Tests were conducted to assess the anaerobic treatability of grease trap wastes, septage, and municipal sludge. Tests were conducted in four phases: Phase I was analytical characterization of the individual waste streams. Phase II consisted of screening tests using bench-scale reactors supplemented with anaerobic respirometer tests to evaluate biochemical methane production potential and to determine if toxic impacts occur. The test program continued into Phase III using septage alone as well as a blend of septage, grease trap waste, and sludge. Phase IV used several different blends of grease trap waste and glycol to attempt to determine toxic threshold for the Grease Trap waste feedstock.
Test results showed that pure grease trap waste was toxic to the reactors but grease trap waste, when blended with other materials, degraded well at high solids retention times. The maximum percent blend of grease trap waste that could be applied without reactor failure was determined. Methane production volume and rates were good at higher reactor solids retention time.