Optimization of Methane Production Based on Mixture Content of Sewage Sludge, Food Waste, and Glycerol

Abstract

This paper presents bench scale experiments related to anaerobic co-digestion of aerobic sewage sludge from a pilot WWTP (waste water treatment plants), raw glycerol from a biodiesel industry and food waste. Assays were conducted in 100 mL non-stirring penicillin vessels, at 30 °C and planned according to three optimization phases: (1) binary mixture of sewage sludge and FW (food waste); (2) binary mixture of sewage sludge and glycerol; and (3) ternary mixture of sewage sludge, FW, and glycerol. In the first and second phases, the highest SMP (specific methane production) was achieved by 10% (v/v) FW and 0.5% (v/v) glycerol mixtures. The optimization of the ternary mixture during the third phase was reached by the combination of 10% (v/v) FW and 0.4% (v/v) glycerol. Despite the low SMP value, the addition of glycerol and FW contributed to doubling the SMP value of the sludge sample control.