Combination of wastewater treatment technology with food production
4 June, 2050
ROOF WATER FARM
Waste water source
Domestic wastewater of 250 inhabitants is separated into two different flows: black and grey water. Black water is wastewater from toilets and grey water is wastewater from washing machines, sinks, dishwashers containing lesser contaminants. Additionally the rainwater of 2,350 m2 roof area and 650 m2 sealed area is used.
The distribution system is very locally, in the same building.
Industrial water from greywater
RWF variant I: Treatment of domestic greywater for the use of industrial water for fish farming as well as for household-related reuse (toilet flushing), fertilization of the plants takes place via the use of nutrient-rich production wastewater from fish farming.
RWF variant II: Treatment of domestic grey water for plant water use for plant breeding and for household-related reuse (WC flushing), optional use of domestic black water for NPK liquid fertilizer production, fertilization of plants via the cultivation-specific dilution of highly concentrated NPK liquid fertilizer together with the process water.
Process water from rainwater
RWF variant III: Use of operating water from rainwater of the roof surface as process water for fish farming, fertilization of the plants takes place via the use of nutrient-rich production wastewater from fish farming
RWF variant IV: Use of rainwater from the roof surface as process water for plant breeding, optional use of domestic black water for NPK liquid fertilizer production, fertilization of the plants via the cultivation-specific dilution of the highly concentrated NPK liquid fertilizer together with the process water.
Hydroponic modules use the liquid fertilizer resulting from the black water treatment for the production of plants. Aquaponics is composed of the terms aquaculture and hydroponics and refers to the combination of fish and plant production in an integrated system. Products such as carp species, salad and strawberries showed good performance.
Waste water treatment description
Nutrient removal : Membrane bioreactor and anaerobic processes
Pesticide removal : none
Disinfection : biological purification by a membrane bioreactor and UV light disinfection
Suspended solids removal : Mechanical pretreatment, sedimentation
Other : Two different flows of treatment operate depending on the water source.
For black water, three mechanical pretreatment steps are performed followed by an aerobic treatment stage and a membrane bioreactor (MBR). Grey water treatment consist in sedimentation, biological purification and UV light disinfection.
The amount of grey water represents 10 m3/day, while black water production reaches 1 m3/h.
Extent of the agricultural beneficiaries
Operating water price of approximately 3 euros/m³. Depending on the construction investments made (new or existing building) as well as the selected operator model. The payback time for RWF hydroponics and aquaponics is estimated between 8 to 11 years.
Type of agreement
Due to the complex combination of real estate, water and agriculture and the close proximity to the everyday life of city dwellers, different actors play important roles in different areas when implementing ROOF WATER-FARM concepts. The most importart actors involved are property owners, residents, technology providers, architects and building planners, urban farmers, municipal utility and disposal companies and urban planners. Possible roles in the implementation of ROOF WATER-FARM are:
- Regulatory Framework, which enacts laws or regulations or grants permits.
- Initiator of ROOF WATER-FARM projects, either as an embodiment of framework conditions in the form of incentives or prohibitions, or quite practically as an investor or designer / architect, offering the concepts for a new construction or refurbishment as an alternative to conventional building concepts.
- Profiteer of the ROOF WATER-FARM during operation or implementation.
- Operator of the water treatment or roof farm of a ROOF WATER FARM.
ROOF WATER FARM Manual: Million, A .; Bürgow, G .; Steglich, A. (ed.) (2018): ROOF WATER FARM. Urban water for urban agriculture. TU Berlin, Berlin. ISBN 978-3-7983-2986-7 (print), ISBN 978-3-7983-2987-4 (online) Bürgow, G. (2014): Urban Aquaculture - Water-sensitive transformation of cityscapes via blue-green infrastructures. Dissertation 25.11.2013, Technical University Berlin. Publication series of the Reiner Lemoine Foundation, Herzogenrath: Shaker Verlag. ISBN 978-3-8440-3262-8. doi: 10.2370 / 9,783,844,032,628th Million, A. / Bürgow, G. /
Steglich, A. (2016): Urban Waters for Urban Agriculture - ROOF WATER-FARMs as Participatory and Multifunctional Infrastructure. In: Sustainable Urban Agriculture and Food Planning, Rob Roggema (ed.), Book Chapter 9, pp. 142-165. Routledge, New York. ISBN: 978-1-138-18308-7 Bürgow, G. / Steglich, A. / Million, A. (2017): Application of ROOF WATER-FARM building-level technology for integrated infrastructure design in the neighborhood.
The Roof water farm project resulted in:
- Demonstration of cultivation technologies of water-based plant and fish production (hydroponics , aquaponics) in connection with decentralized water treatment technology of grey, black and rain water.
- Hygienic standards of cultivation and safety of relevant micropollutants were achieved.
- Water and product quality was good in comparison with relevant national and European specifications.
- Production of liquid fertilizer by treating black water as "gold water" for hydroponic plant production.