
V. Elevation Water Purification Station
VI. Arrangement of devices for application of coagulant
VII. Section of English Filter No. 1 •.
VIII. Section of English Filter No. 2 :
IX. Section of American Filter No. 3
X. Section of American Filter No. 4 :.,.
XI. Diagram showing various sands and gravels used in filters
XII . General view of American Filters and Controllers
Title Page
34
8
52
54
59
61
65
64
68
71
74
Pi,A NS FOR Proposed Sewerage and Waterworks System.
Ismail sewerage maps showing contours and first contracts
proposed 211
XIV. Characteristic borings 213
XV. Profile Front Main Sewer 220
XVI. Sample Sewage Collection " Cut Sljeets " 220
XVII. Sample Sewage Collection ** Elevation Sheet " 221
XVIII. Sample sheet showing underground obstructions in "conduit
area'^ , 223
' XIX. Map showing all available distant sources of water supply 226
XX. Tabulation, cost of delivery of unfiltered water from various
distant sources to city line , 226
XXI. General plan: Intake, Coagulant House and Purification and
Pumping Plant 236
XXII. Plan Purification and Pumping Plant 236
XXIII. Sketch section of Intake and Pumping and Purification Plant.... 236
XXIV. General Plan Main Lines of Water Distribution System 236
XXV. Sample proposed general arrangement pipe, hydrants and valves 234
XXVI. Plan Study for Filters 244
XXVII. Elevation Study for Filters 244
List of Tables.
UMBER DESCRIPTION PAGE
I. Observations on turbidity of Mississippi River water at
different parts of cross section 13
II. Observations on turbidity of Mississippi River water at
different parts of cross section 14
III. Summary of Tables I and II 15
IV. Area of principal river basins .16
V. Annual rainfall in river basins 16
VI. Relative stream discharges, area and rainfall 17
VII. Analyses of different tributaries 17
VIII. Urban population of tributary basins 18
IX. Population of cities discharging sewage into lower Mississippi
River 18
X. Mean annual rainfall of Mississippi River valley 19
XI. Mean monthly stages of Mississippi River 20
XII. Floods in Mississippi River at New Orleans 21
XIII. Relation between various methods of turbidity determinations 27
XIV. Average of turbidity co-efficients 28
XV. Suspended matter in Mississippi River at Carrollton, La 31
XVI. Estimated mean average amounts of suspended matter in
Mississippi River water 32
XVII. Average monthly gaug^ readings and silica turbidity at New
Orleans 33
XVIII, Summary of physical data 34
XIX. Estimated daily silica turbidity of Mississippi River water
for normal year 35
XX. Reduction of alkalinity and absorption of coagulant 36
XXI. Observations on alkalinity, turbidity and chlorine (October
1, December IS, 1900) 38
XXII. Chemical analyses of Mississippi River water 39-45
XXIII. Mineral analyses of Mississippi River water 46
XXIV. Mechanical analyses of gravel 62
XXV. Mechanical analyses of gravel Filter No. 3 66
XXVI. Calculated and observed rates of filtration of sands 73
XXVII. Sand analyses 74
XXVIII. Operation and efficiency of SB. 1 (24 hours) 80
XXIX. Operation and efficiency of SB. 1 (48 hours) 81
XXX. Operation and efficiency of SB. 1 (72 hours) 82-85
XXXI. Operation and efficiency of SB. 2 ( 6 hours) 86
XXXII. Operation and efficiency of SB. 2 (48 hours) 87-89
XXXIII. Operation and efficiency of SB. 3 (12 hours) 90
XXXIV. Operation and efficiency of SB. 3 (48 hours) 91-92
XXXV. Operation and efficiency of SB. 4 (12 hours) 93-94
XXXVI. Operation and efficiency of SB. 4 (24 hours) 95-97
UST OF TABLES
XI
TfUMBER
XXXVII.
XXXVIII.
XXXIX.
XL.
XLI.
XLII.
XLIII.
XLIV.
XLV.
XLVI.
XI.VII.
XLVIII.
XLIX.
L.
LI.
LII.
LIII.
LIV.
LV.
LVI.
LVII.
LVIII.
LIX.
LX.
LXI.
LXII.
LXIII.
LXIV.
LXV.
LXVI.
LXVII.
LXVIII.
LXIX,
LXX.
LXXI.
LXXII.
LXXIII.
Lxxrv.
LXXV.
LXXVI.
LXXVII.
LXXVIII.
DESCRIPTION PAGE
Variation of turbidity and temperature of water in subsiding
basins 98
Monthly averages of temperature observations 99
Per cent removal by plain subsidence. Average results 100
Estimated amounts of silica turbidity and suspended matter
in water after subsidence 101
Estimated amounts of suspended matter deposited annually
by Mississippi River 101
Bacteria in influents and effluents of basins 103
Bacterial analyses of effluent of Filter No. 1 after scraping.... ^ 107
Qualitative results of operation of System No. 1 - by periods, 107
Quantitative results of operation of System No. 1 — by periods, 108
Penetration of clay, etc., into sand layer of Filter No. 1 110
Operation and efficiency of CB, 2, with subsided water 117-120
Operation and efficiency of CB. 2, with unsubsided water.... 121
Monthly averages of Tables XLVII and XLVIII 122
Qualitative results of operation of system No. 2 — by periods, 123
Quantitative results of operation of system No. 2 — by
periods 124
Bacterial analyses of effluent of Filter No. 2 after scraping 125
Penetration of clay, etc., into sand layer of Filter No. 2 128
Coagulant required for different turbidities — subsided water, 130
Coagulant required for different turbidities— unsubsided water, 130
Comparison of factors of cost in System No. 2 133
Results of operation of American Filter No. 3 142-154
Results of operation of American Filter No. 4 155-169
Amounts of suspended matter in unfiltered river water sup-
plies of various cities 171
Relation between silica turbidity of filter influent and wash
water, etc 173
Average monthly amounts of silica turbidity and suspended
matter in Mississippi River water before and after sub-
sidence 174
Coagulant required for different turbidities 175
Coagulant required for different periods of subsidence and
coagulation 175
Stratification of sand in filters 180
Effect of agitation in washing American filters 184
Conversion of statements of chemical composition 192
Equivalents of various measures 192
Approximate equivalents of various measures of rate of
filtration 192
Analyses of water from other sources 194-195
Analyses of effluent of English Filter No. 1 1%
Analyses of effluent of Modified English Filter No. 2 197
Analyses of effluent of American Filter No. 3 198
Analyses of effluent of American Filter No. 4 199
Character of Mississippi River water 200
Chlorine analyses of Mississippi River water 201
Chlorine analyses of Mississippi River water 201
Chlorine analyses of Mississippi River water 202
Bacterial efficiency of American Filter No. 3. 203
SEWERAGE AND WATER BOARD
OF THE
CITY OF NEW ORLEANS, LA.
OFFICERS.
PAUL CAPDEVIELLE, President.
CHAS. JANVIER, . President Pro. Tempore.
GEORGE G. EARL, General, Superintendent.
F. S. SHIELDS, Secretary.
SAM'L L. GILMORE, City Attorney.
CHAS. J. THEARD, SpECIai, Counsei..
MEMBERS OF THE BOARD.
Paui. Capdevieixe,
W 11,1,1AM MEHI,E,
J AS. McRACKEN,
Louis Cucui,i,u,
R. M. Wai,msi,ey,
A. Brittin,
Chas. T. Yenni,
Manuei. Abascai,,
jui,es c. koenig,
Quitman Kohnke,
A. DUMSER,
Thos, Harrison,
Lewis Johnson,
Wm. Adi,er,
Paui, Gei.pi,
Henry G. Hester,
f. a. daniei.s,
Chas. Janvier,
Wm. Atkinson,
Wm. T. 0'Reii,i.y,
Geo. G. Friedrichs.
FOUR STANDING COMMITTEES OF THE SEWERAGE
AND WATER BOARD.
Louis Cucui,i,u,
Henry G. Hester,
R. M. Walmsi,ey,
A. Brittin,
EXECUTIVE COMMITTEE.
LEWIS JOHNSON, Chairman.
Jas. McRacken, Paui, Gelpi,
Dr. Quitman Kohnke, Geo. G. Friedrichs.
FINANCE COMMITTEE.
PAUL GELPI, Chairman.
F. A. DANlElyS, Wii,i,iam Mehi,e,
Wm. Adi,er, Jui,es C. Koenig.
COMMITTEE ON SEWERAGE AND WATER.
JAS. McRACKEN, Chairman.
Wm*. ATKINSON, F. A. Daniei^, Wii,i,iam Mehi,e,
Henry G. Hester, Chas. T. Yenni, Dr. Wm. T. 0'Reii.i.y.
Jas. McRacken,
Wm. ATKINSON,
COMMITTEE ON DRAINAGE.
LOUIS CUCULLU, Chairman.
M. Abascai,,
A. DUMSER,
A. Brittin,
Thos. Harrison.
REGULAR FORCE EMPLOYED^ BY SEWERAGE AND WATER
BOARD.
vSECRETARY'S OFFICE.
( To July /, 1902.)
F. S. Shiei,ds ^Secretary.
IRVIN FuERST Chief Clerk and Stenographer.
Leo Bi^essing Porter.
ADVISORY BOARD OF ENGINEERS.
{JuHfy jgoo, to January /, 1903.)
B. M. Harrod New Orleans, La.
RuDOi^PH Herring New York, N. Y.
George W. Fui,i,er New York, N. Y.
*Thos. L.Raymond New Orleans, La.
L. W. Brown New Orleans, La.
A. C. Bei*i* New Orleans, La.
* Died November 15. 1901.
ENGINEERING OFFICE FORCE.
{.As constituted June, 1902.)
Geo. G. Eari. .' General Superintendent.
W. T. CroTTS Principal Assistant Engineer.
JNO. T. Eastwood 1st Asst. Engineer (Sewerage).
JNO. F. Richardson 1st Asst. Engineer (Water).
J. W. Armstrong OflSce Engineer.
Henry Smythe Assistant Engineer.
Ai,Ex. Ai,i,isoN, Jr .'..Assistant Engineer.
Edward FowtER Assistant Engineer.
R. Sidney Hernandez Draftsman.
D. W. Benson .\ Draftsman.
Jno. Davidson Draftsman.
W. L. Raymond.... Rodman.
Talbot Lee Blue Print Man.
EmilE Priez Attendant.
LABORATORY.
(Subsequent to January y 1902 )
John L. Porter Chemist.
Leo Fuerst Clerk.
WATER PURIFICATION INVESTIGATION.
{Prior to January, igo2.)
R. S. Weston Resident Expert.
The force employed under Mr. Weston's direction will be found on page 10.
INTRODUCTION AND TRANSMISSION TO SEWERAGE
AND WATER BOARD.
New ORI.KANS, January 1st, 1903.
ZJ? the Honorable President and Members of the
Sewerage and Water Board:
GentIvEmkn — Since the report herewith presented will be the first
of considerable technical interest issued by the Sewerage and Water
Boards and will be quite widely distributed, it has seemed best that
there should be included in it, not only the account of the water puri-
fication investigation, but also enough plans and descriptive text to
give those who receive it a general idea of the ultimate water purifica-
tion plant which it is proposed to construct, and also of the whole
work with which the Sewerage and Water Board is charged.
Chapters I to VIII, inclusive, contain Mr. R. S. Weston's report
on the water purification investigation.
Following Mr. Weston's report will be found a report by Messrs.
Herring and Fuller, of your Advisory Board of Engineers, briefly
reviewing the water purification problem.
The engineering work leading up to the plans for sewerage and
water works systems, as now proposed, has been carried forward con-
tinuously from June, 1900, to present time, and the main features of
the results accomplished will be found in chapters X and XI.
Chapter X is by Mr. W. T. Crotts, whose efficient services in con-
nection with the sewerage work for the past two years cannot be too
highly commended.
This chapter contains such descriptive matter with regard to the
proposed sewerage system as will be of general interest.
Chapter XI is by the writer, and treats]of the proposed water works
system, giving a brief description of the proposed work, and of the
causes which have dictated the existing plans.
In connection with the water purification investigation a very
brief historical review of the pertinent facts leading up to the investi-
gation will show that the Sewerage and Water Board gave careful and
deliberate consideration to the question of the necessity and wisdom of
making such an investigation, and when onc^e that was satisfactorily
shown, the authority was promptly granted by the Board and the
execution in the hands of the Sewerage and Water Committee was
expeditious.
4 REPORT TO SEWERAGE AND WATER BOARD
The first suggestion of the necessity for such an investigation
came from your General Superintendent in his preliminary report in
February, 1900. In April, 1900, there was an extended report made
upon the question of water purification in other American cities, again
stating the necessity for a thorough investigation into this question for
New Orleans.
Early in June, 1900. the Advisor>' Board of Engineers held its
first meeting, and evidence presented to them by the General Superin-
tendent showed quite conclusively that the cost of a complete water
works system for New Orleans would be about doubled if any source
other than the Mississippi were chosen, and that the available resources
in the hands of the Board were not only too small for the serious con-
sideration of the adoption of any outside source of supply, but that
they were likely to be too small even for the immediate completion of
the cheaper system of water works and of the sewerage system within
the populated area.
Under these circumstances they recommended sufficient further
investigations of outside sources to make certain that the facts were
really as above stated in connection with such sources, and they also
recommended that an investigation be made to determine the cheapest
and most efficient method of purifjdng the Mississippi River water;
they further recommended that such investigation should be under-
taken at once, and should extend through a period of one year. Mr.
Geo. W. Fuller, member of Advisory Board and an expert in water
purification, outlined the general scope of the investigation which he
considered essential, and estimated its cost at about $20,000.
When this recommendation was first brought to the attention of
the Sewerage and Water Board it was not received with immediate
approbation. It was argued that the New Orleans Water Works Com-
pany had tried filtration in 1892, that this trial had proved to be a ver>'
expensive failure, and that there seemed little chance for the Sewerage
and Water Board to succeed by the expenditm-e of $20,000 where
this other effort had failed, despite the expenditure of many times that
amount. A full and detailed report was, however, demanded of the
General Superintendent, and was submitted to the Board in July,
showing the present status of water purification, the causes which led
to the failure of the Water Works Company's efforts in this direction,
the position of several other cities in this connection, and how properly
conducted investigations had brought to them satisfactory solutions of
equally difficult and somewhat similar problems, the methods by which
scientific and successful purification systems had been developed else-
where, and, finally, what had to be learned for New Orleans, how this
knowledge was to be obtained, how it would apply in solving the local
problem and how much it would cost.
INTRODUCTION 5
Having received the information above outlined and seeing clearly
the necessity which existed for such an investigation, it was authorized
in August of 1900, and placed under the supervision of the Sewerage
and Water Committee. Meantime, plans for the required plant had
been worked out, and, as soon as a site for the plant could be> chosen,
a contract was awarded for its construction.
Work was started early in September, and a little later, Mr. R. S.
Weston, Resident Expert, arrived in New Orleans and took personal
charge of the laboratory equipment and detailed fitting out of all parts
of the work with such good results that the basins, filters, etc. , were
put into operation on 15th of December, and the plant run thereafter
continuously to the close of the investigation in August, 1901.
Too much credit cannot be given to Mr. Weston for his indus-
trious, economical and efficient administration of this work, and the
little force under him attended to its multiplicity of duties with a
faithfulness worthy of the highest praise.
Both Mr. Fuller and your General Superintendent received two
reports each month giving in detail all results obtained. Mr. Fuller
was in constant touch through correspondence and made several
special visits to this work. Your General Superintendent visited the
plant frequently, and was in close personal touch with the whole
investigation.
The Sewerage and Water Committee, either as a whole or through
its individual members, made several inspections of the plant, and the
method of operation.
The site chosen for the investigation was in Audubon Park, a
favorite resort for the people of the city; the choice of this site was
made because it was desiried that as many people as possible should
have an opportunity to inspect the plant in operation, and it is pleasant
to note that visitors were numerous, interested and pleased with the
promise of a clear, pure water supply which the effluent from three
of the four systems there in operation never failed to yield.
In considering the question of purification of Mississippi River
water, in his preliminary report, your General Superintendent said, in
substance, that the history of efforts and experiments in the success-
ful purification of such water, thus far, seems to point toward the
following method, viz: plain subsidence for a period of not less than
forty-eight hours in reservoirs operated on the fill and draw plan
(which would require reservoirs holding considerably more than forty-
eight hours' supply), then the adjiition of coagulant, followed by a
short period of auxiliary subsidence, then mechanical or rapid filtration
by gravity through sand filters.
(
6 REPORT TO vSEWERAGE AND WATER BOARD
It will be noted that all of the essential operations were correctly
forecasted, but the relative and total times for plain subsidence and
auxiliary subsidence after coagulation were very far from the final
solution which the investigation has brought. We would not have
dared design a large system on nearly so short a time as twelve hours
of plain subsidence, nor would we probably have considered so long a
period as twelve hours of auxiliary subsidence. The effect, therefore,
of the investigation is to cut down the first cost of the required purifi-
cation plant by many times the cost of the investigation, and to increase
efficiency and decrease greatly the cost of annual operation as compared
with what must have followed any other design than that which the
investigation has indicated as the most efficient and economical.
In concluding this introductory chapter, the writer wishes to
acknowledge with gratitude the faithful, willing and efficient work of
all of the men under his direction in the Engineering Department of
the Board during the two years of preliminary work just passed; his
thanks are also due to the efficient Secretary of the Board, Mr. F. S.
Shields, for his helpful co-operation in every matter where his expe-
rience, good judgment and willing aid could possibly forward the
interests of the Board.
Respectfully submitted,
GEO.vG, EARL.
General S^iperiyitendent.
WATER PURIFICATION REPORT.
INTRODUCTORY.
Mr. Geo. G. Eari.,
General Superintendent^ Sewerage and Water Board of New Orleans:
Sir: — Regarding the investigations at the Water Purification Sta-
tion, the writer has the honor to present the following report :
OBJECT OF WORK.
In June, 1900, the Board of Advisory Engineers passed the follow-
ing resolution :
^^ Resolved y That it is the judgment of the Board of Advisory Engineers that
the water of the Mississippi river, in the vicinity of New Orleans, can be purified
in a thoroughly satisfactory manner and at a total cost within reasonable limits ;
that accurate information is now lacking concerning the range in amount and
character of matters suspended in the water ; that purification works cannot now
be designed in detail consistent with needed economy; that it is, therefore, recom-
mended that the General Superintendent be authorized to conduct, continuously,
a series of investigations upon these points for a period of one year ; and that such
preliminary work should be begun as soon as practicable so that it will not delay
the completion of the entire system of sewerage and water supply."
On July 19th, 1900, the Sewerage and Water Board passed the
following resolution :
** Both for the purpose of carrying into effect Resolution No. 8j and also more
fully the provisions of Resolution No. 7, the General Superintendent, with the
consent and approval of the Committee on Sewerage and Water, and in accordance
with the provisions of Section 13 of the Sewerage and Water Act (No 6), be author-
ized to employ skilled and ordinary labor, and contract for or purchase all the "
tools and material unavoidably required for conducting and executing the work of
experiment as recommended, at a total cost not to exceed |20,000 for materials and
labor of all kinds, employed in such experiment, all of said expenditure to be first
authorized and approved by the Committee on Sewerage and Water. ' '
ThiB fund of $20,000 was expended by June 1st, 1901, and, in
order to continue the investigations, the Sewerage and Water Board
passed the following resolution :
' ' Resolved y That in compliance with the report and recommendation of the
Committee on Sewerage and Water, the water purification investigation now being
prosecuted at the Audubon Park Station, be continued to its ultimate satisfactory
completion and the compilation of the necessary reports, at a cost on the average
not exceeding f 1000 per month, for a period not to exceed four months from June
1st, proximo."
8 WATER PURIFICATION
Doubtless a purification plant could have been designed an the
basis of the results of the investigations at Louisville, Pittsbiu-g: and
Cincinnati, but the available evidence was not definite enough to accur-
ately determine how large the subsiding basins should be built, in order
to provide a period during which the clay, silt and coarser particles of
the river water could be most efficiently and economically removed, by
plain subsidence. Again, there was equal uncertainty regarding the
size of the basins in 'which the water would have to be further clarified
at times of muddy water, by the use of a coagulant and thus properly
prepared for advantageous filtration. From this it may be understood
that the uncertain elements in adapting a design to successfully cope
with the peculiar local problems were ones which markedly aflEected
the cost of installation, due to the expense of basin construction. In
solving these problems there was, of course, opportunity to carefully
study the adjustment of a number of other phases of the processes to
the local conditions^ as well as to collect more definite information
about the character of the Mississippi River water at various stages.
GENERAI, DESCRIPTION OP THE WATER PURIFICATION STATION.
The Water Purification Station was located at Audubon Park. It
had a capacity of 93,000 gallons of water per day, or enough to supply
about 1,000 people. In a few words, the plant consisted of the follow-
ing structures :
1. An intake, pump and force main, to supply water from the
river to the station.
2. Four complete systems of water purification, on a small scale,
each consisting of a filter, subsiding basin, and, in three out of four
cases, a coagulating basin.
3. A water supply, for use in washing the filters, and also to
supply water to the laboratory and boilers.
4. A boiler house, containing two boilers, work bench and stor-
age room for tools, supplies, etc.
5. A laboratory building, of cheap construction, equipped with
sufficient and necessary apparatus and supplies to allow the necessarily
numerous and complete chemical and bacterial analyses to be made.
Besides the above, the plant was equipped with the necessary valves,
meters, gauges and other devices and tools, both for its operation and
for a careful record thereof. Most of the filtered water was discharged
into a pipe leading to the Audubon Park wading pool.
MODIFICATIONS OF TpE WATER PURIFICATION PI,ANT.
As the work progressed, the results clearly indicated that certain
modifications in the schedule of operations should be made. These
changes were as follows:
/
il
INTRODUCTORY 9
1. During April, it was decided to modify the subsiding and
coagulating basins so that only those data might be obtained which
previous results had indicated would be of most practical value. ^
2. In July, arrangements were made to supply filter No. 2 with
the eflfluent of subsiding basin No. 1. In order to do this, it was
necessary to shut down filter No. 1.
Besides the above, several minor changes and improvements were
made from time to time to facilitate the operation of the plant or the
study of special problems.
PERIOD OF INVESTIGATION.
\
The writer was engaged as Resident Expert on September 8th,
1900, arriving in New Orleans on September 21st, to take charge of
the investigations under the joint direction of the General Superinten-
dent and Mr. Geo. W. Fuller the member of the Board of Advisory
Engineers, especially concerned with the water purification problems.
Plans were drawn for the basins and buildings (with the exception of
the laboratory and boiler house) , and contracts were let for the same
just before the writer took active charge of the work. The construc-
tion of the Water Ptirification Station occupied the months of October,
November, and the first half of December.
On December 15th, the plant was put into regular operation. It
ran continuously until August 17th, 1901. A portion of the plant
has been kept in operation since August 17th, in order to supply the
Audubon Park wading pool with filtered water.
AMOUNT OF ANALYTICAL WORK.
The following amount of analytical work was accomplished in
order to determine the character of the water, before and after treat-
ment, in the four purification systems, thereby making a record of
the efficiencies of the same:
Number of complete analyses 387
Number of * * suspended matter ' ' determinations 1 , 050
Number of ** silica turbidity * ' determinations ,...8,995
Number of mineral, analyses 20
Number of quantitative bacterial analyses 8,878
Number of tests for Bacillus coli communis. 100
Number of tests for Bacillus enteritidis sporogenes 29
Number of microscopical analyses 8
Besides the above, special analyses were made of the filter sands,
basin sediments, sulphate of alumina, etc. A careful study of the flora
of the river was also made and nine previously undescribed species of
bacteria were isolated.
10 WATER PURIFICATION
FORCE EMPLOYED.
The regular force of trained assistants consisted of four men,
besides the writer, as follows:
Mr. John L. Porter, - - - Assistant Chemist.
Mr. J. Beasley Perkins, ) a • . .. rM.
^^ r^ r^ ^ h Assistant Chemist.
Mr. O. C. Reppel, )
Mr. Alexander Allison, Jr.,^
Mr. Edward A. Fowler, > Engineering Assistant.
Mr. W. L. Raymond, J
Mr. Andrew Allison, - - - Assistant Biologist.
Mr. Perkins resigned on July 1st on account of ill health. Mr.
Reppel was appointed in his place. Messrs. Allison, Fowler and
Raymond were all in the employ of the Board. One or another of
these gentlemen was employed at the Water Purification Station. Mr.
Allison, during the period of construction, and Mr. Fowler, during the
period of operation, except during a short sick leave when Mr.
Raymond took his place.
Besides the above, there were two filter attendants and two firemen;
and mechanics and laborers were employed for the construction,
alteration and repairing of the plant.
The writer wishes to thank his staff of assistants for their faith-
fulness and devotion to the work, the success of which was largely •
due to their efforts. He wishes to thank the General Superintendent
for his interest, advice and co-operation, all of which were very im-
portant factors in carrying on the work. He wishes to thank the
Secretary for the advice and assistance which he has freely given. He
also wishes to thank the Assistant Engineers of the Board, Mr. Adam
Wirth, City Chemist, and Messrs. Kendall and Fuerst, students in
the laboratory, also Dr. Stubbs, of the Louisiana Experimental Station,
and the U. S. Engineer officers stationed at New Orleans for important
help rendered at various times.
The general policy of the investigation was shaped only after
consultation with Mr. Geo. W. Fuller, of the Advisory Board. This
was effected both by correspondence and by five personal consultations
as follows:
1. In New York, September 17th and 18th, 1900.
2. In New Orleans, December 14th and 15th, 1900.
3. In New Orleans, April 10th to April 13th, 1901.
4. In New York, June 21st and 22d, 1901.
5. In New Orleans, July 30th and 31st, August 1st, 1901.
These consultations were indispensable factors in carrying out the
work, besides being exceedingly agreeable and profitable to the writer.
INTRODUCTORY 11
COST OF INVESTIGATION.
The cost of the Water Purification Investigation up to October
1st, 1901, is as follows:
Building and settling tanks $5,734 76
Filters and clear water tanks 1,327 75
Pipes and fittings and tools 1,808 65
Boilers and machinery 722 50
Extra labor .' 1,521 41
Freight and drayage 241 90
Laboratory apparatus 2,298 12
Pay roll 7,640 41
Coal, supplies and miscellaneous expenses 2,115 35
Insurance... 120 00
Repairing roadway in Audubon Park 75 00
$23,605 85
BRIEF OUTLINE OF REPORT.
The report begins with a description and a record of the character
of the Mississippi River water at New Orleans, together with the
meteorological data which are logically connected therewith. Then
follows a condensed description of the Water Purification Station,
illustrated with drawings and photographs. Next, there is a descrip-
tion of the operation of the subsiding basins, and after that comes a
description and discussion of the operation of the three coagulating
basins receiving subsided water, and the four filters. The report ends
with an untechnical resume of the conclusions deduced from the
investigation.
The report is divided into seven chapters, which contain the main
results of the investigation. Some of the more detailed results, how-
ever, are given in the appendices. The list of chapters is as follows :
LIST OF CHAPTERS.
Chapter I. — Composition of the Mississippi river water at New
Orleans.
Chapter II. — Decription of the Water Purification Station.
Chapter III. — Description of the operation of the subsiding
basins.
Chapter IV. — Description of the operation of the English filter
and discussion of the leading factors associated therewith.
Chapter V. — Description of the operation of the modified English
filter and discussion of the leading factors associated therewith.
Chapter VI. — Description of the operation of the American
filters and discussion of the leading factors associated therewith.
Chapter VII. — Resume of the preceding chapters with especial
reference to the efiiciencies and cost of operation of the various systems.
CHAPTER I.
Composition and Character of the Mississippi River Watelr.
As this report has to do with the purification of the Mississippi
River water, it is essential that the composition and character of the
water with which a purification system would have to do should be
understood as thoroughly as the data at hand will allow.
MOST CHARACTERISTIC FEATURES OF THE MISSISSIPPI RIVER WATHR.
The Mississippi River is a clay-bearing stream whose water, at
New Orleans, possesses many characteristic features, chief among
which are the following :
1. The wide variation in the amount of suspended matter. This
variation is not so wide, however, as in the case of many of the
tributaries.
2. The comparatively large proportion of the suspended matter,
which is made up of fine clay particles.
3. The absence of sudden changes in the amounts of suspended
matter in the water.
4. The frequent but not sudden changes in the character of the
water, due to the predominance of one or another of the tributaries.
5. The absence of appreciable evidences of sewage contamina-
tion. This is because of the great dilution of the sewage entering the
stream, the remoteness of the sources of pollution, and the almost
complete piuification effected in the river itself by natural agencies,
during the stream's passage through the delta, the surface of which
drains away from instead of into the river.
VARIATIONS IN THE TURBIDITY OF THE CROSS-SECTION OF
THE STREAM.
It was very important to know how closely the water which was
taken from the river during these investigations represented the aver-
age water of the river. The intake of the Water Purification Station
was located on a making bank, while the proposed intake for the new
purification plant is to be located on a caving bank. Observations by
Humphrey & Abbott* and others go to show that the amounts of
suspended matter contained in the river increases somewhat with the
depth below the surface. Observations during this investigation indi-
*Report on the Mississippi River— 1861.
COMPOSITION OF MISSISSIPPI RIVER WATER
13
cate that this is more evident during a rising than during a falling
stage of the river, as the following data will illustrate, the results of
w4iich .are expressed in parts per million.
Two sets of observations were made; one during a rising, and
one during a falling stage of the river.
TABLE I.
First Observations — April ist, igoi.
Stage of the river: 9.5 feet and rising slowly.
Turbidity of the water at the Station intake: 850 parts.
Upper End of a Making Bank at Nine Mile Point.
Distance from Shore.
Depth below Surface.
silica Turbidity.*
feet.
feet.
810 parts.
25 feet.
5 feet.
750 parts.
50 feet.
8 feet.
900 parts.
100 feet.
feet.
900 parts.
100 feet.
24 feet.
875 parts.
200 feet.
feet.
875 parts.
200 feet.
25 feet.
875 parts.
200 feet.
50 feet.
875 parts.
Middle of a Straight Reach near Coalport,
Distance from Shore.
Depth below Surface.
vSilica Turbidity.
feet.
feet.
800 parts.
40 feet.
feet.
975 parts.
40 feet.
6 feet.
975 parts.
80 feet.
feet.
925 parts.
80 feet.
9 feet.
975 parts.
100 feet.
feet.
975 parts.
100 feet.
15 feet.
975 parts.
160 feet.
feet.
925 parts.
160 feet.
30 feet.
, 1075 parts.
* For explanation of " 3ilica turbidity," see page 24.
No sub-surface samples could be taken opposite the caving
bank at Carrollton on account of the swiftness of the current;
surface samples contained 850, 800, 875 and 800 parts of turbidity,
respectively.
14
WATBM FTRinCATSOX
TABLE II.
Sammd Obs€rzmti4fni—Julr 24tk. i^i.
Stage of the liTer: 2.S feet a:id iallizig siowly.
Avenge turtcdity of the water at the Statioa intake: 375 par
Upper End of a Making Bank at Sime MiU Point.
Irmxaet irf^m Short.
Dcf^^ \0tjom scrfitfT-.
feet.
feet.
25 feet.
feet.
25 feet-
25 feet.*
100 feet.
feeC
100 feet.
50 feet.
275 parts.
2u0 pans.
554J parts.
25U parts.
S^ij parts.
l/a^^£/^ ^ Reach opposiU ike Proposed Intake.
XiMtaacrfraa More.
Depth bekm Soriace.
Silica T*TbiditT-.
feet.
feet.
26«j parts.
50 feet.
feet.
360 parts.
50 feet.
45 feet.^s^
575 parts.
100 feet.
feet.
375 parts.
100 feet
25 feet.
350 parts.
100 feet.
50 feet.
325 parts.
Xcar bc/CU/m,!
Caving Bank above Southport Docks.
IrMsMtut from Sh'/re
Depth below Surface.
Silica Turbidity.
feet.
feet.
250 parts.
25 feet.
feet.
300 parts.
50 feet.
25 feet.
375 parts.
75 feet-
feet.
275 parts.
75 feet.
25 feet.
325 parts.
75 feet.
50 feet. ,
350 parts.
150 feet.
feet. !
300 parts.
150 feet.
50 feet. ,
!
375 parts.
The following table shows the results in a more compact form:
COMPOSITION OF MISSISSIPPI RIVER WATER
TABLE III.
15
Table Showing the Relative Turbidities of Samples of Mississippi River
Water, taken Opposite Different Types of Banks, and at Different
Depths.
Average Turbidity— Parts per Million.
Source of Sample.
Surface.
Middle Depths.
Near Bottom.
April.
July.
April.
July.
April.
July.
Makine" Bank
860
920
850
850
260
330
280
290
850
975
360
340
350
940
1025
550
Straight Reach
Cavins^ Bank
575
350
Mid Stream
As the end of the intake of the Water Purification Station was
suspended from a house-boat in the middle depths of the stream, it
would seem that water of about the average composition was supplied
to the purification plant. This is believed because the observations
show that water drawn from a point midway between the surface and
the bottom is fairly uniform, whether the sample is taken from near a
making or a caving bank or a straight reach.
The practical significance of these observations is, that in order to
get the clearest water, an intake should be located at the surface of the
river.
DESCRIPTION OF THE WATER-SHED.
The water-shed of the Mississippi River has an area of about
1,240,000 square miles. Naturally, such a large water-shed exhibits
great variations in the amounts of rainfall, geological formation and
climate, therefore, great differences in the character of the many tribu-
taries of the great river which drains it.
While it is not within the province of this report to describe the
water-shed in detail, there are certain features which must be meur
tioned because they affect the character of the Mississippi River water
at New Orleans.
The water-shed area includes eleven States and Territories and
parts of twenty others; also a part of Canada. It is very easy to
comprehend the diversity in the character of the river which flows by
New Orleans when one considers that within the Mississippi Basin are
the slopes of the Alleghanies and the Rockies; the lakes of New York,
Minnesota and the Far West; the limestone forming country of Ken-
tucky and Tennessee, and the black bottoms of the Dakotas; the fer-
tile plains of the Central West and Colorado, and the swamp lands of
the Central Valley itself.
Tbft -:ri:irii-«: -/a-* 'X tilt rr-riT er:"JC^r» -i-x ir^ar r2C:rriI i:
TABLE r.
*«:Tar» 3C -* pTrrrrr-iirf :c T:Ci
</:,/. >:7-«i !•>
' V>*!r Mrv-'r-rpc,^ I^o '^v 13
M:^x:r: ,V. 527 :5-i 43
Ark;«r,*>a* 1**^ 3*»i 15
^^:j^,, •<!• t«>i 07
Orr.tral Valltr.- »V^ ••<• «:»»
To*;a! 1.2-*«> Or*) 1*»
Tr>: 'irr^^harges of the tributaries, however, do not var>- direct'y
v,:*r, th^ rfze^j of the water-sheds, because of the great diserences in
*/,<: ^rr,o*:nt of rainfall in the different sections. For example: The
M:r*//*:r: l/a^in, which receives the least downpour, has the largest
Tr>r following table shows the amount of annual rainfall in the
var:oi:s x'v:i:x basins, the figures being taken from the records of the
V. S. Weather Bureau:
TABLE V.
AnnucU Rainfall in River Basins.
BASIS, IndMS per Tcsr.
Ohio 44.2
Upper Mi.ssi.s.sippi 31.9
Misv^uri 19.4
Arkansa.s 29.6
Rerl 39.1
Central Valley • 51.5
iintire Mississippi [ 29.8
COMPOSITION OF MISSISSIPPI RIVER WATER
17
The following table illustrates the relative stream discharges,
areas and rainfalls for the various basins, the quantities varying with
the values of the figures:
TABLE VI.
Showi7ig Relative Stream Discharges y Area and Rainfall
for the Various Basins.
BASIN.
stream Discharge.
Area.
RAINFAI.I,.
Ohio
1
4
3
5
6
2
2
4
1
3
5
6
2
T JnDer Mississinoi
4
Missouri
6
Arkansas. ,
5
Red
3
Central Vallev
' 1
The waters of the various tributaries of the Mississippi vary
greatly in composition since they drain areas which differ in their
characters.
The data in the following table, although incomplete and not
directly comparable, will serve to illustrate these variations:
TABLE VII.
Illustrating Differences in the Analytical Character of Tributaries of
Mississippi Riven Water,
Tributary .
lyocality.
Turbidity— Silica Standard..
Color— Hazen's Standard .-
( Albuminoid ( Total .
^ Ammonia ... ( Suspended..
P § • Free Ammonia.
.5 Nitrites
^ (.Nitrates ,
Chlorine ,
Incrusting Constituents
Alkalinity
r Total
Residue on.. J
Suspended .
Evaporation^jjig^Ql^^^
Carbon dioxid (free and half
bound)...
Authority
Louis-
ville.
Cincin-
nati.
420
15
370
.280
.044
.008
.T7
17.
18.
65.
S0».
350.
150.
Fuller,
275
15
.290
.200
.025
.003
.60
10.
33.
45.
350.
230.
120.
25.
Fuller.
Pitts-
burg.
.128
".018 '
.000
.61
22.6
9.
31.
190.
55.
135.
Hazen,
Knox-
ville.
250
50.
456.
375.
71.
Soper.
IS
s
Minne-
apolis.
Shreve-
port.
7
43
.190
.023
.014
.005
.10
.32
0.
142.
209.
9.
200.
240.
120.
Weston
St
I/>uis.
Quincy.
Ills.
15.
987.
Whit-
man
143
71
.458
.203
.004
.014
.36
6.3
13.
90.
293.
126.
167.
5.8
Kllms.
Note.— In estimating^he silica turbidities of the waters in other localities the turbidity co-
efficient of 1.20 has been assumed.
The urban population of the Valley is estimated to be about
9,000,000, including all towns which have 4000 or more population.
fe¥ -Ser^trTti nitrf V rite 3c=jw» '.c !'*-•». Tbe div -:.-xi o€ tbe {wpcKlJAti'-
TABLE Viri.
^X.'J'. ....
3^--*r<,»ir:
AriiTL-r^:*
;r*fi
3.315
•>7>
3.117
•>S5
1 •.Ci:^
152
327
7:>
1»3
•152
>^2
I7u
^yc tii*^ trxal jr^crrlitfoci 15.374 li-.-e in Loai^iana. V>.335 ia Ar-
k.ir:rt«ft» :'* ».3> ns Mi*-^:^:p^. an-i 116.^31 in Ttsraef^ee, thcnefore,
*ijt tc^ific: y/'^rijirJi'Xi of tiLese Slates, in <o for a* their arca<- lie writhin
t3ie yLy^j^^jdi r^artcn 2* 25.'^ I Mi, Only a small portion of the popa-
^ftty>c "Ji'rsz.z 'v^^.'iT.TZ. v» rnijes of New Orleans discharges its se-«rage
frsv^ true yL'j^i.^^j^Ji River, as wiH be seen from the following table:
TABLE IX.
'ik/^'y^tn^ tkjt P:pju,'2th7n cf Ciiu% uhich Discharge Srwage int^ :he
Miiiiiiip^ Rrz^tr abiyze SeiL Orleans and thf Distames fri>tm the
p<nnt ;/ fnvcharg^ t4> \ru OrUans, by River.
CrTT. Popalatxrii.
Dutaace frxMB
V^//:. Ifofi^e 11.269 131 miles.
X^'iiiez ,,, , 12,210 265 miles.
A>rxaryiria 5,648 300 miles.
\'/*x,'*t,-z'^ 14.834 554 miles.
43.961
It i* to he Tf^memYjtrtd that the natural drainage in the Mississippi
^r!ta itself is away from the river, hence many cities do not discharge
thfAr ^wage into the river, as would be the case in other parts of the
<y^*intry.
The e*?timated* discharge of the Mississippi river water is as
follows:
Maximum 1,353,000 cubic feet per second.
Minimum 191,000 cubic feet per second.
Average 685 , 000 (?) cubic feet per second .
If the above figures of population and discharge are considered,
it will be seen that the dilution of the sewage of these four cities,
which alone, in the light of our present knowledge, could be assumed
* Report of Mi<MM«ippi River Commission.
COMPOSITION OF MISSISSIPPI RIVER WATER
19
to materially affect the sanitary quality of the river water in New
Orleans, is as follows:
Maximum... 30,800 cubic feet per second per thousand people.
Minimum ... 4,350 cubic feet per second per thousand people.
Average 15,600 cubic feet per second per thousand people.
RAINFALL.
The following table shows the amount of rainfall in the Mississippi
River Valley during the period of these investigations, compared with
the normal rainfall. It will be seen that the precipitation during the
period of these investigations has been much less than the normal, and
although there seems to have been a great deal of rain at the head
waters of the Mississippi and Ohio, there was a corresponding scarcity
of rain in the water-sheds of these tributaries most productive of high
amounts of suspended matter, the rainfall in the Missouri basin being
especially low.
TABLE X.
Showmg the Mean Yearly Rainfall in the Mississippi River
also Rainfall for the Year ending September isty ipoi.
Valley,
BASIN.
Main Yearly
Rainfall.
Inches.
Rainfall
Sept. Isl, 190O,
to
Sept. 1st, 1901.
Percentage which
Rainfall is of the
mean yearly
Rainfall.
Ohio,
Pittsbure^
36.6
42.1
42.2
47.2
50.2
40.7
19.6
32.5
33.0
47.4
Ill
Cincinnati...
Indianapolis
46.
77.
Louisville
70
Nashville
Q4
Average... 80.
Upper Mississippi.
St. Louis
40.8
33.3
30.7
28.2
25 4
19.8
40.2
36.0
62.
Davenport
60.
La Crosse
St. Paul
131.
128.
Average... 95.
Arkansas.
Little Rock
54.2
48.2
42.6
52.7
60.3
41.2
35.9
32^1
51.8
58.3
76.
Red.
Shreveport
74.
Central Valley.
Cairo
75
Vicksbure^
98.
New Orleans
97.
Average... 90.
25 •»-,-•?.* ?-^*:?Ti.t.7:..%
v^«utf:tt;i*r% irxA/*: iryi vjcne tnzis* ''M^xjm \zjt Tr^: sii;rt -c ilat m«r f-ir
*r*n*v-£v*: ;«ir% Or: the '3CT*:z±z*t b:^ -r -sr libe rr-i^rs: mi!? ijiwi&r.
yCi^x^^tyu Jfr.er f'vr tjje jear endir.z 0:t:oer I-m I ^ I. xz>i ihc ?r?tfar:
JiwvRthlj «a^t* ^ve the n- *r f'^r t^^e pe^ tw-rsttj-f-* 3 -isr?--
TABLE XI-
3fr.5r:H.
Ortz/oer 2 "^ :.»>
3»f/#etnrjer 3 •,• !.*•
J^tcember 5,2 3.»'
Jantiar:/ 3.5 -^-**
Fer^^::;«rv 4.7 S.7
Mar-h f 4.»> !.>>
April IM.7 12.1
May 11.7 11.^
Jnr^ 7.2 <• S
Jr;:y 4.1 7.t>
Ac^-t 2.1 3.**
S-;.teR;ber 2.** 2.3
Mean 5.21 6.07
FLOODS,
T>,e <yyT.--ideration of this topic is not so important, from a water
|/*jrff;ca|y>n «>tandpoint here at New Orleai.s. as on some of the tribc-
tarje^^ f^>r wh:ie the amount of suspended matter may be expected,
r^/n^'Ay. Ui rif^ and fall with the stage of the river at all times on
wh tril>»itar;e5> as the Ouachita, the White Ark. . and the Wabash,
aoi/i while the writer belie\'es that this general law may hold go d for
the Mmi*^JppJ Rfver at New Orleans. pro\-ided the data are extended
^//er 5K^eral years it seems that there was only a remote relation
t>^ween the fvtage of the river and the amount of suspended matter
^//nt^in^'A in the water during this investigation. This is due to differ-
*t>^/^ in the rat^ ^A discharge of the main tributaries: the di^erences
in the anuAWi^ of suspended matter contained in the water of the
trj>/tifaries at different times; and the great niunber of permutations
and ^//fril/inatir>ns of these factors possible under such conditions. To
WUnirzU:, a fl/xxi may occur on the Red River while the river at New
<>r\^zHii\ \s at a V>w stage. The Red River is hea\'ily charged with sus-
l^rti/Wl mmUrr dtiring fiftfjds, but its discharge is less than that of any
Mli#rr main tributary, Th'ref<^/re, the amount of suspended matter in
fli^ river at N'^rw ^'^I'-ans might be greatly increased while the stage of
COMPOSITION OF MISSISSIPPI RIVER WATER
21
the river would be affected but slightly. Again, a flood from the
comparatively clear Upper Mississippi River frequently follows after a
flood from the turbid Ohio, thereby maintaining the stage of the river
at New Orleans, while the suspended matter decreases in amount
daily as the turbid Ohio water is displaced by that of the clearer
Mississippi.
The following table from Bulletin E of the U. S. Weather Bureau,
supplemented by data obtained from the report of the Mississippi
River Commission, shows the significant data for the floods of the
Mississippi River since 1872:
TABLE XII.
Floods and Highest Waters in the Mississippi River at New Orleans
{Carrollton' Gauge),
Highest
Stage.
DATE.
River above Danger I,ine— 13 Feet.
Year.
From —
To-
Number
of Days.
1872
12.3
12.9
16.0
11.3
12.7
11.1
11.3
10.8
14.2
12.6
15.0
15.4
13.6
13.8
14.5
14.4
11.6
16.0
16.0
17.2
( 13.2
il7.4
13.4
10.1
13.7
19.0
f 13.8
(15.9
16.1
12.5
12.7
May 6.
June 3, 4.
April 15.
May 3-5-14-16-18.
May 11.
June 4-8.
March 21.
February 20-22.
April 23. 24.
April 12.
March 27.
April 7.
January 22, 23.
May 31.
April 6-9.
April 26
March 13, 14.
March 14-17-22.
March 16.
June 12, 13.
March 17.
June 22-24.
April 5-7.
April 8.
April 24.
May 7-14.
February 15.
April 25.
April 21.
March 28-30.
May 15.
1873
1874
1875
March 17.
May 18.
63
1876
1877
1878
1879
1880
1881
March 22.
May 21.
61
1882
1883
1885
1886
1887
1888
1889
February 11
March 17.
January 22.
April 27.
March 9.
April 16.
May 12.
June 16.
Feb'y 14.
June 11.
April 19.
May 11.
91
92
24
46
42
26
1890
1891
1892
1893
1894
1895
February 3
February 20
April 14.
March 15.
May 7.
April 1.
May 30.
May 19.
July 25.
March 23.
July 14.
April 12.
117
89
103
9
69
12
1896
1897
1898
1899
1900
April 19.
March 18.
February 9.
April 5.
March 18.
April 27.
June 13.
Feb'y 19.
June 10.
May 19.
9
88
11
67
63
1901
22
WATER PURIFICATION
An inspection of the table will show the abnormally low stage of
the river during the period of these investigations.
COMPARATIVE ABSENCE OF SUDDEN RISES.
Another noticeable fact in connection with the floods of the Mis-
sissippi River at New Orleans is the comparative absence of sudden
rises and falls. Generally speaking, the mean annual oscillation of
the Mississippi River is a long steady rise of about six months' dura-
tion, and a corresponding fall, the crest of the rise passing New
Orleans about May 1st. The June rise, so apparent in the upper
river, which is caused by a corresponding rise of the Missouri River,
is apparent here only as a diminution in the rate of fall.
The Ohio is the most important of the tributaries affecting the
stage of the river at New Orleans, and its rises are followed, on the
average, by rises of the Upper Mississippi and Missouri, in close
succession.
As a rule, the flood discharges of the Red and Arkansas Rivers
have little or no effect upon the stage of the river at New Orleans.
However, they often effect great changes in its physical and chemical
character.
ENTRANCE OF GULF WATER DURING LOW STAGES OF THE RIVKR.
When the stage of the Mississippi River becomes low, salt water
enters the mouth of the river from the Gulf, and when the stream-
flow approaches very nearly its minimum, the taste of sea salt may
become perceptible in the river water at New Orleans at rare intervals.
Although the stage of the river was low during the past year, this
was not noticed. It is said, however, that this occurrence was noted
once in the last ten years, but at that time it was perceptible for a few
days only.
In this connection, it is to be stated, that water taken from the
surface of the river is less influenced by this factor than water taken
from near the bottom. The explanation of this, of course, is to be
found in differences in the specific gravity of the water. It may be
said, in passing, that the presence of very small quantitit- s of sea salt
in the water supplies of some seaboard cities which are supplied from
tidal streams is occasionally noted. A trained observer by tasting can
detect as little as 200 parts of .salt (sodium chloride) in a million parts of
water. Prof. A. 1,, Metz, of this city, has announced that he found at
least three times this amount in the Mississippi River water on one
occasion during the last period of extreme low water. Some popular
saline spring waters, however, found regularly on the local market,
contain over 1000 parts of common salt per million. It may be stated
COMPOSITION OF MISSISSIPPI RIVER WATER 23
in positive terras that this feature of the local river water, based on
past experience, would not be detrimental to the health of consumers.
As to the use of filtered river water for boiler purposes during
very low river stages, it is likely that there might be a little extra
** foaming*' of the water in boilers, but there is no reason to ex-
pect serious increase in the amount of boiler scale. During such
periods the amount of incrusting constituents increases somewhat,
independently of the influence of Gulf water. Naturally, this causes a
somewhat greater formation of boiler scale, which though chiefly due
to calcium sulphate (gypsum), is, in some instances, at least, wrongly
attributed to the presence of sea water. The maximum quantity
of incrusting constituents during the past year did not exceed 30 parts
per million — a very moderate figure for waters in the South and
West.
EFFECT OF WIND STORMS UPON THE TURBIDITY OF THE MISSISSIPPI
RIVER WATER.
Several times during the low water periods it was noticed that
the turbidity of the water suddenly increased during wind and rain
storms. This increase was caused by the erosion of the banks of the
river, both by the waves and also by the rain water which fell upon
and ran off from the battures. Upon investigation, it was found that
this was a condition which prevailed only near the banks; as only very
slight increases in turbidity were apparent at points from SO to 100
feet distant from the shore line.
AMOUNT OF SUSPENDED MATTER NOT AIRWAYS PROPORTIONAL TO
THE STAGE OF THE RIVER.
The transporting power of a stream for suspended matter varies
directly as the sixth power of its velocity, and because the velocity of
the Mississippi River is a function of the height of its stage, one might
expect that the water would be most ttu-bid during highest stages, and
vice versa. This theory is based upon the assumption that the Missis-
sippi River always obtains as much eroded material as it can transport.
Such is not the case, however, as the following citation from the
records of this investigation will illustrate.
T^„t^ Turbidity Stage of River,
Date. (Parts). (Feet).
Highest turbidity Dec. 6 1460 6.3
Highest gauge reading May IS 400 12.7
These phenomena are explained by Humphrey & Abbott* as being
possible because the amount of sediment contained in the river is far
less than the transporting power of the stream would allow, provided
the necessary material to be transported was at hand. Assuming this
*loc. cit.
24
WATER PURIFICATION
theory to be correct — and the results of this investigation indicate that
it is — it follows that a flood in the Red or Arkansas Basins, when tlie
Missouri and Ohio Rivers are both at their low stages, maj^ materially
increase the turbidity of the river at New Orleans. Likewise, the
turbidity is increased when large amounts of material are being thrown
into the river by the surface caving or sloughing off of the banks of
the stream during falling stages. The material thus obtained is
naturally composed of differently sized particles, varying from coarse
to extremely fine; the former settles out very soon, while the latter
persists to the mouth of the river.
SYNOPSIS OF THE LEADING FEATURES OF THE MISSISSIPPI RIVKR.
Although the average stage of the Mississippi River during these
investigations was comparatively low, and, as a consequence, abnormal
conditions prevailed, it is thought best to describe the leading charac-
teristics of the water as they occurred, and also to estimate the signifi-
cant data for a normal year as accurately as the information at hand
will allow.
Summary of the Amounts of the Several Constituents Found hi the River
Water for the Period Between December loth^ igoo, and August
1 7 thy I go I.
CONSTITUENTS.
PARTS PER MIIyUON.
Minimum.
Average.
Silica Turbidity
Total Suspended Matter
Total Dissolved Residue
Nitrogen as Suspended Albuminoid Am
monia
Nitrogen as Total Albimiinoid Ammonia..
Nitrogen as Free Ammonia '.
Nitrogen as Nitrites
Nitrogen as Nitrates.
Chlorine....
Incrusting Constituents
Alkalinity
Dissolved Oxygen
Free Carbon Dioxide
Bacteria per Cub' c Centimeter
Temperature — Degrees C
1460.
1250.
250.
598
0.677
0.036
0.023
0.56
20.9
24.
115.
11.5
75.
6500.
31.1
90.
75.
80.
0.015
0.054
0.000
0.000
0.02
6.0
5.
57. .
5.3
0.
60.
17.0
405.
440.
145.
0.188
0.251
0.012
0.008
0.14
9.2
14.
79.
9.0
34.
2065.
17.6
ANAI^YTICAI, DESCRIPTION OF THK MISSISSIPPI RIVER WATER.
The above table gives the summary of the leading analytical
results of the investigation. It remains to estimate for a normal year
the amounts of those constituents which are most important from the
COMPOSITION OF MISSISSIPPI RIVER WATER 25
water purification standpoint and to give a more detailed description
of other constituents which affect the general character of the river
water.
PLAN OF ANALYTICAL WORK.
Complete physical, chemical and biological examinations of the
water were made throughout the whole investigation, as required.
SAMPLES.
From October 1st until December 10th, 1900, daily samples of
the river water were taken, but only for the determination of turbidity,
chlorine and alkalinity. Beginning December 10th, complete physical,
chemical and bacterial analyses were made of daily average samples of
river water, but as the work progressed, the daily determination of
the less important constituents was discontinued. When the plant
was put into operation, frequent samples of the basin and filter efflu-
ents were taken, some for the determination of turbidity, some for the
determination of turbidity and bacteria, and others for complete
analysis.
A few determinations of the number of higher microscopical
plants and animals contained in the river and settled waters were
made from time to time. Frequent bacterial examinations were made
of the various samples to determine, first, the priesence or absence of
Bacillus coli communis and Bacillus enteritidis sporogenes, two species
associated with sewage pollution, and, second, to identify several
species of bacteria, including some species not hitherto described,
which constituted the flora of the river water.
METHODS OF ANALYSIS.
Physical,
Color, — The Hazen platinum-cobalt standard was used. In order
to have the results in harmony with the results of other determina-
tions, it has been decided to express them as parts per million instead
of parts per- 10,000 as has been the practice.
Silica Turbidity. — A diaphanometer (described elsewhere*) was
used in order to determine the turbidity of the various samples by
optical means. This instrument determined the vanishing depth of a
brightly illuminated cross of light which was placed at the bottom of
a brass tube 35 m.m. in diameter and 1 meter long. The instrument
was calibrated by determining the vanishing depths of standard sus-
pensions! of pulverized silica (diatomaceous earth). When tables of
♦Paper by the writer. Technology Quarterly, Vol. XV, 1902.
fWhipple & Jackson. Technology Quarterly, Vol. XI I, No. 4, December, 1899.
p
-*r:::j"',i^^t^ iiart Vi»ti or»oar*frt -lit- t-t^*:*:.- -r ur^.Mir^ iesmmxanj . fl-
ii'ir;* riiirh p(rir,#iju'i»ri 'lie -^me ':ir*,Mi:'* TTicae T5:Hiit5 jre "!,i.-^ -
,ti*^Ter ->f r ster^ irhirn liaii It^s^ -IloH -»♦• tbts -3-r aullii n .f Tilira 'ir
♦»#1jf/ VI -hrrr^nt "A lie 'jtr.^'r^A u 'lie nine if die inrfnnitiit. ir!urr'-r-
:r^^ v^itf^n *Iv^ -:ir-*u::r^- -,f :Iie -v-kix^ -wia -rftTii—ilexit :li tfiar prrxim:^:
V' >s-^ *h;iti ^M 3^r--i ->f silica per anllii,n. -Jie -^mr.ies ^rere zsmpai"-:
^Jr-^'^' irt.i 'he -.ranriari ^ispen.*^i<iii3 if -Hlioa, > u. ■■ir.imrt i in
••^htfe ijJasH vvrtles 'On :lie orlier lanit, iccanre znmpa 'mi ■ "n
h^r*/*^ -!rynUi nr>t le made is Tari.-^facti.r:!:' is Trrrh. i t^ fXT7 irawfiwr**^.^
TT*!*^ he -.atnpleft hart 1 -iiiica mr^.ictiry -^f i^er •!•» pars ac aiTlIi':ii.
The TfT-inltA r^t *h's silica turhidirr ieciraxmanca were
P^**!* ^ I'l.jra
a*=3nr?iaj
I :n 35
X
j^7~n^if TT"""
Vi -^. !•/♦)
5
I i": :r> .V/i
1}
V,T :r> I'i«>i
''^
•>il :r> .34/j#7
3)
,>'tr:r.^ :he itiv^sri^iticn, co«nparts«:t:s of riese aieciofs with ±-r
7r:r* ^,r H;izen merhr^i xere frerriestlv mriiV Tiis -anre metbod ex-
^<^'*<¥>^ *he *;tr*",tri:t7 aft the reciprocal of the vaniijcin^ depth, m
jtiz-h/^-? '-^ ;t Vio^nr Siatintsn or aInziinTini wire, oce TniZirEeter ir
'iijitii^t^^r f;%s,feneri ^it the er^ri of a ^radtiated nd md at nght angles
'A :'H >-nc<''i^. Th;«% 7P:rt method i:, the oce in sic^jt .^eieral ase and
'h#* ^^^ mrAr iz.p.:rjitie tor £eld work d'^irin^ davh^ht. In rfie hands
o^ '!n4* or^»;n{^7 o^/^err^r :t does not -aeeni to gtTe precise results with
r^^fAT^ Tv'r,\rhr ha-y^ a silica tiirV-dity of over 4*» ports p^- miHioc.
7>> vin^^!^'^ wh:r h h;iv^ a hr^h tnr*:,id::y miL-t be trst diluted before
''Iv* *^*^;m^*.^n in rr^Jide. The diaphanocieter can be nsed daring day
Th<* //•^Or'wrr,^ *;ir/e *r:fEoes to compare the results of obgervati'^n
Ky *hA ^.?f*r^,r me*hry*.^ withfn their limits of accuracy. Samples
'/'h,/K •»<'r>' v^, *'ir'v,d f/> r^e read accurately by any of the methods
-TAr*- f.r^t A/z-i^^fi -wrh Renown amounLs of distilled wat^. The figures
'4r'/^n ^r*- fr^ rr^^t.x of ^ lar^e number of observations, extending
fhrv.j^h v^/'T^I ?r^yr»*h^. and are indicative of the results which conld
V */fpy«'i'f/d ^/ ^-h/- ^';*^^^y/: trained analyst:
COMPOSITION OF MISSISSIPPI RIVER WATER 27
TABLE XIII.
Table Showing the Relation between the Various Methods of Turbidity
Determination.
By Direct Comparison
with Silica SUndards.
By Diaphanometer
Expressed as Parts
of Silica per MiUion.
Wire Reciprocal of
Vauishine Depth
in inches.
5
0.018
10
0.037
IS -
0.049
30
0.070
25
0.078
30
0.090
40
40
0.12
50
, 50
0.15
60
60
0.18
70
0.21
80
0.24
90
0.27
100
0.30
120
0.35
140
0.40
160
0.44
180
0.48
200
0.52
220
0.55
240
0.58
260
0.62
280
0.66
300
0.69
320
0.72
340
0.76
360
0.79
380
0.82
400
0.86
450
0.94
500
1.02
The above are average determinations on samples from all sources.
Single determinations by the diaphanometer varied from time to
time with different intensities of light, different observers, and differ-
ent suspensions of silica. The total variation reached 15 per cent, at
times. The personal error of reading was as much as 7 per cent. The
two suspensions of silica used were practically identical, being prepared
from the same diatomaceous earth.
Turbidity Co-efficient — All optical ^methods for the determination
of turbidity are naturally compared with the gravimetric determina-
tion of the suspended matter which produces the turbidity. Equal
weights of suspended matter do not necessarily produce the same tur-
bidity. For example, waters which contain suspended silt or sand
exhibit less turbidity per unit of suspended matter by weight than do
waters containing finely divided clay. Therefore, the ratio between
28
•;
-^
WATER PURIFICATION
silica turbidity, determined optically, and suspended matter, deter-
mined gravimetrically, is most important, as it is an index of the
character of the suspended matter producing the turbidity. To
express this relation most conveniently, the term 'turbidity co-
efficient" has been adopted.
\ Suspended Matter.
Turbidity Co-efficient equals ■{ ■
( Silica Turbidity.
Naturally, this co-efficient varies with different waters, generally
increasing with the size of the particles composing the suspended
matter. Thus, the samples of unsettled river water have the highest
turbidity co-efficient, while samples from the effluents of the three-day
subsiding basins have the lowest, as the following table will show:
TABLE XIV.
Tadie of Average Turbidity Co-efficients.
,„ ^ Turbiditv
^Vater. Co-efficient.
Mississippi River water 1 . 08
Mississippi River water, after 6 hours* subsidence O.90
Mississippi River water, after 12 hours' subsidence 0. 87
Mississippi River water, after 18 hours' subsidence . 86
Mississippi River water , after 24 hours' subsidence . 85
Mississippi River water, after 48 hours' subsidence O.80
Mississippi River water, after 72 hours' subsidence 0.76
Mississippi River water, after 24 hours' subsidence and coagula-
tion O.60
This table is very easy to understand, since the coarser particles
of low turbidity-producing power and somewhat higher specific gravity
gradually separate out according to their hydraulic values, the finer
particles of high turbidity-producing power and somewhat lower
specific gravity remaining longest in suspension.
CHEMICAL.
In general, the methods advfsed by the American Public Health
Association Commi:tee, which was appointed to recommend uniform
methods of water analysis, have been followed.
DETERMINATION OF SUSPENDED MATTER — GRAVIMETRIC
The suspended matter was determined by estimating the residue
on evaporation of the water, both before and after being passed
through a Berkfeldt filter tube, the difference between these results
being the suspended matter. Pasteur filter tubes were tried, but were
found to introduce errors into the determination, while the error arising
from the use of the Berkfeldt filter tube, which was used throughout
most of the investigation, was negligible. All residues were dried at
105 degrees C. for at least one hour before cooling and weighing.
Much difficulty was experienced during the rainy summer months in
COMPOSITION OF MISSISSIPPI RIVER WATER 29
-weighing the dishes containing the residues; in fact, for two weeks at
one time during a period of daily showers, the humidity was so great
that the correct weighing of the residues was impossible. All results of
this determination are recorded to the nearest five parts per million, in
order to escape fictitious accuracy.
BACTERIAL.
The bacterial work was carried out in brief, as follows:
Quantitative. — One cubic centimeter of the water, diluted if neces-
sary, was mixed with five cubic centimeters of 10 per cent nutrient
gelatine of a 2 per cent acid reaction, contained in a petri dish. The
gelatine was then hardened in the ice box and incubated for two days,
at a temperature of from 19 to 20 degrees Centigrade. The colonies
were then counted in the usual way. Media containing 12 per cent
of gelatine was used during the summer months.
Owing to the large number of liquefying colonies present, the
cultures could not be incubated much longer than two days without
becoming completely liquefied; in fact, on the average, about 15 per
cent of the surfaces of the plates were liquefied at the time of count-
ing. As high a temperature (19 degrees to 20 degrees) was main-
tained as would allow the plates to develop visible colonies and at the
same time avoid liquefaction.
Some difiiculty was experienced with spreading colonies, which
were caused by the condensation of moisture on the surface of the gel-
atine during periods of very humid atmosphere. The bacterial counts
were corrected for significant figures, as follows:
umber of Colonies.
Recorded to
1 to 50 .
Nearest unit
51 to 100
*' 5
101 to 250
10
251 to 500 '
25
501 to 1000
50
1001 to . 5000
100
5001 to 10000
500
QUAUTATIVE — METHOD FOR BACII.I.US ' ENTERITIDIS SPOROGENES
(KLEIN*).
From 1 to 25 cubic centimeters of the sample of water were mixed
with from 10 to 100 cubic centimeters of sterile neutral milk. The
whole was then put in an atmosphere of hydrogen and incubated for
two days at 37 degrees C. Cultures which then produced a character-
istic coagulation of the milk and an odor of butyric acid were inocu-
lated into Guinea-pigs — one cubic centimeter of the clear whey being
allowed to each 200 grams of the animal weight. If the Guinea-pig
died with the formation of characteristic lesions, the identity of the
bacillus was considered established.
* For details of method, see Klein's original article in the report of the Medical Officer of the
British I,ocal Government Board for the years 1895 to 1898.
30 WATER PURIFICATION
METHOD FOR BACILI.US COU COMMUNIS.
The method used varied considerably during the course of the
work. At the beginning, when the bacterium was occasionally isolated,
from 1 to 25 cubic centimeters of the sample to be tested were sown into
dextrose-broth and the cultures showing positive results were plated
out on lactose-litmus- agar plates. Characteristic red colonies were
then selected for seeding the various conventional media. Later on,
however, it was necessary to concentrate a large sample of water — 300
cubic centimeters — in a centrifugal machine. The concentrate was
then sown into phenol-dextrose-broth contained in fermentation tubes,
which was incubated at blood temperature for forty-eight hours. Cul-
tures which then showed the possible presence of the looked- for bac-
teria were sown on lactose-litmus-agar plates as described above.
The results of most of the above works were negative.
PHYSICAI. CHARACTER OF THE MISSISSIPPI RIVER WATER.
This part of the analytical description supplements what has been
written above. The following physical characteristics demand con-
sideration:
Color. — The Mississippi River water, independent of the suspended
matter contained therein, has almost no color. This color is so small
in amount that only a trained observer would detect it. This fact is
especially remarkable because the drainage of many of the water-sheds
in the Central Valley, and at times, the water of the Upper Mississippi,
are quite highly charged with dissolved color which, however, becomes
absorbed by the clay particles, 'so that when the sediment is removed,
the color is removed with it.
Odor, — The Mississippi River water has a very faint vegetable —
earthy odor. This odor would not be ordinarily detected by the
average consumer, but can be detected in the laboratory by an experi-
enced observer.
I ' Taste. — The Mississippi River water, in its natural condition, has
' a very slight taste, which may be designated as clayey or earthy, and
which is due to the suspended matter entirely, because, when the
suspended matter is removed, this taste disappears. The taste of the
filtered water is all that can be desired, its pleasantness being doubtless
enhanced by the amount of carbon dioxid (carbonic acid gas) , which
is dissolved in the water.
Suspended Matter. — Previous to and during this investigation, the
methods for the optical determination of suspended matter (silica
turbidity), have been so improved that they form the most useful basis
for the comparison of the amounts of suspended matter contained in
the local water at different times.
COMPOSITION OF MISSISSIPPI RIVER WATER 31
The average amount of suspended matter, (ietermined gravi-
metrically, contained in the Mississippi River water during this inves-
tigation was 441 parts per million, and the average silica turbidity of
the water, determined optically, was 405 parts per million. The
relation between these is best expressed by the * ' turbidity co-efficients ' '
(suspended matter divided by the silica turbidity, see page 27) which
averages 1.08 for the period of these investigations.
The record of the daily average silica turbidity is included in the
table showing the composition of the Mississippi River water, following
page 38.
Prom what foregoes it is easily seen that during the period of
these investigations the amount of rainfall and the mean stage of the
river were somewhat below the normal. The amounts of suspended
matter were also below the normal. The results obtained by the
Mississippi River Commission demonstrate the truth of this statement,,
as is shown in the following table. These results extend over fifteen
years:
TABLE XV.
Suspended Matter Contained in the Mississippi River Water at Carroll-
ton, La, {New Orleans,) Parts per Million,
Year.
Average
Average Suspended
Suspended Matter.
Matter— Corrected.
1879.
456
434
1880.
803
769
1881.
825
785
1882.
642
610
1883.
817
779
1884.
589
561
1885.
877
835
1886.
543
517
1887.
641
611
1888.
1098
1044
1889.
521
496
1890.
574
547
1891.
581
552
1892
732
698
1893.
621
592
Jges
688
649
ence: Report of
the Chief of En
gineers U. S. Army, 1894,
p. 1345.
Author: Report of Major James B. Quinn.
MKAN MONTHI.Y AVERAGE AMOUNTS OF SUSPENDED MATTER, BASED-
ON FOREGOING DATA.
The average amount of suspended matter contained in the river
water during each month of a normal year is as follows:
' r
» ' 32 WATBR PrRIFICATION
II
j| TABLE XVI.
Showing' the Mean Average Amounts of Suspended Matter Contained in
the Mississippi River Water, Expressed as Parts per Millio7i .
Month. Suspended Matter.
January 385
February 640
March 1150
\M April 1425
May 1350
June 920
July 600
August 410
September 290
October 185
I November 160
December 260
I Average 650
The method used by the Mississippi River Commission to obtain I
i; . the above values provides for the drying of the suspended matter first
collected upon a tared filter, at room temperature, while the customary
' laboratory methods provide for the drying of the residue upon evapo-
j ration, in platinum dishes, at a temperature of 105 degrees C. It was
learned that when the same samples of water were tested by both
methods in this laboratory, that the methods used by the Mississippi
River Commission gave results which averaged 5 per cent too high. \
\ This excess was due to the presence of unexpelled moisture in the sus- '
j pended matter as weighed by the analysts of the Mississippi River
,! Commission.
■i Applying the above correction to the results in the table, we may
' then assume that the mean amount of suspended matter in the Missis-
sippi River water at New Orleans is about 650 parts per million. If
\ the turbidity co-efficient (1.08) determined during this investigation,
I is assumed to be correct for the normal condition of the river, then the
* mean silica turbidity of the river water is about 600 parts per million.
The average silica turbidity for the year ending September 30th, 1901,
i was 370 parts per million, therefore, it may be assumed that the river
I water contained only about two-thirds of the silica turbidity during
this investigation which it would have contained during a normal year.
CORRECTNESS OF TURBIDITY CO-EFFICIENT.
Perhaps one assumption in this estimate may be questioned,
namely, the value of the turbidity co-efficient (1.08) for average condi-
tions. This was determined during the abnormal conditions of these
investigations when the average amount of suspended matter was
nearly as low as that of the lowest year of the fifteen years recorded
by the Mississippi River Commission in the above table. The question
COMPOSITION OF MISSISSIPPI RIVER WATER
33
is based upon the general hypothesis that the coarseness of the sus-
pended matter increases as the velocity of the stream, and, therefore,
tlie turbidity co-efficient would correspondingly increase.
The fact that the Missouri river was abnormally low this season
and that much of the suspended matter contained therein was probably
very coarse, is also a cause for doubting this assumption. These
objections would, of course, be well-grounded if the Misssissippi River
^were completely charged with suspended matter at all times. Such,
liowever, is not the case, and the results of this investigation confirm
tlie opinion that the turbidity co-efficient varied independently of the
stage of the river, as the following table will show:
TABLE XVII.
Showing the Average Monthly Gauge Readings and the Average
Turbidity Co-ejfficients of the Mississippi River Water at New
Orleans.
Average Gauge Readings, 1900-1901.
Month.
Feet.
Turbidity
Co-efficient.
Average
Suspended
Matter.
December ,
January....
February..
March
April
May
June
July
5.2
3.5
4.7
4.6
10.7
11.7
7.2
4.1
0.95
1.18
1.29
1.13
1.14
1.06
1.03
0.88
449
-223
294
425
713
436
469
527
At certain periods of low velocity, however, the Mississippi River,
below the mouth of the Red River, acts as a vast subsiding basin,
and the water has a low turbidity co-efficient, while at certain, not
all, periods of flood reverse conditions may be met with. For any
short period of days, the turbidity co-efficient of the Mississippi River
water is not exactly constant within the limits of accuracy of the
determination.
The averages of the *' suspended matter'* and ''silica turbidity*'
results on twenty- two samples of water, which contained between 600
and 700 parts and averaged 648 parts of suspended matter per million,
are 652 and 607, respectively; hence the turbidity co-efficient for this
condition is 1.07, which is within 1 per cent of the turbidity co-effi-
cient — 1.08, the average result of over seven months' observation.
Therefore, it seems quite safe to assume that, on the average, the
"suspended matter" in the Mississippi River water is equal to 1.08
times the silica turbidity as determined optically.
34
WATER PURIFICA^XON
For convenient reference, the significant physical data for
Mississippi River water at New Orleans are grouped as follows:
TABLE XVIII.
Summary of the Physical Data,
Average Suspended Matter, 1900- 1901
Average Silica Turbidity, 1900-1901
Average Turbidity Co-efficient, 1900-1901 ..
Average Recorded Suspended Matter, fifteen
years
Average Suspended Matter Corrected for Ana
lytical Errors
Average Turbidity Co-efficient for twenty-two
samples of water having between 600 and
700, and averaging 648 parts of suspended
matter per million..
Estimated Mean Silica Turbidity
Maximum Suspended Matter, 1900-1901
Maximum Suspended Matter, fifteen years...
Estimated Mean Maximum Silica Turbidity.
pstimated Mean Minimum Silica Turbidity .
441 parts per milli
406 parts per milli
1.08.
§688 parts per milli
650 parts.
1.07.
600 parts.
1250 parts.
§2500 parts.
1500 parts.
125 parts.
I Report of Mississippi River Commission.
DAILY NORMAI, AMOUNTS OF SIIyICA TURBIDITY.
It is desirable to estimate the amount of silica turbidity which
water contains for each day of a normal year. In addition to tl
above data, the records of the stages of the river must be taken ini
account. The plate which accompanies this chapter depicts
following data:
(a) Mean hydrograph of the Mississippi River for twenty-fi
years.
(^) Hydrograph of the Mississippi river for the year endic
September 30, 1901.
(r) Curve of the average daily silica turbidity of the Mississipp
River for the year ending September 30, 1901.
(^d) Curve of normal (mean) silica turbidity.
(<?) Curve of average silica turbidity for 1900-1901.
It is assumed that the normal curve of silica turbidity would vary 1
on the average with the normal hydrograph, and that the maximum I
and minimum normal turbidities would be approximately coincident
with the mean maximum and the mean minimum stages of the river.
The following table is based upon the foregoing evidence, and
shows the estimated silica turbidity for each day of the normal year:
/
COMPOSITION OF MISSISSIPPI RIVKR WATER
35
TABLE XIX.
Showing the Estimated Silica Turbidity of the Mississippi Water for
Each Day of the Normal Year,
Date.
Jan.
Feb.
Mar.
April.
May.
June.
July.
Aug.
Sept.
Oct.
Nov.
Dec.
1
230
425
780
1350
1500
1125
620
400
280
240
125
140
2
240
435
790
1350
1500
1125
610
400
280
240
125
140
3
245
440
810
1350
1500
1100
600
390
270
230
125
150
4
245
455
830
1375
1500
1075
580
390
270
220
125
150
5
250
465
850
1375
1475
1050
570
380
270
220
125
150
6
255
470
860
1400
1475
1025
560
380
270
220
125
150
7
260
480
880
1400
1475
1025
550
370
270
210
125
160
8
265
490
900
1400
1475
1000
540
370
260
210
125
160
9
270
500
920
1425
1475
980
530
360
260
200
125
160
10
280
510
950
1425
1450
%0
520
360
260
200
125
160
11
285
520
980
1450
1450
940
520
350
260
190
130
170
12
290
535
990
1450
1450
920
510
350
260
190
.130
170
13
295
550
1000
1450
1450
910
510
340
260
180
130
170
14
300
560
1025
1450
1425
890
500
340
260
180
130
470
15
310
570
1050
1450
14'25
880
490
340
250
170
130
170
16
315
580
1075
1450
1400
850
480
330
250
170
130
170
17
320
600
1100
1475
1400
830
480
330
250
160
130
180
18
325
620
1100
1475
1375
820
470
330
250
160
130
180
19
330
630
1125
1475
1350
800
470
320
250
150
130
180
20
340
640
1150
1475
1325
780
460
320
250
150
130
180
21
345
650
1175
1475
1325
770
450
320
250
150
140
190
22
350
660
1175
1475
1300
750
450
310
250
140
140
190
23
360
680
1200
1475
1300
730
440
310
250
140
140
190
24
365
700
1225
1475
1275
720
440
310
240
140
140
200
25
370
710
1250
1475
1275
700
430
300
240
140
140
200
26
380
730
1275
1500
1250
690
430
. 300
240
130
140
210
27
385
740
1275
1500
1225
670
420
300
240
130
140
210
28
390
760
1300
1500
1200
660
420
290
240
130
140
210
29
400
770
1300
1500
1200
640
420
290
240
125
140
220
30
410
1325
1500
1175
630
410
290
240
125
140
220
31
415
1325
1150
410
280
125
220
ABSORPTION OF COAGUI.ANT BY SUSPENDED MATTER.
When sulphate of alumina is added to the river water for the pur-
pose of coagulation, a certain amount is absorbed by the suspended
matter contained in the water, and does not react with the dissolved
carbonates to form alumina hydrate. Theoretically, each grain of
3ulphate of aluminum used during this investigation, when added to a
gallon of water, would react with 8.2 parts per million of dissolved
carbonates, i, <?., the alkalinity of the water would be reduced by 8.2
parts per million; the difference between the actual -and the theoretical
reduction of alkalinity is a measure of the amount of sulphate of
alumina absorbed directly by the suspended matter.
The following table shows the results of several experiments made
in this laboratory to determine the extent of this reduction with the
various classes of local river water. These results vary greatly
according to the composition of the river water at the time the experi-
ments were made. It was learned that the greatest absorption
occurred when the -local water most resembled the Red River water in
character:
36
WATER PURIFICATION
TABLE XX.
Showing Reduction of Alkalinity in, and Absorption of Coagulant bj,
Mississippi River Water,
li
•^1
< 5
Reduction of Alkalinity, iu Parts per Million, per Graio
Coagulant per Gallon Water.
Datb
1901
si
O
3|
si
2I
si
si
1
<
April 11
** 23
660
520
660
510
440
540
450
450
325
660
700
725
75.0
71.7
72.8
70.6
103.5
102.7
81.5
77.0
80.9
93.5
86,2
85.7
0.5*
4.0
■4.4"
2.8
6.0
7.0
7.0
6.8
7.8
7.9
7.1
8.5
2.8
4.7
8.3
7.6
6.2
6.0
3.6
5 9
7.1
7.8
7.5
7.6
4.3
5.1
7.7
7.3
6.8
7.8
5.1
5 6
7.3
6.9
7.7
7.8
5.5
5.7
7.3
6.5
7.8
7.4
5.3
5 7
7.4
6.9
7 1
7.3
5.4
6.0
7.1
6.8
7.0
6.0
5.6
6.1
6.8
7.3
7.0
7.7
5.2
6.7
7.2
6.8
6.2
6.0
5.3
6.3
7.2
7.1
7.1
7.8
4.0
5.4
7.5
7.0
6.8
6 3
S.2
8 '^
** 27
8 ?
May 9
8 '^
June 3
8 ?
6
8 ?
*' 12 '.....
8 ?
** 20
8 ?,
'* 27
8 ?,
Tulv 9
fi 7
*♦ 12
4.5 8.2
'* 18
5.9 8.2
CHEMICAI. CHARACTER OF THE RIVER WATER.
The following set of tables contains the results of regular sanitary
and technical chemical analyses of the river water, including, alsio, as a
matter of convenience for reference, the average numbers of bacteria
and the records of color, turbidity and temperature.
EXPI.ANATION OF THE TABI^ES.
Certain points in these tables need a brief explanation, as follows:
Form of Expression, — All results are expressed as parts per million,
meaning milligrams per liter. A table for the conversion of the different
forms of expression, in common use, is given in Chapter VIII.
Oxygeyi Co7isumed, — This determination is considered to be a
measure of the amount of carbonaceous organic matter contained in
the water. It is not a measure of the nitrogen content.
Nitrogen as Albuminoid Ammonia, — This determination is a
measure of the amount of nitrogeneous (albuminous) organic matter.
The results of this determination are recorded as total, suspended and
dissolved albuminoid ammonia. It may be noted, in passing, that the
organic matter is mostly absorbed by the suspended matter and forms
but a small portion of the dissolved matter contained in the water.
Nitroi^en as Free Ammonia, — When the water is distilled without
the addition of chemicals, a certain amount of ammonia is carried ovtx
with the distillate. This is called free ammonia and is a measure
of the amount of nitrogen in the form of ammonia which has been set
free by the decomposition of nitrogenous organic matter. In other
words, it is the first step in the decomposition of nitrogenous organic
matter through the action of bacteria in the presence of oxygen.
COMPOSITION OF MISSISSIPPI RIVER WATER 37
Nitrogen as Nitrites. — ^This process of decomposition is called
nitrification, and this determination shows the amount of nitrogen
which has reached or is passing through the second stage of the process.
Nitrogen as Nitrates, — This determination indicates the amount
of completely oxidized mineral nitrogen which has passed through the
cycle of changes. Water containing nitrates is admirably suited to
tlie growth of microscopic plants (algae). They, in turn, furnish food
for animals (infusoria and fish), which, in turn, pass through the
cycle of changes from albuminoid ammonia to nitrates.
Chlorine, — Chlorine is present in the water largely as common salt.
In some localities it is customary to record this as a measure of sewage
contamination. Here at New Orleans, however, one must take into
account the number of mineral deposits which affect the character
of the river water, especially those in the southwestern river basins.
Incrusting Constituents, — This determination includes the chlo-
rides and sulphates of calcium and magnesium, substances which are
important from a technical standpoint, chiefly because they form in-
crustations in steam boilers.
Alkalinity, — This determination is an index of the amount of mag-
nesium and calcium carbonates contained in the water. It is also a
measure of the power which the water has to decompose the coagulat-
ing chemical used in connection with certain systems of water purifi-
cation. Some analysts record the ** total hardness'* or the soap de-
stroying power of a water. This value is approximately equal to the
sum of the alkalinity and the incrusting constituents.
Residue on Evaporation. — ^This determination measures the amount
of solid matter contained in the water after evaporation. It is made
on the sample of water both before and after passing through a Berk-
feldt filter tube. The method is also discussed in connection with the
determination of silica turbidity on page 25.
The suspended residue is the constituent of the water which must
be entirely removed by any successful system of purification, there-
fore, the record of its amount and character is the most important
feature of the tables.
Iron, — ^This determination is of little importance except as it
evidences the character of the suspended matter, because practically
all the iron contained in the water is in suspension.
Carbon Dioxid, — There is considerable carbon dioxid (carbonic
acid), contained in the river, both free and also combined with calcium
and magnesium. The degree of alkalinity of the water is more or
less dependent upon the amount of carbon dioxid contained therein,
since calcium and magnesium are much more soluble in water contain-
ing it than in water containing none. The corroding power of water
is largely dependent upon the amount of carbon dioxid contained in it.
Dissolved Oxygen, — This determination is the measure of the
amount of atmospheric oxygen absorbed by the water, and is most
important in connection with the consideration of the corroding power
38
WATER PURIFICATION
•of a water, especially in connection with the study of the action of
water upon metals.
LIST OF TABLES.
Table XXI. This table gives the results of the turbidity, alka-
linity and chlorine determinations which were made between October
1st and December 15th, the latter being the date when complete an-
alyses were begun.
Table XXII. This table gives the results of regular sanitary and
technical chemical analyses, including the average numbers of bacteria.
Table XXIII. This table contains the results of partial min-
eral analyses of the Mississippi River water.
Beyond an increase in the amount of sulphate, due to the influences
of the Southwestern tributaries, the amounts of dissolved mineral
constituents varied but little during the investigation.
TABLE XXI.
Showing Turbidity^ Alkalinity and Chlorine Contained in the Mississippi
River Water ^ from October /, igoo, to December /f, igoo.
DATE.
SI
5
i
<
1
1
DATK.
A
n
<
1
S
October 1
90
90
75
80
80
100
140
140
140
140
140
140
150
220
220
200
250
325
350
290
260
230
210
220
230
260
280
240
230
280
300
280
270
270
116
114
113
120
121
123
125
126
133
133
135
136
132
130
124
125
122
116
112
105
104
101
99
120
101
97
%
102
99
97
99
89
99
97
14.3
14.2
13.0
12.6
12.0
12.4
10.1
10.5
10.1
10.3
10.6
10.9
11.3
11.4
11.2
11.3
44.1
36.7
19 9
16.6
13.5
11.6
12.0
13.2
14.6
13.9
12.8
11.9
11.0
11.1
November 9
260
240
250
270
270
280
300
320
600
500
550
500
625
500
425
350
325
325
500
850
750
625
925
1200
1450
1350
1250
1225
1200
1200
1300
1300
1250
1250
98
98
99
103
98
96
92
86
83
85
84
86
87
92
88
93
89
94
96
100
99
97
94
86
82
84
70
70
71
59
68
69
71
65
2.
10
12
3
4
13
14
15
5
6
8
16
17
9
10
19
20
21
22
11
12
13
15
23
16 . . .
24
17
26
27
18
19
28
20
29
30
December 1 1...
22
23
24
2
25
3
26
4
27
5
29
6
30
7
31....
8
November 1
9
2
10
3
11
5
12
6
13
7
14
8
15
COMPOSITION OF MISSISSIPPI RIVER WATER
39
Bacteria, per Cubic Centi-
meter.
Dissolved Oxygen.
2000
2,200
2,400
2.600
],aoo
1,600
1,100
800
3,100
2400
1,200
i;800
5,000
2000
3,000
1,900
900
600
1,800
6600
600
600
m
HMi HMNNIMMIMMM
< 2
Free.
Free and Half-bound.
: : i :
Iron.
253Ci929 ^" aj^ ?!• !^» ** "3 ^- "*•* •« « op -^ "* ** 00 "* QOii 'POei ©
f
I
I
X
6
<
(li o
S 2
Total.
i§j§ai§gi§i§iii§§ii§iiiii§§§ii
Suspended.
iiiiiiii§§ig§§s§§iiis§§iii§§§§
Dissolved.
flS§§§§§®§^§§§gS§§§§i§§§SSSSSS
Alkalinity.
r^3SS»tSr^^3SDS8^^|!?^f3S^SS;r^?:^?i^^SSS
Incrusting Constituents.
SS :SS^ShSSS : ImS^SISSSS^^'^'m^'^SS
Chlorine.
oeeooooedee .eoioe<diOQOOMOu9u9u9oao.ioioeoai0 9eieo<-4«e
«-HO»c-!4e^> :o6t>t^Q6a6a6bla6»^blo6a»Q6a6oke»Q6e»ooooo
Nitrates.
• toeeooeooooeooeddoooboooooooo
Nitrites.
g§§§§§§i§i§iii§§§§§§si§§§gii
e'ddoedoddddoddddddodboooodod
§iii§§§g§§§§§3ii§§iiiisi|§i§§§
Total.
Suspended.
Dissolved.
sS§=3iS§iiiiiii§§iiiiliSlli§§§
Oxygen Consumed.
^wt»e«N©oo©oocoooco»<ee«or*i-coN-«*«N^o»a&osi> '
»o«o»oe«i>'«QOQOcoiO"*»io^iou3**«»'"*'<«"*'<«^"*eooooo'«»
Color.
oio>ou5ao«oustftt«ii3t«o»o^adoooo-HOO»oo>^adoaooooo
Silica Turbidity.
iii§iiiiii§igi§iiiii§igss§i§§
Temperature, Degrees, Cent.
:C6 Aocoe^
2d22S2;2;s::i2S^c58^'S§sdds'8S3'"^«^'"='«'''^'**,
»-3
40
WATBR PURIFICATION
I
I
I
{
M
X
6
S
Bacteria,
meter.
per Cubic Centi-
iS§§gs8S|g§i§§§l§§§§§t§§§t§§§§§
Dimolved Oxygen.
11
Free.
: i**s*«tiasa*«5?a8sg3a«»85!S5!as98«s
Free and Half-bound.
j j99SS?SSS$9^SSS988?5SessSSr:3SI^3iSS
Iron.
looooteoiootooioioeeusieioeioiooioioieeooiooioo'
^^ ^ ^* ^^ ^ B^ t"^ ^^ ^^»^^^^<^^^i^^ ^^ r^ ^^ 1^ p.^ ^^
is
a J
" 1
Totol.
i§is§ss§§§siiigsis§g§§§g§sgiiii
Suspended.
§§§§iii§§§igs§i§iii§s§§§§§s§§igi
DiasolTcd.
SSSssg2S22S2gg2g2sgss2§82ss§sg§
Alkalinity.
SaBSSS3t:SSSSSSSSSer:SS3S?^gr:SS£SSS^^S
Incrusting Constituents.
«>s»)3aas»-**«»^ssss2a3*2aass2s2255;ssg5
Chlorine.
'««aQe^ooeQOt^o^o-<^oiot«iOioiot«t«io«iO'«o»a-riooB>«x»
Nitrates.
8:3;:jaSS::323=:s;!:S86Sz;8Bas;SB::::3SSS^s;s
ooboobeobeddbddedoeddoo'edddodo'o
Nitrites.
33i8833S3§i8i8iS3oS33So3SSS3SSS
<
1
<
Free.
iii§§§§§§i§§§i§§§§S3§§ii§iii§i§
1
<
Totel.
Suspended.
dddddddddddddddddddbdddbbdobbob
Dissolved.
isi§§§iiiiiii§§iii§i§s|iiigi§§f
ddddddddddddddddddddoddddddddob
Oxygen Consumed.
Color.
^^ ^ ^< ^ ^ ^ pH ^ ^^ »^ ^H^ ^^ ^H 1— 1 ^ ^ F^^ ^^ w^^^r^ rH ^H ^.4 t^ ^H
Silica Turbidity.
§SSg§gi§SgS§3gS§g§|||ggg|§S§|S§
Temperature, Degrees, Cent.
N e« .H ^ N CO OS b. o CO cii 00 .-1 i*. OS •<<< © eo "^j CO ^ © N N !>. 00 Oft o» '•' ^ (N
bb b^ t^doo 00 00 00 00 00 oob 00 oobbbbbbd^boo 00 o6b 00 o6 00
i
1
* iS
COMPOSITION OP MISSISSIPPI RIVER WATER
41
. |§§§iiJMIil§JIIP§i§ii§i§§i§§§§§i^
'^etf. : s . :.e»eciNM-Hi-ie(ieoeooi^^-«eC>H»%>. wi ^ j«w«<ee«5"^©f3«0'*'*
e<^ o eeoo «> o -^ iH to *4 e^ o o» e^ lo «D to o o u3 CO 00 90 «-4 A 00 c^ «p lo eo Oft 1-^ A
s:!8SSo|S@t^^SS;^^!SSIg{:SSSISSS§?:SS@!$8S^S^Sgb!SgS&sgSSt:S@S§§@S^^S
udoieiooo»0i0koioieotoioiooieooioookooioooioieoooiooo6io»0icooiooooo>coooo
RR;:£3;S?^S8SS$;^;^^Se&gS^S^?:f:SSS^53S3SSIo.S^^|SS2gSS5S^^?:it^i::t:S
aboeeao»ioo»^oooaoot<;eoeoioa»e^QO'^coo»cept*0'«iipiooaoeo-v^o«toceocbO^^«HM
o»oot>a6Q6t<^a6o»o6i>b^e»QCoiao»a»o6a6a6Q6a6a«6AObO»Obce^^o^e4e4M
Saa33aqsaaS:3SSSSSS2e5S2aS22S8S8g583S882B8S2S2a2SH
o d do dooooododo d c»dod d ddobbpbd 06066 booooeoooo 66 6 6 66 6 6
si§§§§§§l§ii§§i||§i§iii§§§ii§§§iiii§iii§ii§§§s§§§ii
opoooopo8ppoooooS3^^oooooopoooopoooSooo3ooooooSoS
i§iiiiipiiigii§p|i§fil§ip§i|gi§§i§iiigigipipgi
ppOi-HOt^'^o>Hppeoi>9^p^x»d»«ooeoici>940eot^or«c«>-HOoa»t«^otCi090000eo^S40b>to
iototoiOiOiAio>ou3d>o6io6tei6^^^^ioi6'^-^^iou3^^'^eoeo-^co-^
c^OQOQopi>po»oeop94eopp-^t«ppp^eopQO^io>o 000000 soo-vt«eo>oo»«ci 000004 Mtoe^i 00
I
:
d C0 1«« 10 « r* oo a o -•
8c5aSS(f5§S55a'^*''''^'**^**2:;22;2:22J522gc5
|:.-.
»^»-caco
3 Oi 3
42
WATER PURIFICATION
Bacterid, per Cubic Centi-
meter.
Dissolved Oxygen.
le o t« CO 4» -^ 4» le «o
«b ae ab OD 9 ob «b i<^ ob
< 2
Free.
jj5«^ooggj;5j|5 : :g :«i :g : :0 :^
:^ ■: 1%
Free and Half-bound.
2«Ss^9S9?8 I :;s IS ;;$ ; :}R ;s
^
I
k
.^
.S
'■43
a
(3
d
«
Hi
o
oooooootoo . :0 :o :o : o :0 o
siascs^^sssss i is; ^^ iss 1 u\i s
ToUl.
Sigg§si§iisEgfi§igg§§gsiiiiisgi
<
>
Suspended.
§g§iiiis§iiiig§ggs§§i8S§§iig^§i
Dissolved.
§§§§§§§§SS§§SS§s§^§§§§S§§§§§^S
Alkalinity.
««fegfe?:?2^ff?«gSg?:gsePI?geegSS|gff^gS:SS
Incrusting Constituents.
«»2«3g252J2SfcS2?2J5 :25 :S : :S :S :52 : : :S : :fl '•
Chlorine.
•©^•►••■♦"^•eio : :i* :io t-w : ;'«j :»Q :*^ : : :oo : :•
b-r^«<p4»««>«»«> : !• :• :«b • :«b •• :r^ * * '-^ ' '"^
Nitrates.
:5S»SaS=:a^ I jS :22 :8 :S IS :$ : : S j -S :
obbobboob : :b :b :b : :b :b :b : : b • b I
Nitrites.
i§§i8§§§l§88 1
dbbbbbbbbbbb b
§ M§ i§ i§ i r§ ! 1
Free.
I§f §§§§§§ M§ :§ is ! § il il i i i§ i iS
^^G<>^C>C>^^ : :b :<
Total.
Sgl^SSSII I i IS i^ I IS IS 19 ; MS i it
osoeooeoo
Suspended.
lifMSigi jig IS i§ h§ ii i§ j i 11 1 1
c>G<>^d<»Scic> ' :b ^b :b : :b :b :b : : :b : :b
Dissolved
g|g§|g||§
^9 9C>d9z>9<:i
iiiil
Oxygen Consumed.
MQO^OOO-^ — QO :"* :C9 :o ; :io :r»
«-^-^-^»^«c<is<ip-J • :b :b lb : lb :o6
Color.
Ntooo'v^'^uacoso : :U3 :-^ :« : :m :c<i rc* : : :©
Silica Turbidity.
iigi§i§§i§igi§igi&iig|ggg§i§
Temperature, Degrees, Cent.
NI>OOO®»0C<5OOO©^»"^U5«l>-0ll>.'«f<O©OU3OOOO«3O
n" c«i CO c<i c4 ei c4 N cc CO 00 5C CO « eo eo CO ai oc i« ■rfi j2 »^
^iiiiot^ccsiO^c^co^katot^coc
a:
: r 3 :: 3 3 :: 3 : 3 |:: :: :
COMPOSITION OF MISSISSIPPI RIVER WATER
43
MSi
;Ci| :
: :^ :
: CO :
: ^ i
04 :
CO :
; :0 :
iiSi
1^ i
:ee
: : : : JQO j j :
: :S \
;«s ;
: :N :
58 ;
; ;a ;
;a i
I S ':
:g :
: :5 :
:S :
I ■:& :
iS
: : :'* :8 : : :
\ 1® 1
ia =
ii'^i
:§:
iiSi
isi
: :ao :
:2 1
ii^l
JS 1
ii8i
i^
1 i iS iS i i i
i i !=: I i2i i I id
:S : 13 : i :8 IS
ko o :
^ ^ i
g§ii§§i§i§§§iiiiii§§iii§siiii§ii§gi§§ii§§i§§§ii§i§i
{^iS^?3;^SS(SS£gSSSS$S3?:^SS3Si;5SS3S83SSSSSSSoSSS|Ss:^?:?!grf3F!f3f3?g
: :oo : : :o
I** : :^ : : :oo : :c
:» 'OJ : : :
t-^ : tN :: :r» : too :::©::«>:: :os : :o :::•: .00 :::oo: :i-j : : :io :«»
:8 : :8 : : :S j ^ I i :8 : :8 : j :S : :S : i -5^ I :8 j : j8 : :8 : I : iS :!h :
:b ' :c> : : ib : o i : 'd i -d : • :o • :c> : : d • 'd s ' id : id : s • ^d -d i
8 ! :8
d : :©
i ;§ i i § I i§ I i i§ i i§ i I i§
§■1
§ i 11 i I ;§ i i§
:d :
§ ; i i§ M§ i i
§ i i i IS
iS;
S : s
d :d
8 : IS
d : »d
;§iii
:b : :d
§ii
: I'N : :e<i : : :»
::«0::«0:::'*-:©::::«H:G
iig§§i§i'aii§§iiiiiiiiii§§§igi§§iiii§i§^i§§i^i§iii§i
O O O O O O O O O » « » » © O "S* 05 t* CO CO t* ?a 00 O N O '«< »0 N lO t* O O Ca so O -^ '•^ 00 00 ea © O ■^ 00 ON <D 00 » QO
ej «c t.: q6 © d j^ N w 2; i2 d J;f oc » © jH jji ;^ a ^ S fc
s-
»-3
44
WATKR PURIFICATION
if
r
1
a
o
X
6
Bacteria, per Cubic Centi-
meter.
Dissolved
Oxygen.
Free.
Free and Half-bound.
Iron.
^§i
Total.
Suspended.
Dissolved.
Alkalinity.
Incrusting Constituents.
Chlorine.
Nitrates.
Nitrites.
Free.
Total.
Suspended.
Dissolved.
Oxygen Consumed.
Color.
Silica Turbidity.
Temperature, Degrees, Cent.
;5 : :?S : : :ei : :»
: :53 I -a I : :« :
SS : :S : : :SS : :|^ : : :S : :S3 i : lis : :(; : : :&
o . :io : : :o :
S^ i is i i is ^
is 1 is;
§igiii§gg§§gsgiii§i§i§ii§i§§f^i
s§§§s§Si§§iiii§s§i§§ggig§§i§igg
8g§gSg§3gSgSggggSgSgSgggSS^Sggg
S:^f3S8SSS8S8BSS£g3SSasSS^fSr:r:?SSS§S^2S§c
25 : ;S J : IS : :* : : :g : :i: : :^ I l^ : i ti
:3 i :2 i i is : :* : : j* : '^'^
^ i iS i i jS : j& i : jB '
id : id : : id
r§
8 i
!§ i If i ! i§
s
§ i i§ I i i§ ri i I i§
d : :d
^ i i^
d : :d : : :d : :d : : id : id :
! '§ i IS I i i§
:d
i§
i =
d
I Mi i Mi
:« I :« : : :iM
ii§i§?iiiiiii§§ggf§^iiggg§i§iis
o o» e<i « oo o C4 to t-* oo oa o o o kC o» oo C4 c^ ud e<i A o » to o u3 ee tf: a> o
-iNcO'J'tocDt^QOO:© — cucc^ic^t^oost
Sc^g^S^^^
COMPOSITION OP MISSISSIPPI RIVER WATER
45
CO : jio
on : : :0 : : : : : :0 : :« : : .i> : :i>
iS i
jS : : :S ! IJo :
"<p :::"?: :»o :: :o
lO : lO
■^ ^ ^CO C>d 00 Ow CO CO oi CO Co 00 S
g§s§iSi§iiiiiiji
g^§SSgSg^SS8§88SS8S22::22S
»o :
» : :q6
§ : |— : : :;g : l!^
S : :S
00 : : :kO ; :oQ
© j : jS : i©
© : :© ' : :© : i©
:©
iS
:©
S 1
i^: © ::o>::«0:: »0:.©
CO : -co : :N : :co i : ;© i \6
^ :: :N : :W :::--: :g :::©: :co :
§§iili§§l§§§i§§§§§^^ISS
a)t>>ooo©e<iec4©ooi>ooa)©i-;ea»u3©ao©iOiO
3 3 3 3
a
o
3
46
WATER PURIFICATION
><
.^
i
^
•I
X
6
Alkalinit
g!.
CO,.
Magnesium, Mg.
Calchim, Ca.
Iron, Pe.
Aluminum, At.
Nitrogen as
Nitrates.
Chlorine, CI.
Carbon Dioxide.
Free and Half-
Bound, CO,.
Sulphates, SO4.
Silica, SiO,.
Residue on
Evaporation.
05 «o
Number of Portions,
in Average Sample.
\OvOt^t^t^a6a6t^vOvot^v2>t^aboQOt^t^aoao
8SggS8« 888 888 888 8888
fH ri o iH M d o d 6 d o d o o d d d d fo d
r1f'5<^iHiHiHOOfHiHiHtHfHiHOiH»H»H»HfH
c^GGOOC>c>GGOGO d d d d d d d d
: :^fioSvSKt>.voKv883Sv5S?
S88?58aSaS«3«5?SS8S?S;
f*5t^«f0'^0»oa\v0t^'^v0f0«0000t^
ss
ri d fH d 0^ 00 fH 00* vO d vO «H 00 X vO ^ to X o o^
!8S18S«18?l?^»»?^SSg««^^S
llllliillllllljlllll
»Hr-iOO»HOOW»HT-i»HrJ»-«»H»Hr^rJ»Hvpf3vpro
•4-*
T3
pq
p
V OS
a^ •
O ^ w
•ai«
III
N S §
O a y
a 2'^
^5 «
111
IP
'. '^
s -s
5
COMPOSITION OF MISSISSIPPI RIVER WATER 47
B101.0GICA1. Character of the Mississippi River Water.
BACTERIAL FLORA.
Quanlitative. — The numbers of bacteria were determined in each of
three samples daily, and the averages of these three determinations are
recorded in the foregoing tables. It is evident that the numbers of
"bacteria contained in the Mississippi River water are low in comparison
with those contained in the water of some other clay-bearing streams,
and in the water of some of the upper tributaries, especially the Ohio.
Qualitative — ^The most important problem in this connection was
the determination of the extent of the occurrence of the normal intes-
tinal bacterium — Bacillus coli commimis. Occ^ionally search was
made for the Bacillus enteritidis sporogenes (Klein*), which is said to
abound in cultivated soil, and is also said to be associated with cases
of severe diarrhoea, especially the diarrhoea of infants. Considerable
time was spent in determining the species of the bacterial flora in the
river water, and while the work was not exhaustive, nine hitherto
undescribed species of bacteria were isolated, and it is believed that the
methodsf of species differentiation and classification were improved.
In addition to the nine hitherto undescribed forms, several well
known species were isolated.
BACILLUS COLI COMMUNIS.
In waters which contain unpurified sewage, the test for this
intestinal organism is of the utmost importance. In the Mississippi
River iit New Orleans, however, there is evidently so much self -purifi-
cation effected by natural agencies, such as dilution, sedimentation,
etc. , that this normal intestinal bacillus was one of the least common
of the forms isolated. In about 100 tests with volumes of water
varying from 1 to 300 cubic centimeters, its presence was demon-
strated only three times, although the larger samples of water were
concentrated in a centrifuge before being seeded into the media con-
tained in fermentation tubes. Two kinds of media were used in the
fermentation tubes, namely, dextrose-broth and dextrose-broth con-
taining O.IS per cent phenol.
RestUts. — Fifty per cent of the ordinary broth-cultures and forty
per cent of the phenol broth-cultures show the presence of gas-pro-
ducing bacteria. The amount of gas produced was small, and the
amount of carbon dioxid (COg), contained therein, never equaled the
amount of other gases produced.
BACILLUS ENTERITIDIS SPOROGENES.'
As this bacillus is found widely distributed in cultivated soil, its
occurrence in a river constantly eroding such large quantities from its
* Medical officers' report in supplement to the report of the British Local Government Board,
ld97-8.
t See paper iij the Journal of the American Public Health Association, bjr R. vS. Weston and A.
I. Kendall, on "Some Common Bacteria in American Streams, including nine species isolated at
New Orleans", September, 1901.
48
WATER PURIFICATION
banks as does the Mississippi, and receiving from its numerous tribu-
taries water heavily charged with eroded matter, though a matter of
importance, is by no means remarkable. Perhaps more remarkable is
the fact that the number of times it was found occurring in the river
water was so small in proportion to the number of tests for its presence
which were made. The species had previously been isolated by the
writer in samples of the Red River water at Shreveport, La., during
the spring and summer of 1900.
Five out of twelve tests made at New Orleans during January,
1901, showed the presence of these bacteria, 10 cubic centimeters of
water being used in each case. After January 30, frequent tests
failed to isolate the bacillus^ from the river water, even when 25 cubic
centimeters of water were used for a test.
SPECIES OF BACTERIA ISOLATED.
The bacteria isolated from the Mississippi River water at New
Orleans agree in character with the published descriptions of the fol-
lowing species, and are probably identical with, or closely related to
them, in so far as the present status of bacterial knowledge will allow.
In general, the bacterial flora of the Mississippi River water at New
Orleans is characterized by the presence of large numbers of non-
pathogenic, fluorescent and liquefying forms, and the absence of gas-
producing forms and the forms usually associated with sewage con-
tamination. The names of the species are as follows:
Number.
NAME.
Investigator.
1
2
3,
4
S
6
7
.8
9
10
11
12
13
14
IS
16
17
18
19
20
Bacillus fluorescens liquif aciens* .
' ' New Orleans No. 1
' ' New Orleans No. 2
New Orleans No. 3.
*' plicatus
* ' New Orleans No. 4
Sarcina New Orleans No. S ,
Bacillus New Orleans No. 6
*' violaceus
'' mycoides
subtilis
' * cloacae
** punctatus
'* enteritidis sporogenes. . .
** liquidus
'' New Orleans No. 7
New Orleans No. 8
*' coli communis
'* proteus zopfii
New Orleans No. 9
Fluegge.
Zimmerman.
Frankland.
Fluegge.
Ehrenberg.
Jordan.
Zimmerman.
Klein.
Frankland.
Escherich.
Hauser. ^
COMPOSITION OF MISSISSIPPI RIVER WATER 49
It will be noticed that no names are given to the hitherto unde-
scribed species which are designated as '* New Orleans, Nos. 1 to 9 ";
these species are described elsewhere.*
MICROSCOPICAL FLORA AND FAUNA.
* The turbidity of the water was so great during the period of this
investigation that little opportunity was offered for the growth of algae
and diatoms, but when the water was allowed to subside in the basins,
growths of tetraspora, oscillaria, drapamaldia and chaetophora col-
lected about the margins of the water surfaces. Practically, no free
swimming forms were found. Eggs of rotifera and Crustacea were
observed during the winter and a few rotifera, cyclops, daphniae,
bosminae and common shrimp appeared during the spring. A few
aquatic insects, snails and small fish also found their way into the
basins at different times during the investigation.
RELATIVE PURITY OF THE MISSISSIPPI RIVER WATER AT NEW
ORLEANS, WHEN COMPARED WITH OTHER AMERICAN RIVERS.
From what goes before it will be seen that the Mississippi River at
New Orleans, as evidenced by the data obtained during this investiga-
tion, is unusually pure from a sanitary standpoint. For instance, it
is believed that if 100 cubic centimeter samples of water were taken
from the Merrimac at Lawrence, the Hudson below^ the Mohawk, the
Schuylkill, the Potomac, the Ohio at Cincinnati, they would show the
presence of Bacillus coli communis as a rule. Such is not the case
with the Mississippi River water at New Orleans, because, as stated
above, the opportunities for natural purification are so great during
the last few hundred miles of its flow, and the amount of additional
pollution received is so small in comparison to the discharge of the
river, that the bacteria which one is accustomed to consider to be the
normal inhabitants of surface water apparently crowd out those ab-
normal bacteria which are carried into the river with the drainage
from populated and cultivated areas. It must also be remembered
that the banks of the Mississippi, above New Orleans, are protected
by levees. These levees also, in turn, protect the river from contami-
nation except where sewers exist. Since it is usually more convenient
for the towns immediately above New Orleans to carry their drainage
away from the river, almost no local pollution exists.
The chief objections which can be raised against the use of the
unpurified Mississippi River water are, therefore, aesthetic, not hygienic.
The river carries vast quantities of suspended matter; a million gal-
* Journal American Public Health Association. Report of Buffalo Meeting 1901. loc. cit.
so WATER PURIFICATION
Ions, on the average, contamtng 2.7 tons of dry mud. This means
that a purification plant large enough to supply a city like New Or-
leans would have to remove about 108 tons of mud, on an average, and
at times of greatest turbidity would have to remove as much as 435
tons from each day's supply. The mechanical removal of this quantity
of suspended matter, in itself, is an engineering problem of considerable
magnitude; and the feasibility of the purification of the water is largely
dependent upon its economical accomplishment.
It is not known that water containing these amounts of suspended
matter causes harm when taken into the system. It is believed that
suspended matter, per se, is not the direct cause of disease, though it
is quite possible that slight digestive derangements of a temporary na-
ture might occur in cases of strangers who drink freely of the water
before becoming accustomed to it. On the other hand, the local water
has long enjoyed an excellent reputation for healthfulness for use on
shipboard.
This suspended matter, however, gives the river water an un-
sightly appearance and it, therefore, is far from being a satisfactory
source of supply, even when aesthetic considerations are forgotten, be-
cause the water is so unfit for table, laundry and bathing purposes that
the community is forced to use water from cisterns and other sources,
which water is not always satisfactory from a hygienic point of yiew.
Thus, indirectly, does the use of this water, itself hygienically un-
objectionable, affect the general health of the community.
In a few words, therefore, the Mississippi River water, as a source
of supply is objectionable, because it contains large amounts of sus-
pended matter, while the amount of sewage pollution is so slight that
it is believed that any system of water purification which will satisfac-
torily clarify the water from an economical and aesthetic standpoint,
will consequently effect a satisfactory purification of the same from a
hygienic one.
CI.ASSIFICATION OF THE WATER.
At times the Misssissippi River water partakes largely of the
character of one of its main tributaries, at times of another, while at
other times the characteristics of no one stream predominate to any
measureable extent. It is possible to divide the water met with in
this investigation into classes, crudely, to be sure, according to the
character of the predominating tributary, as follows:
Class I.— October 1, 1900, to April 26, 1901. This class com-
prises water which most resembles in character that of the upper
tributaries.
COMPOSITION OF MISSISSIPPI RIVER WATER Si
This class may further be divided into —
Sub' Class A, — October 1 to December 21, 19Q0. Water between
the beginning and the end of a rise.
Sub-Class ^— December 22, 1900. to March 16, 1901. Water of
low turbidity,
Sub-Class C— March 16 to April 26, 1901. Water from the
beginning of a rise until the characteristics of Class II predominated.
CI.ASS II. — April 27 to August 17, 1901. This class comprises
water which most resembles the Western tributaries in character.
This class may be further divided into —
Sub-Class A, — May 21 to 31, 1901. - Water partaking largely of
the character of the streams of the Arkansas basin.
Sub-Class B, — June 1 to 11, 1901. Water partaking largely of
the character of the Red River.
The term *' Upper tributaries'* applies to the streams which unite
at Cairo, while the term *' Western tributaries ''applies to the streams
of the Red and Arkansas basins. During August, 1901, there was an
abnormal rise of the Ohio River which effected an' abnormal rise of the
Mississippi at New Orleans, after the close of these investigations.
CHAPTER II.
Description of the Water Purification Station.
Location, — The Water Purification Station was located in Audub
Park on a plot of land adjacent to the Louisiana Experiment Static
and situated between it and ihe Mississippi River. Audubon Pa
was selected for the location of the Station on account of its acces
bility for the public; the easy approach to the river, and the neariK
of the proposed intake location. Besides, no sewers were known
empty into the river immediately above.
New Orleans has a river front of about 11 miles. Canal street
about 3, and Audubon Park about 9, miles above the lower city lii
The proposed intake location is 2.1 miles above Audubon Park.
of these distances are along the river front.
general arrangement of plant.
The general arrangement of the plant is shown on Plates III,
and V. The plant consisted of the following structures:
1. Pump and Intake.
2. Four Subsiding Basins.
3. Three Coagulating Basins.
4. Four Filters; two each of the English and American typ
with appurtenances.
5. Tower Tank.
6. Boiler House.
7. Laboratory.
The general arrangement is briefly described here below. A mo
detailed description is given further along.
Water was constantly pumped from the river into each of fol
subsiding basins, out of which latter it flowed into a filter, in one caa
and into coagulating basins and thence into filters in each of the thrl
other cases. Thus there were four separate processes or systems %
water purification, giving opportunity to study a sufficiently wii
range of conditions as to plain subsidence, coagulation and supplemen
tary subsidence, and of filtration through beds of sand at a slow rat^
as well as of filtration at a high rate, with the aid of coagulatiofl,
through beds of sand which are cleaned by mechanical means.
In the field of water purification the nomenclature is on a very
unsettled basis at present. Subsiding basins are called sedimentation
DESCRIPTION OF STATION S3
T^asins by some, and settling basins by others. The process of filtra-
tion, which originated in England seventy years ago, is variously
Isinown as English filtration, sand filtration, and also slow filtration;
^while the other well-known method of filtration, originating in
tliis country, is called American filtration, mechanical filtration and
rapid filtration. Each term has its merits and demerits. The terms,
English filters and American filters, have been used in most places
^where investigations have been made upon the purification of very
turbid river waters in this country; and, as they are the ones to which
the writer is most accustomed, they will be used throughout this re-
port. The full set of devices used to effect the complete purification
of the water, comprising subsiding basins, coagulating basins and fil-
ters, with their appurtenances, is called a system of purification.
These four systems have been called Systems Nos. 1, 2, 3 and 4,
respectively.
System No. i. — The English system provided for three days of
plain subsidence, and filtration through about S feet of fine sand', stip-
ported upon 7 inches of graded gravel, at a rate of 2.56 million gallons
per acre per day, the standard German rate.
System No, 2. — ^The modified English system provided for two
days of plain subsidence and one of coagulation, and filtration through
about 3 feet of medium sand, supported upon 7 inches of graded
gravel, at a rate of 5.2 million gallons per acre per day.
The clogged sand layers of the filters in Systems 1 and 2 were
cleansed by draining and scraping the surface of the same.
Systems Nos. 3 and 4. — ^The American systems were similar. They
both provided for plain subsidence: No. 3 for 12 or 48 hours; No. 4
for 12 or 24 hours. They both provided for various periods of coagu-
lation: No. 3, for 0.5, 3.0, 6.0, 9.0, or 12 hours; No. 4 for 0.5, 6.0,
12.0, or 24 hours, and they provided for filtration through about 2.9
feet of sand, at a rate of 125 million gallons per acre per day.
The clogged sand layers in both systems were cleansed by washing
the snnd in situ by reverse currents of water, agitating the sand in
System No. 3 by currents of air, and in System No. 4 by revolving
rake arms driven by steam power.
The combined output of the plant in operation (four systems) was
about 93,000 gallons of water per 24 hours.. Some of this was pumped
to the tower tank and became the water supply for the boilers and
laboratory, also for wa^^hing the American filters, and for refilling the
English filters from below after scraping. The boiler plant furnished
steam for the necessary machinery and the heating apparatus. There
was also an adequate laboratory and office.
54 WATER PURIFICATION
A more detailed description of the plant is as follows:
INTAKE AND PUMP.
The intake was constructed of 4-inch pipe, wrought iron from the
suction inlet of the pump to the river side of the levee, and cast iron
for the remainder of the distance. There was a valve on the outer end
of the cast iron pipe; and 25 feet of rubber suction hose with, strainer
and foot- valve extended beyond this into the river. The end of the
suction was constantly held Just beneath the surface of the water b\' a
rope attached to a house boat, moored near the shore. The intake was
located on a making bank. The levee at the point of intake was 10
feet high. In order to avoid cutting into the levee, or getting an
accumulation of air at the top of a syphon, the pump was placed in a
raised pump-house, the elevation of the floor of which was the same
as that of the top of the levee. Therefore, the suction chamber of the
pump was at the highest point in the suction line. This intake was
laid with great care. This was necessary because the maximum suc-
tion lift, including friction, was 28 feet. The pump was a Worthing-
ton Duplex, 6 inches by 5.75 inches by 6 inches in size.
SUBSIDING BASINS.
Concerning the construction of the subsiding basins, four in num-
ber, it may be best understood from Plates IV and V, and from the
photographs (Plates I and XII) accompanying this report. The sub-
siding basins had a combined area of 45 by 50 feet; which area was
further divided, by partitions, into four different sized basins, each 10
feet deep.
Subsiding Basin No, i. — This basin was 50 feet long by 10 feet
wide by 10 feet deep. It held 36,000 gallons, or three normal days'
supply for Filter No. 1.
Subsidifig Basin No. 2. — ^This basin was 50 feet long by 5 feet
wide by 10 feet deep. It held 18,000 gallons, or two days' supply for
Filter No. 2.
Subsiding Basin No, j. — This basin was 50 feet long by 20 feet
wide by 10 feet deep, and held 72,000 gallons, or two days' supply for
Filter No. 3.
Subsiding Basin No. /. — This basin was 50 feet long by 10 feet
wide by 10 feet deep. It held 36,000 gallons, or one day's supply for
Filter No. 4.
The basins were constructed of heavy yellow pine timber, which
was lined with three-ply tarred paper, overlaid on the sides with two
layers of tongued-and-grooved ceiling, and on the bottom with one layer
DESCRIPTION OF STATION 55
of tongued-and-grooved flooring. The joints, angles and corners were
caulked, and 2-inch by 1-inch pieces were spiked into the angles.
The subsiding basins were not covered.
A 2.5-inch pipe led from the discharge of the main pump to the
2.5-inch header which ran across the tops of the basins at their inlet
ends. In this header, opposite to the center of each basin, there were
placed tees which connected with the 2.5-inch globe valves and finally
w^ith the perpendicular inlet pipes, which latter reached to within 2
feet of the bottom of the basins.
The outlets of the basins were invariably near the surface of the
vv^ater therein, and consisted usually of several 2-inch holes bored
through the partition separating the subsiding and coagulating basins.
The outlet of Basin No. 1, however, consisted of two wrought-iron
pipes — 1-inch and 1.25-inches in diameter, respectively — whose basin
ends terminated in two driven well points. These latter were for the
purpose of preventing the passage of fish, snails, water beetles, etc.,
into Filter No. 1.
Each basin was provided with a 2.5-inch washout pipe, which was
placed in the floor of each basin, near the outlet of the same.
RE- ARRANGEMENT OF SUBSIDING BASINS.
Between April 11th and May 3d, 1901, the basins were remodeled
to some extent, as follows:
Basin No. i. — This basin had a total capacity of three da3^s' flow
and was first arranged so that samples could be taken after three days'
subsidence only. It was necessary to increase existing knowledge of
the results of one and two days' plain subsidence, respectively; conse-
quently baffles and overflow partitions were placed in the basin at
points one-third and two-thirds of the distance from the inlet to the
outlet end of the basin, respectively. This permitted the sampling of
the water at these points, the samples representing water which had
remained in the basin for one and two days, respectively.
Basin No, 2, — This was arranged in a similar manner to Basin
No. 1, and one overflow partition or baffle was placed in it so as to
permit sampling after 6 hours of plain subsidence.
Basin No. j. — ^This basin was transformed from one of 48 hours'
into one of 12 hours' capacity by building a tight partition at a
point one-quarter of the distance from the inlet to 'the outlet end
of the basin and by by-passing the water from this partition by means
of a wooden trough directly to the coagulating basin, thus throwing
three-quarters of the basin out of service.
Basin No. 4.. — This basin was transformed from one of 24 hours'
into one of 12 hours' capacity by building an overflow partition
56 WATER PURIFICATION
and baffle across its middle. Thus the part which had been used
previously as a subsiding basin became a part of the coag-ulating
basin. On July 9th, another overflow partition and another baffle were
placed in the basin in order to permit sampling after 6 hours of plain
subsidence.
All of these baffles were constructed of tongued-and-grooved pine
sheathing. It was found necessary, however, to cover this sheathing
with cotton sheeting to prevent a diffusion of water through the parti-
tions and baffles.
COAGULATING BASINS.
The coagulating basins were three in number, and were con-
structed of heavy lumber, lined with tarred paper and tongued and-
grooved sheathing, in a' manner similar to the subsiding basins. The
inlet to each basin was just below the level of the water surface. As
the water flowed into each coagulating basin, it crossed a trough made
of 0.875-inch by 12-inch boards. These troughs were open on top,
'\ and were known as coagulating troughs. Their length was the vv^idth
of the coagulating basins, and their width was about 10 inches. Their
top edges were 2 or 3 inches below the normal level of the water
in the coagulating basins. The flow of water was across these trough^.
In the bottom of each trough there was a lead coagulant pipe 0.5-inch
in diameter. This pipe was drilled with 0.125-inch holes about 6 inches
between centers. One end of the pipe was closed with a plug; the
other led to a point near the device for feeding the coagulant solution.
The coagulant solution was fed at will into any one of these pipes at
the desired rate. As the coagulant issued from the small holes in the
coagulant pipe, it was taken up by the water as it passed across the
trough.
System No. i, — System No. 1 had no coagulating basin.
System No. 2. — System No. 2 had a coagulating basin of 9,000
gallons, or 24 hours' capacity. It was 25 feet long, 10 feet deep and
IJ 5 feet wide. There was a baffle at a point 3 feet distant from the inlet
end of the basin, which extended from the top of the basin to within
2 feet of the bottom of the same. This baffle prevented the direct
passage of water from the inlet to the outlet.
The outlet of Basin No. 2 first consisted of two wrought iron
pipes 1-inch in diameter and 1.25 inches in diameter, respectively,
I which pipes reached to within 18 inches of the flow line of the basin.
These pipe^ were shortly replaced by strainers, and, on May 1, the
strainers were enclosed by a box- weir whose top came to within about
4 inches of the flow line of the water in the basin. During June, July
I
DESCRIPTION OF STATION 57
and August it was necessary to remove the strainers, because the
growths of algae in this basin prevented the free passage of water into
I^ilter No. 2.
System No. j — System No. 3 had a coagulating basin of 18,000
gallons, or 12 hours' capacity. It was 25 feet long, 10 feet wide and
10 feet deep. It was divided into five compartments by means of
wooden partitions. Each compartment was fitted with a coagulant
feed trough containing a coagulant feed pipe. These troughs were
located on the side where the water entered the compartment, and,
when the inlet and outlet of any compartment were both near the flow-
line of the water in the basin, a baffle was constructed to extend from
the top of the basin to within 3 feet of the bottom of the same. The
point of application of coagulant in the 0.5-hour or final coagulating
basin was at its bottom, the stream of coagulant mingling with the
stream of water as the latter flowed into the final compartment from
the previous one. This arrangement of coagulating troughs and
coagulant pipes permitted the addition of coagulant at points equivalent
to about 12, 9, 6, 3 and 0.5 hours before filtration, respectively, when
the rate of flow through the basins was 25 gallons per minute.
The outlet of this coagulating basin was located in the 0.5-hour
or final compartment at a point 2 feet below the normal flow line of
the basins.
System No. 4.. — Originally this basin was constructed like that of
System No. 3, except that it was divided into only three compart-
ments, permitting the application of coagulant at points equivalent to
12, 6 and 0.5 hours before filtration, respectively, when the rate of
flow through the basin was 25 gallons per minute.
Between April 23d and May 3d, 1901, however, another partition,
baffle and coagulating trough were constructed at a point half way
across Subsiding Basin No. 4, which, in conjunction with the already
existing coagulating* basin, permitted the use of a maximum coagula-
tion period of 24 hours. The period of plain subsidence was cor-
respondingly reduced from 24 to 12 hours by this change.
At first the coagulating basins were covered with a shed roof, but
this was removed from Coagulating Basin No. 2 during April, and
from Coagulating Basins Nos. 3 and 4 during May. These covers
were removed for the purpose of studying the effect of sunlight upon
the growth of algae in the basins.
58
WATER PTRIFICATIOX
ir
DESCRIPTION OF STATION 59
IDEVICES FOR PREPARING THE CHEMICAL SOI.UTIONS, AND FOR DISTRI-
BUTING THE SAME TO THE POINTS OF APPLICATION.
The general arrangement is shown on Plates IV and V.
Chemical r — Sulphate of alumina was used as a coagulant, and S
per cent solutions of it, by weight, were invariably prepared.
Chemical Tanks. — Two barrels served as chemical tanks. These
barrels were placed on a platform just beneath the tower tank, from
which latter they could be readily filled with filtered water. They
^were provided with depth gauges, to which they were regularly filled.
The coagulant was placed in one of the barrels, together with the
required quantity of water. After solution, the contents of the barrel
Tvere well mixed. One barrel was used as a supply tank while a new '
solution was being prepared in the other. Washout pipes were provided
for each barrel. They were washed out before each new solution was
made. A O.S-inch pipe, provided with a valve, led from each barrel.
Both of these terminated in a common tee, which, in turn, connected
with the O.S-inch lead supply pipe, which connected with the feed
tanks.
Coagulant Feed Tanks. — There were five of these in use. Three
were used for the initial application of coagulant in Systems Nos. 2,
3 and 4, while two were occasionally used for the secondary application
of coagulant to the water, 0.5 hour before filtration, in Systems Nos.
3 and 4. A sketch showing the arrangement may be seen on Plate VI.
The feed tanks consisted, briefly, of ball-cock tanks supplied with
solution from the barrels through the lead pipe mentioned above.
Bach tank was provided with a feed cock, upon which, of course, the
ball-cock maintained a practically constant head. Some of the feed
cocks were of fine construction, and were provided with quadrants
and pointers, so that the rate of flow might be adjusted more easily.
All of the feed tanks were provided with filtering partitions of cloth,
which materially prevented the clogging of these feed cocks. Regula-
tion of the rate of coagulant addition was effected by noting the
number of cubic centimeters w^hich flowed from the cocks in a given
time.
The coagulant solutions discharged into funnels, which, in turn,
were connected to a O.S-inch rubber hose, which, in turn, could be
readily connected with any one of the lead pipes which terminated
either in the perforated pipes in the coagulating troughs or at the
bottoms of the O.S-hour coagulating basins. During April a settling
and filtering chamber was placed in the pipe line leading from the
coagulant barrels to the feed tanks.
FILTERS.
The general arrangement of the filters is best shown on the
plates accompan> ing this chapter. They may be described as follows :
ENGLISH FILTER NO. 1.
Tank. — The filter tank was made of cypress. It was 16 feet in
diameter and 10.2 feet deep. The sides and bottom were 2.25 inches
60
WATER PURIFICATION
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DESCRIPTION OF STATION 61
thick and the staves were held in place by eight galvanized hoops of
varying widths and thicknesses. Four circumferential grooves, each
0.625-inch wide and 0.62S-inch deep were cut around the inner surface
of the tank. They were 12 inches apart, the lowest groove being 14
inches above the bottom of the tank. These grooves were designed to
guard against the more rapid percolation of water around the periphery
of the filter, between the walls of the tank asd the sand layer. As a
further precaution, the walls of the tank were first coated with black
asphaltum varnish and then sanded. The bottom of the tank was
level and the sides were vertical.
Piping Connections. — There were two inlets for Filter No. 1 — of
1-inch and 1.25-inch wrought-iron pipe, respectively. These pipes
entered the filter tank at points 4 feet below the top of same. Both
inlet pipes were provided with valves and terminated inside of the
filter in elbows which were turned upward so as to avoid disturbances
of the sand layer during the operation of the filter. A 1-inch pipe in
the botton of the tank served as an outlet. This outlet pipe was fitted
with a valve and was connected with a 1-irich Worthington water
meter. Suitable 1-inch piping connections permitted the refilling of
the filter, after scraping, with filtered water, from below, and also the
by-passing of the basin effluent around the filter and through the meter
during scraping.
Gauges, — Loss-of -head-gauges consisted of glass tubes attached to
the filters. One of the tubes connected with the gravel layer and
measured the pressure in the under-drains. The' other connected with
the water above the sand layer, and showed the pressure at the sur-
face of the same. The difference in the height of these two water
columns showed the loss of head.
Under- Drains. — The sand was supported upon a layer of graded
washed gravel. Generally speaking, a layer of gravel will remain on top
of a lower layer, provided it contains no particles less than one-third the
size of the particles of the material upon which it rests. Working on
this principle, the coarser material on the local market was sized into
three grades, and the finer — that which is used for cement sidewalks —
into two. The sizes of the sieves used for this purpose were deter-
mined from the inspection of the results of the mechanical analysis
of the raw material. All gravel was washed before being put into the
filters.
The following layers were put into the filters:
1. Stones 2 inches thick.
2. Walnut Gravel... 2 ''
3. Pea Gravel ...1 ''
4. Buckshot Gravel.l ''
5. Coarse Sand 1 ''
62
WATER PURIFICATION
The coarser gravel came from Portugal as ballast. There is an '
equally good gravel on the market from Prophet's Island, in the Mis- ■
sissippi, near the mouth of the Red River.
The results of mechanical analyses of these gravels are given in
the next table.
TABLE XXIV.
Mechanical Analyses of Gravels,
Percentages by Weight Finer than Given Diameters.
Stones
Walnut Gravel
Gravel lyayer No. 1
Gravel l«ayer
No. 2.
Size in Millimeters
Percentage
Finer
Size in Millimeters
Percentage
Finer
40.0
100.
25.0
100.
31.7
89.
17.1
79.
28.2
82.
15.8
64.
27.2
76.
15.3
52.
26.6
70.
14.8
41.
25.9
65.
14.0
31.
24.7
60.
12.9
23.
23.5
52.
12.1
16.
22.5
45.
11.0
11.
22.1 •
40.
10.2
7.4
21.6
34.
9.5
4.1
21.1
27.
22.
6.8
0.0
19.9
19.3
15.
10.
5.0
Effective size
10 ft m
m.
18.3
18.0
Uniformity co-efl5cient 1.43
15.8
1.4
12.1
0.22
6.6
0.016
Effective size
19.3 m.m.
Uniformity co-efficie
mt 1.28
Finer than ,
(Millimeters)
Percentages by Weight
Pea Gravel
Gravel I^yer No. 3
Buck.<;hot Gravel
Gravel I^yer No. 9
Coarse Sand
G ravel I^yer No. 5
8 15
100.00
70.45
52.70
30.00
1.35
0.04
6.97
5.81
100.00
93.69
23 10
0.25
0.13
0.07
0.06
0.06
0.05
4.52
1.92
1.23
0.937
0.653
100.00
99.86
60.27
31.02
9.36
0.456
0.314
3.62
2 19
0.237
1.10
1.75 m.m.
2.00
0.66m.ni.
1.87
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Effective size 3.35 m.m.
Uniformity co-efficient 1.64
Sand Layer, — The original sand layer was 4.5 feet thick and was
composed of very fine sand of an effective size of 0.21 millimeters and
having a uniformity co-efficient of 1.57. This was an extreme thick-
DESCRIPTION OF STATION 63
less of sand layer, composed of the finest sand obtainable upon the
narket at the time of purchase. This construction was decided upon
:or the filter because experience in other places had shown that, other
tilings being equal, thickest layers of finest sand gave the highest
qi^ualitative efficiency. It was desired to have this filter operate under
tlie most favorable conditions. A table of sand analysed is given beyond.
Construction of Sand Layer. — The sand for the filter was shoveled
upon a platform of planks which was suspended from the top of the
filter, and which reached to within three feet of the bottom. The sand
was first shoveled on this platform and thence on to the filter, each
shovelful being spread as thrown. The sand for this filter was sieved
through a 1 millimeter perforated metal sieve in order to remove balls
of clay, leaves, sticks, etc.' After the first scraping it was desired to
put in new sand in order to increase the depth of the sand layef to 5
feet as originally intended. Accordingly this was done after the sand
had been scraped as usual to the depth of 0.97 inch. This procedure
was found to be impracticable, however, as clogging took place at the
place of junction between the old and new sand layers, so, after another
scraping, the second addition of sarid was removed. There still
remained 4.1 feet of sand in the filter. The sand layer had compacted
about 10 per cent since first placed in the filter.
MODIFIED KNGIvISH FII^TKR NO. 2.
The tank of this filter was 9.8 feet in diameter and 8.2 feet deep.
It was first filled with 3.0 feet of Horn Island sand of 0.385 milli-
meters effective size, and of a uniformity coefficient of 1.48. After the
eleventh period of operation, the Horn Island sand had decreased to a
thickness of 2.1 feet, and, accordingly, 9 inches of sand were placed in
the filter, first removing all the upper layer of dis.olored sand. The
new sand had an effective size of 0.33 millimeters, and a uniformity
coefficient of 1.42. With the above exceptions, the filter was con-
structed, fitted and under-drained similarly to Filter No. 1.
AMERICAN FILTER NO. 3.
This was a 4-foot gravity filter of the American type, constructed
by, and purchased from, the New York Continental Jewell Filtration
Company. This kind of filter is known to the trade as the Continental
Filter. It departed in no essential particular from the usual designs of
the American type of filter, except that air, instead of the more common
mechanical agitator, was used to agitate the sand during washing.
In general, the filter consisted of a steel tank, at the bottom of
which there were placed strainers for the collection of filtered water,
and for the admission of water or air during washing. This tank con-
tained a sand layer supported upon a layer of gravel. The various
! 1
64
WATER PURIFICATION
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DESCRIPTION OF STATION 65
parts are described in order, first, — as purchased from the Filter Com-
pany, and then as rearranged by the Company in February, (Plate IX. )
Steel Tank.— -The tank which held the sand layer was composed
of two parts, an inner and an outer tank;
The inner tank was 4 feet in diameter and 5 feet 7 inches deep.
Twelve inches above the bottom of the tank there was a partition
which formed a support for the filtering layer. Into this partition, the
strainer cups were screwed, and the space between the false and true
bottom acted as a filtered water chamber. This chamber held, approxi-
mately, 12.6 cubic feet, or about 4 minutes' normal flow of the filter.
The main portion of the inner tank was occupied by the sand layer,
which was 2.6 feet thick. The sand layer was supported upon a layer
of fine uniform gravel, 4.5 inches thick. The upper 9 inches of this
tank served as a water space above the sand layer.
The outer tank, the top of which projected 1 foot above the inner
tank, was a ring of steel, 4 feet 4 inches in diameter and 3 feet high.
This was slipped over the inner tank for two-thirds of its height, form-
ing a circumferential trough, 2 inches wide and 2 feet deep. This
trough received the wash- water as it flowed over the edge of the inner
tank during washing, and also served to distribute the water applied to
the filter during filtration.
Piping Connections, — All piping connections were 2.5 inches in
diameter, with the exception of the waste pipe, which was 3 inches in
diameter. The outlet and wash water supply pipes were joined just
outside of the filter, and were connected to. the filter just above the
bottom and below the false bottom of the inner tank. The inlet pipe
was connected to the filter at a point 2 feet below the top of the outer
tank. The waste pipe was connected with the circumferential trough
near its bottom. A by-pass connected the inlet and outlet pipes so
that water could be wasted through the controller at normal rates,
thus permitting the stopping of the filter without interrupting the flow
of the water through the basins.
Strainer System, — Perforated brass cylinders, 50 in number,
formed the strainer system of this filter. They were screwed into the
false bottom, and were spaced about 6 inches from center to center.
These strainer cups were made of brass tubes 1 inch in diameter, closed
at the top. The tops and sides were drilled with thirty 0.06-inch holes,
and projected above the false bottom for about 1.0 inch. The total
area of holes in each strainer was .092 square inches, or 46 square
inches for the whole strainer system. Naturally, the holes in these
strainers were too coarse to retain the sand used in the filter, and, con-
sequently, a 4.5-inch layer of fine uniform gravel was placed in the
filter to support the sand. The mechanical analysis of this gravel is
given below :
TABI,E XXV.
Mechanical Analysis of Filter No, j Gravel,
Finer than 4.52 m.m 100.00 per cent.
Finer than 1.92 m.m 0.38 per cent.
Finer than 1.23 m.m 0.07 per cent.
The average mean diameter of the particles equaled 3.1 m.m.
66
WATER PURIFICATION
-
\
DESCRIPTION OF STATION 67
Modifications of the Strainer System. — In February the; strainers
A^ere removed from the false bottoms and were screwed into a system
:>f effluent pipes which rested upon the false bottom itself. The main
pi j>e of this system followed the diameter of the filter, and was made
3f 3-iiich wrought-iron pipe. Into this main pipe, l.S-inch lateral
pip>es were screwed. The holes in the false bottom were pluged, the
wliole system was imbedded in Portland cement mortar, and 6 instead
of 4.5, inches of gravel were placed above it. This system of piping
found its outlet through a vertical 3-inch pipe which passed through
the bottoms of the filter at its center. This change was made in order
to effect a better distribution of air — used in washing — than had been
possible \Yith the filter avs earlier arranged.
Tests were made of the frictional losses occasioned by the strainer
cups, gravel layer and effluent piping system, with the following
results:
IvOSSES OF HEAD IN FII>,TER NO. 3 WHEN OPERATING AT A RATE OF 25
GAI.I.ONS PER MINUTE, OR 125,000,000 GAI,I,ONS PER ACRE PER
DAY.
FILTER NO. 3.
Old Strainer System,
Velocity head of efiiuent piping 0.04 foot.
lyoss of head due to effluent piping 0.55 ' *
and strainers 0.60 ''
strainers and gravel... 0.70 ''
New Strainer System,
lyoss of head due to effluent piping 0.55 feet.
** and strainers 0.60 ''
'' strainers and gravel.... 0.76 ''
Since the total friction of this filter, directly after washing, varied
from 1.6 feet to 5.9 feet, at the regular rate of filtration, depending
upon the size of the sand and the thickness of the sand layer used, it
will be readily seen that the sand layer was the most important tactor
in causing losses of head in this filter.
Agitating Device. — An agitating device was provided for the
purpose of stirring the sand layer during washing. This device con-
sisted of a Knowles air pump and a system of air distribtition. The
air pump was 5 inches by 10 inches by 7 inches in size. From this
blower a 0.75-inch pipe led to the space below the false bottom. A
deflector was attached to the end of this pipe. A branch of this pipe
68 WATER PURIFICATION
was connected with an escape pipe so that the pump could be run con
tinuously and the air allowed to escape or to be discharged into th
filter at will.
The distribution system was quite simple. Each strainer tub
projected below the false bottom for about 1.5 inches A 0.06-inci
hole was bored in the side of each of these tubes at points just belov
the false bottom, thus forming traps. Air was pumped into the spac<
between the true and false bottoms. The air was then supposed tc
pass through the small holes in each strainer and to find its wa>
uniformly up through the sand layer. A deflector was fastened to th^
end of the 0.75-inch air supply pipe with the intention of spreading
the air in a thin stratum which would not be thick enough, at any one
place, to allow the air to pass up through the bottoms of the strainers
instead of through the small air holes. The reciprocating air-pump,
however, produced such an irregular flow of air that the latter wa^^
spasmodically admitted to the under-drains and sand layer through
the bottoms of the strainer tubes and caused the gravel to be displaced,
as is shown in Chapter VI. Consequently, the air distribution system
was modified by a representative of the Filter Company, as follow- s:
Modifications of the Air Distribution System, — The modificationb
of the strainer system have been noted above. The air distribution
system was modified so as to make the air escape just beneath each
strainer by means of a system of pipes within the efiiuent pipe system.
This pipe system consisted of a main 0.75-inch pipe, within the 3-incli
effluent pipe, and of 0.37-inch lateral pipes, closed at the ends, within
II the 1.5-inch lateral effluent pipes. A .0625-inch hole was drilled in
this pipe system directly beneath each strainer. This arrangement
practically overcame the ill effects of the irregular discharge of the
air pump.
AMERICAN FILTER NO. 4.
This was a 4- foot gravity filter of the American type, having
strainers screwed into a false bottom; and it differed from the original
Filter No. 3 in nothing except strainers and agitating device. There-
fore, the description of the original Filter No. 3 (before February
alterations) will suffice for Filter No. 4, .except in the following
particulars:
Strainer System, — The strainer system consisted of 50 brass
strainer cups screwed into the false bottom of the filter. These
strainers were of the usual Jewell inverted cone-shaped pattern. The
f lace of the cup was covered with a punched bronze sheet, the sheet
,|: being secured to the cup by a metal ring which was riveted to the cup
j flange. These strainers are too well known to need further descrip-
11"^ tion. The loss of head due to this strainer system and the connected
|i effluent piping at the regular rate of flow, was 0.70 foot.
DESCRIPTION OF STATION
69
d
u
J
D
Oi
z
y
h
z
<
S
u .
<
u.
o
(0
z
6
u
-H
If^?n?T^
I ■ + 1 ■ I - ' J" zP".' ■ ■ ' ' ■" - ■ ■
'Tap i ' i "' ii "TT^-'^
70
WATER PURIFICATION
Agitator, — The agitator consisted, briefly, of two horizontal rake
arms, one of which carried 3, and the other 4, rake teeth made of 0.875-
inch square iron, and extending down into the sand layer to within 1.5
inches of the top of the strainers. On April 20th, when gravel was
put into this filter to a depth of 9.5 inches above the top of the strainers,
the rake teeth were cut off so as to just touch the top of the gravel
layer. This agitator was attached to a vertical shaft, which could be
revolved in one direction by means of a 2-horse power vertical engine
connected with the agitator by belting, shafting and bevel gearing.
Gravel to a depth of 9.5 inches above the top of the strainers, and
of the same size as used in Filter No. 3, was put into the filter on April
20th. This was done that the same thickness of sand, and the same
distance between the top of the sand and the top of the wash water
overflow partition might exist in each filter.
A sketch showing the main features of this filter may be seen on
Plate X.
Ideal cross scctions or American and cnglish rlters.
SHOIMINO RELATIVE TNICKMCSSeS OF PILTCmNe MATERlALa,
AND CHANOCft IN UNOCRORAINO AT OirPERCMT TIMCS.
! r nr
PLATC, IMS 11
.i.
1^
^'
NOTE.
rbLTCMS, No. 1 AM» 2 •flA»BO •MAVKL
riLTC«s.No.3.A.-3. B.* A-.B. VNiroAM •ma vei. .
FiLTftfC. No.^.A. HO «f«AVCL.
FtLTEHitf * A
ni.TCR.M?4 B.
SANDS USED IN FOUR FILTERS.
As it was important to learn which of the available local sands
was best suited as a filtering medium in the various filters, especially
in Filters Nos. 3 and 4, the sands were changed quite frequently,
DESCRIPTION OF STATION 71
-Again, it was desired to have Filters No. 3 and No. 4 operate with the
same thicknesses of sand layer, and therefore, because the depth of
IFilter No. 3 was less than that of Filter No. 4, a correspondingly
thicker layer of gravel was put into Filter No. 4.
The following diagram, Plate XI, illustrates the relative thick-
nesses of sand and gravel layers in the four filters at different times:
Figure No. 1 shows a representative cross-section of Filter I^o. 1.
Figure No. 2 shows a representative cross-section of Filter No. 2.
Figure No. 3 shows a representative cross-section of Filter No. 3,
before changes were made in the strainer and air distribution systems.
Figure No. 4 shows the same as Figure No. 3, but after the
changes were made in the strainer and air distribution systems.
Figures No. 5 and No. 6 show representative cross-sections of Filter
No. 4 before and after the placing of the gravel layer in the filter.
What immediately follows shows the mechanical analyses, albu-
minoid ammonia contents, and periods of use of the various sands used
in the four filters:
Filter No. i, — This filter operated with only one kind of sand,
known to the trade as I^ake Shore Sand. This sand came from the
bed of the Tchefuncta River; it was pumped up from beneath the
water by a suction dredge. This sand contained 1600 parts of clay per
million. It was passed through a 1-millimeter sieve before being put
into the filter. This sieving effected the removal of a large part of the
clay, also shells, pieces of leaves, bark, etc.
Filter No, 2, — ^Two sands were used in this filter, both of which
were washed before use.
Sand No. 1 was said to have come from Horn Island in the Missis-
sippi Sound. It was clean, beautiful, white sand with rounded grains,
which was free from clay, but which contained a small amount of veg-
etable detritus, most of which was removed by washing.
Sand No. 2 was from a bar at the mouth of one of the rivers flow-
ing into the north side of Lake Pontchartrain. It was similar to Sand
No. 1, excepting that it had a very slight reddish color, due to a small
amount of iron. It was called gravel sand. This was the sand which
was used on July 10th to restore the sand layer to its original thick-
ness. The sand which was replaced, however, consisted partly of
Sand No. 1. which had been removed from the filter by scraping and
which was washed and replaced on top of Sand No. 2.
Filter No, j. — Sand No. 1 was a sifted beach, sand from Norfolk,
Va. It was a very clean sand with rounded grains. This sand was
in use from December 15 to February 26.
Sand No. 2 was Horn Island sand, the same as was in Filter No.
2. This sand was in use from February 27 to April 10.
72
WATER PURIFICATION
Sand No. 3 was called Henderson Point sand, and was said to
have come from Henderson Point, which reaches out into Mississippi
Sound on one side of Bay St. L^uis. This sand was in use from May
3 until June 14.
Sand No. 4 was Lake Shore sand, the same as that used in Filter
No. 1. This sand contained clay and vegetable matter, most, but not
all of which was removed by sieving, and washing in the filter. This
sand was in use from June IS until August 8.
Sand No. 5. This was a mixed sand from Prophet's Island, which
is situated in the Mississippi River near the mouth of Red River. This
was a very fine sand, containing 2,500 parts of clay per million, and
a small amount of coal. This sand was quite free from organic mat-
ter. The size of the sand furnished by the dealer did not correspond
with the size of the sand in the sample taken from the pile. Accord-
ingly, much finer sand was put into the filter than was intended. This
sand was in use from August 9 until the close of the investigations.
Filler No, 4 — The sands used in Filter No. 4 were identical with
those used in Filter No. 3. However, the periods of use varied
slightly, as follows:
Sand No. 1 was in use from December IS until February 24,
Sand No. 2 from February 28 until April 5.
Sand No. 3 from April 8 until June 26.
Sand No. 4 from June 27 until August 6.
Sand No. 5 from August 7 until the close of the investigations.
MINERALOGICAI, COMPOSITION OF THE SANDS.
With the exception of the sands from Norfolk and from Prophet's
Island, all the sands used were composed of almost chemically pure
quartzite.
MAXIMUM RATES OF SANDS IN FILTERS NOS. 3 AND 4.
The usual mechanical analysis of a sample of sand determines a
value which is known as the effective size. This means that 10 per
cent by weight of the sand is finer than the given size in milli-
meters. The mechanical analysis also determines another value
which is called the uniformity co-efficient, and which varies inversely
with the uniformity of the sand. The velocity of the water passing
through sand in a filter under conditions of practice has been expressed
by the formula
y=cd'j (t°Fahn + I0O)»
Where V equals the velocity in vertical meters per day, or approxi-
mately in million gallons per acre per day.
d equals the effective size of the sand grains in millimeters;
k equals the loss of head;
{Hazen: Report Massachusetts State Board of Health, 1892, p. 553.
Hazen: Filtration of Public Water Supplies, 3d edition, p. 22, New York, 1900.
Clark: Report Massachusetts State Board of Health, 1894, p. 703.
DESCRIPTION OF STATION
73
/ equals the thickness of the sand layer;
/ equals the temperature (Fahrenheit);
c equals the approximately constant factor.
The value of c is generally taken as 1,000. Clark, however, has
shown that the value of c varies with the compactness of the sand
layer, the chemical composition of the sand, the presence of loam and
fine particles, the age of the sand layer and the uniformity co-efficient.
All the above factors affect the value of c — that is, affect the relation
between the effective size of the sand grains and the friction of the sand
layer — to a great extent, so that it varies in practice from 500 to more
than 1,000. It might also be noted that in the case of American
filters, which, of course, are washed by reverse currents of water,
there is a possibility that this value of c might be affected under cer-
taiii conditions by the stratification of the sand layer, according to the
hydraulic values of the sand grains.
Sands are sometimes sized by determining their maximum rates;
that is, the rate at which water free of sediment at a temperature of
50 degrees F. will flow through sands in filters when the loss of head
equals the thickness of the sand layer, or, in the above formula, when
J equals 1.
The following table shows the differences between these maximum
rates, determined experimentally at this station, when the materials
were new, and those calculated from the formula. These differences
are, perhaps, explained by the differences in the uniformity of the
sands, in the percentages of fine particles, and also in the shape of
the particles, as mentioned above.
TABLE XXVI.
Table Showing the Differences Betwee7i the Calculated afid Experi-
me7ttally Oetermiyied Maximum Rates of Filtratio7i for Four of the
Sands Used in the American Filter No, j.
Name of Sand.
Effective
Size.
Uni-
formity
Co-
efficient.
Per Cent
Finer than
0.237 m.m.
t°(F)
Maximum Rate in
Million Gallons per
Acre per 24 Hours.
By
Formula
C = 1000.
By Experi-
ment.
Norfolk
Horn Island
0.54
0.385
0.25
0.18
1.30
1.48
1.80
1.83
0.02
0.08
5.96
23.80
50
45
46
80
292
148
125
32.4
176
131
Lake Shore
123
Prophet's Island
65.7
The thickness of the layer of Norfolk sand was 41 inches; of the
other three sands, 34 inches.
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GENERAL VIEW OF AMERICAN FILTERS AND CONTROLLERS.
DESCRIPTION OP STATION 75
CONTROLtERS FOR FILTERS NO. 3 AND NO. 4;
Automatic controllers, of the form designed by E. B. Weston, M.
Am. Soc. C. E., were used to keep the flow of water through these
filters constant. The general form of this controller is shown on
Plates IV and V and in the photograph of Filters No. 3 and No. 4
(Plate XII). It has also been described several times by the en-
gineering press.
The controller is simply a nicely constructed chamber in which
there is an annular orifice, over which a constant head of water is
maintained by means of a float which operates the butterfly inlet
valves. The orifice can be easily varied in size. The head above the
orifice could also be slightly varied in order to adjust the discharge of
the controller accurately. These controllers worked very well and
kept the flow of water through the filters to within about 2 per cent of
the desired rate.
CONTROLLER BOXES AND CLEAR WATER TANK.
The controllers discharged into two controller boxes (Plates IV
and V), which were provided with baffles and standard orifices, for
the purpose of niaking check measurements of the discharge of the
controllers.
The water from the controller box of Filter No. 4 flowed into a
clear water tank. This tank was constructed of brick masonry,
plastered on the inside with cement. It was 6.5 feet long, 3.6 feet
wide, and 3.0 feet deep. It had a capacity of about 500 gallons. A
2.5-inch suction pipe led from the clear water tank to a 4-inch by 3.75-
inch by 4-inch Worthington pump, which latter discharged into the
tower tank shown on Plates III and IV.
•
TOWER TANK.
A trestle 33 feet high supported a cypress tower tank. This tank
was about 10 feet in diameter and 5.5 feet deep and held about 3,000
gallons of water when full. From the bottom of this tank a 3-inch
stand pipe depended, the lower end connecting with the tank pump.
This pipe was provided with connections, as follows:
a. — A pair of 1-inch pipes leading to the coagulant barrels.
b. — A 3-inch connection leading through a 2.5-inch meter to the
wash-water inlets of Filters No. 3 and No. 4, and also to the outlet
pipes of Filters No. 1 and No. 2.
c. — A 2.5-inch connection for the fire hose.
WATER PURIFICATION
d. — A 1-inch pipe which led to the discharge of the main pump,
by means of which — and by a by-pass around the pump itself — the
suction intake pipe could be filled with water between the foot valve
and the pump.
e. — A 1.5-inch pipe leading to the boilers and laboratory.
There was a float in the tank which was connected with a valve
in the steam pipe of the tank pump and which shut off the steam
supply whenever the tank became fnll.
The top of the tank was 30 feet above the bottoms of Filters No. 3
and No. 4.
BOILER HOUSE.
The boiler house was a rough wooden building, 25 feet long by 15
feet wide. It served to protect the boilers, gas machine, tools, oil,
supplies, etc.
The two boilers were of the ordinary vertical tubular type, each
6 feet high by 3 feet in diameter. A small duplex pump acted as a
boiler feeder. The general plan of the boiler house is shown on
Plate IV.
LABORATORY.
A rough, but well-lighted and adequately equipped wooden build-
^ing was erected for use as an office and laboratory. It was supplied
with steam and gasoline gas. The water supply was taken from the
tower tank. The general plan of the laboratory is shown on Plates
IV and V.
I
CHAPTER III.
Manner of Operation of the Pi.ain Subsiding Basins, and the
Efficiency of Plain Subsidence for Various Periods in
THE Clarification and Purification of the River Water.
general plan of operation.
There were 4 continuous subsiding basins in operation, known
as Nos. 1, 2, 3 and 4, respectively. At the beginning of the investiga-
tions the period of subsidence in these basins was nominally 72, 48, 48
and 24 hours, respectively; but these periods were changed during
April, as is described below.
Continuous Plan, — All the basins were operated on the continuous
plan, the water entering at one end of each basin at a point about 2
feet above the bottom, and issuing at the opposite end near the surface.
Cleaning, — All of the basins were cleaned twice; once during
April, and again during August, subsequent to the final shutting
down of the plant.
LATER modifications IN GENERAL PLAN OF OPERATION.
The general plan of operation was practically unchanged during
these investigations. During April, however, baffles and partitions
were put into Basins Nos. 1, 2 and 4, as is described in Chapter II, in
order that data might be obtained regarding the efficiencies of shorter
periods of subsidence, and in order to reduce the period of subsidence
which experience up to this time had indicated to be too long. Accord-
ingly, the nominal period of subsidence of Basin No. 3 was reduced
from 484:o 12, and that of Basin No. 4 from 24 to 12 hours, respectively.
During the earlier part of the work there were several - delays
incident to the tightening of the wooden basins.
The following notes, which were presented in chronological order,
will give a more detailed and comprehensive view of the operation:
1900.
December 6. — Began filling the basins with water.
December 15. — All basins except No. 1 put into operation.
December 17. — All basins in operation; Basin No. 1 operating at
half -rate. *
1901.
January 8. — Partially drained Basins No. 1 and No. 2 to put in
an auxiliary pipe connecting basins and filters.
Increased the flow through Basin No. 1 to the full rate.
February 2. — Stopped Basin No. 3 to make alterations in pipe
system of Filter No. 3.
February 9. — Basin No. 3 again put into normal operation.
78
WATER PURIFICATION
Shut down Basin No. 3 on April 11th, and No. 2 on April 12th lo
remove sediment and put in baffles.
April 17. — Entire plant was shut down because of a severe rain
which flooded the steam pipe connecting the boilers with main pump
and effectually prevented the pump from running because of condensed
steam in the pipe. This cotidition lasted until April 18th.
Shut down Basin No. 1 on April 18th> and Basin No. 4 on April
23d to remove sediment and to put in partition baffles.
After these modifications the basins were again put into operation
as follows:
Basin No. 1 on April 22d.
Basin No. 2 on April 23d.
Basin No. 3 on April 28th.
Basin No. 4 on May 17th.
May 20. — Partially drained No. 4 to repair baffles.
June 5. — Basin No. 2 was put out of service. After this date the
unsettled river water was supplied directly to Coagulating Basin No. 2.
June 25 to August 10. — During this period the river was so low
that the main pump had to be stopped several times for slight repairs
which were rendered necessary by the excessive suction lift, which at
times amounted to 28 feet, including friction.
The entire plant was also shut down for a few hours because of
the flooding of the steam pipe during a severe rain storm.
As a general rule, the operation of the plant was as continuous as
could be desired, and delays and accidents were few.
DESCRIPTION OF TABI.ES SHOWING RESUI.TS OF OPERATION OF SUBSID-
ING BASINS.
In the following tables are presented all the leading results of
operation of the subsiding basins, arranged by dates, and also the
total averages for the entire investigations.. The leading data presented
may be briefly explained as follows:
Collection of Samples, — Three samples of river water, and two or
three samples of subsiding basin effluents were collected each day for
the determination of silica turbidity. The suspended matter was
determined gravimetrically on daily averages of samples from each of
the above sources. As the work progressed, however, the frequency
of the gravimetric determinations of suspended matter was diminished.
After the baffles and overflow partitions had been put into the basins,
the number of silica turbidity samples was increased so as to include
the turbidity samples which were taken at the intermediate points.
In general, bacterial samples were taken corresponding to the
turbidity samples. The regular hours of sampling were 8 o* clock in
the morning, 4 o'clock in the afternoon, and at midnight, respectively.
Special samples were taken from the basins for microscopical examina-
tion, and for the determination of the degree of stratification- of the
suspended matter. The temperature of the water in the basins at
different depths was frequently determined.
OPERATION OF SUBSIDING BASINS 79
Dates. — The dates given are those on which the sample was taken
from the basin. They were compared with river samples which were
taken previously, and which might be said to fairly represent the basin
sample before being subjected to subsidence.
Stage of River. — The stage of the river at 8 a. m. on the date
corresponding to the river sample taken is recorded. ' "
. Period of Subsidence. — The period of subsidence in hours was con-
sidered equal to the total capacity of the basin in gallons, divided by
the rate of flow in gallons per hour.
Silica Turbidity. — ^The silica turbidity of the river water and that
of the basin samples represent the turbidity of the same water before
and after subsidence as nearly as working errors will permit..
Suspended Matter. — The results recorded are those of average
daily samples, and correspond to the average of the silica turbidity
results for the same date.
Bacteria. — The numbers of bacteria per cubic centimeter in the
river water and in the subsided water are given. The recorded
results are the averages of two or three determinations.
Efficiencies. — The efficiency of removal by plain subsidence of
silica turbidity, suspended matter and bacteria, respectively, are
recorded. These efficiencies are expressed in the usual manner as the
percentages of difference between the amounts contained in the river
water and in the same water after subsidence for different periods.
Methods of Analysis. — ^These are the same as outlined for the river
water (page 25). In this connection, it may be said that the diaphano-
meter proved to be a most useful instrument for quickly and correctly
recording the results of plain subsidence.
Leakages. — During the investigation, there was more or less
leakage of the basins. This occurred chiefly at the beginning when
water was first put into the tanks, and toward the end of the investi-
gation when the sides of the basins had become more or less water-
soaked and pervious. Leakage in these basins probably did not affect
the accuracy of* the work, since its amount was well within the limits
of accuracy of the methods.
TABUI.ATED LIST OF TABLES.
Showing the Operation and Efficieyicies of the Various Subsiding Basins
After Various Periods of Plain Subsidence.
Table No. Subsiding Basin No. Period of Subsidence.
XXVIII.
XXIX.
XXX.
XXXI.
XXXII.
XXXIII.
XXXIV.
XXXV.
XXXVI.
1.
24 hours.
1.
48
1.
72
2.
6
2.
48
3.
12
3.
48
4.
12
4.
24
80
WATEK PTRIFICATION
TABLE No. XXVIII.
Showing the Operation and Efficiencies of Subsiding Basin JVo. i ,
Using 24 Hours of Plain Subsidence.
-^ - --
"
Silka TurV:^.itT.
Silica Turtwdity.
"^r
DATK.
^oT
I^AT K,
vffn.
River.
Sa-r-ided
'^ of
vn.
Rirer.
River.
Subsided
% of
River
Water.
Removal.
Water.
Renio\-aL
April -n.
11.2
.>Vj
yy>0
:v>
Tunc 21.
7 2
350
160
54
- 23.
11.4
5:^3
3iJ0
4;i
.. 22
7.1
4*J0
190
53
' 25
11.7
62S
:i5ii
44
*• 2:^
7.1
400
170
o.^
* IT
11 8
t>it)
:^7^l
6::
'* 24
6 9
375
190
\^
** 28.
.12
675
220
67
•* 25
6 8
400
\m
bb
*• 29.
12.2
700
120
h3
** 2b
6 S
400
200
50
• :^r
12 1
775
liO
Si
* 27
6 3
450
IfcO
65
May 1
12 2
725
240
6^
- :^
5 9
475
140
70
12.3
725
170
77
" 29
5 5
.550
230
58
3.
12.3
7(/J
SnO
50
Julv 1 .
5
450
200
55
' 4.
12.5
700
450
36
»r .>
4.7
450
150
hi
* 0.
12.4
650
425
35
3
4.4
500
230
54
" ?-
12.6
6^)0
375
3.S
4
4.0
550
200
63
" 7.
12.4
550
375
32
5.
4.1
450
210
53
** 8.
12.6
575
SbO
39
6.
4.3
450
220
51
*» n
12.4
otfO
•280
44
** 7.
4.7
500
270
46
- 12.
12.5
525
260
50
•* 8.
5.0
575
270
53
- 13.
12.6
500
300
40
9
5.6
550
240
56
•* 14.
12.4
475
350
26
" 10.
5.8
650
230
65
' 15.
12.7
400
280
30 1
- 11.
6.0
675
250
63
* 16.
12.7
400
260
3.5 i
" 12.
6.1
725
200
72
- 17.
12 6
400
250
37
•* 14.
5.7
725
210
71
♦' 18.
12.6
375
240
36
•* 15.
5 4
725
220
70
'* 19.
12.6
350
190
46
** 16.
5.0
700
250
64
'* 25.
11.3
260
150
42 1
- 17.
4.5
700
220
as
♦* 26.
10.8
250
125
.50
** 18.
4.0
775
130
83
♦* 27.
10.3
270
150
44 ;
•• 28.
3.0
350
170
51
- 28.
9.8
260
140
46 ;
- 29.
2.8
250
140
44
*' 29.
9.1
270
170
37 1
" 30.
2.7
260
120
54
'♦ m.
8.4
250
170
32 j
** 31.
2.4
220
120
45
'' 31.
8.0
300
160
^7
Aug. 1.
2.2
190
110
45
June 3.
7.1
525
180
66 1
- 2.
2.0
160
120
2b
4.
6.9
425
180
58 1
- 3.
2.0
160
120
25
•* 5.
6.8
600
180
TO
" 4.
1.9
160
120
25
6.
7.1
625
170
73
5.
1.9
160
110
31
7.
7.0
550
180
67
** 6.
2.1
130
100
23
'* 8.
7.1
525
170
71
7.
2.2
150
100
33
9.
7.2
500
180
64
- 8.
1.9
180
90
31
** 10.
7.6
5«K)
170
66
9.
1.8
120
90
25
♦' 11.
7.8
425
170
53
" 10.
1.9
120
90
25
•* 12.
8.1
500
110
78
- 11.
1.7
110
85 •
23
•* 13.
8.4
450
190
58
- 12.
1.6
130
90
31
♦ 14.
8.7
400
210
48
•• 13.
1.6
110
85
23
♦• 15.
8.7
450
200
55
»» 14.
1.7
95
80
5
•♦ 16.
8.6
475
190
59
*♦ 15.
3.2
90
100
...._....
•• 17.
8.2
450
190
58
** 16.
5.4
150
100
•♦ 18.
7.8
450
190
58
*• 17.
2.0
140
100
29
•* 2f).
7.5
350
170
52
1
NOTK— stage of River corresponds to River Turbidities.
Date corresponds to Subsided Water Turbidities,
Silica Turbidity results given in Parts per Million.
\
OPERATION OF SUBSIDING BASINS
81
TABLE No. XXIX.
Showing the Operation and Efficiencies of Subsiding Basin No, z,
Using 4.8 Hours of Plain Subsidence,
Silica Turbidity.
Silica Turbidity.
Date,
1901.
Stap
River.
Date,
1901.
Stap
River.
Subsided
%of
Subsided
%of
River.
Water.
Removal.
River.
Water.
Removal.
April
22.
11.2
600
375
37
June
21.
7.5
350
140
60
i<
23.
11.2
550
220
60
22.
7.2
350
140
60
( 1
26.
11.6
575
150
74
23.
7.1
400 .
140
65
<(
27.
11.7
625
140
77
24.
7.1
400
150
62
((
28.
11.8
650
170
74
26.
6.9
375
160 •
57
(<
29.
12.0
675
110
84
26.
6.8
400
150
62
i(
30.
12 2
700
140
80
27.
6.8
400
160
60
May
1.
12.1
775
325
58
28.
6.3
450
120
73
(i
2.
12.2
725
180
75
29.
5.9
475
130
73
i(
3.
12.3
725
280
61
July
1.
5.2
475
120
75
<(
4.
12.3
700
350
50
2.
5.0
450
110
75
Xi
5.
12.5
700
350
60
3.
4.7
450
120
73
4C
6.
12.4
650
350
4^
4.
4.4
500
190
62
i(
7.
12.6
600
300
50
1 «'
6.
4.0
550
190
72 •
ii
8.
12.4
550
290
47
6.
4.1
45U
200
56
(i
11.
12.6
525
290
45
7.
4.3
450
190
58,
ii
12.
-12.4
500
220
56
8.
4.7
500
180
64
<(
13.
12.5
525
230
51
9.
5.0
575
180
69
. ((
14.
12.6
500
350
3Q ^
10.
5.6
550
180
67
((
15.
12.4
475
270
43
11.
5.8
650
180
72
I(
16.
12.7
400
230
42
12.
6.0
675
150
78 ■
l(
17.
12.7
400
210
48
14.
5.8
700
120
83
i(
18.
12.6
400
230
42
15.
5.7
725
190
74
-((
19.
12.6
375
230
39
16.
5.4
725
' 160
78
((
25.
11.6
260
85
71
17.
5.0
700
160
77
4(
26.
11.3
260
90
65
18.
4.5
7oa
170
75
((
27.
10.8
250
110
56
28.
30
400
160
60
a
28.
10.3
270
. 110
59
29.
3.0
350
130
63
*i
29.
9.8
260
150
42
30.
2.8
250
110
56
it
30.
9.1
270
150
46
31.
2.7
260
90 .
65
it
31.
8.4
250
120
52
Aug.
1.
2.4
220
90
59
June
3.
7.3
375
110
71
2.
2.2
190
110
42
*' ((
4.
7.1
525
110
79
3.
2.0
160
110
31
((
5.
6.9
425
120
72
4.
2.0
160
110
31
((
6.
6.8
600
120
80
5.
1.9
160
85
47
((
7.
7.1
625
120
81
6.
1.9
160
85
47
((
8.
7.0
550
120
78
7.
2.1
130
90
31
((-
9.
7.1
525
120
77
8.
2.2
150
75
50
((
10.
7.2
500
120
76
9.
1.9
130
70
46
.((
n.
7.6
500
120
76
10.
1.8
120
65
46
.!(
12.
7.8
425
75
82
11.
1.9
120
70
42
.({
13.
8.1
500
120
76
12.
1.7
110
65
41
U(
14.
8.4
450
150
67
13.
1.6
130
70
46
<(
15.
8.7
400
150
62
14.
1.6
110
75
32
((
16.
8.7
4o0
160
67
15.
1.7
95
95
((
17.
8.6
475
170
64
16.
3.2
90
90
({
18.
8.2
450
170
62
17.
5.4
150
80
47
((
20.
7.6
400
130
67
....
....
...
Note— Stage of River corresponds to River Turbidities.
Date corresponds to Subsided Water Turbidities.
Silica Turbidity results given in Parts per Millon.
82
WATER PURIFICATION
TABLE No. XXX.
Showing the Operation and Efficiencies of Subsiding Basin No.
Using J2 Hours of Plain Subsidence,
Date,
1901.
SU^e
River.
Silica
Turbidity.
Parts per mil.
River.
Sub-
sided
Water.
Suspended
. Matter.
Parts per mil.
River.
Sub-
sided
Water.
Bacteria.
Per cub. cent.
River.
Sub-
sided
Water.
Average Kfficiency
of Subsiding^ Basin
in % Removal of
Silica I Sus-
Tur- pended
bidity. Matter. I
Jan. 8
' 9
10
11
12
13
U.
16
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Feb. 1
2
3
4
5
6
7
8
9
10
11
12
18
14
15
16
17
18
19
20
21
22
23
24
25
26
27
2.4
2.U
2.8
2.7
2.9
3.1
3.0
3.0
3.0
3.1
29
2.7
2.8
3.0
3.4
3.8
4.2
4.6
5.0
5.4
5.4
5.8
6.2
6.1
5.9
5.9
5.7
5.4
5.1
4.8
4.7
4.8
4.7
4.5
4.5
4.5
4.7
4.8
5
5.2
5.4
4.7
4.9
5.9
5.8
5.6
5.7
5.3
170
180
180
170
160
170
150
150
180
160
170
220
250
200
200
160
170
150
160
160
170
180
190
210
200
260
280
260
270
250
270
260
230
210
220
200
210
210
220
220
210
210
210
220
210
230
230
220
220
250
260
90
85
65
65
90
85
100
70
90
loo
140
150
130
no
85
85
100
100
90
90
80
80
90
110
120
130
140
150
160
150
160
140
140
140
130
140
140
140
140
140
130
100
120
95
110
100
130
140
140
140
130
200
200
180
160
160
176
170
165
186
175
205
265
260
240
235
2a5
210
175
195
2CK)
210
230
285
325
345
390
455
455
415
380
370
116
285
250
250
245
256
266
290
270
295
275
275
275
290
285
290
280
290
360
310
66
60
60
60
76
90
75
60
85
145
125
110
100
95
115
135
100
65
70
75
80
85
70
60
100
140
135
130
115
90
80
75
90
105
100
90
90
90
95
105
100
75
95
70
85
95
105
115
115
110
110
600
600
100
1,300
850
6M)
550
600
800
350
60
260
950
1,000
650
760
700
500
600
600
660
660
575
960
1,800
1,100
1,100
1,800
4,200
3,800
6,000
2,300
2,600
2,100
4,500
3,400
3,100
3,000
2,800
2,000
1,200
1.200
2,200
16,000
10,000
15,000
4,600
6,600
15,000
8,500
6,000
220
375
950
6,000
13,000
27,000
15,000
12,000
550
600
650
1,200
300
800
5 200
17,000
4,700
29 000
31,000
49,000
20,000
14.000
16,000
14,000
9,500
1,200
4,8n0
6,100
1,800
2,000
1,000
1,400
1,300
950
1,800
6,000
9,500
6,500
6,000
48
63
63
62
44
50
33
53
50
30
18
32
50
45
58
47
41
33
44
44
52
55
53
48
66
50
50
43
41
40
41
46
39
33
41
30
33
33
36
36
38
52
43
57
48
66
44
36
36
44
50
72
70
67
63
53
4rt
56
64
54
60
17
37
39
58
62
60
51
34
52
15
63
20
64
7
62
62
50
63
77
81
71
64
70
71
72
76
78
35
68
58
60
80
68
65
66
14
67
56
61
66
73
65
74
71
58
67
68
64
36
69
60
...
70
65
OPERATION OF SUBSIDING BASINS
83
TABLE No. XXX.— Continued.
Showing the Operation and Efficiencies of Subsiding Basin No, i.
Using 72 Hours of Plg.in Subsidence.
Silica
Suspended
Average Efficiency
Turbidity.
Matter.
Baciena.
of Subsiding Basin
I
)ATE,
1901.
Stap
River.
Parts per mil.
Parts per mil.
'rn%
Removal of
Sub-
Sub-
Sub-
Silica
Sus-
Bac-
River.
sided
River.
sided
River.
sided
Tur-
pended
Matter.
Water.
Water.
Water.
bidity.
Keb
28
5.1
240
130
285
115
3,200
6,500
46
60
I^ch
. 1
5.1
230
120
255
100
3,800
3,200
48
61
16
4 (
2
4.7
210
110 '
240
85
2,800
4,9(0
48
65
• •«
( (
3
4.4
190
110
205
80
1,700
2,200
42
61
• *•
C C
4
4.3
190
86
215
75
1,400
1,900
65
65
...
( t
5
4 1
190
95
210
bO
1,600
350
60
62
73
C (
6 :
4.0
180
90
190
80
2,400
650
50
58
77
tl
7
3.8
180
85
225
80
1,500
400
55
64
73
((
8
3.4
210
95
260
75
1,100
3o0
56
56
68
1 (
9
3.1
180
90
…[truncated]