Document text
ACAS ^.ggj ■
- ■ .
Ao Experimental Water
Purification Plant and its Results i
5
Mun. & San. Engineering
B. S.
19 08
UNIVERSITY
OF
JLL. LIBRARY
UNIVERSITY OF ILLINOIS
LIBRARY
IN
Class Book Volume
My 0X-15M
4 -tN^^P
^ - 4-
AX EXPERIMENTAL WATER
PURIFICATION PLANT
AND ITS RESULTS
BY
FIDEL VI DAL LARRACAS
THESIS
TOK THE
DEGREE OF BACHELOR OF SCIENCE
IN
MUNICIPAL AND SANITARY ENGINEERING
COLLEGE OK ENG1NEEK I N< I
UNIVERSITY OF ILLINOIS
PRESENTED JUNK, 1908
teas
I- 3> £
UNIVERSITY OF ILLINOIS
June 1 r mS
THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY
FIDEL VI DAL LARRACAS. -
ENTITLED AN EXP ERI tIMT AL Y/ATER PURIFICATION PLANT AMD ITS RESULTS
IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE
degree of B acfcelcr of Science in Municipal and Sanitary
Engineering
Approved:
Instructor^ Charge.
head of department of Municipal and Sanitary
Engineering
114591
Digitized by the Internet Archive
in 2013
http://archive.org/details/experimentalwateOOIarr
L}> "L
INTRODUCTION .
All natural waters contain more or less foreign matters
either in suspension or in solution, and the degree of purity-
is dependent on the locality. These foreign matters may be
divided into three classes: (1) The corrosive impurities, such
as sulphate of iron ( FeSO^.), carbonic acid ( HgCOjj), etc.
(2) The scale-forming impurities, such as iron carbonates
Fe (HCO3), calcium carbonate CaCO-, etc.. (3) The alkaline
impurities, such as potassium and sodium carbonates NagCOs
and KCO3. All of these are more or less detrimental to boilers,
pumps, valves, and water pipes.
The University of Illinois water supply which is drawn
from the same geological formation as that of Champaign and
Urbana is no exception to the above. Prof. Bartow, Director
of the State Water Survey, and Mr. Lindgren of the University
of Illinois in their paper entitled w Some Reactions During
Water Treatment" have shown that the University water supply
presents " a variety of unsatisfactory features, viz: turbidity
on exposure to air, sediment varying in color from black to
red according as the amount of oxidation of iron salts varies;
trouble from crenothrix in the water mains j soft-scale, clogging
the feed pipes of boilers and trouble in dairying and photography*.
On account of this unsatisfactory condition the importance of
improving the University water by some treatment is evident.
It is the object of this thesis to aid by experiment in determin-
ing the best method of removing some (if not all) of the im-
parities named above such as, for example, iron, calcium
carbonates, turbidity, hardness, alkalinity and color by the
use of mechanical filter with the aid of a coagulant. For
convenience, the whole subject will be treated into four differ-
ent parts, namely:
(1) Theory.
(£) Description of the Experimental Plant,
(3) Operation and Results of Tests,
(4) Conclusion,
(1) THEORY.
The carbonates and iron in water may be removed or great-
ly reduced by coagulation, sedimentation and filtration. The use
of a chemical as a coagulant enables the filtration to be carried
at higher rate yet with greater efficiency. The coagulant with
the water forms a gelatinous precipitate which not only subsides
much more quickly than the suspended matter ordinarily contained
in the raw water but from its sticky gelatinous nature it has
the faculty of collecting and carrying down the suspended matters
in it.
Caustic lime is the only chemical that was used in con-
nection with the experiment, and this lime was in the form of
saturated lime water (Ca(OH) ). This acts upon the carbonates
of lime, and magnesium ( if there is any) which are in solution
in the form of bicarbonates . These substances react with the
soluble "bicarbonates to form insoluble carbonate of lime ( and
hydrate of magnesia); and carbonates of iron will be precipitat-
ed as hydrate of iron. Some of the reactions that take place
are :
Ca(HC03)2 -+- Ga(OH)o = CaC03 + 2H20.
Pe(HC03)2 2Ca(0H)2 = Fe(0H)o + 2H20.
The paper before referred to by Prof. Bartow and Mr.
Lindgren gave 4 stages of reaction taking place. " During the
1st. stage the reaction is between the calcium hydroxide and free
carbon dioxide. At the second stage, the calcium hydroxide
reacts with the calcium acid carbonate. In the third, the calcium
Hydroxide reacts with the sodium bicarbonate, and in the fourth
the calcium hydroxide reacts with the magnesium bicarbonate."
2. THE EXPERIMENTAL PLANT.
The experimental plant as shown on plates 1, 2, 3, 4, and
5 consists of two lime water mixing tanks and one lime v/ater
controller tank, one raw water supply tank, one sedimentation
tank, one rapid filter and one filtered water tank.
Raw water supply tank. -This tankis made of galvanized iron
and is circular in form, four feet in diameter and two and one
half feet deep, with a capacity of 255 gallons. This tank is
located on a elevated platform about eight feet above the floor,
close to the east side wall of the laboratory room. The head of
water in this tank is regulated by a float valve, and the supply
may be entirely cut off or regulated at will by a hand valve
on the outlet from the tank.
The influent and effluent pipes are both of one inch
diameter, the former leading from the pumping room thrubovered
wooden conduit to the supply tank, and the effluent from this
tank thru the room about seven feet above the floor to the
sedimentation basin.
Lime water tanks:- Branches from the supply main to the
raw water tank lead to two lime water mixing tanks which are
5.
made of #22 galvanized iron, and of different sizes. One, circu-
lar in form, is four feet in diameter and two and one half feet
in depth, with a capacity of 235 gallons and is located directly
above the other which is also of circular form, six feet in
diameter and three feet deep, with a capacity of 625 gallons,
and located on the same level as the raw water supply tank.
Pipes lead from each of these two tanks to the lime water con-
troller. This is square in form, its dimensions "being two feet
side and one and one half feet deep with a capacity of 45
gallons, and is provided with a float valve which regulates the
head of lime in it. A one-half inch effluent pipe connects it at
one inch above the bottom of same to the effluent pipe from the
raw water tank.
Sedimentation Tank:- The sedimentation tank, rectangular
in shape, is 15 feet long, 7 feet wide and 3.85 feet deep, made
of wood lined with tin, and having a capacity of 2950 gallons.
A slotted wooden baffle is placed across the tank at one and
one-half feet from the inlet end, and one wooden weir one-half
inch thick and 42 inches deep at one foot from the outlet end.
The inlet pipe enters the basin from above ending one and
one-half feet from its top and is provided with a float-valve.
The outflow pipe is located at the other end and at about two
inches from the bottom of the tank.
Filter:- The mechrnical filter as shown on plate5, is made
of # 1C galvanized iron 20 inches in diameter and nine feet in
depth. The bottom is provided with a drainage system consisting
of a two inch main collector with five one inch laterals and 19
6,
mechanical filter strainers obtained from PittsburgFilter
Manufacturing Company. The filter is provided with wash water
and air pipes which connect to the strainer system and Y/hich
may he shut off or opened by means of hand vales. The air is
piped from the boiler room and is under 30 pounds pressure. The
wash water is drawn from the University supply under pressure.
An overflow pipe is provided at one foot above the surface of
the sand to discharge the wash water. The head of water is
regulated by a float valve connected to the influent pipe. Tv:o
glass-gages are provided to measure the loss of head, one
connected to the filter above the sand and the other connected
to the effluent pipe close to the filter.
The total thichness of sand is 51 inches composed of
the following layers:
12 inches of one fourth to one-half inch gravel.
6 tr of - to one fourth inch gravel.
16
33 tf of sand.
The latter material came from Redwing, Minnesota, and has an
effective size of .43 m.m. and a uniformity coefficient of
1.51. xhis r*1 is aomewkat ©earsej? tkan that ordinarily used
in filtration plants, and the uniformity coefficient is low.
Filtered Water Controller:- The controller consists of a
galvanized iron tank two feet in diameter and twenty-one inches
ep with one "lu nt pipe from th filter, a float valve
and one inch discharge pipe controlled by one inch discharge
valve. The floatvalve maintains the head of the filtrate in the
tank' constant, and the jate valve regulates the rate of filtratio
7.
3. OPERATION AJTB RESULTS OF TESTS .
The method of operation was as follows: One -of the lime
water tanks was filled, with water , and sufficient lime was
added to make the solution saturated. The solution after set-
tling was allowed to flow from the tank "by opening the valve
to the controller. While this was running, mixing of lime
was done and solution allowed to settle in the other tank,
so that when the former tank runs out the latter may supply
the lime water. The controller is connected to the raw water
pipe which leads from the raw water tank to the sedimentation
"basin "by a inch cast iron pipe, the amount of solution used
2
bei"g regulated "by the amount of opening of a gate valve in
this pipe. This arrangement seemed to work fairly well at first,
after
but^a few days of the experiment some difficulties presented
themselves. These difficulties have, to the writer's opinion,
been due to two causes: (1) the clogging of the pipes, and(2)
the smallness of head from the controller. By this arrengement,
successful tests were made only by constant flushing of the
pipe. The above difficulties, therefore, necessitated the reno-
vation and redesigning of the system.
The arrangement of the new system was as follows: The
controller was raised three feet above its former elevation,
and the lime water to it was supplied only by the upper tank,
the lower tank being used as a mixer from which the lime water
was pumped by a hand pump to the tank above. The amount of
lime water was controlled just as before, and it flowed thru
a
a glass funnel to the raw water pipe. This new arrangement
seemed to work fairly well, and no trouble was experienced
during the experiment.
The filter was started on May first and tests continued
until May 16, hut no sample was taken till the 5th. The modifi-
cation of the system was made after tv/o fairly good representa-
tive samples CtrL^d iff e rent amount of coagulant under the former
system were taken, and this was on May 8. The coagulated raw
water was estimated to remain in the tank about eight or nine
hours, depending on the rate of filtration which varied from
3.7 to 4.4 gallons per minute or from 105 to 127 millions gallons
per acre per day. Samples of the raw water were taken only once
every time the filter was run, and they were taken several hours
"before those of the filtrate. The reason for taking only one
sample was that the condition of the raw water thruout the
experiment was practically constant as may be seen from the
table number 1. Samples from the sedimentation water were taken
at intervals of one hour, and usually two hours before the
samples of filtrate.
All these samples were analyzed for iron, alkalinity to
both phenolphthalein and methyl orange, for turbidity, hardness
and color. The methods used for these analyses wer<3 : For iron,
the color standard, concentrated nitric acid and potassium sulpho-
cyanide solution as reagents; for alkalinity, phenolphthalein
and methyl orange as indicators andsQ sulphuric acid; for tur-
bidity, the silica standard; for hardness, the soap method; and
for color, the color plates standard. The results are tabulated
9
on table 1 page 10 •
The average loss of head at the start of the filtration
was three feet and. five inches, and at the close of the run
was six feet and four inches.
The sand was washed in the following way: the influent
and the ef f luentvalves of the filter were closed. The air was
forced thru the sand for five minutes, the pressure "being regu-
lated by the amount of opening of the valve , and then clean
wash water was allo?/ed to flow up thru the sand until the
drained water from the filter appeared clear. The average length
of time in cleaning was 25 minutes.
10.
RESULTS OP CHEMICAL ANALYSES OP THE
INFLUENT , SEDIMENTATION and EFFLUENT.
TABLE 1
Kind
_r
o\
Wafer
Hour
collection
"Dale
i
collection
Am't. of
lime.Gr.
perg oil •
T?ote of
Fi'lt. Gal-
per rlin.
Alkaliniff+o
H-Orar^e.. Var\s
per Hill.
A|k. k>
Phenol-
"Rii-ts/ri.
Turbid.
p^r Mill.
Iron.
■Parts
pgr1 Hill.
Color.
Park
per Mill
Madness
parts
per Mill.
Raw
11:30
May 5
__ —
186.0
.00
10
39
49
407
Filtrate
4:00p.m.
»
9.17
4.36
178.0
0
0
25
0
371.5
it
8:30 "
it
it
tt
160.0
0
o
30
0
371.5
t»
9:15 "
tt
tt
tt
155.0
0
0
25
0
364.4
ti
9:45 "
tt
»
tt
155.0
0
0
30
0
3 64.4
Raw
5:00 "
.t 7
184.0
0
10
39
49
a o7 n
Filtrate
3:30 "
tt
11.63
3.95
152.0
0
0
20
0
300. 0
t»
5:00 "
tt
it
ft
146.0
0
0
20
0
300. 0
N
6:00 "
it
it
tt
150.0
0
0
25
0
507. 0
7:00 "
tt
it
it
149.0
0
0
25
0
300. 0
„
8:00 "
tt
tt
tt
146.5
0
0
20
0
314. 5
9:00 "
it
tt
tf
143.0
0
0
25
0
5 07.0
Raw
2:00 "
9
186.0
0
10
39
54
385.5
II
6:00 "
tt
186.0
0
15
39
49
5.5
Sedimen.
5:30 "
it
12.0
4.4
159.0
30,0
o
o
27
343.0
IT
6:00 "
it
tt
it
155.0
16.5
5
& 5
30
350.0
tf
7:00 "
it
it
tt
165.0
16.5
7
27
35
343.0
Filtrate
6:00 "
tt
tt
tt
162.0
0
0
0
550.0
it
8:00 "
it
it
it
163.5
0
0
0
7.0
11.
TABLE 1 (Cont.)
Kind
°f
Wa+er
Hour
c^ol lectin vi
Collection
Am* of
lim«.Gr
per gal
T?a+e of
Filrr.Sal.
pei-m*n.
Alk.ro M.
Orange. V^rb
f>er Kitlion
A|k. fo
Phenol,
ffcrlspern
Turbidity
TtartS per
Mill.
Iron
per Mill.
Color-
■Pbrts pc
Mill.
Mill.
Raw
2 :00p.n.
Hay 13
-186.0
0
10
39
49
385.5
Sedimen.
5:00 "
11
8.0
3.95
128.0
23
5
25
30
300.0
Filtrate
8:30 "
II
ii
it
130.0
19
0
25
0
500. 0
n
9:30 "
It
ii
ti
134,0
15
0
20
0
307.0
Raw
1:30 "
15 ■
185.0
0
10
49
385.5
Sedimen.
6:30 "
ii
G.O
3.8
136.0
5
2 5
30
300.0
ti
8:00 "
ii
ii
ii
137.0
23
5
0 c
3 0
3 00.0
Filtrate
8:00 "
ii
ti
ii
133.0
15
0
20
0
307.0
it
9:00 "
ii
ii
ti
133.0
15
0
20
0
514.5
Raw
5:00 "
1G
185.0
0
10
59
49
407.0
Sedimen .
5:30 "
ti
3.0
3.7
138.0
12
5
25
25
314.5
ii
7:30 "
ii
ii
it
140.0
15
9
25
328.5
Filtrate
7:30 "
ii
ii
ii
142.0
0
0
25
0
328.5
n
8:30 "
ii
it
ii
140.0
0
0
0
321.5
12.
TABLE SHOWING PERCENTAGE OP REMOVAL BY
SEDIMENTATION .
TABLE 2
Grains .
per
gallon,
Lime
Rate .
11 .gal.
per
acre/day .
PERCENTAGE.
Alkali.
Turb.
Iron.
Color .
i
Hardness .
127.0
14.2
46.0
32.4
O O . (~>
10.4
o
114.0
31.0
50.0
36.0
63 . 0
22.2
6
110.0
26.2
50.0
36.0
63.0
22.2
3
105.0
24.4
50.0
36.0
28.5
19.3
PERCENTAGE OP REMOVAL
BY SEDIMENTATION AND FILTRATION.
Lime
Grains per
gallon.
Rate in Mi 11.3a!
per acre /day.
PERCENT AG1
alkalinity
Iron.
Hardnes;
12.0
11.6
9.2
8.0
6.0
3.0
127.0
114.0
126.0
114.0
110.0
105.0
12.5
19.6
13.0
29.0
28.0
23.75
36.0
42.2
30.8
42.2
48.5
36.0
Vt Turbidity and color were entirely removed
8.3
25.2
9.6
21.3
19.4
S3 n 9
13.
4. CONCLUSION.
Table 1 pages 10 and 11 shows the general results of the
tests, and table 2 page 12 gives the percentage of removal by
sedimentation, and by sedimentation and filtration.
With 12 grains of lime per gallon and 127 millions gallons
per acre per day as rate of filtration, the percentage of re-
moval of alkalinity by sedimentation as referred to the raw
water was only 15; of turbidity 45; of iron 32 and of color
and hardness were 35 and 10.3 respectively; while with 3 grains
per gallon and 105 millions gallons per acre per day as rate
of filtration, the removal of alkalinity was 24,4%, of turbidity
50 %, of iron 36 %t of color 28.5 % and hardness 19.3 %. With
the exception in color the percentage of removal in the last
case was higher than in the former. These two rates represented
the maximum and minimum both of grains per gallon and rate of
filtration. 8 grains per gallon with 114 millions gallons per
acre per day seemed to be the best amount, as the percentage
of removal in all cases was higher; viz. : in alkalinity the
removal was 31 %, in turbidity 50 %, in iron 36, in color 63 %,
and in hardness 22 %•
Turbidity and color were completely removed by the filter.
The percentage of removal of alkalinity, iron and hardness by
14.
sedimentation and filtration did not differ much from that hy
sedimentation alone. 11.6 grains per gallon and 114 millions
gallons per acre per day as rate of filtration showed higher
percentage of removal of hardness and iron, hut low in alkalini-
ty; and 8 grains per gallon with the same rate of filtration
had better effect on alkalinity and iron hut deficient in
hardness. This variation of results together with the shortness
of test maketrather difficult to draw a very definite conclusion;
hut it seems to he safe to conclude that eight grains per gallon
is the he st amount for the treatment of this water.
The length of time for the treated water to pass thru
the sedimentation "basin was another factor that produced some
effect. In the higher rate of filtration, such as 127 millions
and 12 grains per gallon as the amount of coagulant, the treated
water was calculated to remain in the sedimentation basin for
eight hours, while in the lower rate, such as 114 millions
gallons and eight grains per gallon, the treated water was
estimated to remain in the tank for nine and one-half hours.
The results under these two conditions varied to some extent;
the longer the time of sedimentation the higher the percentage
of reduction was.
It was desired to use shorter periods of sedimentation
but owing to the clogging of the pipe leading to the sedimen-
tation basin this was imDossible.
The writer wishes to acknowledge his obligations to
Prof. Bartow and Mr. L. I. Birdsall of the State V/ater Survey
for their valuable suggestion in conducting the chemical analyses
GENERAL VIEW OF FILTER.
GENERAL VIEW OP SUPPLY AND
CHEMICAL TANKS .
18
Lime Water Controller
Enlarged View of ClearWcrter Controller
LtmeWciW Mixing Tank
Lime vJahsr Mining TanW
♦
21.
r1
5
Cears
Crra
Details ox \\\q Strainer Syslem
Dra/n p'f>e
\' Air fit fa
i-V/asfi 1/aJ-er
Filter
SKETC H
MECHANICAL FILTEK
socle ^ *= iff.
4
+ 4
■