The project consisted of major improvements to two 60-foot diameter anaerobic digesters with new pump and nozzle mixing systems and fixed steel covers, and a new, expanded digester control building with a hot water system, sludge heat exchangers, sludge recirculation and transfer pumps, and electrical room. The new cogeneration system consists of two 65-kW micro-turbines which utilize digester gas to produce electricity and also produce waste heat for the hot water system, minimizing use of the natural gas boiler.
The City realized savings of more than $100,000 by utilizing electricity and waste heat produced by the micro-turbines and reducing the use of natural gas. Approximately 20% of the plant’s power needs were supplied by methane-generated electricity via the micro-turbines. The City is also benefiting from improved solids destruction in the digesters by reducing its annual biosolids disposal budget by $50,000.
Wessler’s ingenuity and foresight expanded West Lafayette’s treatment options while generating significant savings. The project earned the City the United States Environmental Protection Agency's (EPA) Performance and Innovation in the SRF Creating Environmental Success (PISCES) award and the Indiana Governors Award for Environmental Excellence.