When the original sewage treatment plant in Wooster, Ohio, began operation in 1938, it consisted of primary settling tanks, an anaerobic digester, and sludge drying beds. Over the years, the facility has been upgraded several times, but failed to meet performance standards for digestion and solids handling. Something had to be done.

The city evaluated several proposals and formed a partnership with a private company. The company provided some capital investment, engineering, construction, and expertise, while the city delivered manpower and infrastructure and paid a monthly management services fee. The city council approved the funds to begin the project and offered support. Managers in the city and utility worked closely with the private company during construction, startup, and early operations.

The three existing digesters in the Wooster facility were enlarged, and new mixing, cover membranes, and heat exchangers were all added along with a gravity belt thickener (for city biosolids), a solids receiving vault, a liquids receiving pit, and a feedstock holding tank. A larger combined heat and power unit was installed to heat the new organic biosolids receiving building and all the tankage in the anaerobic digestion system. In order to produce enough methane to utilize the larger heat and power unit and supplement the city’s biosolids, the facility accepted organic third-party waste streams. Tipping fees were collected by the private partner, and the city offered discounted fees to benefit local businesses or as an economic development tool to attract new business to the area.

The city’s Water Pollution Control Plant became known as the Water Resource Recovery and Bioenergy Facility. Within 12 months of startup, the power generation was exceeding the facility’s daily demand. To optimize the anaerobic digestion system, the city installed an electric transmission line to the nearby water treatment plant and eliminated the electric meter at that location. At times, both facilities are “off the grid” to become what may be the first electrically self-sufficient water/wastewater utility.

The facility upgrade provides a means to harness waste streams into renewable energy. Rate payers benefit from reduced energy costs. The city benefits from additional revenue. The facility is operating with a focus on environmental stewardship and reducing operating costs.

In 2018, the facility produced 3.9 megawatts of power for the operation of the treatment facilities, which resulted in nearly $250,000 in energy savings. The ability to accept feed stock, septage, and food waste solids to create the methane provided nearly $900,000 in additional revenue. Ultimately, this provides self-reliant power sources, but also a nutrient-rich soil product that saves farmers money and eliminates commercial fertilizer runoff from agricultural areas.

The Water Resource Recovery Facility is leading edge. No other facilities in Ohio produce the power from an anaerobic digestion process to power both water and wastewater facilities. The facility innovation was confirmed with a 2018 Utility of the Future Award from the Water Environment Federation.

Learn more about the ICMA Awards Program here.