Energy, Water, United States, North America, Government
Energy + Water
Food Waste to Fuel
Innovative Upgrades for WWTP Efficiency
Wastewater treatment plants are challenged with energy management, causing many to creatively produce and reuse energy. Harnessing methane from anaerobic digestion is used to produce heat, electric power, or biofuel (biomethane) and offset facility power needs. Today, we are helping plants take this one step further with co-digestion—enhancing digestion with organic waste. The addition of fat, oil and grease (FOG), as well as food waste, to anaerobic digestion accelerates this process, producing more methane gas for beneficial reuse and reducing the amount of solid waste conveyed to landfills.
The addition of FOG and food waste to anaerobic digestion accelerates this process, producing more methane gas for beneficial reuse and reducing the amount of solid waste conveyed to landfills.
The Riverside Public Works Department wanted to expand the capacity and advance the efficiency of its regional water quality control plant. We are helping with upgrades, including a new 26-million-gallon-per-day membrane bioreactor, new primary clarifiers, a solids handling facility, two new digesters and a permanent FOG unloading station.
Although the plant’s original digesters were performing well and producing energy to help run the facility, the department felt that the plant could do more. Based on the city’s pilot testing, we were able to increase the amount of FOG loading to 20 to 30 percent and improve volatile solids destruction by 5 to 10 percent while increasing gas production. We have also partnered with Arizona State University (ASU) to test a sludge disintegration technology that breaks down cell membranes in waste activated sludge (WAS) prior to anaerobic digestion to increase gas production. The ASU study results indicated as much as a 30-percent increase in gas produced from WAS.