Semi-decentralized infrastructure in the development areaof Knittlingen, Germany
Marius Mohr and Walter Trösch Fraunhofer-Institute for Interfacial Engineeringand Biotechnology Stuttgart, Germany
Introduction
The waste water treatment in Germany has today reached a really high standard.
Referring to German statistics in the year 2001 94.6 % of all the inhabitants had access tothe public sewer system. 98 % of the waste water was cleaned up to the recommendationsof the EU rules. If it is additionally assumed that Germany is rich in ground water
resources and situated in a region with sufficient rainfall, why to look for new solutions
for urban infrastructure and water management.
But there are several reasons for a revision towards sustainability:
The reconstruction of 485 000 km of public sewers which have been invested in thelast 100–120 years is very expensive and will become even more expensive theolder the canal system gets.
In the different water bodies an increase of organic micro pollutants (hormones likesubstances, pharmaceuticals) have been recorded which can not be degraded instandard waste water treatment plants. Additionally there is no hygienic barrierbetween treatment plants and the receiving water bodies, causing the distribution ofpolyantibiotic resistancies in the microbial world.
By climatic change along with the global temperature increase it has been analyzed
that rain events tend to be shorter and heavier without changing the yearly quantity
resulting in increased hydraulic problems and floodings. In addition with aprolongation of the climatic trend drinking water resources may also be shortened inGermany.
The demographic change especially in the new federal states of Germany shows
the inflexibility of the existing infrastructure and state of the art technique forwaste water treatment: By reduction of inhabitants in several regions the specificcosts for the water treatment have increased to non acceptable levels.
The increasing global demand for energy which is covered mainly by fossilmaterials results in increasing costs for energy, stimulating savings of energy andthe search for new resources.

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This challenge is mirrored by a new innovative water management concept ofFraunhofer-IGB in the frame of the Project DEUS 21, which is funded by the Ministry ofEducation and Research (BMBF) as a technical demonstration.
Whereas standard water management is mainly operated in centralized big installations
DEUS 21 tends to semi decentralized systems. In a first order of magnitude systems of
100 to 10,000 inhabitants are in the focus of basic designs. Main principal of the design iscircuit processing. Thus biogas is the recycling product in respect to the carbon bone oforganic pollutants. Additional value recycling substances are Ammonia and Phosphorous
to be used as artificial fertilizer. Rain water collection and reuse as new resource of a
specific quality of drinking water is incorporated to the concept. The demonstration plantis set in operation in the small town Knittlingen near Pforzheim, Germany, in a newresidential zone for about 100 individual houses.

Rainwater from the roofs of the buildings and the residential streets is collected
separately and stored in underground stainless steel containers. This water is cleaned up
according the requirements of the drinking water rule of the European Union andachieves drinking water quality. As so called „care“ water it is redistributed to thehouseholds in a separate net.
Waste water is collected by a vacuum sewer system. In a central station the vacuum is- 298 -generated. The waste water of the buildings is collected in a buffer store and sucked away
by opening an air valve at the end of the pipe grid. As option the vacuum sewer system canbe installed inside the building to make use of water saving toilets and kitchen waste
mixers.
The semi decentralized waste water cleaning unit is situated in the centre of theresidential zone to minimize the sewer grid. By using an anaerobic low temperatureprocess water depollution is realized along with biogas production. Biogas is used in acogeneration unit to produce electricity and heat. The value substances Ammonia andPhosphorous are recycled in form of crystalline artificial fertilizer, which easily
compete economically to synthetic fertilizers. The outflow of the treatment plant is freeof solids especially pathogens in regard of the micro filtration integrated to thebioprocess. The effluent shows bathing water quality (EU-recommendations) and canbe reused as irrigation water without poisoning soil and ground water.
Water house
The water house is the operation centre for all techniques of the DEUS 21 water
management concept. It is also information and presentation centre for the population andexternal national and international visitors. The building itself is a cube partially withunderground floor. The big window front allows insight to the process and the operationunits.

Water house Knittlingen

The water house contains the following process steps and containers:- 299 -3.
•The upgrading and redistribution techniques for rainwater and a 10 m big
container for "care" water ready to use.
•The vacuum station, which causes the depression in the canal system anddoes by means of this extract the waste water by suction.
•The waste water treatment plant as pilot unit for 50 – 70 inhabitants andlater on for all inhabitants of the residential zone
As the water house is situated in direct neighbourhood to residential buildings with theadvantage of short distances for the sewer, care water and drinking water nets the zero
emission standard must be very high: Especially noise emission has to be decreased andindividual noise reduction techniques have been installed for individual noise sources.

Rain water use
Rainwater is not only available in a certain quantity covering about 50 % of the drinking
water demand but also represents water in a special quality. Rain is a product of solar
irradited evaporation of surface water which is recondensed by natural climatic conditions.
Source collected rain water has compared to drinking water reduced salinity andtherefore is qualified to be used in all cases where water is heated to reduce calzification:dish washer, washing machine, water heater inside buildings for showers etc.
In addition rainwater collection and storage if used area wide reduces the danger offlooding.

In Knittlingen rain water of roofs and residential streets is collected. In a first filtration
step (0.6 mm) rain water is cleaned from coarse solids. Included in the first separation
apparatus is a possibility to get rid of the higher polluted first liquid flush. The precleaned
water is then stored in tanks of 300 m total volume. It is soften oxiginated duringstorage to prevent fouling.
3- 300 -Cisterns for rainwater storage

To create care water in quality (hygienically) of drinking water the rain has to pass aceramic ultra filtration (60 nm) membrane with an extremely sharp cut off to make sure to3

retain all the bacteria and viruses. The cleaned care water is stored in a 10 m container tocover demand peaks.
In a circuit distribution tube the soft care water is transported to the households incomparable pressure as the drinking water net is operated. The circuit is hold at constantcircuit flow to pass cyclic a UV-desinfection unit to prevent back contamination bymicroorganisms.
Vacuum sewer system
As an advantage over conventional flushing sewer systems the vacuum sewer uses tubeswith reduced diameter so that investment and operating costs can be saved at infrastructure
realisation. In addition the system is flexible to demographic changes (ups and downs). The
user has in principle two options to get use of the system. The first option is conventional
dewatering of buildings. Waste water is collected in a special underground reservoir whichacts as fitting system to the vacuum sewer. Second option is the integration of the vacuum
tube inside the building to get use of vacuum toilets and kitchen waste mixer.

- 301 -Vacuum station installed in the water house

The vacuum itself is generated inside the water house in a vacuum tank by two
redundant vacuum pumps. The tank is the reservoir and equilibration volume for thewaste water.

Waste water treatment
Waste water from the vacuum station is pumped into the anaerobic psychrophilic waste
water treatment reactor where the waste water is digested by anaerobic bacteria at inflow
temperatures. The reactor is equipped with a ceramic micro filtration unit in form of arotating disc filter. The filtration is operated in dead end mode to increase bacteriaconcentrations together with incoming solids inside the bioreactor.

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Rotation disc filter and reactor for waste water treatment

The special operating mode as dynamic filtration unit allows "in operation" cleaning fromfouling layers at disc surfaces by centrifugal forces. Thus high constant flux rates areobtained. The anaerobic organisms digesting at first organic substances to methane and CO(biogas), which are used in a cogeneration unit to cover the energy demand of the cleaning
process, liberate nitrogen components during digestion of organics as NH and solublePhosphorous, too. By the addition of Magnesium salt to the filtrate of the membranebioreactor MAP is precipitated and can simply be recovered. The quality of the concentrate
is so good that the fertilizer is ready for use in agriculture.

2+4

Residual NH is adsorbed to an ion exchange material to concentrate the value substance.
From the regenerate is will be possible to strip Ammonia in an economic form to recover asecond artificial fertilizer: Ammoniumsulfate for example.
3Conclusion
The demonstration waste water treatment plant in Knittlingen shows that it is possible torecover value substances from the water stream along with water regeneration ready forsecondary use: infiltration, irrigation, service water. The recycled products are biogas from- 303 -

C-bone of pollutants and fertilizer components. In regard of exporting the system todeveloping countries or arid zones the water treatment can be stopped after biogas recovery
if the water is sustainably used to irrigate and fertilize agricultural zones.

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- 305 -Archivierungsangabe

Drinking water

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Fraunhofer

Wastewater

Rainwater

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

GroundwaterSpecific treatment and reuse

RiverRainwater storage reduce the danger of flooding

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Fraunhofer-Institute forInterfacial Engineering and Biotechnology,
Stuttgart, Germany

Prof. Dr. Walter Trösch

10th Japanese German Workshop on Water Technology,
Berlin, 09.-10.10.2006

Drinking Water
Processing

Semi-Decentral urban Water- and Waste Water Management

Semi-DEcentralized Urban Infrastructure System DEUS 21

Archivierungsangabe

Archivierungsangabe

Drinking water

Centralwastewater
treatment
plant

River

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Irrigation

Rain water
storageRain Collection

Gär-RestDigestion
Rest
DisposalDecentralized
Sewage treatment unit

Energy/P-N Fertilizer

Kitchenwaste

Sewage Sewer
Vacuumsewer

Water

Application in house

Drinking water net

Rain water treatment

Rainwater net

DEUS 21

Knittlingen „ Am Römerweg“Semi-DEcentralized Urban Infrastructure System DEUS 21

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Sewer system

Fraunhofer

Wastewater

Rainwater

Drinking water
processing plant

Salt/heavy metalsEndocrine activities
Recombinant bacteria ( Multiresistance byhorizontal gene tranfer)
Pharmaceuticals

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 306 -IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Al2O3

Archivierungsangabe• Excellent Cut-off

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB• Membrane surface: 352-1450 cm2

4,5 mm• Discdiameter ∅: 152-312 mm• pore diameter: 0,2- 0,02 µm• Thickness:

2,5 (0,3)

5,0

Drinking waterrule (EU)Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Cross-section of a single discUltrafiltration disc for rainwater cleaning• Material:

Archivierungsangabe

0,06

Conductivity :(mS/cm)0,01

9,5Rainwater

COD (mg O2/l):

Desalinatedwater

Quality of rainwater in Stuttgart: 10.10.2002(unfiltrated, private rainwater collecting unit, Trösch)Semi-DEcentralized Urban Infrastructure System DEUS 21

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Archivierungsangabe

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Filtration discSurface layer

Fouling prevention by centrifugal forces / in operation cleaning

Archivierungsangabe

Zur Anzeige wird der QuickTime™
Dekompressor „TIFF (LZW)“benötigt.

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 307 -Archivierungsangabe

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Irrigation

Rain water
storageRain Collection

Gär-RestDigestion
Rest
DisposalDecentralized
Sewage treatment unit

Energy/P-N Fertilizer

Kitchenwaste

Sewage Sewer
Vacuumsewer

Water

Application in house

Drinking water netRain water treatment

Rainwater net

DEUS 21

Knittlingen „ Am Römerweg“Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Pilot-scale ultrafiltration unit with rotating disks

Semi-DEcentralized Urban Infrastructure System DEUS 21

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Archivierungsangabe

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Scheme of a vacuum sewer system

Urban watermanagement DEUS 21

Archivierungsangabe

Dynamic ultrafiltration units (2 x 7,4 m2)
and pressure station for care-water
distribution

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 308 -IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Archivierungsangabe

4anaerobic

aerobic

1g/l COD = 0,4 l Biogas (70%CH4)

CO2, NO3, SO4, PO4

CH4 + NH3 + H2S +H3PO4-NH4

O2

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Consequence: Anaerobic psychrophilic waste water treatment-POC-OH

Biologically catalysed reactions within biodegradation gaseous products escape to the atmosphere

Archivierungsangabe

Reduced investment costs
for the sewer

Reduced digging costs

Development area Knittlinen: Vacuum sewers DN 60

Semi-DEcentralized Urban Infrastructure System DEUS 21

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

9lFraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Total organic load : 3.6 g/l d

Load stage 1 : 8.33 g/l dstage 2 : 2.60 g/l d6l

Biomass concentration:
12 g/lOutput COD: < 100 mg/lAnaerobic Waste Water treatment: Two stage cascade with intergrated
Microfiltration at 15-20°C

Input:
4,3 g COD/lArchivierungsangabe

Vacuum station

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 309 -IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Archivierungsangabe

4anaerobic

aerobic

CO2, NO3, SO4, PO4

CH4 + NH3 + H2S +HPO3-NH4

O2

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Aerobic biodegradation = Reduction of waste without economical benefit-POC-OH

Biologically catalysed reactions within biodegradation gaseous products escape to the atmosphere

Archivierungsangabe

Biogas lift loop bioreactor withsurplus sludge containment

Semi-DEcentralized Urban Infrastructure System DEUS 21

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Archivierungsangabe

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

without the addition of chemicals

Precipitation of Mg-ammonia-phosphate

Recycling and recovery of phosphor
components is possible:

MAP - Precipitations from digestion filtrate

Archivierungsangabe

Photo of the technical plant; in thefront and on right hand side therotation-disc-filter
and in the back the anaerobic gas
lift loop bioreactor

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 310 -Archivierungsangabe

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Air stripping at elevatedTemperature andprecipitation in an
appropriate acid

Ionexchange toconcentrate thedissolved AmmoniaPrecipitation of Ammoniumsulfate to recover the remaining Ammonia
after MAP

Semi-DEcentralized Urban Infrastructure System DEUS 21

Archivierungsangabe

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGBHigh poduction numbers reduce investment costs !

Industrially preconstructed, each identical, remotecontrolled

Modular Water Infrastructure system including
rainwater catchment, water redistribution
and waste water purification
In modules:
for 1.000 Inhabitantsfor 10.000 Inhabitantsfor 50.000 Inhabitants??

Final conclusion:

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 311 -Archivierungsangabe

Archivierungsangabe

2

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

31IndustryCity

Semi-decentralized
waste water treatment units designed for thereuse of cleaned waste water

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Optimized sewer gridfor collection and redistribution

area

Agricultural

Semi-DEcentralized Urban Infrastructure System DEUS 21

FraunhoferRainwater collection
without problems ofinfiltration/exfiltration

Archivierungsangabe

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Liquid soil technique:Archivierungsangabe

Microfiltration 2

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 312 -Archivierungsangabe

Archivierungsangabe

Picture of thesettlement:

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik• Blau: Bioreactors• Rot: Pumping station• Grau: Microfiltration

3D-graphic of the module

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Semi-DEcentralized Urban Infrastructure System DEUS 21

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

Semi-DEcentralized Urban Infrastructure System DEUS 21

Fraunhofer

Advantage:• No flushcleaning necessary• Reduced costs compared to vacuum sewers or free flowsystems• Construction of 7 pumping stations with 180 l pumping
volume per pumping act

Archivierungsangabe

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

Microfiltration of raw waste
water to separate solid andvolatile COD
Microfiltration of nitrification
effluents to produce a
Microorganisme free water
stream for infiltration or irrigation

Technical installation ofa high load aerobic waste
water treatment plant:

Archivierungsangabe

KA

Pressure sewers:(Variant 2)

Sewer development

Semi-DEcentralized Urban Infrastructure System DEUS 21

- 313 -Archivierungsangabe

Fraunhofer

Institut
Grenzflächen- undBioverfahrenstechnik

IGB

MBR in Heidelberg Neurott

Semi-DEcentralized Urban Infrastructure System DEUS 21

Archivierungsangabe

Fraunhofer

IGB

Institut
Grenzflächen- undBioverfahrenstechnik

0,4l /g COD

Semi-DEcentralized Urban Infrastructure System DEUS 21