Comparison of the methane production potential and biodegradability of kitchen waste from different sources under mesophilic and thermophilic conditions

The methane production potential of kitchen waste (KW) obtained from different sources was compared through mesophilic and thermophilic anaerobic digestion. The methane yields (MYs) obtained with the same KW sample under different temperatures were similar, whereas the MYs obtained with different samples differed significantly. The highest MY obtained in S7 was 54%-60% higher than the lowest MY in S3. The modified Gompertz model was utilized to simulate the methane production process. The maximum production rate of methane under thermophilic conditions was 2%-86% higher than that under mesophilic conditions. The characteristics of different KW samples were studied. In the distribution of total chemical oxygen demand, the diversity of organic compounds of KW was the most dominant factor that affected the potential MYs of KW. The effect of the C/N and C/P ratios or the concentration of metal ions was insignificant. Two typical methods to calculate the theoretical MY (TMY) were compared, the organic composition method can simulate methane production more precisely than the elemental analysis method. Significant linear correlations were found between TMYorg and MYs under mesophilic and thermophilic conditions. The organic composition method can thus be utilized as a fast technique to predict the methane production potential of KW.