Reduction of energy consumption and greenhouse gas emissions in wastewater treatment plant: A case study of utilizing anaerobic sludge digestion

The energy consumption of a wastewater treatment plant (WWTP) is influenced by many factors, such as the wastewater flow rate, organic strength, and the treatment process for the liquid and sludge. In this study, a complete inventory of energy consumption and greenhouse gas (GHG) emissions in the WWTP of Qingsui Highway Rest Station was carried out. In this plant, the aeration blowers were used in some units, including the aerobic sludge digestion tank, and they accounted for about 50% of the total power consumption. Four plant operation scenarios, including the existing case of aerobic sludge digestion and its replaced cases of using anaerobic sludge digestion with/without biogas power generators, were applied. The comparison results indicate that for these scenarios inducing anaerobic sludge digestion, the energy consumption and GHG emissions would be reduced by 5.8–13.5% and 13.4–19.0%, respectively. This case study provides a comparison of some feasible engineering strategies for reducing energy consumption and GHG emissions in an existing domestic WWTP that uses aerobic sludge digestion.