Influence of inoculum activity on the bio-methanization of a kitchen waste under different waste/inoculum ratios

摘要

The use of a granular inoculum prevented acidification during the anaerobic batch biodegradation of a kitchen waste for waste/inoculumratios in the range of 0.5–2.3 g VS/g VS, when the alkalinity/COD ratio was 37mg NaHCO3/g COD. In similar experiments but using asuspended sludge with a significantly lower activity, the methane production rates and the biodegradability were significantly lower and thepH decreased below 5.5 at the waste/inoculum ratio of 2.3 g VS/g VS. When the added alkalinity was decreased to 2mg NaHCO3/g COD,the ratio waste/inoculum was clearly more important than the inoculum activity, since, irrespective of the sludge used, acidification occurredat waste/inoculum ratios higher than 0.5 g VS/g VS. The advantage of using granular sludge was further investigated in order to definereasonable condition of waste/inoculum ratio and added alkalinity that could be applied in practice. For a waste/inoculum ratio of 1.35, therewere no significant differences between the results obtained for the biodegradability and maximum methane production rate (MMPR), whenthe alkalinity decreased from 44 to 22 mg NaHCO3/g COD.