Mechanical Engineering Department
University of Wisconsin-Milwaukee
The aim of this study is to achieve a net-zero-energy (NZE) wastewater treatment plants (WWTPs) by utilizing, energy efficiency opportunities (EEO’s), combined heat and power (CHP) systems and other renewable energy sources, e.g. solar and wind powers. This research represents the outcome of energy audits on eight WWTPs in the state of Wisconsin with flow capacities ranging from 1.4 to 110 million gallons per day (MGD) and promoting one of them into a NZE WWTP as a case study. The Industrial Assessment Center (IAC) at the University of Wisconsin-Milwaukee conducted energy assessments on eight WWTPs during the past two years. One of the WWTPs was selected, and the EEOs proposed by the IAC were able to reduce the WWTP’s energy consumption by about 20%. The anaerobic digester gas was utilized in a CHP system to cover about 50-60% of the facility’s consumption, besides reclaiming heat for space heating and a heat process in the plant. Both solar photovoltaic (PV) panels and wind turbines also contributed to achieving the NZE WWTP.