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OBSERVATIONS OF SOME EUROPEAN WATER PURIFI-
CATION AND SEWAGE DISPOSAL PLANTS*
By Edward Bartow
During a trip to Europe in the summer of 1914, some of the
European practices in water purification, in sewage disposal, and
in laboratory control were observed. No special outline was made
for the trip, beyond a plan to visit certain prominent men who
would know the latest developments along the lines to be investi-
gated. No definite schedule was planned, so that places off of a
regular line might be visited, in accordance with the instructions of
the men consulted. After August first, owing to the war, nearly
three weeks of a gradually developed schedule had to be abandoned.
It was impossible to carry out plans to visit Strasburg to see the
fish ponds used for sewage disposal; Lun^ville to see the water purifi-
cation by means of ultra-violet rays; Frankfort, Cologne, the Essen
district and Ghent, to see special methods of sewage disposal. No
attempt was made to see any plants in the neighborhood of Paris.
In London all permits to visit the reservoirs of the water depart-
ment had been withdrawn, and armed guards watched the reser-
voirs day and night.
Many of the European water purification plants and sewage dis-
posal works have been described by others, an attempt will be made,
therefore, to describe only what seemed to be unique. Owing to
the fact that water purification and sewage disposal are so closely
related, a chronological order will be followed in the observations.
Hamburg was the first city visited. The water supply of Ham-
burg is taken partly from the Elbe River and partly from wells.
The water works are located on the river above the city, but, the
Elbe being a tidal water, at times the sewage polluted waters of
the river reach the intake. It is customary only during the ebb
tide to pump the water into the large settling basins. Altona
which adjoins Hamburg down the river, obtains its water supply
* Paper read before a special meeting of the Illinois Water Supply Asso-
ciation (Illinois Section of the American Water Works Association), November
11, 1914.
13
14 EDWARD BARTOW
from a point below the sewers of both cities. Reversing the prac-
tice of Hamburg, Altona pumps water into its purification works
only during the flood tide. The Elbe River through Hamburg and
Altona is therefore like a large tank disposing of the sewage which
is passed into it. The only treatment Hamburg sewage receives
is screening through revolving screens composed of aluminum bars
about one foot long, placed about one centimeter (a little less than
one-half inch) apart. The flow of the water in the river averages
1200 cubic meters per second. The dry weather flow of the sewage
is 3 to 4 cubic meters per second, and the wet weather flow 20 cubic
meters per second, so that there is ample dilution to prevent any
nuisance, and to allow the water to be satisfactorily purified for
drinking purposes. At the water purification plant alum is used
as a coagulant prior to sedimentation. It is thought that Hamburg
has the only purification plant on the continent where a coagulant
is allowed. The water, after passing through large sedimentation
basins, is filtered through slow sand filters (Fig. 1). These filters
are uncovered, and in winter are covered with ice. Owing to the
fact that there is a prejudice against the use of water taken from the
river, the water department is endeavoring to develop a ground
water supply. A number of wells have been sunk, and considerable
water obtained, but the Hamburg authorities are handicapped by
the fact that there is not sufficient area in Hamburg for proper
development of ground waters. Hamburg is unable to extend its
well system into Prussia, and, for the disposal of its sewage, has
purchased from Prussia an island in the lower Elbe. The situation
is similar to one in this country, where New York City cannot go
outside of New York State to Connecticut or New Jersey for its
water supply. The ground water obtained by Hamburg contains
so much iron that iron removal plants have been constructed.
While the sewage from the city of Hamburg itself is easily dis-
posed of by the dilution method, several of the smaller cities under
the direction of the Hamburg authorities are located so far from
the river that another means of purification is necessary. At Berge-
dorf, a city of 15,000 inhabitants, located about ten miles from
Hamburg, no water whatever is available for sewage dilution.
Purification is accomplished by Imhoff tanks and sprinkling filters,
followed by fish ponds.^ This is a modification of a system of
^ K. Allen, Municipal Engineering, 47, 197-201.
WATER PURIFICATION AND SEWAGE DISPOSAL PLANTS 15
purification introduced at Strasburg, under the direction of Pro-
fessor Hofer of Munich,^ where satisfactory results with a dilution
of two or three parts of pure water are claimed. At Bergedorf
with no dilution it has been possible to satisfactorily purify the
effluent from the sprinkling filters. The purification is accomplished
with the assistance of water plants (Fig. 2) which apparently remove
the toxic properties of the sewage, and make the water suitable
for fish culture. Fish placed in the ponds in the spring grow rapidly
Fig. 1. Slow Sand Filters, Hamburg, Germany
during the summer. The flesh is good, especially if the fish are
transferred to pure water for one or two weeks before they are
eaten.
At Berlin the Laboratory for Water Hygiene, located at Berlin-
Dahlem, was especially interesting. In 1901 the Royal Research
and Testing Station for Water and Sewage Purification was estab-
lished. At the end of twelve years the organization had grown so
^ Hofer, Fischer ei Zeitung, 16, 148.
16
EDWARD BARTOW
much that a new building costing $125,000 was constructed (Fig. 3).
The name of the organization has been changed to ^'Landesanstalt
fiir Wasserhygiene. ' '^
This laboratory has control of the water supplies and sewage
disposal plants in the province of Prussia. It also does commercial
work for other German provinces and for foreign countries. Work
of investigation is often done in cooperation with officers in cities
and villages, and joint articles are frequently published by members
of the staff and the city officials. At the present time the staff
Fig. 2. Fish Pond and Laboratory of the Bergedorf, Germany, Sewage
Disposal Works. Photograph by Dr. Keim
numbers forty workers. The scientific publications from the labo-
ratory are of great value. The new building contains library space
which will accommodate 30,000 volumes. In July, 1914, one hundred
and one journals were regularly received. An attempt was being
made to have available for the use of the laboratory staff all liter-
ature in all languages, concerning water. In April and October
instruction is given to water works men in methods of water supply
and sewage disposal. Regular lectures are given, and the men are
^ Mitteilungen aus der Koniglichen Landesanstalt fiir Wasserhygiene, 17.
WATER PURIFICATION AND SEWAGE DISPOSAL PLANTS
17
taken on trips to interesting plants in the neighborhood of Berlin.
Professor Dr. Thum of the laboratory very kindly outlined several
trips which would be most advantageous to take in the limited
time which could be devoted to this section.
The water supply of Berlin is obtained partly from lakes and partly
from wells. In BerUn, as in Hamburg, there is a prejudice against
water from surface sources, and the authorities are endeavoring to
replace the lake supplies by ground water supplies. At Mugglesee
about one-third of the slow sand filters originally used to filter lake
Fig. 3. Laboratory for Water Hygiene, Berlin-Dahlem, Germany
water have been given over to the removal of iron from ground water
supplies obtained from wells near the lake. The water is pumped
from the wells to elevated distributors, from which it trickles over
many series of wooden gratings, during which process the iron
becomes completely oxidized.
A new plant at Wuhlheide obtains ground water from eighty
driven wells. It had been in operation only five days at the time
of this visit. The water from the wells is pumped to the upper
part of a high building (Fig. 4) and sprayed through special nozzles
over beds of coarse gravel. The water having been thoroughly
aerated and the iron oxidized, it is passed through pressure filters
18 EDWARD BARTOW
(Fig. 5). The plant had been in operation only a few days, but,
from the experiments from which the plant was designed, it is ex-
pected that good results in iron removal will be obtained.
The Prussian authorities are very particular to protect the streams
from pollution by sewage. This is especially necessary because of
the small flow and the sluggish character of the streams. Berlin
proper owns large irrigation fields to which the sewage is pumped;
43,000 acres in all are owned; 21,000 are in use. It is rumored that
Fig. 4. Iron Removal Plant of Berlin Water Works, Wuhlheide
Berlin is giving up sewage irrigation. Berlin proper is not doing
so. The suburbs have, however, found it necessary to adopt bio-
logical processes of purification because of the lack of suitable land
for irrigation fields. The sewage from twelve districts in Berlin is
pumped to various sewage fields. The fields at Gross Beeren are
the largest in extent, and are typical of all the fields. The sewage
passes through a pressure pipe line. An indicator tower shows the
rate of flow. The heavy material is removed by open tanks. From
the tanks it flows by gravity through open channels to the fields.
WATER PURIFICATION AND SEWAGE DISPOSAL PLANTS
19
The land in the fields is rented to the peasants, who are willing to
pay twice as much for lands inside these irrigation fields as for land
outside. On some of the fields several crops are harvested each
year. The vegetables raised were especially noteworthy, most of
the vegetables used in Berlin being obtained from the sewage farms.
One other crop is especially noteworthy, Italian rye grass, which
may be harvested six times during the season. It grows to the
height of a meter a month.
1
f 1
rxfTi n II
I
■ ■
Fig. 5. Pressure Filters, Iron Removal Plant, Berlin Water Works,
w^uhlheide
Tanks or sprinkling filters are in use at Wilmersdorf, one of the
larger suburbs, and in other parts of Greater Berlin.
Especial attention was called to the Reinsch screens* in use at
Eberswalde. These are revolving screens having numerous holes
about YS" i^^ch by \ inch. The screens are cleaned by revolving
brushes. The sludge obtained is sold to the farmers who allow it
to ripen for use as a fertilizer. Very complete purification is ob-
* Engineering and Contracting, 42, 273-6.
20
EDWARD BARTOW
tained at Eberswalde. The sewage, after screening, is passed into
septic tanks and through sprinkling filters with a unique system of
distribution (Fig. 6). The sewage passes to a trough along the side
of the filter beds. From this trough it is syphoned to a travelling
cylindrical distributor containing numerous buckets. When these
buckets are filled the weight causes the traveler to move. A check
at the end of the bed reverses the flow and the direction of the traveler.
^^^^^^^O^^D^^^^^^^^^^^^I
^
L^ ) * ^^^^^Bp^^^pi^^
^^P^^Bhi
1^^^^ j^^g^^^gjj^^iMgv
BHBHIr "'12!~^^^H
I^^R-l
*t- _... ^^^^^^H|
P"^
yi
Fig. 6.
Sewage Distributors Sprinkling Filters, Eberswalde,
Germany
It then passes through contact beds and is finally discharged into a
canal.
At Copenick, another Berlin suburb, the sewage is mixed with
finely ground lignite or brown coal, and a small amount of alum to
serve as a coagulant. A very complete mixing is obtained by means
of perforated baffles (Fig. 7). The mixing is much more satisfactory
than when the baffles were solid. The thoroughly mixed sewage
and lignite pass to large sedimentation basins. Much of the sus-
pended matter settles near the inlet. Very little baffling is needed.
WATER PURIFICATION AND SFWAGE DISPOSAL PLANTS
21
and an effluent satisfactory to the government authorities is obtained
Three sedimentation basins are provided. While one is in use as a
sedimentation basin, in the second the sludge is being dried, and in
the third the dried sludge is being removed. The dried sludge is
burned for fuel, alone in the furnaces under the low pressure boilers,
and mixed with one to two parts of coal under the high pressure
boilers, which supply power to the electric light plant of the city.
■^-dV*^-
»»^:
Fig. 7. Perforated Baffle, Copenick, Germany
It is stated that more satisfactory drying of the sludge takes place
when it is piled to a height of several feet, than when spread out in
a thin sheet, probably due to the pressure exerted on the lower por-
ous layers.
At Dresden the water supply is obtained from wells. Serious dif-
ficulties have been experienced because of the manganese content of
the Dresden water supply. Service pipes become filled with a black
precipitate, and the water cannot always be used for the laundry.
Two manganese removal plants are in operation. One consists of
22 EDWARD BARTOW
gravity filters built in the original reservoir. The water passes
through coarse sand on which manganese removing algae have been
developed. These filters are washed by reversing the current, and
are probably the nearest approach to the mechanical gravity filters
in use in the United States. The second plant consists of pressure
filters. One-half are filled with manganese permutit and half with
gravel on which a manganese removing organism has been allowed to
develop. Both processes are satisfactory, but owing to the economy
of the sand and manganese removing organism this process seems
to be better than the manganese permutit. A very satisfactory ac-
count of the experiments performed at Dresden is given by Tillmans.'
Reinsch screens have been recently adopted at Dresden for sewage
treatment. The dry weather flow is taken care of by one screen.
The storm water sometimes requires four to be put in operation.
Without further treatment the sewage is allowed to flow into the
Elbe. There is sufficient diluting water to render the sewage in-
nocuous.^
No photographs could be obtained of a sewage disposal plant at
Coethen, as the plant was visited during a heavy rain storm and pho-
tography was out of the question. This plant has been designed by
Baumeister Benzel with Dr. Dunbar of the Hamburg Hygienic Labora-
tory as consultant. By settling ninety-two per cent of the suspended
matter is removed, and the sludge is withdrawn before it has time
to putrefy. In the bottom are sixteen transverse divisions, each
sloping to a trough to which the sediment settles. When this sedi-
ment is to be removed, a sliding door separates the trough from the
upper part of the tank. The opening of a gate on the side of the tank
allows the greater part of the sludge to flow out, the balance is drawn
out by means of a hoe. The gate is closed, the trough filled with
water and the sliding door opened without any disturbance of the
liquid above. The effluent from the tank passes to sprinkling filters
which are well constructed with an outside concrete retaining wall of
a special design. In the center is a specially designed piece of con-
crete so arranged that the underdrains can be flushed out with hose
whenever desired. Green algae were growing in the effluent drains,
showing a very satisfactory purification. Owing to the fact that the
plant is new, and that it takes care of both sanitary sewage and
^ Journal fur Gasbeleuchtung und Wasser Versorgung, 57, 713-24.
^ Datesman, Journal of the American Water Works Association, Vol. 1,
365.
WATER PURIFICATION AND SEWAGE DISPOSAL PLANTS 23
storm water, and that comparatively few sanitary connections have
been made, the plant should receive a more extended trial before
the design is unreservedly recommended.
At Magdeburg the Puech-Chabal filters of the Magdeburg water
system were visited. Magdeburg has the only large plant of this
kind. The authorities are apparently satisfied with it for they are
doubling its size. At Magdeburg they use not only the prefilters,
but also the socalled rapid filters and final sand filters. It may be
necessary to take such precautions with the water from the Elbe,
but the installation is certainly very expensive and the cost of filtra-
tion must be high. A very good description of these filters is found
in Engineering, 89, 117, 132, 164.
At Munich the sewage without any purification whatever is al-
lowed to flow into the swift flowing Isar River. Sewage purification
is unnecessary because the water below the city is not used for drink-
ing purposes and is too cold for bathing. The engineer stated that
within sixty miles all traces of sewage had disappeared. Owing to
the outbreak of the war, Munich was the last German city visited.
The cities visited in Germany furnish a good series of illustrations
of sewage disposal methods, from straight dilution up to the most
thorough treatment.
Owing to the war the London water works were under an armed
guard, and it would have been necessary to obtain special permis-
sion to visit the plant. Under those circumstances it seemed unwise
to ask the authorities for the special favor.
An interesting plant visited in England was the water softening
plant of the Woolcombers Ltd. at Bradford, where 50,000 gallons
per day of water having a hardness equivalent to thirty grains per
gallon were softened to zero by lime, soda and permutit. Permutit
alone was not satisfactory and the combined soda ash, lime, permutit
plant was installed. The water is first treated with lime and soda,
passed through a settling tank, then over calcium permutit to remove
the suspended matter and excess of alkalinity. A permutit filter
gives the final product of zero hardness. The process is said by the
chemist and superintendent to be very satisfactory. Two pounds
of soap per grain per gallon per 1000 gallons is the saving made.
This is a saving of 60 pounds per thousand gallons.
The largest and probably the only municipal permutit water sof-
tening plant is located at Hooten, near Liverpool. This plant
was built to furnish a water guaranteed to have less than ten
24 EDWARD BARTOW
grains per gallon of hardness. The original water contains about
thirty grains per gallon. Two-thirds of the water is reduced to a
hardness of zero, and is then mixed with one-third its volume of the
original water. Owing to lack of time, the plant was not visited,
but, in an interview Mr. Bettle, the superintendent, stated that the
process was satisfactory, and that, if it were necessary to enlarge
the plant, the same process would be used.
An interesting feature in sewage purification, aeration, was ob-
served at Manchester. The preliminary experiments have been de-
scribed in the 1914 Anniuil Report of the Rivers Department of the
Corporation of Manchester. This process in brief consists in blowing
compressed air through sewage until what is known as activated
sludge is developed. This sludge added to sewage and stirred by
air has the property of purifying the sewage very rapidly. For
example, with a tank containing 1300 cubic feet in which are 300
cubic feet of activated sludge, 1000 cubic feet of sewage can be
treated every six hours, or 4000 cubic feet of sewage can be treated
daily. This allows four hours for treatment, two hours for settling,
emptying and filling. It is claimed that by this process a sewage
efiluent can be obtained which is in better condition than an efiiuent
which has passed through Imhoff tanks and sprinkling filters. If
the claims of the process are borne out by further experience, it is
expected that considerable sums will be saved in the construction of
sewage purification works. Professor Fowler, under whose direction
the experiments have been carried out, has consented to serve as
advisor for carrying on experiments in the laboratory of the Water
Survey. Later his services would be available as consultant for
the construction of plants on a larger scale. ^
To show the stress under which water works men are working, it
need only be stated that in one place six rifles were leaning against
the wall of the office, and the superintendent stated that the three
plants of his company were watched by armed guards night and day.
The men in charge of the various plants visited were very cordial,
and, even after war broke out, when many of the assistants had vol-
unteered and extra work devolved on those left, most courteous at-
tention was extended.
^ Ardern and Lockett, Jour. Soc. Chem. Ind. 33, 523-39.