The Downers Grove Sanitary District in Illinois has dedicated significant resources to reduce its energy footprint.
Improvements in process efficiency including plant automation, aeration system improvements, 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 by the facility is produced on-site using a biogas driven combined heat and power system. 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. The CHP plant was installed in 2017 with a payback time of 3.5 years. Total Infrastructure investments of roughly USD 5 million are expected to have a 10-year payback period.