The optimisation of food waste addition as a co-substrate in anaerobic digestion of sewage sludge

Abstract

Food waste has been regarded as the main source of various environmental pollution in Korea due to the high volatile solids (VS) and moisture content caused by the features of dietary habits. The feasibility of food waste as a co-substrate in anaerobic digestion of sewage sludge was investigated in mesophilic and thermophilic conditions using batch tests. Cumulative methane production, dissolved organic carbon (DOC) and volatile fatty acids (VFA) were monitored to find the optimal mixing ratios of food waste and sewage sludge for the enhanced performance of co-digestion. It was observed that adequately mixed food waste led to the enhanced methane production both at mesophilic and thermophilic conditions. However, a conventional linear regression conducted for the optimisation of co-substrate mixing ratios was not accurate in describing exact methane production trends of co-digestion because of the different biodegradability of substrates. Therefore, a remodified Gompertz equation showing nonlinear relationship between variables was developed to find exact information with the same experimental data obtained at 2g VS/l generally used in biochemical methane potential (BMP) tests. Based on an influential parameter, methane production rate (MPR), the optimal mixing ratios of food waste were 39.3% and 50.1% in mesophilic and thermophilic conditions, respectively. To confirm the application of the remodified Gompertz equation, secondary batch tests were conducted with the substrate concentrations of 1-4g VS/l. In overall range tested, the confident mixing ratios of food waste was adjusted to 30-40% and 40% in mesophilic and thermophilic conditions, respectively. The most significant factor for enhanced performance was the improved organic carbon content provided by additional food waste.

Construction of Biodigesters to Optimize the Production of Biogas from Anaerobic Co-Digestion of Food Waste and Sewage

“…High TVS value in food waste suggests the possibility of biogas production increase, specially methane, when blended with sewage sludge. Work by Kim et al [22] evaluated the blend of food waste with sewage sludge and noted that the addition of organic waste improves anaerobic digestion. Based on the results obtained in the initial phase, the best proportion was 10% in dry weight (DW).…”

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

“…The same figure shows that the highest SMP based on VTS applied load was related to 75:25 ratio (116 mL CH 4 /g VTS applied ), a value 4.3 times higher than the sewage sludge sample control. Kim et al [42] evaluated the co-digestion of sludge (80%) and food waste (20%) and obtained for 71% methane content, which is a SMP 1.4 times higher.…”

Recovery of Sustainable Renewable Energy from Marine Biomass

“…Therefore, it has become a rapidly emerging research topic within the field of renewable energy (Angelidaki et al, 2009;Behera et al, 2010;Heo et al, 2004;Lee et al, 2009;Weiland, 2010). The biochemical methane potential (BMP) test was developed as a standardized method to quantify the CH 4 yield from an organic substrate under specific conditions (Kim et al, 2003;Owen et al, 1979;Rincon et al, 2010). In recent years, a number of different feedstocks including organic wastes and energy crops such as maize and wheat has been used to evaluated the CH 4 yield from these substrates (Behera et al, 2010;Gunaseelan, 2004;Hansen et al, 2004;Oslaj et al, 2010;Rincon et al, 2010).…”