Stevens Point, Wisconsin
2016 ACEC Wisconsin State Finalist Award Winner
Donohue & Associates and the City of Stevens Point received an Engineering Excellence State Finalist Award for the “Brewing a Better Future Together” project from the American Council of Engineering Companies (ACEC) of Wisconsin.
The Problem: The Stevens Point wastewater treatment plant set the goal of achieving net-zero energy use and therefore sought to reduce operating costs and increase efficiency. Increased loadings from a local brewery were causing inefficient treatment.
The Solution: The City of Stevens Point worked with Donohue to design a two-phase project to implement new energy efficiencies and energy production systems. Phase 1 of the project included a low-energy digester mixing system, low-energy pumping, and a biogas-driven engine generator. These improvements allowed the City to realize significant energy savings, to the point where it became routine to push excess power onto the grid. Phase 2 of the project entailed: 1) a new system for diverting high-strength waste from the Stevens Point Brewery, and 2) utilizing excess capacity in the anaerobic digester to accept additional high-strength waste from other sources such as regional grease and food wastes.
Why This Project is Unique: This project is unique in the way it handled the public-private partnership between the City of Stevens Point and the Stevens Point Brewery. A simple, yet specialized waste separation and handling system was constructed at the Brewery. The concept of source separation is not new, however when coupled with reduced energy costs and increased biogas electricity – it is very innovative, especially for an existing facility. The revised system greatly stabilizes the loading to the WWTP, thus increasing system efficiency and performance.
How the Engineer Saved the Day: This project was initially developed to alleviate operability and discharge permit concerns, yet sustainability emanates from every ounce of the project. The project is already saving the City $150,000 per year and has reduced the potential cost to the brewery by $150,000 per year. It also restores excess WWTP capacity for future growth.