発表資料

INSTITUT FÜR SIEDLUNGSWASSERWIRTSCHAFT UND ABFALLTECHNIKLEIBNIZ UNIVERSITÄT HANNOVER
Prof. Dr.-Ing. K.-H. Rosenwinkel

Municipal wastewater treatment in Germany – state of the art
K.-H. Rosenwinkel, Institute for Water Quality and Waste Management,
Leibniz University of Hanover (ISAH), Welfengarten 1, 30167 Hanover, Germany

Introduction
In the EU the Wastewater Directive is an emission–based regulation which defines required
effluent quality in terms of COD, BOD and nutrient concentration. As various bodies of water (e.g.
the Baltic Sea) are becoming eutrophic, the imission and watershed integrated management
approach is being adopted in EU as well. The new EU water-framework-guideline requires animission-based river-basin-management and a good quality for all river-basins in the EU. The
following will present the technology that is currently used in WWTP in Germany and thedeveloping trends.

Wastewater Treatment in Germany
Table 1 presents the current minimum requirements for effluents from municipal WWTPs whichhave to be met as the yearly mean values. Germany adopted the EU Directive, however theeffluent levels must be met in the qualified peak sample (ABWV, 2004) – a considerable stronger
requirement.
Table 1:Minimum effluent requirements from municipal WWTP in Germany and the EU.
(*) denotes “sensitive areas”,(**) “normal areas”
Minimum requirements FRG in (mg/L)
COD
BOD
NH4-N

TN

TP

<1
1-5

150
110

40
25

-

-

-

5 - 10
10 - 100
> 100

90
90
75

20
20
15

10
10
10

18
13

2
1

Size [1000 PE]

Size [1000 PE]

EU requirements in (mg/L) or as minimum (%) Removal
COD (**)BOD (**)NH4-N
TN (*)TP (*)

10 - 100

125 or 75 %25 or 70 -90 %-15 or 70 - 80 %2 or 80 %> 100

125 or 75 %25 or 70 - 90 %-10 or 70 - 80 %1 or 80 %- 37 -

Seite 2

Typical process configuration
The most commonly used BNR processes in Germany are pre-denitrification and simultaneous
nitrification-denitrification (SND). Plants practicing enhanced biological phosphorous removal(EBPR) typically employ Johannesburg, ISAH or Phoredox type configuration. Other plants use
the cascade-denitrification and the alternating denitrification process.
An example of technology development is provided by Hildesheim WWTP which employs SND
and EBPR. Designed in 1982/1983 the plant was commissioned in 1987. In contrast to the warmand concentrated (BOD of 300-400 mg/L) South African wastewater, where BNR processes
originated, the Hildesheim WWTP at times may have BOD5 as low as 100 mg/L due to infiltrationand combined sewers. The plant is operated using the ISAH process, where the return sludge(RAS) is denitrified in a separate pre-anoxic zone to offset any impact on phosphorus release in
the subsequent anaerobic zone. If necessary, additional substrate can be fed from the anaerobic
primary sludge fermentation tank to the pre-anoxic zone. Initially operated as two parallel lines,
the plant had all four passes commissioned in 1997 (Figure 1).

effluent

return sludge

Figure 1: Flow sheet of the Hildesheim WWTP (with digester and EBPR in a fullstream)

The average effluent concentrations in 2001 were 0.12 mg TP/L and 4.0 mg TNmin/L (80%cumulative frequency concentrations: 0.26 mg TP/L and 6 mg TNmin/L), well below the permit
requirements of TN<10 mg/L and TP<1 mg/L (Figure 2). Although chemical precipitation wasavailable the low effluent TP values were almost entirely the result of the biological phosphorus
removal. Plants in Germany benefit from significant financial savings in mandatory wastewater
charges when treatment effects exceed the permit requirements.

- 38 -

Seite 3
P O 4 -P [ m g /l ]0

0 ,1 20 ,20 ,2 6

0 ,4

0 ,6

0 ,8

1

1 ,2

1 ,4

100%

100%

90%

90%

80%

80%

P O 4 -P

70%

70%

60%

60%

N min

50%

50%

40%

40%

30%

30%

20%

20%

10%

10%

0%

3 ,9 80

2

0%

5 ,9 8

4

6

8

10

12

14

16

18

20

N m in [ m g /l]

Figure 2:

Cumulative frequency for the parameters Nmineral (NH4-N + NO3-N) and Ptot in theeffluent of the secondary clarifiers at the Hildesheim WWTP as daily average 2001

The WWTP Husum is an example of a process with SND and biological phosphorous-removal ina sidestream. The side-stream process called the CISAH-Process, consists of anaerobic tanks,
stripper and an optional lime precipitation. The flowsheet of the WWTP Husum is represented in
Figure 3.

Figure 3:

Flow diagram of Husum WWTP without digester and employing SND and side stream
biological-chemical phosphorus removal

The effluent concentrations in 2004 were TP (80%)= 0.17 mg/L without precipitation, and TNmin(80%) = 2 mg/L, averaging (50% data) 0.12 mg TP/L and 1.7 mg TNmin/L. The extremely low
nitrogen concentrations were due to the high COD/N ratio (Table 2). At Husum the SRT is 15.1

- 39 -

Seite 4days in 2004 and the ratio COD/N is 16.2, at the WWTP Hildesheim the SRT is 16 d and the
COD/N ratio is 15. The influent-concentrations of the WWTP Husum are much higher than that of
the WWTP Hildesheim due to industrial influences. In comparison, for another WWTP HannoverGümmervald (approx. 750,000 PE) with a COD/N ratio of only 11.5, the effluent-data of
2001/2002 for the 50% cumulative frequency are 6.6 mg TNmin/L and 0.5 mg TP/L (MAKINIA ET AL
2005). These figures show the important influence of the COD/N ratio to the nitrogen-effluent
quality, in special for nitrate. Table 2 shows the N-effluent concentrations for the three WWTPs
named before, in relation to the COD/N-ratio and the sludge age.
Table 2:

Impact of COD/N in three German plants on effluent total nitrogen concentrations

Capacity

SRT

COD/N

TNmin effluent concentrations

WWTP[1000 PE]

[d]

[-]

50% [mg/L]

80% [mg/L]

Hildesheim

approx. 240

16.0

15.0

4.0

6.0

Husum

approx. 110

15.1

16.2

1.7

2.0

Hannover-Gümmerwald

approx. 750

16.0

11.5

6.2

8.2

Trends in Germany and EU
Integrated River Basin Management
The emphasis in EU begun to shift from the emission to the imission-based approach to water
quality management. This calls for a more integrated, system-wide approach that includes all
sources of pollution within a watershed and within an urban jurisdiction, including sewerage,
treatment plants and the receiver. Germany was one of the first to establish the river watershedwater quality management system such as for the river Ruhr (Ruhrverband). Recently, urban
watersheds became targets with attempts to direct as much as possible of the combined sewer
overflows into the wastewater treatment plants.
As an example, a case study is presented in which the research in a calibrated model focusses
on the influences of different ratios between rain- to dry weather flow on the total emission fromthe effluent of the treatment-plant and the combined sewage overflow (CSO). In case of a heavy
rainfall event high loads are discharged via combined sewer overflows into the receiving waters.
Currently, the usual remedy is the construction of stormwater tanks with overflow; however, thismethod requires large tank volumes and high construction costs. A partial relief from this negative
impact could be offered by utilizing the existing capacity of the WWTP to process the CSO andthus reduce total emission from the sewer system and the WWTP. This could be achieved by
optimization of the available plant capacity with model-based control strategies. Figure 4
describes the area of interest, with the WWTP, the stormwater overflows and the receiving waters
as the focus of attention.

- 40 -

Seite 5

combined / separate system

combined system

Receiving waters

SeweragesystemStorage +Treatment•Simulation

Undocking / Percolation
Use of storage
capacity• Immission

Area of examination

Sewer cleaning• CODsewer ≠ CODeffluent

max. Q?
• Simple balance(NH4 + COD-Load)

Local/Central
control• Reduction emission

WWTP
Optimised operation WWTP in caseof rainfall (MSR, Online-Simulation)

Figure 4:

Area of examination in the urban drainage area and the boundaries for total emission
from WWTP and CSO

The results of the research show that the increase of use from WWTP capacities will lead to
reduction of the total load (e.g. of NH4-N) to the river (SEGGELKE, 2002). The high and highlyvariable WWTP influent loads in case of stormwater necessitate optimisation of control andoperation. Apart from conventional control strategies which are adapted to the situation
stormwater, observation mechanisms with continuous monitoring of the status of the biologicalprocess become necessary. Predictive adaptive control systems, consisting of an on-line coupledmodel and an implemented prognosis calculation tool could determine the maximum possible
loads to the inlet of the WWTP and the optimal utilisation of the capacities while meeting theeffluent values.
Following, the results from the theoretical calculations of the total emission of sewer system andWWTP are shown in Table 3 (focus is on COD and KN). Based on scaled-up results (actual
effluent concentration, fictitious water quantity) of a pilot plant study for a WWTP (73,500 PE), theemissions are calculated under specification of different inflows to the WWTP with thehydrological sewer model KOSIM (SEGGELKE, 2002). The table presents the load reduction
compared to the calculation with the storage volume 8.940 m³ (German ATV A128 design
guideline) in case of storm flows as high as twice of the dry weather flow and keeping the limiting
values of the EU-guideline in case of higher inflows. For reasons of simplicity the concentration of
CSO were assumed to KN = 20 mg/L and COD = 140 mg/L (SEGGELKE AND ROSENWINKEL, 2002).
Table 3:Comparison of the loads from CSO + WWTP and the load reduction for different
combined flows to the treatment plant

Influent(%) DWF

load from total area [kg/a]

load reduction

KN

COD

KN

COD

200

12,95090,600

-

-

300

9,250

64,70013.8 %

8.4 %

400

6,970

48,80022.2 %

13.5 %- 41 -

Seite 6
In the comparison, the reduction of harmful CSO peaks in the receiving waters is neglected. The
example shows a reduction of the KN load of 22% to the river in case when the WWTP inflow isfour times the dry weather flow i.e. instead of the German standard (2 Qdryw). The most important
influence is given for the Ammonia-reduction, this can be reduced effectively only by a biologicalsystem.
Plant Wide Modeling
As an important tool for the development, the evaluation of novel control and operation concepts,
simulation is widely used. One main focus of the works is the modelling on a plant-wide level
including processes for sludge treatment energy consumption/production besides the classicalactivated sludge process. One main aspect in sustainable operation is the consideration andexamination of each relevant emission path. In reference to waste water treatment plants action
with the goal of an optimisation of effluent loads also must be analysed on the implicated effects
on the sludge digestion and the coupled energy production.
For the expansion of the common models of activated sludge systems for the use in plant widemodelling different additional models are necessary including the mechanical pre-treatment (grids,
primary clarification, pre-precipitation etc.), the biological/chemical step with a broad diversity oftechnologies (activated sludge and biofilm systems, sequencing batch reactors, chemical
precipitation, etc.); the sludge treatment (mechanical thickening, anaerobic digestion, drying,incineration) and the energy production and consumption (gas engines, block heating works,
aeration devices, etc.) (ROSENWINKEL, SPERING, 2006).
In addition to the integrated consideration of the treatment-plant and the combined sewage
overflow (CSO), the several currents have to be eliminated. The co-treatment of waste by kitchendisrupters together with sewage can be one example (WENDLER, 2005).
New treatment technologies
Overall removal efficiency shows significant decline in effluent concentrations in Germany (Figure5), mainly due to improved plant design, novel processes and better operation. Significant inroadsin activated sludge treatment are being made in EU by the biofilm technologies. Some 40 plants
with biological filtration operate in Germany today, treating effluent from 1.5 million PE. The plants
use biofiltration for nitrification and also for denitrification. The reactors include aerated
submerged-bed upflow filters, downflow filters, and continuously or discontinuously backwashedfiltration. The effluent suspended solids concentration of filtration units, following conventional
final clarifiers are below 5 mg/L, the nitrogen concentrations in the effluent are covering a wider
scale, depending on variations of inlet flow and composition, mode of operation, e.g. dosage ofexternal carbon.

- 42 -

Seite 75045Concentration

40
35
COD g/m³
BOD g/m³
NH4-N g/m³
Ntot g/m³
Ptot g/m³

30
25
20
15
10
5
0
1994

1996

1998

2000

2002

2003

Year

Figure 5:

Mean yearly effluent concentrations of German plants (DWA 2003)

Increasingly stringent nitrogen standards call for separate treatment of sludge processing liquors
using physical, chemical and biological methods. In a few cases, the nitrogen load is decreased
by incineration of raw sludge, e.g. at Vienna or Berlin.
The membrane bioreactor (MBR) technology begins to be implemented more often and for larger
facilities. In the MBR the secondary clarifier is replaced by a membrane module yielding highclarity final effluent. Smaller reactor volumes are typically the result of higher contents of MLSS
(up to 15 g/L and above) in comparison to standard activated sludge systems. Today 40 MBR
plants operate all over Europe, with 16 of them in Germany. The capacities vary from 150 to
200,000 PE. The technology promises to reduce the suspended solids to zero and to minimise a
lot of harmful substances in the effluent (e.g. endocrine disrupters and pharmaceuticals).
Of special importance for the evaluation is the fact, that the membrane is only a physicalselection-tool and the reaction is to be done by the biological system. The advantage of theeffluent-quality with meeting the high standard of the EU-bathwater-guideline stands in contrast to
the higher energy demand and the sensitivity against peak-concentrations like ammonia.
Membrane technology has been used in municipal wastewater treatment involving the applicationof polymer membranes for more than 10 years now. Polymer membranes have proved
themselves, despite exhibiting material dependent disadvantages such as limited chemical
stability during cleansing or anti-fouling measures. Ceramic membranes appear to hold significant
potential in this area. An extensive implementation of ceramic tubular membranes (cross-flow) for
wastewater treatment results in high module and operating costs for the operator. Ceramic flat
membranes, which can be implemented in the form of submerged low pressure membranes (TMP
<1 bar) are to be tested as alternatives. Their suitability for the treatment of large-volume
wastewater streams or types of wastewater that are unsuitable for polymers due to their chemical
properties, in combination with a high lifespan of the material involved, facilitates economical
deployment (BRINKMEYER ET AL., 2006).

- 43 -

Seite 8
Deammonification process for the treatment of sludge water
By a separate treatment of the sludge water, the biological stage of a municipal wastewater
treatment plant may be discharged significantly. For sludge water treatment chemical andphysical methods as ammonia-stripping are used as well as biological methods like e.g.
nitrification/denitrification. Typically the sludge water is characterized by high ammonia content
and low COD/N ratio which makes it unfavourable for conventional biological treatment. Fullnitrogen removal by nitrification/denitrification may only succeed by addition of an external carbon
source like acetic acid which leads to high operating costs. With the process of Deammonification
nitrogen can be biologically removed from wastewater with low COD/N ratio without any additional
carbon source.
The Deammonification Process can be described as a process divided into two different steps,
which are performed by two groups of organisms. The first step, the aerobic conversion ofammonia to nitrite is done by bacteria of the nitrosomonas group, for the following, anoxic
conversion of nitrite and ammonia to elementary nitrogen, organisms which are members of thegroup of planctomycetales are hold responsible. Figure 6 shows the application of both steps in a
biofilm.

NH +4
NH +4 + 2 HCO3− + 1,5 O 2 → NO2− + 2 CO 2 + 3 H 2 O

O2 = 0

Biofilm

O2 > 00,5 O 2 + NO −2 → NO3−

NH +4 + NO −2 → 2 H 2 O + N 2*

Carrier*Broda, 1977

Figure 6:

Deammonification in a Biofilm

The members of the planctomycetales group seem not to be able to build up an own biofilm
structure but need an existing biofilm to enrich in. Thus, the first step of starting up
Deammonification is an aerobic operation with high substrate load and adequate aeration which
will result in a mixed biocoenosis containing aerobic and anoxic ammonia oxidisers. In a Moving
Bed-system the thickness of the biofilm is limited by the shear forces caused by intense mixing,
which means build up of anoxic zones for the second step of Deammonification is only possible
by ensuring a low oxygen concentration in the reactor. Another possibility is to divide the twoprocess steps ‘time-based’ by an alternating aeration or ‘physically’ by using different reactors.
To ensure Deammonification it is necessary to perform only the first step of nitrification and notoxidise the ammonia to nitrate but nitrite. Therefore the nitrite oxidising nitrobacter bacteria haveto be inhibited selectively. One possibility to establish nitritation is to completely wash out thenitrobacter out of a system of suspended solids by simply adjusting the sludge age appropriately.
This can be done, because at higher temperatures the growth rate of nitrosomonas is becoming
higher than that of nitrobacter. The point of washing out nitrobacter at e.g. 25°C is at a sludge ageof about 1.3 days. The patented SHARON-system is based on this principle and can be used to- 44 -

Seite 9
easily apply a nitritation system (MULDER AND VAN KEMPEN, 1997). SHARON-reactors already arein operation at several WWTPs. Because the washing out of certain bacteria by regulation of thesludge age is not suitable for a biofilm process, different methods for inhibition of nitrite oxidisers
must be developed, which do not have a negative influence on aerobic ammonia oxidisers. For
example the sensitivity of nitrosomonas bacteria on free ammonia (NH3) is lower than that of
nitrobacter. Thus, nitritation can be established by adjusting the pH value because the balance
between ammonia as NH4 and free ammonia as NH3 is based on the ammonia concentration,
temperature and the pH value. By rising the pH by addition of a base like NaOH free ammonia will
also rise and nitrobacter will be inhibited. The ammonia concentration and the pH will have to beobserved accurately because, if free ammonia rises too much, nitrosomonas also will be inhibited.
Another possibility of selective inhibition of aerobic nitrite oxidisers is based on the different
conversion rates in relation to the oxygen concentration. At low DO, nitrosomonas is growing
faster than nitrobacter so nitrite will be enriched (HIPPEN, 2001). Also an intermittent aeration of anitrification reactor will lead to nitrite enrichment if the aeration time is adjusted appropriately,
because after switching on aeration again, nitrobacter seem to have a „lag-phase“ that is longer
than the one of nitrosomonas (KATSOGIANNIS ET. AL., 2002). This method of discontinuous
aeration is successfully used to ensure nitritation in the full scale plant at Hattingen which is
describe in the following chapter.
In the year 2000 a full scale sludge-water treatment plant was built at the WWTP of Hattingen by
the Ruhrverband, Germany. Within the scope of a research project, the process of
Deammonification should be implemented, using the Kaldnes®-Movig-Bed System. Project
partners were the Ruhrverband, the PURAC GmbH, Merseburg, and the Institute for Water
Quality and Waste Management Hanover. Figure 7 shows the flowsheet of the full-scale plant in
Hattingen.
Q = 200 m3 d-1

pH

pH

pH

BypassRecycle (optional)
V = 684 m3
CNH4-N = 530 mg L-1

Figure 7:

Nitritation / Anoxic Ammonia-Oxidation

Degasification

V = 104 m3
Aeff = 20.400 m2
DO = 0-4 mg L-1

V = 24m3

V = 67m3
Aeff = 13.400 m2
DO = 0-4 mg L-1

V = 67m3
Aeff = 13.400 m2
DO = 4 mg L-1

Flowsheet of the full scale Deammonification at Hattingen (ROSENWINKEL ET AL., 2005)

Some results of the Deammonification Phase are shown in Figure 8. In this Figure the nitrogen
feed for the plant is shown together with the temperature of the wastewater and the load
converted to elementary nitrogen. Maximum performance is at approx. 70-80% converted at a

- 45 -

Seite 10
load between 100-160 kg N d-1 during normal operation. In the beginning of 2004 a reduced
nitrogen elimination of down to 25 kg N d-1 was detected, caused by very low wastewatertemperature and, following, by biofilm loss. Meanwhile by rising the nitrogen load and oxygen
supply, the biofilm thickness has developed again and nitrogen elimination performance hasreached a satisfactory level. In winter 2004/2005 plant performance could be ensured, because
the water temperature did not drop below 20°C due to the installation of a cover to the sludge
water storage tank. Nevertheless the measurement of the biomass cultivated on the Kaldnes®carriers has become one of the most important factors for running the Deammonification plant.

70

5
.0

.0
4

5
.0
.0
2

01

01

.0
.1
2

4

4
.0
01

4
.0

.1
0
01

4

.0
8
01

4

.0

.0
01

4
01

.0
4

.0
.0
2

.0
6

3
.0

.1
2
01

01

.0

3

3
.0

.1
0
01

01

01

.0
6

.0

.0

.0
4
01

.0
2

01

01

01

3

0
.0

0
.0
8

10

3

20

3

20

2

40

2

30

.0

60

.0

40

.1
2

80

2

50

.0

100

.1
0

60

.0
8

120

01

N, Elimination [kg d-1]

140

Figure 8:80

N InletElimination
Temperature

Temperature [°C]160

Overall performance of the full scale Deammonification (ROSENWINKEL ET AL., 2005)

Optimisation of Phosphorus Recovery by MAP Precipitation (Magnesium-AmmoniumPhosphate)
Another trend is the development of techniques for phosphorus recovery, which can be done byrecovery from the liquid phase, from the sludge or from the ash. The stream used for P recovery
is selected based on the recovery potential to be utilised, the acceptable effort for phosphorus
redissolution and the desired quality of the precipitation.
Figure 9 shows the phosphorus balance of a WWTP with enhanced biological P-removal (EBPR).
Approx. 10 % of the phosphorus remain in the effluent and approx. 11% are incorporated in the
primary sludge (Jardin, 2003). The potential of p-recovery from the liquid phase accounts forapproximately 37 %, from digested sludge or ash nearly 90 %.

- 46 -

Seite 11
Influent : 1,9 g/p*d = 100 %Effluent
0,2 g/p*d
approx. 10 %Excess sludge+ simultanuos
precipitationPS

0,2 g/p*d
approx. 11 %0,8 g/p*d
approx. 42 %approx. 53 % in the sludge

Figure 9:

Potential of
p-recovery fromthe liquid phase

0,7 g/p*d
approx. 37 %optimisation

Potential for phosphorus recovery from the liquid phase (ROSENWINKEL ET AL., 2005a)

The recovery from the liquid phase shows in comparison with recovery from digested sludge or
ash the slightest potential. However it is relatively easy to apply and to integrate near-term inexisting plants. Furthermore, processing of the received phosphorus-products of P-recovery by
crystallisation or MAP-precipitation is much easier and without or with only low application ofchemicals. It is thus cheaper than a P-recovery from digested sludge or ash.
In case of plants with enhanced biological P-removal, the goal is to re-extract the phosphorus
stored in the phosphorus accumulating organisms (PAOs). For this, a reactor is placed in the
return activated sludge line. In this reactor an anaerobic phosphorus release is initiated by dosing
readily biodegradable carbon. Through subsequent precipitation and separation, the stored
phosphorus can be recovered and re-used as e.g. fertiliser.
Among optimisation of precipitation the optimisation of phosphorus-redissolution plays a crucialrole regarding to utilise as much as possible potential of phosphor-recovery.
Known measures for optimisation of phosphorus-redissolution are increasing the supply of readily
biodegradable substrate, adjusting the optimum of pH-value and temperature as well as anadequate anaerobic contact time. Considering excess sludge, thickened sludge offers an otherchance of optimisation. Due to a lower flow, less tank volume is needed. Furthermore bydisintegration of the excess sludge by extensive cell disruption more redissolution can beachieved.
The precipitation of phosphate and magnesium respectively as NH4MgPO4 × 6H2O is known in
the analytic chemistry since 1825. In the chemical nomenclature, the hardly soluble salt is named
ammonium-magnesium-phosphat-hexahydrat. In wastewater engineering it is applied for
precipitation of ammonium or phosphorus and it is called magnesium-ammonium-phosphat (MAP)or struvite.
The technical reaction equation of MAP-precipitation results with regard of the chemicallycombined water:
Mg2+ + NH4+ + PO43- + H2O ↔ MgNH4PO4 ⋅ 6 H2O- 47 -

Seite 12
MAP-precipitation is influenced by temperature, supersaturation degree achieved in the reactor
related to pH, Mg2+, NH4+ and PO43- concentrations, and the presence of other ions such as Ca2+.
Uncontrolled precipitation of MAP can produce pipe blockages and problems in the succeeding
aggregates of the dewatering process. However, MAP can be crystallised under controlled conditions. Figure 10 shows an example for a MAP-precipitation unit on a WWTP with EBPR.
P-redissolution

MAP-precipitation
N

C

Mg

effluent

Pdissolved

Sludgeof EBPRsludgeMAP

Figure 10: Flowsheet of a potential implementation of a MAP-precipitation unit on a WWTP with
EBPR

Readily biodegradable substrate, required for P-redissolution, can be obtained from thesupernatant of the acidification of primary sludge. Sludge liquor from plants with sludge digestion
can be used as nitrogen source.
WWTP with anaerobic sludge stabilisation have a higher sludge age and different sludge balance
than plants without sludge stabilisation. It would be interesting to analyse the influence of thisdifferences on the phosphorus recovery.
Anyway, the controlled MAP-precipitation enables EBPR plants to achieve very low levels of
effluent phosphorus concentrations and to recover phosphorus as a product that can be used asa fertiliser.

Conclusions
EU has introduced minimum effluent (emission) standards in 1991 which led to implementation of
biological nutrient removal. The trends in EU and Germany also point towards lowering theeffluent nutrient levels to below those required by EU Directive, leading to lower discharge feesand protection of eutrophic receivers.
In spite of local preferences for a particular BNR configuration, similar tendencies were observedin Germany with the most common process employing anaerobic/anoxic/aerobic configuration
with pre-denitrification, with many plants capitalizing on the simultaneous nitrification and- 48 -

Seite 13
denitrification (SND) and with practicing enhanced biological phosphorus removal (EBPR) in
fullstream or sidestream.
The main new trends in EU and Germany include the integrated river basin management, thedeammonification process for the treatment of sludge water, the optimisation of phosphorus
recovery by MAP and the membrane technology (MBR and ceramic membranes) especially forthe elimination of endocrine disrupters and pharmaceuticals.

References
AbwV (2004): Verordnung über das Einleiten von Abwasser in Gewässer, Bekanntmachung der
Neufassung der Abwasserverordnung vom 17.Juni 2004. BGBI. I S. 1108
Brinkmeyer, J.; Rosenwinkel, K-H.; Binkle, O.; Braun, G.; Gabriel, K.; Nonninger, R. (2006):
Development of a submerged ceramic plate module within the scope of a DBU project, Vortrag
auf der Industrial Water 2006, Dechema, 06.02.2006 in Frankfurt
Broda, E. (1977): Two kinds of lithotrophs missing in nature, Zeitung Allg. Mikrobiol. Vol. 17, No. 6,
pp. 491-493
EU (1991) Rat der Europäischen Gemeinschaften: Richtlinie des Rates vom 21.05.1991 über die
Behandlung von kommunalem Abwasser (91/271/EWG); Amtsblatt der Europäischen
Gemeinschaften Nr. L 135, 1991
Hippen, A. (2001): Einsatz der Deammonifikation zur Behandlung hoch stickstoffhaltiger
Abwässer, Publications of the Institute of Water Quality and Waste Management, University ofHanover Vol. 116
Jardin, N. (2003): Phosphorbilanz bei der Abwasser- und Klärschlammbehandlung In:
Rückgewinnung von Phosphor in der Landwirtschaft und aus Abwasser und Abfall, Tagungsband
zum Symposium am 6./7. Februar 2003 in Berlin
Katsogiannis, A. N.; Kornaros, M.; Lyberatos, G. (2002): Enhanced Nitrogen Removal in SBRs
Bypassing Nitrate Generation Accomplished by Multiple Aerobic/Anoxic Phase Pairs, e21344a,
IWA 3rd World Water Congress, Melbourne, Australia, 7.-12. April 2002
Makinia, J., Rosenwinkel, K. H., Spering, V. (2005) Long Term Simulation of the Activated Sludge
Process at the Hannover Gümmerwald Pilot WWTP. Water Research 39, 1489-1502
Mulder, J.W.; van Kempen, R. (1997): N-removal by SHARON, Water Quality international, IAWQ
(Edit.), March/April 1997, pp. 30-31
Obenaus, F., Rosenwinkel, K.-H., Alex, J., Tschepetzki, R. und Jumar, U. (1999): Components ofa model-based operation system for wastewater treatment plants. Water Science and Technology,
39 (4), 103-111
Rosenwinkel, K.-H., Cornelius, A., Thöle, D. (2005): Full Scale Application of the
Deammonification Process for the treatment of Sludge Water. IWA Specialized Conference,
Krakow, Poland, 19.-21. September 2005

- 49 -

Seite 14
Rosenwinkel, K.-H., Beier, M., Pabst, M. (2005a): Optimierung der Phosphorrückgewinnung aus
der wässrigen Phase mittels MAP, Tagungsband zum 75. Darmstädter Seminar Rückgewinnung
von Phosphor aus Abwasser und Klärschlamm, Schriftenreihe WAR, Band 167
Rosenwinkel, K.-H., Spering, V. (2006): Plant Wide Modeling als Instrument
medienübergreifender Emissionsbetrachtung; 13. Simba Anwendertreffen; 18. bis 19. Mai 2006,
Wernigerode
Seggelke, K. (2002): Integrierte Bewirtschaftung von Kanalnetz und Kläranlage zur Reduzierung
der Gesamtemissionen. Dissertation am Institut für Siedlungswasserwirtschaft und Abfalltechnik
der Universität Hannover, Veröffentlichungen des Institutes für Siedlungswasserwirtschaft und
Abfalltechnik der Universität Hannover, Heft 124
Seggelke, K., Rosenwinkel, K.-H. (2002): Online-Simulation of the WWTP to minimise the total
emission of WWTP and sewer system Water Science and Technology, 45 (3), 101-108
Spering, V. (2006): Plant Wide Modeling von Abwasserbehandlungsanlagen als Teil einer
Gesamtbetrachtung von Stoffeinträgen, Vortrag 18. Norddeutsche Tagung für Abwasserwirtschaft
und Gewässerentwicklung; 2006
Wendler, D. (2005): Erfassung und Behandlung ausgewählter Stoffströme in der
Siedlungswasserwirtschaft, Veröffentlichungen des Institutes für Siedlungswasserwirtschaft und
Abfalltechnik der Universität Hannover, Heft 131, 2005

- 50 -

- 51 -

[mg/l] (**)

[mg/l] (**)--

[mg/l]

Ptot.

90

90

75

5.000 – 10.000

10.000 - 100.000> 100.000

BOD

15

20

20

[mg/l]

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

TNmin = TN mineral (without organic)

COD[mg/l]

Size

TNmin

13

18

-

[mg/l]

1

2-[mg/l]

Ptot.

10 or 70 - 80 % 1 or 80 %Leibniz
Universität Hannover(*) for „sensitive areas“, (**) „normal areas“

10

10

10

[mg/l]

NH4-N

Minimum requirement FRG[mg/l] (*)

15 or 70 - 80 % 2 or 80 %[mg/l] (*)

N tot.

FRG Effluent requirements

125 or 75 % 25 or 70 - 90 %[inhab. equiv.]> 100.000

10.000 - 100.000 125 or 75 % 25 or 70 -90 %[inhab. equiv.]

Size

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Leibniz
Universität Hannover• Moving bed systems• A-B Technology / 2 stage

Total number of municipal WWTP‘s in FRG: 6110

• Biofilter (Nitrification andNitrification / Denitrification)

Biofilm Systems• Phoredox System/Phostrip• ISAH System• Johannesburg System• EBPR (combines with any activatedsludge system)• Membrane bioreactors• SBR-Technology• Sludge stabilisation• Alternating denitrification• Intermittent denitrification• Preliminary denitrification• Cascade denitrification• simultaneous denitrification

P removal

Activated Sludge Systems
N – Elimination

EU Effluent requirements

Requirements EU-Standards
COD
BOD
NH4-N

Typical process configurations

Leibniz
Universität Hannover

Effluent requirements

Institut für Siedlungswasserwirtschaft
und Abfalltechnik- P-Recovery / Energyrecovery

Sidestream Elimination and Recovery:- Deammonification- Biofilm Technology- Membrane Technology

Technology:- Integrated River Basin Management

Management:• Trends in Technology and Management:• Typical process configurations• Effluent requirements

Content42

- 52 -

0

5

10

15

20

25

30

35

40

45

50

1996

2000

Year

1998

2002

combined system

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Leibniz
Universität HannoverPredictive, adaptive control system with an online coupled model
prediction and regulation

Ö continuous observation of the state + prognosis

Ö optimisation of the control strategies

Research approach

Optimised operation WWTP in caseof rainfall (MSR, Online-Simulation)• Reduction emission• Simple balance(NH4 + COD-Load)

Surplus Sludge

4

10

11

5

13

12

1

TS, O 2 , pH

Institut für Siedlungswasserwirtschaft
und AbfalltechnikÖPlausibility Control of the Modell-inputÖDefault Value strategyÖSetpoint tracing=> Continous simulation WWTP

WWTP-Online
Simulation(SIMBA-Process)

6

IDM

Inlet

Simulation
sewer
Generate
Inflowscenarios

Rain:meassure +forecast

Leibniz
Universität HannoverPredictiveSimulation

Rain? =>Start

Leibniz
Universität Hannover

DN

RS-

P

Bio -

P

Bio -

NH 4 -N, NO 3 -N, PO 4 -P

2 x NO 3 -N, O 2

7

8

15

14

9

16

17

Simulation WWTP
Calculation of
influent max. Q

current state of
the Modell

measured data from WWTP

Predictive Control Strategy using simulation

ls

can’t be excluded in case of rainfall

max. Q?

• CODsewer z CODeffluent

3

2

O2

Returnsludge

OutletInstitut für Siedlungswasserwirtschaft
und Abfalltechnik

IDM

IDM, TS

6

8

Simultaneous N – Elimination and EBPR in a fullstream

WWTP Hildesheim

o

WWTP

Local/Central
controlÖ significant reduction of the emission

Area of examination• Immission•Simulation

Receiving waters

7

OutletSecondary settlerCÖ but: exceeding of the limiting values

Sewer cleaningÖ inflow WWTP > 2 Qdryweather

Use of storage
capacity

Storage +Treatment

combined / separate system

Undocking / Percolation

Seweragesystem

COD g/m³
BOD g/m³
NH4-N g/m³
Ntot g/m³
Ptot g/m³

Leibniz
Universität Hannover

2003

Integrated River Basin Management

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

1994(Source: DWA 2003)

Mean yearly effluent concentrations of german WWTP‘s

European Water Framework Directive:
Ö imission based approachÖ river water quality management
Ö integrated systemwide approach
Case Study

Aim

Concentration

Full Scale Experiences

.
äd
Pr
ro
nt
gy
te
a
tr

Width: 110 mm

800/300/200/80/
50 nm¾ 3 aerator tubes forcross flow

¾ 3 x 25 cm plates

surface¾ 0.172 m² active filtering

Laboratory module

Institut für Siedlungswasserwirtschaft
und Abfalltechnik¾ Pressure resistance > 10 bar¾ Membrane material D-Al2O3¾ Pore size

¾ Internal channel 21 units,  3 mm

Thickness:
6.5 mmStandard
length 250
mm

Nanopore£ -ModelF 21/30/1100

Laboratory Tests

Institut für Siedlungswasserwirtschaft
und AbfalltechnikÖCasestudies-simulation with calibrated modelsÖControl by measurements sewer, WWTP, river

Laboratory system

Leibniz
Universität Hannover

Leibniz
Universität Hannover¾Capacity of 0.11 to 1 m² offiltering surface¾Fully automatic process
management & data
recording¾45 l activated sludge tank2) Integrated view: influence on river (Optimisationpotential)

1) Online-simulation WWTP + prognose-simulation plant + sewer

Phase 2: fullscale plant (KA Hildesheim)(ASM 2d)

Ö Very good results for longtime simulation

developedÖ MSR-concepts for rainwether conditions

Ö Capacity up to 4 Qt (critical: Nitri + final clarifier)results:

69.6

55.1

39.1

0

100

100.1

123.6

160.7

150

69.1

NH4-N-Fracht
KA WWTPund Kanal [kg]Ammonia-load
CSOaus
plus

50

125.0

From laboratory to pilot system at the municipal wastewater treatment plant

04Institut für Siedlungswasserwirtschaft
und Abfalltechnik

0

25

50

75

100

125

150

175

200

8

12

12

10

16

20

24

28

32

40

44

48

Betriebszeit [d]

36

56

60

64

68

72

76

80

Leibniz
Universität Hannover

52

84

Good comparability of laboratory values¾ Permeability after 80 days: 30 l/m²hbar¾ TMP= 300 mbar

¾ TS= 2-5 g/l¾ 4 m² filtering surface

250

+14 %

0%

+5%

+18 %

Leibniz
Universität Hannover200

194 kg

170 kg

179 kg200 kgSumme: zu IST:

Municipal wastewater pilot system

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

2*Qs+Qf

3,2 x Drywetherflow

3.2*Qs+Qf IST

4*Qs+Qf

6.2*Qs+Qf

2) Test of Online-simulation

NH4-Fracht KA

Heavy Rainfall
Starkregenereignis
30.6.2001

NH4-N-load from Sewer and WWTP (Simulation results)

Trends: Integrated River Basin Management

NH4-Fracht MS

1191) Influence of increasing Q, optimal MSR-strategy etc.

Phase 1: „pilot-scale plant“ ( Hannover-Gümmerwald)

Research project ISAH (founded BMBF)

Permeabilität, normiert 20,0°C [l/m²h bar]

- 53 -

- 54 -

O2

Q

O2

O2

O2

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Fluidised Bed

O2

Q

Rotating Disc React.

Q

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Moving Bed

Trickling Filter

Q

Biofilm Technologies

Q

Leibniz
Universität Hannover

Leibniz
Universität Hannover

Biofilter

O2

Q

15

Q

Submerged Fixed Bed

O2

13

Leibniz
Universität Hannover

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Leibniz
Universität HannoverFull scale plant at Hattingen

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

14

16

NH4  NO 2 o N2  2H2O

NO 2  org. C o N 2

Deammonification
NH4  O 2 o NO 2

Denitritation

NH4  O 2 o NO 2

NO 3  org. C o N 2

NH4  O 2 o NO 2

Nitritation

Denitrification

Nitratation
NO 2  O 2 o NO 3

Nitritation

Biological Nitrogen Removal via Nitrite

Deammonification

40

15
10
5
0

40

20

0

20

25

30

35

45

COD removed

Nitrogen In

50

Nitrogen removed

Temperature

60

80

100

120

140

160

180

Leibniz
Universität Hannover

Renewable Energy
Sources Act

not reported

heating energy (incl. wood)electricity

heat energy and electric energy

0[BMU, Mai 2006]

2000

4000

6000

8000

10000

12000

Leibniz
Universität Hannover

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05
19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20

0

10000

20000

30000

40000

50000

60000

70000

80000

Real production of biomass energy inGermany

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

heating energy [GWh/a]Anaerobic Digestion of Wastes and Energy crops

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

02 .02 .02 .03 .03 .03 .03 .03 .04 .04 .04 .04 .04 .05 .05 .05
8.
0
2
2
5
7
9
2
2
4
7
9
1
1
4
6
.0 0.1 9.1 7.0 8.0 7.0 5.0 4.1 2.0 2.0 1.0 9.0 8.1 7.0 7.0 6.0
1
0
1
1
2
0
1
2
0
1
2
0
0
1
2
0
1

Nitrogen-Load,
Elimination [kg/d]

Nitrogen-, COD-Elimination over the full scale Plant

electricity [GWh/a]- 55 -

Temperature [°C]1917

Leibniz
Universität Hannover

0,8 g/p*d
approx. 42 %optimisation

0,7 g/p*d
approx. 37 %Potential of
p-recovery fromthe liquid phase

Institut für Siedlungswasserwirtschaft
und Abfalltechnik• KREPRO bzw. Kemicond process• Aqua Reci process• PHOSTRIP process• SEABORN process• Recovery from anaerobic digested sludge

Leibniz
Universität Hannover• Recovery from Surplus-sludge PRISA Process (MAP precipitation)

approx. 53 % in the sludge

0,2 g/p*d
approx. 11 %PS

Excess sludge+ simultanuos
precipitation

0,2 g/p*d
approx. 10 %Potential of phosphorus recovery in plants with EBPR
Influent : 1,9 g/p*d = 100 %Effluent

Phosphorus Recovery

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Design of the Mixing Facilities R1 & R3

20

18

- 56 -

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Leibniz
Universität Hannover

23

21

Leibniz
Universität Hannoverwww.seaborne-erl.de, 2006

RGU – Regenerative Gas Upgrading

NRS - Nitrogen Recycling System

Pilotplant Owschlag SLH
Fullscale plant Gifhorn NDS

RoHM - Removal of Heavy Metal

SEABORN process

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

MAP precipitation in digested sludge pipes

Mg

MAP

Leibniz
Universität HannoverConclusions and final remarks

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

sludgePdissolved

N

MAP-precipitation

Institut für Siedlungswasserwirtschaft
und Abfalltechnik

Leibniz
Universität Hannover

22

24

effluent• Minimum Requirements for C/N/P are fullfilled in germany• Applications of different Technologies for N and P-removal are in
operation, most activated sludge, but also biofilmtechnologies• Integrated Management of sewer and WWTP is nessecary for
optimisation costs and efficiency• Membranetechnology gives chances to improve the hygienic aspects in
the riverquality• Sidestreamtechnology for deammonification is a efficient application of
biofilmtechnology• Energyrecovery from waste and sludge is efficient, energyproduction
from crops must be validated, the competition to the food production inagricultural area must be very carefully observed• Future technology must consider harmful substances, endocrine
disrupters and personal careproducts

Sludgeof EBPRC

P-redissolution

Optimising MAP precipitation

- 57 -

Institut für Siedlungswasserwirtschaft
und Abfalltechnik
Leibniz
Universität Hannover

THANK YOU FOR YOURATTENTION

Final

25