Evaluation the anaerobic digestion performance of solid residual kitchen waste by NaHCO3 buffering

Abstract

Anaerobic digestion has been considered as a promising energy-producing process for kitchen waste treatment. In this paper, the anaerobic digestion (AD) performances of solid residual kitchen waste (SRKW) with or without NaHCO3 buffering were investigated. The results indicated that the methane production reached the maximum of 479mL/gTSadded at the inoculum to substrate ratio (ISR, based on VS) of 1:1.4 without buffering, accompanied by VS removal rate of 78.91%. Moreover, the anaerobic digestion capacity increased by 33.3% through NaHCO3 buffering, and the methane yield at ISR 1:2.8 was improved by 48.5% with NaHCO3 addition. However, the methanogenesis with or without NaHCO3 buffer was suppressed at ISR 1:3.5, indicated from the lowest methane yield of 55.50mL/gTSadded and high volatile fatty acids concentration of more than 14,000mg/L. Furthermore, proteins in SRKW were not degraded completely at excessive organic loading, since the concentrations of ammonia nitrogen in ISR 1:3.5 groups with (2738mg/L) and without NaHCO3 buffering (2654mg/L) were lower than the theoretical value of 3500mg/L and the protease activities in ISR 1:3.5 groups were also inhibited.