Water reclamation of urban waste water
4 June, 2050
Wastewater Association Braunschweig
Waste water source
The wastewater treatment plant Steinhof treats the urban wastewater coming from Braunschweig. In addition to the wastewater from the urban households there are 377 indirect dischargers (hospitals, dental surgeries…). The industry in Braunschweig is very heterogeneous so that about 15 different branches of industry discharge their wastewater into the sewerage. Most of the cities sewerage has a separate system but the city center of Braunschweig has a combined system which leads to a mixture of household wastewater and stormwater. The COD of the raw influent is about 840 mg O2/l, the concentration of particular components is 290 mg/l.
From the reclamation facility the reclaimed water is first distributed via gravity-flow pipes to four pumping stations located in the agricultural fields of the Wastewater Association Braunschweig. Pressure pipes transport the reclaimed water from the pumping stations to the irrigations systems. The irrigation system consists of a hose drum with a classic sprinkler at the end, which can cover a radius of 3,000 - 5,000 m². The hose drums and the sprinklers are shifted regularly by employees of Wastewater Association Braunschweig. The pipe network has a total length of 130 kilometers which distributes the reclaimed water to 1,350 tapping points.
The farmers using the reclaimed water mostly cultivate grain (44 %), energy crops (32 %), sugar beets (17 %) and potatoes (4 %). All the farmers practice rotating farming. The reclaimed water coming from the wastewater treatment plant Steinhof is distributed via pumping stations to all fields. In the field itself, a with a sprinkler is used for irrigation.
Waste water treatment description
Nutrient removal : Struvite precipitation and nitrogen stripping
Pesticide removal : none
Desinfection : none
Suspended solids removal : yes
The wastewater treatment plant Steinhof has a capacity of 2,160 m³/hfrom February till October. The volume of the reclaimed water used for irrigation from February till October represents 10 hm³. The volume of digested sludge which is irrigated together with the reclaimed water is 65,000 m³/year.
Extent of the agricultural beneficiaries
The area provided with the reclaimed water is about 2,700 ha. More than 100 farmers are provided with reclaimed water. The average crop yield of grain is about 30 ton/ha, the crop yield of energy crops (maize) is about 50 ton/ha.
In 2018 the operational and maintenance costs of the reclamation facility were about 11 million euros. The irrigation system costs about 6 million euros. The farmers receiving the reclaimed water pay 80-110 €/ha.