FOG – A Proven High Efficiency Renewable Energy Source, Not a Nuisance

In addition to economic benefits, the codigestion of brown grease also known as fats, oils, and grease (FOG) has multiple environmental benefits in reducing landfill load and carbon footprint. Over the past 30 years, more than 40 wastewater treatment agencies in the United States have been codigesting FOG to produce more digester gas for an extra renewable energy. A telephone survey of 13 agencies for 14 facilities indicated a digester gas production increase from 5% to 100% and a 5% to 6% methane gas improvement. Design and operational issues are minor and manageable. Design parameters for FOG codigestion are inconsistent and are yet to be standardized.This paper details the methodology and results from the two large-scale pilot studies conducted at the Regional Water Reclamation Plant in Riverside, California, and at the Hyperion Wastewater Treatment Plant in Los Angeles. It also discusses the results of FOG codigestion since 1976 at the Wastewater Treatment Plant 2 in Bakersfield, California, as well as the design features of the recently commissioned FOG facility at Wastewater Treatment Plant 3 in Bakersfield.