Eawag News 1 (1973) (English) - Eawag-Empa Library / Empa ...

Swiss Federal institutes
of Technology
Federal institute for
Water Resources and
Water Pollution Control
~EAWAG CH - 8600 Diibendorf, Switzerland .Ianuaryi9?3l
Tests carried out at the Jona Wastewater Purification Plant
K. Wuhrrnann andH. Leidner
BetweenJuly 1969 and the end of April
1971 the EAWAG carried out extensive
tests at the wastewater purification
plant of Jona.
The Jona plant isthefirst inSwitzerland
to dispose of all three stages of waste-
water treatment, which can be broken
down as follows:
1) Mechanical primary sedimentation
(screen, degritter, aerated oil separator,
primary sedimentation tank)
2) Activated sludge stage
(combined tank of the Aero-accelatortype,
Lurgi AG)
3) Subsequent chemical precipitation
for P elimination (post precipitation)
(Cyclatortype, Lurgi AG)
In the choice of a sludge treatment
method, aerobic sludge stabilization
wasjustifiably preferredtoconventional
digestion, as it offers theadvantagethat
the exess sludge, which accumulates as
a result of subsequent precipitation, can
be used as a conditioning agent to de-
water the ,,organic" sludges in the filter
press.
Some 4000 inhabitants were serviced
by the wastewater purification plant
during testing.
The testing periods were broken down
into smaller units of time, the length of
which was determined by the duration
of the tertiary stage of treatment under
the various testing variables. Indepen-
dentvariablesweresetfortheindividual
testing objects. The minimum observa-
tion period for plant operation under a
particular testing variable was four
weeks. More important tests, however.
lasted considerably longer and, in the
case of stabilization and post precipita-
tion, were repeated after long intervals
of time.
Testing variables
Indicated below are the values anticipated
by the program and used as a
criterion for determining the units of
time for each test run.
Post precipitation
- L~me precipitation at a pH of 10.5 toll
with1 mg Fe(lIlj11 usedasaflocculant
- Lime precipitation at a pH of 10.5 toll
with polyelectrolyte used as a flocculant
- Lime Fe (Ill) precipitation with 10 mg
Fe (III)/l and a limeadditive until a pH
of 8.8 to 9 is reached in the precipi-
tation chamber.
Simultaneous precipitation
- Fe (Ill) used; dosing until theeffluent
has a total P content of 0.5 mg P/1.
Sludgestabilization
Two temperaturescales: ,,summerw and
,,wintere' periods
Sludge conditioning
- using limeand Fe (Ill) as recommended
by Lurgi
- using sludge from post precipitation.
possibly supplemented with lime and
Sludge pressing
- pressing the stabilized, conditioned
organic sludge alone
- pressing the sludge from subsequent
precipitation
- pressing a mixture of the sludge from
stabilization and post precipitation.
Table 1 gives a compilation of the main
results and the actual values of the
variables for all testing units. It shows
that among the processes for post pre-
cipitation, only those using lime pre-
cipitation and flocculation with Fe (Ill)
or combined lime Fe (Ill) precipitation
were effective enough to produce the
desired effluent concentration. Post
precipitation with Fe (Ill) alone or Ca
(OH)> precipitation with flocculation by
means of polyelectrolyte proved un-
satisfactory. Although this might seem
surprising particulary for the latter pro-
cess, it was found that the polyelectro-
lyte was adsorbed to the precipitated
CaC03, hamperingthegrowthof apatite
and the adsorption of further compounds
to a considerable extent. The insuffi-
cient efficiency of Fe (Ill) precipitation,
which roughly corresponded to that of
simultaneous precipitation, isalso inter-
esting. It must be concluded that, as in
the case of post precipitation, the organic
matter in the wastewater considerably
impairs the adsorption capacity of the
precipitated Fe (OH)&
The unsatisfactory effluent quality with
respect to P concentration duringsimultaneous
precipitation that resulted despite
the generous Fe (Ill) dose of
19.2 mg/l was noted with surprise.This
finding must, however, be accepted as
valid for the process since no technical
defects in the ~lant were found.
The tests carried out on sludge stabilization
under different testing variables
(temperature, sludge concentration,
02 input, mixing) revealed that no
indication as to characteristic changes
to be expected during stabilization
could be inferred from the chemical
composition of the solid matter in
sludge. On the other hand, the observations
showed that a correlation
between stabilization variables and
effects could be found on the basis of
sludgewaterproperties.Sludgeconcentration,
02 input, mixing as well as the
speed with which oxygen is distributed
to all points in the stabilization tank are
decisive factors for effective stabilization.
Experience has shown that the
sludge concentration should not exceed
209 DS/I, and the 02 concentration
should be about 3 mg 021 1 (table 2).
Agood solution tothe problemof sludge
dewatering lies in the use of a filter
press, which is safe and easy to operate
and brings regular results (less than
70% water content of the end product,
less than 5%0 solid matter recycled to
the plant for treatment). The sludge
from subsequent precipitation that
accumulates during the various
processes of P elimination could be
left to dewater without subsequent
conditioning. The effectively "stabilized
organic sludge could be thickened and

easily dewatered after conditioning with advantageous conditioning method tion without adding any further chemi-
lime and Fe (Ill). From the economic was to mix the .,stabilized, organic cals: this mixture is the easiest to de-
and operational point of view, the most sludge with sludge from post precipita- water.
Table 7; P eliminafion
79.4 1 7.6 8.9 3.4 5.3
95.7 11.1
98.2 9.5
Post Mean
-
precipi-
173.2 1.4 /10.8- 6.4 1 9.6
1 7.9 0.24 92.8 30 sam'plings
I / Mean 1
I I 1 I ; 91.9 1
I
System
Sirnuit.-
precipit.
Test
Number
/ I Y I 1 I-,, / 1 U ,
OA18
'Calculated on the basis of concentrations
"PE = Polyelectrolyte
pH in
reactor
Table 2: Sludge stabilization (Composition of the sludge water)
NO. Stabilizer
Dose
Ca (OH)! Fe3;
mgll I mgll
1 19.2
I
Pb (1I)Species in Natural Waters
by Halka Bilinskiand WernerStumm
The rate of release of lead exceeds the
rate of natural circulation. Approxima-
telyl million tons of Pb is introduced per
year into the geosphere.Approximately
75% of this quantity enters the waters.
In order to understand the distribution
of lead in naturalwaters(sedimentation.
adsorption,association withsuspended
materials, incorporation into the food
chain) and its possibletoxicity, informa-
tion on the forms of occurrence of Pb in
dissolved and solid phases is necessary.
With the help of anodic stripping (inversevoltammetry)
using hanging drop
mercury electrodes, the speciation of
lead(ll) in dependence of solution variables
(pH, alkalinity, organic ligands) has
been investigated. Because of its great
sensitivity, inversevoltammetry permits
to investigate the solution behavior in
the pH range of natural waters without
precipitating of thesolid phases.
PE"
mg/l
Primary effluent
ortho-P total P
mg PI1 mg PI1
"U ,
,,U
Final effluent
ortho-P 1 total P I total P
mg PI1 1 mg PI1 %elim.'
/ ","I / ,,I I , 4 1
I
1 7.1 1 3.3 6.6 1 Org2 1 'lrZ / 23 samplings I
Sludge water
(after sludge sedimentation) mg/l Odor patterns during
thickening
"L,
1473 463 rapid odor development
174 51 remains "fresh"
1571 648 rapid odor development
101 20 remains "fresh"
in peak potential observed with increa- low 6.5; anionic lead complexes prevail
sing ligand concentration (figure 1). at pH values above 9.3.
The following stability constants have
been determined (25OC. I = 0.1) : In natural waters, most of the available
With these constants a representative lead(ll) is associated with suspended
distributionof Pbllll-soeciescan becal- materials.Amonq the Pbilll-soecies. the
Pb(0H)z and thePb~03-species are very
strongly adsorbed at interphases. Figure
3 givessomedata on theadsorbability
of PbC03; under similar conditions,
i.e. solutions that do not contain C03'-,
Pbz+-species are not adsorbed to interfaces
to any significant extent.
cilated (figure 2):dbiously in most na-
tural waters the carbonato lead com-
plex, PbC03, will be the most prevalent
species. This has to be considered in
evaluating the solubility of PbC03 (s)
and Pb3 (C03) 2(OH) 2 ($.Tentative de-
terminations on the solubility of lead
carbonate have given the following re-
sult (25OC, I = 0.1):
PbC03 (c) = Pb~+ + C032-
log K.o = - 12.54
In natural waters, the following species
Pbs (C03)z (0H)z (s) = 3PbZ' + 2C05 + 20H- log Kso = - 45.03
can occur:
Pb2+. PbC03, Pb(C03)2'-. PbOH',
-, , , ,
vD~un'z.
Hence, a solution that i ~10-~ M in total
carbonate ~ives within the DH ranne7-
9 a total led solubility of ci.10-~ 1\71, the
The stability of these complexes has predominant species being PbC03 free
been determined by obsewing the shift lead ions oredominate at pH values be-

mean N:P ratio in flowing pre-alpine
waters varies from 20 to 200:1, while
the figure for Central Switzerland is 60
to 900:l. In Switzerland the tertiary sta-
ge of wastewater purification, that is,
the elimination of phosphates, is stipu-
lated by law in the catchment area of
lakes. Hence the N:P ratio in the drain-
age area of lakes will never drop below
20:l. Given balanced algal growth, the
nutrients phosphorus and nitrogen are
assimilated by these algae in a 7:l ratio
by weight; consequently algal growth in
such waters will be hampered by the
phosphorusandnotthenitrogensupply.
Although excessively high nitrate con-
centrations can be a threat to ourdrink-
ing water supply, our struggle to curb
eutrophication must be oriented toward
reducing phosphorus losses in the soil
however insignificant they may be from
the economic point of view.
OIO
100
Vollenweidefs (15) tolerance valuesfor
phosphorus in lakes. Figure 2 shows
clearly that intensive land cultivation
with yearly yhosphorus losses of 35 to
70 kg P/km (seefig.1) is irreconcilable
with an oligotrophic lake. Even with an
annual phosphorus loss of as little as
35 kg P/km2, 90% of our lakes would be
endangered; this means that only 10%
would still be oligotrophic, 30% mesotrophicand
60%eutrophic.Fortunately,
however, thecatchment area of none of
our larger lakes is used entirely for agri-
/ / cultural purposes. Parts are always
l ~ l ' l ' l b
wooded, while others are unproductive
1 (glaciers, rocks).
10 20 30 40 50
Yet ohosohorus lossesfrom thesoil are
onl; one source of the phosphorus load
p - (kg p/km? ~ Jahr) ~
inlakes.
~
If
~ 3 g PI capitaper
~ ~
day are reckoned,
the following phosphorus loads,
Figure 2
relative to the oo~ulation densitv. are
added by municipal wastewaters
The tolerable and dangerous phospho- Degree of eutrophication in Swiss lakes
rus loads from the drainage area of 28 with more than 1 kn? in surface area in A = Percentageofendangeredlakes
Swiss lakes with a surface area of over relation to the phosphorus loads from ~mesotrophicandeutrophicl
1 km2 were calculated on the basis of drainageareas. B = percentage of eutrophic lakes
Tablel: Phosphorus accumulation (kg Plkn? theeffectivenessofthewastewaterpuri-
year and based on specific surface areal fication plant
in relation to the population density and
Population density Mech. and biol. purification Tertiary treatment
Inhabitants/kmz P elimination: 30% 85% 95%
If we examine the values given in fig. 1 phosphorus is eliminated from waste- fromwastewaterforapopulationdensi-
and 2 and tablel, we may concludefrom water as soon as the population density tyof over100 inhabitants/km2 will have
figure 2 that the goal of pollution con- exceeds 50 inhabitants per km2. Since thedesiredeffectonlyifthephosphorus
trol, i.e. prese~ingtheoligotrophiccon- high population density usually coinci- losses from agriculture can be reduced
dition of most of our larger lakes. can des with intensive agricultural cultiva- concomit antly.
only be reached if at least 85% of the tion even 95% phosphorus elimination
Authors: Dr. K. Wuhrmann is Professor Dr. Halka Bilinski is Researcher in the Editor: D. Stickelberger is the Deputy
of Applied Biology and Head of the Bio- Chemistry Section of EAWAG. Dr. Head of EAWAG's International Refer-
logy Section of EAWAG; Dr. Leidner is Gachter is a biologist in the Limnology ence Centre of Wastes Management
a chemist in Dr. Wuhrmann's section. Section and Acting Head of the Lim- (WHO).
Dr.WernerStummisProfessorofWater nologicaILaboratoryatKastanienbaum.
Pollution Control and Director of EAWAG,

Phosphorus Losses from the Soil and the Implications for Water Pollution
Control
by Rene Gachter
Among the macro-nutrients the great- Figur 1 shows the nitrogen and phos- In both the pre-alpine regions and Cenestarowth-limitinafactorsinlakeswere
ohorus loads measured in terms of tralSwitzerland.woodedareassufferno
found to be phosplhorus and sometimes
phosphorus losses worth mentioning.
nitrogen. Since both these nutrients,
However, assoon asthe catchment area
together with potassium, are the main
is set aside entirely for agriculture, yearcomponents
of inorganic fertilizer, it
ly phosphorus losses of about 35 kg
was assumed that the undesirableeu-
P/km2 and 70 kg/P/km2 can be expecttrophication
of our waters was caused
ed in the catchment areas of Central
not only by municipal and agricultural
Switzerland and the pre-alpine regions
wastewaters but also by the percolation
respectively. Despite greater specific
of minerals and soil erosion from inten-
run-off and less phosphorusfertilization
sively cultivated soil. Topography, soil
in catchment areas with the'same'type
quality, climate and type of cultivation
of soil cultivation, dissolved phosphorus
all have a bearing on nutrient erosion
compound concentrations in pre-alpine
and percolation.To beabletodetermine
waters are slightly higher than concenat
least part of these factors as accura-
trations found in Central Switzerland.
tely as possible, we limited ourselves to
This is due mainly to the fact that in the
the analysis of results gleaned in rela-
steeper pre-alpine regions the phophotively
small, easily Surveyable drainage
rus compounds are not only washed
areas (1.2.3.4.9.10.11.12).
awaythrough percolation butalsoeroded
by surface run-off.
specific surface dimensions in correla-
tion to the portion of the catchment
area used for agricultural purposes. A
distinction was made only between two
very general types of land use, agricul-
ture and forestry, while the method of
fertilization and type of cultivation -
whether pastureland, meadowsorfields
- were disregarded. The pre-alpine re-
gions differ from Central Switzerland in
their higher altitude, steeper slopes
and greaterspecific run-off. Contrary to
Central Switzerland, where cultivation
includes natural meadows, pastureland.
artificial meadows, viticulture and vari-
ous types of soil tillage, land use in the
pre-alpine regions is more homogene-
ous (natural meadows and pastureland)
(5.8).
kg plkrn2 year Swtss lowland kg plkrn2 year W r Alps
40 -
y = 0.23 + 135.23 - 0,231 x
30 - r = 0.867
20-
10-
I
I , I I
20 40 60 80 100 '.
agr,cultuial used area
kg N/krn2 year kg N/km2 year
2800- 1400-
2400- y = 959 + 12102 - 9591~ . -
r = 0526
200Q 1000-
1600- -
1200- 600-
800- -
2b 4b
60- y = -3.6+(68.9 +3,61x
r = 0.828
40-
20-
t
I I I I I I I I I I
20 40 60 80 100%
agricultural used area
r= 0871
! I I 1 , I
I I I I 4 I
60 80 100%
20 40 60 80 100%
agr~cultural used area agi~cultural used area
'a'stands for the P (N) loads from a speci-
Figure 1 drainage area in the pre-alpine regions
area used for forestry
and Central Switzerland to be used for
Annual loads of dissolved phosphorus ,b, = land used for agriculture
agriculture,
and nitro.qen com~ounds in relation to 'x' = 1 siqnifies that the entire drainage
the relatiie amount of land of the total In the equation y = a + (b + a) x area is used for agriculture.
In the pre-alpine regionsnitrogen losses well as to more intensive biological ni- lated forthis area.
amount to a yearly average of about 82 trogen turnover - induced by climatic Calculated in relation to the quantity of
kg N/km2 for land used for agriculture conditions - in the soil of the lower re- fertilizerusedannually, thenutrient los-
alone. In Central Switzerland nitrogen gions. The heterogeneous pattern of ses from agricultural land lay between
losses are always greater despite the land use in Central Switzerland explains 16 to 25 per cent for nitrogen and about
'same' type of land use, afactwhich can the scattered distribution of the single 0.7 to 1.4 per cent for phosphorus. De-
be ascribed to increased fertilization as values around the regression line calcu- pending on the type of cultivation, the

Figure 1: 0.1 M KN03 ,25'C
The shift in peakpotentialobserved with
increasing carbonate concentration per- C, E (v)
mits the determination of the stability of
the complexes PbC03 andPb(C03)z.
Figure 2:
The speciation of lead(lll in waters con-
taining a total carbonate concentration
of 70-3M.
Figure 3:
PbCO3 complexes are adsorbed much
more strongly than free PbZ"
0 ! \.----l
0 -1 -2 -3 - 4 -5 - 6
Log [co?]
T '0
0 - n
a N
- E
s I

EAWAG-Publications
(November 1972)
'392.
Sturnm.W.: Einige okologischeGesichtspunkte
beirn Gewasserschutz.Tagungsbericht
IAWR, Zurich1971.
393.
Zehnder, A,: Verhandlungsbericht des
5. Symposium uber Fragen der Cyanophytensytemat~k
in ~astanienbaum
1969.Schwe1z Z Hydrol 32,481 (19701
394.
Bosli-Pavoni, M.: Blaualgenliteratur aus
den Jahren 1969 und1970.Schweiz.Z.
Hydrol. 32,481 (1970)
397.
Stickelberger, D. u. Sturnrn, W.: Gewasserschutz
- Versuch einer schweiz.
Standortsbestirnrnung. Tech. RundschauNr.
24.4.6.1971.
398.
Blurrier, M.: Verunreinigung derGewasser
durch 01 - Zurn Problem der persistenten
Chernikalien in der Urnwelt.
Zurich 1971.
399.
Stickelberger, D.: Vergleichbare Kostenerrnittlung
auf dern Gebiet der Mullbehandlung.
Wasser- u.Energiewirtschaft
63,186 (1971)
400.
Munz, W.: Die hydraulischeBernessung
von Regenuberlaufen rnit Drosselstrecke.
Schweiz. Bauzeitung 89, 50
(1971)
'401.
Weber, H.: Wasser fur Masada - Noch
imrner ein Geheirnnis? Wasser- und
Energiewirtschaft 63,161 (1971)
402.
Stadelrnann, P.: Stickstoffkreislauf und
Primar~roduktion irn rnesotrophen Vierwalds6ttersee
(Horwer ~ucht) und im
eutrophen Rotsee. Schweiz. Z. Hydrol.
33,1(1971)
403.
Gachter, R.; Szabo, E. u. Mares, A.: Die
lokale Beeinflussung eines stehenden
Gewassers durch eine punktforrnige
Abwasserbelastung. Schwei2.Z. Hydrol.
33,66 (1971)
404.
Gachter, R.: Zur Frage der Einleitungvon
gereinigtern Abwasser in Seen. Schweiz.
Z. Hydrol.33,73 (1971)
405.
Bosli-Pavoni, M.: Ergebnisse der limnologischen
Untersuchungen der Oberengadinerseen.
Schweiz. Z. Hydrol. 33,
386 (1971)
'406.
Sturnrn, W. u. Leckie, J. 0.: Phosphate
Exchange with Sediments; its Role in
the Productivity of Surface Waters, Proc.
5th lnt. Wat. Poll. Res. Conf. San Francisc01970.
407.
Peter, G. u. Wuhrrnann, K.: Contribution
to the Problem of Bioflocculation in the
ActivatedSludgeProcess. Proc. 5th lnt.
Wat. Poll. Res. Conf. San Francisco1970.
408.
Sturnm, W.: Manipulation der Urnwelt
durch den Menschen. Die Beschleunigung
der hydrogeochernischen Kreislaufe.
NZZ No. 441. 22.9.71.
409.
Weber, H.: Ungenugender Grundwasserschutz.
NZZ No. 439,21.9.1971.
410.
Sturnrn, W. u. Koblet, R.: Binnenschifffahrt
und Reinhaltung unserer Gewasser.
Gas-Wasser-Abwasser 51, 257 (1971)
411.
Schegg, E.: A New BacteriologicalSampling
Bottle. Limnology and Oceanography
75,5,820 (1970)
41 2
O'Melia, Ch. R.: An Approach to theModelling
of Lakes. Schwei2.Z. Hydrol.34,
1 (1972)
413.
Schegg, E.: Produktion und Destruktion
in der trophogenen Schicht - Untersuchungen
okologischer Parameter im
polytrophen Rotsee und in der rnesotrophen
Horwer Bucht. Schweiz. Z.
Hydrol.33,425 (1971)
414.
Sturnrn, W.: Einfache Modelle im Urnweltschutz:
Der Mensch und die hydrogeochemischen
Kreislaufe. Jb. Vom
Wasser38,1(1971)
415.
Wuhrmann, K.: Verantwortung der Industrie
fur den Gewasserschutz. Industr.
Organisation 41 (1972)
418.
Sturnrn, W.; Traupel, W.; Diitsch, H. U.
u.Arnbuhl, H.: DietherrnischeBelastung
der Urnwelt. NZZNo. 203.2.5.1972.
419.
Wuhrmann, K.: Uber die dritte Reinigungsstufe
bei biol. Klaranlagen. Seifen-Ole-Fette-Wachse
98,8,203 (1972)
420.
Stumrn. W. u. Sturnm-Zollinger. E.:
Chernostasis and Homeostasis in Aquatic
Ecosystems; Principles of Water Pollution
Control. Advances in Chemistry
Series, No.106 (1971)
421.
Sturnrn, W.: Wechselwirkung Land -
Wasser in okologischer Sicht. Bern
1972.
422.
Weber, H.: Schwernewichts-dl-~b-
scheider. as-~asser-~bwasser 52,
153(1972)
423.
Sturnrn, W. u. O'Melia. Ch. R.: Chernische
und physikalische Vorgange bei der
Filtration. Zurich 1972.
424.
Sturnm, W. u. Roberts, P. V.: Die Bedeutung
der Grenzflache beirn Gewasserschutz.
Chem. Rundschau No. 35,
30.8.1972.
425.
Hirschheydt, A. v.: Uber Versuche zur
Beseitigung von Abfallolen und olhaltigen
Abfallen rnit Hilfe der Kompostierung.
Wasser und Boden.
426.
Wuhrmann, K.: Bedeutung der Mikroorganismen
fur aquatische Stoffkreislaufe.
Pathologia et Microbiologia.
427.
Huang, C. P. u. Sturnrn, W.:The Specific
Surface Area of i-AlzOaSurfaceScience
32,287 (1972)
428.
Gachter, R. u. Furrer, 0. J.: Der Beitrag
der Landwirtschaft zur Eutrophierung
der Gewbser in der Schweiz. I. Ergebnisse
von direkten Messungen irn Einzugsgebiet
versch. Vorfluter. Schweiz.
Z. Hydrol. 34.41-70 (1972)
'out of orint
Reprints of most of these publications
are available upon request to
The Secretariat of EAWAG
CH-8600 Dubendorf