Client: Western Lake Superior Sanitary District

Location: Duluth, Minnesota

The Western Lake Superior Sanitary District (WLSSD) retained Donohue to collaboratively develop an Energy Master Plan for their wastewater treatment facility. This plan serves as a dynamic and living energy roadmap to guide the District’s transformation to energy independence. This shift is consistent with the national movement for wastewater utilities: shifting from net energy resource consumers to energy producers.

The evaluation included a study of current energy use at the 160-million-gallon-per-day wastewater treatment facility and associated costs. Donohue also conducted an extensive evaluation of biogas utilization at the facilities, including using engines, micro-turbines, and fuel cells to produce electricity. Heat recovery systems from effluent, biogas utilization, and the aeration system were also explored.

Donohue then developed a plan to prioritize capital improvements based on condition assessments and energy efficiency. The roadmap provides recommendations for repairing and replacing infrastructure based on age, safety concerns, and reliability, as well as energy efficiency, with the goal of decreasing energy demand and increasing production. The result is a comprehensive Energy Master Plan that will guide the District to energy independence.

Coupling new technology with conservation projects, WLSSD is headed toward generating electricity to meet about half its needs by 2018 — keeping regional wastewater treatment costs stable and contributing to Minnesota’s renewable energy goals. Capitalizing on “biogas”, a methane-rich by-product of wastewater treatment, WLSSD will produce both clean water and clean, renewable energy. Watch a video about biogas and learn more at wlssd.com/news/biogas-harnessing-energy-from-wastewater/