case study braunschweig – 100 years practical experience ...€¦ · monitoring of sludge and...

Cornel/Hartmann/Müller 04/07/2012

DWA-AG BIZ 11.4 Water reuse – Case Study Braunschweig –

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Univ.-Prof. Dr.-Ing. Peter Cornel Dipl.-Geoökol. Katharina Müller TU Darmstadt, Institut IWAR, Fachgebiet Abwassertechnik Dipl.-Ing. Andreas Hartmann KompetenzZentrum Wasser BerlinGmbH, Berlin

Case Study Braunschweig – 100 Years Practical Experience in Water Reuse DWA-Slide Presentation „Water Reuse“



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Content

Overview and historical development Percolation fields:

Framework data Functions and treatment principle ecological importance

Agricultural irrigation Wastewater collection/sewerage system Nutrient utilization Added value of the concept



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Overview map

Source: Abwasserverband Braunschweig [Hartmann 2010]

Catchment area of WWTP

Irrigation area

Percolation fields

WWTP



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Historical Development

Since 1895: trickle percolation of waste-water on the fields of the “Gut Steinhof” to the North of Braunschweig cultivation of vegetables

Until 1954 the collected sewage was irrigated without treatment on fields of Gut Steinhof (450 ha)

1954: Funding of the wastewater association Braunschweig and the use of spray irrigation for the excessive volume of wastewater on agricultural areas (3000 ha)

1979: Construction of biological pre treatment step on the grounds of the present-day treatment plant

[Stadtentwässerung Braunschweig 2008]



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Historical Development

Until 2005, stepwise expansion of treatment plant (nutrient elemination, digesting system, co-generation plant)

Until now a third of the water treated in the WWTP is discharged on the percolation fields, partly used for agricultur

Agricultural areas are irrigated with the remaining treated water using spray irrigation

The treated water is conveyed from the WWTP via a pressure pipeline to the percolation fields

Further distribution on the fields takes place with open flow splitters, channels and slide gate valves distribution

Infiltration into the upper soil layers, drainage into drainage ditches and con- veyance via the Aue-Oker-Canal directly to the River Oker or pumped to agri-fields

[Abwasserverband Braunschweig]



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Percolation Fields Braunschweig – Data and Facts

Area Total: ca. 270 ha effective percolation area: ca. 220 ha

Capacities Daily mean water volume: ca. 20, 000 m³ Daily max. water volume : ca. 40, 000 m³ average area loading rate ca. 3, 500 mm/year Storage capacitiy: ca. 300.000 m³

[Abwasserverband Braunschweig, Stadtentwässerung Braunschweig]



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Percolation Fields Braunschweig

Inflow of treated wastewater to the percollation fields

[IWB Dresden]



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[Klein]

[IWB Dresden]



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Function of Percolation Fields

Initially, water flows through ponds and meanders and then through the soil layer and aquifer

Post treatment of biologically treated domestic wastewater: treatment with plants and microorganisms in soil, high treatment performance for Nitrogen and endogenous germs

Retention of treated wastewater: retention time > 10 days retention of heavy storm water events

During summer reserve of water for the irrigation association

[IWB Dresden]



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Functions of the Percolation Fields

Source: Abwasserverband Braunschweig; SE/BS; ISWW

[Hartmann 2010]



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Ecological Importance

Percolation fields are today a bird sanctuary Resting and feeding place for wading birds An area for migratory birds to rest, breed and stay over winter




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Ecological Importance

Improved quality of surface water of the river Oker and its tributaries downstream of Braunschweig


None to very slight load

Slight load

Moderate load

Critical load

Heavily contaminated

Very heavily contaminated

Excessively contaminated

Water quality class



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Overview Map

Source: Abwasserverband Braunschweig

[Hartmann 2010]

WWTP

Percolation Fields

Irrigation Area

Catchment area of WWTP



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Agricultural Irrigation

Sprinkler irrigation takes place on 3000 ha. During the growing period, stabilized sewage sludge is added as

fertilizer to the irrigation water 2006: Construction of a biogas plant for the wastewater association Since then: cultivation of corn and rye for energy on 1/3 of the area Other field crops: sugar beet, wheat, potatoes 20 km long gas pipeline to the central combined heating plant in

Braunschweig Provision of power for 3,800 households Heat energy for ca. 1,000 households

[Klein et al. 2011]



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Sprinkler irrigation

28.09.2016 16 Braunschweig model



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Agricultural Irrigation

0

10

20

30

40

50

60

20092008200720062005200420032002200120001999199819971996

Perc

enta

ge

Year

MaisZuckerrübenGetreideKartoffelnSonstige

CornSugar beetCerealsPotatoesOther

Picture: W. Küchenthal [Hartmann 2010]



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Wastewater Collection – Sewerage System

1,361 km total length - Rainwater: 667 km - Wastewater: 552 km - Mixed water: 79 km - Pressure pipes: 63 km

City of Braunschweig + adjacent communities

Over 400 companies; industry Since ~ 1970: Heavy metals in

wastewater and sludge: Discharge control and pre-

treatment of industrial wastewater

Source: SE/BS [Hartmann 2010]



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Heavy metal load to irrigation since 1980

Basis of a safe sludge reuse: - Discharge control - Pre-treatment - Cooperation and

coordination - Reduction of heavy

metals and other pollutants at the source.

[Hartmann 2010]



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Treatment and reuse system: Overview

Wastewater

wwtp

Energy cropsand other

Sludges

Treated wastewater(Former) Sewage Field

Digester towers Dewatering

Digested sludge: (winter)

Digester gas

Recipient

Co-substrates

(summer)

External use ofdewatered sludge

Cogeneration unit

Digester

WWTP Former sewage field

Irrigation (3.000 ha)

Heat & Energy

Process water

Biogas plant

Source: Abwasserverband Braunschweig; SE/BS; W. Küchenthal

[Hartmann 2010]



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Nutrient reuse: Phosphorus

~ 200 t/year, almost completely reused: - Inside the system: Irrigation of digested sludge (summer) - Outside the system: Sludge dewatering, storage and reuse as

dry fertiliser (winter)

Only small amounts of P have to be applied by artificial fertilisers Decoupling from fertiliser market Fossil deposits of P can be protected

[Hartmann 2010]



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Nutrient reuse: Nitrogen

40% of N is used within the system; 10% outside Loss due to denitrification: 40 - 45% Artificial fertiliser is needed, because N is continuously applied with

water and sludge, can scarcely be stored in soils and is subsequently degraded when N cannot be used by plants

wwtpN in wastewater:

1300 t/year

350 t fixed in sludge 102 t used outside system

252 t to irrigation

270 t dissolved in water

210 t to irrigation60 t sewage field

denitrification500-600 t/year

The system can be optimised by…

- the optimisation of N-application

- (the reduction of N-degradation)

- Current projects

[Hartmann 2010]



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WWTP future concept: nutrient recovery



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Wastewater and sludge irrigation: Advantages for…

the operators of the WWTP: - Sludge disposal - Post-treatment of water, buffering

farmers: - Nutrient and C-application - Balance of water deficits

the environment: - Protection of N- and P-resources - Protection of the recipient river - Groundwater recharge instead of groundwater

withdrawal - Saving of energy (production of artificial fertiliser) - Production of renewable energy

0

20

40

60

80

100

Janu

ar

Februar

MärzApril Mai

Juni Ju

li

August

Septembe

r

Oktobe

r

Novembe

r

Dezembe

r

NiederschlagVerdunstung

mm

April - SeptemberØ 1923 - 06 = - 114 mmØ 1997 - 06 = - 226 mm

Data source: DWD

[Hartmann 2010]



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Nutrient, water and energy cycles: An overview

WWTP

Irrigation area

City of Braun-schweig

Biogas plant and cogeneration unit

Crops

[Hartmann 2010]



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Main elements of wastewater reuse

Organisation, coordination and management Contractual obligations between water/nutrient

supplier (WWTP) and user Efficient infrastructure Acceptance

- Long-term experience and know-how - Transparency, communication, PR - Prevention of aerosol spray by hedges

alongside roads

Monitoring of sludge and water Monitoring of soils and groundwater

[Hartmann 2010]



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Literature Abwasserverband Braunschweig: Rieselfelder. Online verfügbar unter http://www.abwasserverband-

bs.de/Rieselfelder/rieselfelder.html, zuletzt geprüft am 15.06.2012.

Abwasserverband Braunschweig; Stadtentwässerung Braunschweig GmbH: Die Braunschweiger Rieselfelder: Symbiose für Mensch und Natur seit mehr als 100 Jahren. Online verfügbar unter http://www.amtenbrink.de/kunden/sebs2009/web-content/dokumente/Flora_und_Fanua_AVB_SEBS_Info.pdf, zuletzt geprüft am 15.06.2012.

Hartmann, A. (2010): Long-term experience with water reuse in Braunschweig: Prospects and Risks. Co-Authors: Klein,D.; Dockhorn, T.; Dichtl, N.; Sardet, C.; Teiser, B. EWA-Symposium IFAT München, 14.09.2010. EWA-Symposium IFAT München, 2010. Online verfügbar unter http://dwa.de/portale/ifat/ifat.nsf/C125734C003E2A55/EC5860EAC5FBFFB8C12577AD0052349F/$FILE/pp-Hartmann_03%2009%202010.pdf, zuletzt geprüft am 29.06.2012.

IWB Dresden: Ökologische Umgestaltung der Rieselfelder Braunschweig. Online verfügbar unter http://www.iwb-dresden.de/index.php/de/projekte/10-rieselfelderbraunschweig, zuletzt geprüft am 15.06.2012.

Klein, D.; Dockhorn, T.; Dichtl, N. (2011): Anpassung der Nährstoffrückgewinnung auf Kläranlagen an den Bedarf der Landwirtschaft am Beispiel des Braunschweiger Abwassersystems. In: Gesellschaft zur Förderung des Institutes für Siedlungswasserwirtschaft an der Technischen Universität Braunschweig e. V. (Hg.): Tagungsband 3. Internationales Symposium "Re-Water Braunschweig". Implementierung und Realisierung. 21. und 22. November 2011. Braunschweig (Veröffentlichungen - Institut für Siedlungswasserwirtschaft - TU Braunschweig, 81), S. 99–114.

Stadtentwässerung Braunschweig GmbH (2008): Die Stadtentwässerung. Imagebroschüre. Online verfügbar unter http://www.stadtentwaesserung-braunschweig.de/fileadmin/redakteure/download/oeffentlichkeitsarbeit/SEBS_Imagebroschuere_2008.pdf, zuletzt geprüft am 15.06.2012.

case study braunschweig – 100 years practical experience ...€¦ · monitoring of sludge and...

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