Near Future Energy Self-sufficient Wastewater Treatment Schemes

Abstract

Achieving energy self-sufficiency is critical for wastewater treatment plants (WWTPs) to comply with rapidly changing environmental regulatory standards in a sustainable manner. Currently, a small percentage of WWTPs around the world produce energy for beneficial use and only a handful of these plants are energy self-sufficient. We propose three energy-positive wastewater treatment schemes and use quantitative analysis to assess their potentials for carbon and nitrogen removal and energy generation from municipal wastewater. This research identifies potential challenges in the selection and implementation of energy recovery process configurations and proposes practically feasible energy-positive wastewater treatment process configurations. Energy self-sufficiency can be achieved through biogas production while simultaneously minimizing the energy consumption for treatment. Furthermore, energy recovery can be enhanced in the near future (i) by increasing the COD capture in primary treatment to enhance energy production; (ii) by replacing activated sludge process with other less energy-intensive biological treatment technologies; and (iii) by increasing energy production from digesting supplementary feedstock in anaerobic codigestion (AD) schemes. This paper presents a quantitative analysis of three process schemes that progressively build upon the concept of transforming the conventional activated sludge wastewater treatment plants (CAS-WWTP) into energy self-sufficient wastewater treatment facilities. These schemes also include a hypothetical but practically feasible WWTP configuration, which represents an alternative energy self-sufficient wastewater process scheme for future designs.