Braunschweig
Braunschweig is one of very few large-scale agricultural reuse sites in Germany, and serves as water reuse showcase for Germany and Central Europe. It reuses the effluent of Steinhof WWTP for agricultural restricted irrigation (fodder and industrial crops).
The site has developed from a sewage farm that treated the wastewater since 1895. After introduction of engineered wastewater treatment (1979) the sandy soils in the area with poor nutrient contents and low groundwater tables still allowed for high hydraulic loads.
The plant treats an average volume of 21 hm3/yr, of which two thirds are used for the irrigation of the 3000 ha of agricultural area of the Sewage Utilization Association of Braunschweig. The remaining third enters infiltration-percolation fields as a final treatment step, before it is discharged into the Aue-Oker-Canal, a small discharge body.
The wastewater treatment includes primary sedimentation, activated sludge for the removal of bulk organic carbon and biological treatment to eliminate nutrients (i.e. nitrogen and phosphorous). No specific additional advanced treatment is applied before reuse. The produced sludge from primary sedimentation and the activated sludge process is digested in an anaerobic treatment step. During summer the digested is mixed with the effluent of WWTP and is used for the irrigation of agricultural areas. In winter the sludge is dewatered and used as fertilizer on agricultural areas. By this practice 100% of the yearly produced sludge is land-spread in agriculture.
Due to its long reuse history the scheme has overcome main water reuse barriers. However, strict regulation could potentially impact sludge reuse. Thus, nutrients management decoupled from water management will be implemented in the coming years, backed up by appropriate risk assessment and intensified discharge control.
Within DEMOWARE the site will:
- Provide new technologies and concepts for nutrient recovery and serve as a demonstration site of decoupling nutrients water management.
- Demonstrate of partial disinfection strategies in the framework of risk assessment.
