Thermal Energy Recovery From Small Sewage Treatment Plants in Northern Canadian Communities

This paper presents feasibility study and concept design of a thermal energy recovery system with an adsorption heat pump integrated with a small sewage treatment plant in northern Newfoundland communities. Treated fluids from the sewage treatment systems are quite warm even in winter. For example measured fluids temperature is averaged at 17 °C when air temperature is at −10 °C in the town of Whitbourne. This provides an attractive heat source particularly for winter seasons. Four heat pump concepts, i.e., vapour compression, absorption, adsorption and chemical heat pumps, were reviewed and compared. The results show that the adsorption system best fits the sewage treatment plants with minimum power requirements. Thermal fluidic parameters of the key components were designed with fluid flow and heat transfer analysis. A brief economic and environmental analysis showed that the integrated energy recovery unit would lead to a net reduction of CO₂ emission and feasible payback time.