In 2007, the City of Fergus Falls, MN, undertook a study to evaluate adding thick corn stillage to the anaerobic digesters at its wastewater treatment plant. The goal was to determine the potential for codigesting syrup with biosolids to increase biogas production, while avoiding operational and regulatory problems. The plant processes about 2.3 million gallons per day of wastewater. A few years ago, a steam boiler was converted to a hot water boiler capable of burning biogas, fuel oil and natural gas to heat the digesters and buildings at the facility in the winter. Sufficient biogas was produced during the study period to satisfy the maximum daily heating requirements in the winter. During the summer there would be enough excess biogas to operate a small generator. Fergus Falls investigated installing a small cogeneration system with the local power company, but decided not to pursue the option.