The potential impact of an implementation of microalgae-based wastewater treatment on the energy balance of a municipal wastewater treatment plant in Central europe

Integration of a photobioreactor for WWT by microalgae is calculated as a future alternative for cost-efficient and environmentally-friendly nutrient removal for municipal WWTPs. High growth rates and higher biogas yields (compared to conventional sewage sludge) of algal biomass can significantly improve WWTP energy balances. This study focuses on temperate climate zones with changing seasons and discusses energy potential of microalgae-enhanced wastewater treatment for an existing WWTP (32,000 PE) in Central Germany. For WWTPdimensioning and determination of energy-rich biomasses for anaerobic digestion and CHP, actual influent load data was used and calculation was carried out according to valid regulations. Algae growth figures are based on pilot-scale test series from Germany and correspond to the relevant climatic and local process conditions. Computed results show a shift in the energy balance from a current energy demand of 662,173 kWh a(-1) to an energy production of approx. 1,9 MWhel. a(-1) and 1 MWhth. a(-1).

Automated summary

Integration of a photobioreactor for wastewater treatment by microalgae is considered as a cost-efficient and environmentally-friendly alternative for nutrient removal in municipal WWTPs. The high growth rates and biogas yields of algal biomass can greatly improve the WWTP energy balances. This study focuses on temperate climate zones, analyzes the energy potential of microalgae-enhanced wastewater treatment in an existing WWTP in Central Germany, and calculates the shift in the energy balance.