Integration of wastewater source heat pump and solid-state anaerobic digestion for residential waste treatment and energy production

Abstract

Recovering energy from waste is gaining growing interest worldwide. The tremendous amount of residential waste, e.g. wastewater and food waste, spurs researchers to develop appropriate waste management methods and energy recovery technologies. Wastewater source heat pump (WWSHP) and solid-state anaerobic digestion (SS-AD) are well established methods for treating wastewater and organic waste. This study proposes a novel combination of these two technologies to handle residential wastewater and solid waste. In the proposed integrated system, WWSHP recovers heat from residential wastewater and then supply heat to SS-AD so that keeps the digesters at a desired operation temperature. The digester uses residential solid waste as feedstock to produce biogas, which is a renewable energy carrier. A case study taking a 1000-resident community as an example showed that the total electricity generated from this system can supply 8% of the community and also provides 1.53×10 12 J useful heat per year which can greatly reduce building energy consumption.