Net-zero energy operations at WWTP,
Downers Grove, Illinois, USA

The Downers Grove Sanitary District is responsible for treating wastewater from the city of Downers Grove and the cities of Westmont, Woodridge, Lisle, Oak Brook and Darien, Illinois.
DGSD handles wastewater from over 60,000 consumers daily, and has the capacity to treat 11 million MGD.

The Downers Grove Sanitary District has dedicated significant resources to reduce its energy footprint. Improvements in process efficiency including plant automation, aeration system im-provements, upgrades to HVAC and building management systems, and variable frequency drives have resulted in a 30% reduction in electricity usage at its wastewater treatment plant.

The remaining electricity used at the plant is produced on site using a 2x375kW biogas-powered gas engine plant supplied by NISSEN energy.

Biogas is produced by co-digesting hauled food waste and sewage sludge generated on-site. The biogas is used as fuel to drive an engine-driven electric generator. Furthermore, heat recovery in the form of circulating hot water is used for plant process heat.