Renewable Natural Gas from Anaerobic Digestion with Combined Heat and Power Recovery Transforms Biosolids Management at the City of Grand Rapids, Michigan Water Resource Recovery Facility

The City of Grand Rapids Water Resource Recovery Facility (WRRF) had only one option for biosolids management that relied on landfill disposal of un-stabilized wastewater residuals. A long-term strategy was developed that implemented an anaerobic digestion approach consistent with sustainability and environmental stewardship goals. A project was commissioned in 2018 to design and construct a Biodigestion with Combined Heat and Power Recovery facility with a Renewable Natural Gas (RNG) Conditioning system. The biogas from the process is refined with a renewable natural gas conditioning system and subsequently sold to the utility company. The combined heat and power system produces heat for the digestion process and provides electricity that is utilized within the plant to offset the power needs of the WRRF operation. The facilities have been constructed and operational for nearly 12 months and this is the first WRRF in Michigan to convert biogas to utility grade RNG.