ap-4-10.dvi

Acta Polytechnica Vol. 50 No. 4/2010

Prague’s Sewerage System in the 1930’
and the General Sewerage Project (1933–1936)

K. Drnek

Abstract

Prague’s sewerage system was built at the end of the era of the monarchy in the united town that Prague was transformed
into. The system was soon overloaded, and was not able to remove all the sewage produced by the citizens.
To deal with this hygienic threat, the city council and the management of the wastewater services undertook several

actions to build a new system or improve the existing system. The most ambitious and extensive measure was the general
project carried out between 1933 and 1936.
The project was invented to resolve the problem once and for all by introducing new ideas and cut out the problem of

placing a new sewage plant instead of the old one. For the present-day observer it also offers a range of spectacular and
interesting ideas on urban wastewater treatment.

Keywords: sewerage, sewage plant, Máslo-Douda project, Řež, competition, projects, Dorr, Čistá půda, Roztoky.

1 Introduction to the problem

OnJanuary 1st 1922GreaterPraguewas formed. The
cities ofPragueand their surroundingsweremade into
a single capital city. Amongst other problems (admin-
istrative or technical), the city council was faced by
the problem of providing adequate treatment for the
sewage discharge by citizens in thewhole city. At that
time, the city was using the prewar Prague system,
which had only been extended and improved within
the limits of prewar technology.

1.1 Original sewerage

The sewerage system in prewar Prague was success-
fully finished in 1906 after almost 20 years of con-
struction. It covered 88509 km2 of settled area, and
all the sewage was drained to central sewage plant in
Bubeneč, near the Imperial Island (Císařský ostrov).
This sewage plant used a mechanical system for

treating the sewage. The wastewater was delivered to
the plant, where it passed through first line of filters,
the coarse racks (česle). This procedure removed the
coarse trash – wood, old cloth and remnants of food.
The nextphase removedthe sand fromthewater. Due
to thedirty streets, thewaterwas full of sand, itwould
have been wasteful not to recycle the water.
The grid chambers (lapač písku) were pools 34 m

in length and 6m in depthwith a slightly sloping bot-
tom. The water passed slowly through it and heavier
sand sank to the bottom, from where it was collected
and taken away for disposal.
Then water passed through the fine racks and fi-

nally into the primary clarifiers (usazovací nádrž),
where the final sludge was separated. The water was

then discharged into the river and the sludge into the
sludge drying bed (in winter) and into a sludge barge
(in summer).

1.2 Limitations of the old sewerage
system

The sewerage and the treatment plant were designed
for only 500000 people with 120 l of sewage per day
and person. When the capital city of Prague was es-
tablished, the numbers of users and the area that was
covered rose dramatically.
In 1929, when the possibility of building a new

system was raised, the area to be covered was about
172104 km2 and there were more than 600000 users
of the system. Besides the late 19th century technol-
ogy,whichwas not able to dealwith amount of sewage
discharged by all the citizens, the sludge and the pol-
lution of the river were major problems. The amount
of the sludge gradually rose to a level of more than
250 m3 per day, and dealing with this huge amount
was becoming problematic. The second problem was
that the riverwas slowly losing its self-cleaning ability,
and thus the old sewage plant was also losing its main
pillar.

1.3 Project in 1929

In 1929, first attempts were made to prevent the city
falling into serious hygienic trouble. Ing.E.Máslo and
Ing.V.Doudawere asked to set up a project for a new
sewage plant, fully compatible with the old canaliza-
tion system. They submitted their proposal for autho-
rization in 1929.
Both engineers set out to locate the sewage plant

outside the city precincts, in order not to subject the

Acta Polytechnica Vol. 50 No. 4/2010

citizens to the smell of the sludge and to be able to
handle this valuable agricultural product better and
more comfortably. The riverbankby thevillageofŘež,
about 11 km from the old sewage plant was chosen as
thebest location. Thenewplantwasdesigned to clean
the water in the old way. The treatment was only
mechanical, because the advanced biological methods
were still controversial. Mechanicalmethodswere also
much cheaper.

Fig. 1: Picture of the original “Máslo-Douda” project

While the Douda-Máslo project was passing
through the authorization procedures, Ing. Zika, the
chief of Prague’s sewers, introduced new projects to
build sewage plants with biological purification either
in Řež or on Imperial Island.
This dualism in planning came about because the

planning of these complicated systems took years,
and in the meantime the technology was advancing
very rapidly. The originally proposed technology was
outdated before the project reached the construction
stage.
Zika’s project introduced the problem of how to

manage all projects to meet the rising demands of the
citizens for a clean river. Thenew sewageplant on Im-
perial Island was cheaper, but the authorization pro-
cess was already running and some land in the neigh-
borhood of Řež had already been bought for the new
sewage plant.

2 Competition

As the result, the city council held a competition to re-
solve the questionof the best location for anewsewage
plant and to introduce new ideas. The competition
was announced on May 2nd, 1933, and the deadline
wasMarch15th, 1934. The competitionwas open only
to citizens of Czechoslovakia.
A commission was nominated by the city coun-

cil and comprised 17 members and 2 experts. Dur-
ing the standing time of the commission, 2 mem-
bers died and others were nominated to replace
them. The committee finally consisted of the fol-

lowing members: Ing. B. Bartošek, Ing. O. Cvrk,
MUDr. J. Čančík, Ing. V. Douda, Ing. A. Ernest,
Ing. K. Holinka, Ing. V. Krouza, Ing. T. Mrkvan,
Ing. A. Nový, MUDr. L.Procházka, PhDr. F.Schulz,
Ing. Arch. V. Prokop, Ing. Dr. J. Racek, arch. F. Ši-
máček, Ing. E. Thoma, Ing. F. Topinka, Ing. B. Von-
dráček, Ing. Dr. V. Vrbenský, Ing. R. Žižka.
The rules of the competition set several conditions:

• Theaverageamountof sewageperdaywas129 l in
1927 and 118 l in 1929. TheMáslo-Doudaproject
set a value of 160 l.

• The number of users in the period between 1940
and 1960 would rise from 1 mil. to 1.6 mil. In
1929 there were only 601000 users.

• The treated sewage should contain notmore than
250 mg of dry sludge. Mud taken within clean-
ing processmust not rot, sand from the sandpool
must not contain more than 10 % of dry residue,
sludge from the sedimentation tank should not
contain more than 91 % of water.

• The location of the new sewage plant must not
offend hygienics and aesthetics. It could be lo-
cated in a populated area but the hygienic mea-
sureswouldhave tobemore accurateand stricter.

• The new sewage plant was required to treat all
sewage from the city.
Each project was evaluated in terms of:

• location
• technical elaboration of the project
• hygiene
• system economy
• chemical processes
• agricultural interest
• mechanical processes
• influence on the river
• space for improvings
• cost

3 The projects
Fifteen projects were submitted before the deadline.
Finally, only 13were admitted and 2were rejected be-
cause they did not comply with the conditions. How-
ever, they were so interesting that the committee also
screened them.
I have categorized the projects into four groups.

I will deal with the three projects, in greater detail.
However, I will also consider projects that were as-
sessed as non-competitive because they did not deal
with all problems and were not selected to carry out
the project.

3.1 Projects locating the plant on
Imperial Island

Projects located on Imperial Island, where the old
treatment plant was, relied on modern treatment pro-
cedures without creating a bad smell or hygienic trou-

Acta Polytechnica Vol. 50 No. 4/2010

bles, which would have prevented the construction of
a sewage plant inside the city limits. The sludge, a
major cause of bad smell, would be pumped to a place
located somewhere outside the city.
However, the Island was not an uncontroversial

location. First, the state regulation committee was
planning to use the Island as a well-located recreation
area. Second, the river in this place was already very
dirty, and locating the plant there would cause even
more pollution inside the city. Third, the regulation of
the river meant that there was not a sufficient stream
there, and regular floods were a constant threat.
Fourof theprojects located the sewageplanton the

island: “Ostrov”, “Zdraví”, “Zdraví všem” and “Čistý
vzduch”. Only two of them were adjudged worthy to
be bought – “Ostrov” (15000 Kč) and “Zdraví všem”
(10000 Kč). All of them suffered from being located
on the island. Although this locationwas not banned,
it prevented the projects from being selected for im-
plementation.
Each of the four projects proposed the same treat-

ment process. After the mechanical processes, tradi-
tionally a system of screens and grit chambers, there
was a biological process in aeration tanks. The sludge
was then left for some time in the final clarifiers and
was finally transported through pipelines to sludge
drying beds somewhere outside the city.

Table 1: Survey of the projects in the Island group

Project Creator Price

Ostrov Ing. J. Staněk 91 mil. Kč

Ing. J. Ledvinka

Ing. G. Novák

Ing. V. Maděra

Ing. V. Hoffmann

Zdraví L. Bill a Comp. 48.8 mil. Kč

Dr. K. Skorkovský

Zdraví všem Ing. E. Zejda 290 mil. Kč

Čistý vzduch Lanna comp. 436.5 mil. Kč

3.2 Projects in Roztoky

The projects in this group located the new plant in
Roztoky. The group contains the projects: “Roztoky”
and “Praze ku zdaru”. Both projects involved both
mechanical and biological water treatment. The sys-
tem was almost the same as in the group of plants on
the Island. The differences were in the details. Since
the “Roztoky” project won the third prize, and will
be discussed later, I will write only about the second
project.
“Praze ku zdaru” was interesting in the way it

planned to use the old sewage plant. It proposed
coarse cleaning in Bubeneč and only water without

garbagewouldbefloateddowntoRoztoky. The sludge
disposalwas alsodifferent. The sludgewouldbe trans-
ported immediately by train and by barge. This was
themainproblemthatprevented theproject fromwin-
ning. However, the project contained good ideas and
was bought for 15000 Kč.

Table 2: Survey of the projects in the Roztoky group

Project Creator Price

Praze ku zdaru Ing. J. Gregor 347 mil. Kč

3.3 Projects next to the Labe

Third group contains projects planning to discharge
their sewage into another river than the Vltava, into
the Labe. These projects are “Spád” and “ Druhá
řeka”. Both of them planned to use long tunneled
pipelines to get the sewage fromPrague to the sewage
plants (16 km for “Spád” and 16.7 km for “Druhá
řeka”, about 14 km underground). Both projects also
proposed a natural biological treatment process, as bi-
ological pondswere plannednext to the sewageplants.
Themechanically treatedwaterwould be released into
these natural pools and would be cleaned naturally.
Due to the locations, these projects had problems

mostly with the incoming pipelines and with the river
Labe itself, which has a slower water speed than the
Vltava. In addition, it would have been really difficult
and expensive to construct such long pipelines.

Table 3: Survey of the projects next to the Labe

Project Creator Price

Spád Ing. J. Lanč 157 mil. Kč

Druhá řeka Doc. E. Snížek 258 mil. Kč

Ing. B. Belada

3.4 Projects with special treatment
programmes

The projects in this group proposed some special way
to dispose of the sewerage. The “Hygiena 3” project
located the plant next to Drahaňská rokle. After me-
chanical cleaning of the sewage, the sludge was to be
coagulated by an electrolytic process on 27600 elec-
trodes. However, this treatment method was consid-
ered too expensive. Nevertheless, ideas put forward
in the project were so interesting that city bought the
project for 5000 Kč.
The “Závlaha” project proposed three sewage

plants, including the old plant in Bubeneč, and also
one subsidiary sewage plant, where preliminary filtra-
tion treatment would be done. Then the sludgewould
be transported by pipeline (18.92 km long, the longest
in all the projects) to the main plant near to the vil-
lage ofVeltrusy,where itwouldbedeposited ondrying

Acta Polytechnica Vol. 50 No. 4/2010

fields. On these fields the sludge would undergo bio-
logical treatment. The project was too expensive, the
cleaning process was not very effective, and a huge
area of land would have had to be bought. However,
there were some good points in the project and it was
bought for 10000 Kč.
The last project, “Úspora”, was only a small and

modest proposal to reconstruct the old sewage plant
in Bubeneč. However, it contributed several ideas
on how to reconstruct the old facility effectively and
cheaply. This project was assessed as apropriate and
was bought for 15000 Kč.

Table 4: Surveyof theprojects proposing special treatment

Project Creator price

Hygiena 3 Ing. J. Roth 199 mil. Kč

Ing. F. Ballasko

Ing. Dr. J. Bulíček

Závlaha Prof. Ing. J. Zavadil 537 mil. Kč

Úspora Ing. J. Staněk 15 mil. Kč

Ing. J. Ledvinka

Ing. G. Novák

Ing. V. Maděra

Ing. V. Hoffmann

4 Winning projects

Three projects were considered good enough to be
awarded full prizes and were bought for implementa-
tion in the wastewater treatment system for Prague.
These projects were: “Dorr”, “Čistá půda” and “Roz-
toky”.

4.1 “Dorr”

This project located the new sewageplant on the right
bank of the river in Podhoří, 2 km away from the ac-
tual sewage plant. The cleaning process was divided
into a mechanical part and a biological part.
The mechanical part consisted of coarse and fine

racks, which were cleaned by hand and also mechani-
cally. The sand pools were square with rounded cor-
ners and the sand was collected with special Dorr
system-rakes (named after well knownAmerican com-
pany Dorr, which specialized in sewer systems). The
sedimentation tanks used the same system. The acti-
vated tanks used theRelling-Hausen system (a combi-
nation of shaking and aeration). The settlement pro-
cess was almost the same as sedimentation tanks. For
the digestation tanks, it was planned to use a new
thermophile methane fermentation system. The fer-
mented sludge was then to be transported by pipeline
to Čimice.
The “Dorr” project was declared the best project

in the competition. All members of the commission

agreed that “Dorr” had some of the best technical
drawings and carefullymade calculations. The “Dorr”
project was awarded 55000 Kč.

Fig. 2: Picture of the winning “Dorr” project

4.2 “Čistá půda”
This project, designed by the Lanna company, was lo-
cated in the originalplace of theDouda-Másloproject,
near to the village of Řež. It had also considered a lo-
cation nearRoztoky, but this town refused permission
to build a sewage plant to its neighborhood, as a local
water plant was planned for this location.
The incoming pipelines from the townwere to take

sewage from the whole city. The pipelines were to be
10.7 km in length (only 0.92 km underground). The
sewage stream was to be natural, slightly accelerated
by pumping water from the river.
The preliminary treatment and filtration of the

garbagewasplanned ona systemof double racks,with
4 grit chambers and 4 skimming tanks. Primary clar-
ifiers were planned with the skimming BAMAG sys-
tem (rakes moving in the vertical axis). Aeration was
to be performed either in aeration tanks or in tanks
with a sprayed area. The digesters were also from
the BAMAG system, like the primary clarifiers. They
were plannedwith amoving ceiling to facilitate access
to the sludge. At the end of the process, the sludge

Acta Polytechnica Vol. 50 No. 4/2010

wouldbemovedto sludgedryingbedsnear the villages
of Drasty and Tursk.
The project was awarded second place and prize

45000 Kč. It was adjudged the most precise and well
planned, but it was also one of the most expensive
projects and therefore did not meet the financial re-
quirements of the competition.

Fig. 3: Picture of the “Čistá půda” winning project

4.3 “Roztoky”

This was one of the group of projects which located
their sewage plant inRoztoky. The creators chose this
location as the first acceptable place outside the city
boundaries. This made the incoming pipelines shorter
and cheaper – they were only 7.4 km in length.
The project proposed preliminary treatment of the

sewage in theold sewageplant inBubeneč,where there
is a different filter system for the upper and lower area
of the city. The pipelines joined up behind the plant
and pumped the treated sewage into the primary clar-
ifiers in Roztoky. Aeration was performed in aeration
tanks using the HURD system. The diggested sludge
was to bemoved to special drying beds near Zdiby.

Table 5: Survey of the winning projects

Project Creator price

Dorr Ing. J. Staněk 89 mil. Kč

Ing. J. Ledvinka

Ing. G. Novák

Ing. V. Maděra

Ing. V. Hoffmann

Čistá půda LANNA comp. 480 mil. Kč

Roztoky Ing. J. Staněk 193 mil. Kč

Ing. J. Ledvinka

Ing. G. Novák

Ing. V. Maděra

Ing. V. Hoffmann

The project won third place and received a prize
of 20000 Kč. It was not considered such a carefully
made project as the first two, and it did not take into
account an appropriate amount of sludge. Neverthe-
less, it was rated one of the best.

Fig. 4: Picture of the “Roztoky” winning project

5 Conclusion
The results of the competition were announced on
May 22nd, 1935 and until 1936 there was a debate on
the winning and losing projects.
The winners of the competition have been dis-

cussed above. However, the final outcome was a sur-
prise. Although therewere threewinning projects and
another 6 projects were bought for future considera-
tion, none of them was accepted as good enough to
replace the original Máslo-Douda project and none of
them was successfully constructed.
By the time the competition was completed, the

project for a sewage plant in Řež was licensed. The
original goals of the competition, bringing innew ideas
and designs for a new sewerage system for Greater
Prague, were fulfilled, but they were never imple-
mented.
For the record, how did the Máslo-Douda project

end up? It, too, was never completed.

Acta Polytechnica Vol. 50 No. 4/2010

Acknowledgement

The researchdescribed in this paperwas supervisedby
Prof. I. Jakubec, Faculty of Arts, Charles University
in Prague.

References

[1] Keclík, T.: The competition on a general project
for new sewage plants for the capital city Prague.
Gas, water and sanitation engineering, 1936,
Vol. 16, No. 4, p. 1–3.

[2] Schulz, F.: Report on the conclusion of the com-
petition. Gas, water and sanitation engineering,
1936, Vol. 16, No. 4, p. 3–5.

[3] Topinka, F.: Brief survey about the projects.Gas,
water and sanitation engineering, 1936, Vol. 16,
No. 4, p. 7–16.

[4] Vondráček, B.: Brief survey about the general
conclusion of the committee accredited to judge
projects in the competition for new sewage plants
for the capital city of Prague. Bulletin of the
Capital city of Prague, 1935, Vol. 42, No. 25,
p. 517–520.

[5] Košacký, M.: Development of the Prague sewer
system in the 19th and 20th century, graduation
thesis, Prague 2000.

[6] Jásek, J.: 100 years of modern sewerage system in
Prague. Prague, 2006.

About the author

Kryštof DRNEK was born in Prague on Febru-
ary 24th, 1985. After graduating from Gymnasium
Českolipská in 2004, he started studying history at the
Faculty of Arts, Charles University in Prague, where
he graduated with a bachelor degree in 2007. Since
then he has been studying for amaster’s degree in eco-
nomic history in the Department of EconomicHistory
at the Faculty of Arts, Charles University.

Kryštof Drnek
E-mail: drnekk@gmail.com
Dept. of Economic and Social History
Charles University
Náměstí Jana Palacha 2, 116 38 Praha 1
Czech Republic