VFAs' Formation and their Effects on the Biodegradation of MSW with different Aeration Modes

摘要

Four bioreactors with different aeration modes, i.e. passive aeration, passive aeration with leachate recirculation, intermittent forced aeration with leachate recirculation and forced aeration with leachate recirculation called as R1, R2, R3, and R4, respectively, were carried out for 50 days to investigate the effect of acidification percentage and volatile organic acids on the decomposition of municipal solid waste. R4 was operated as control. The concentration of chemical oxygen demand (COD), volatile fatty acids (VFA), acetic acid, propionic acid and butyric acid in leachate were regularly monitored, and the acidification percentages were also calculated. The percentage between VFA and COD was much low, less than 5%. The variation of acetic acid and butyric acid with time had similar trend in R1, R2, R3, and R4, and the fluctuation was not so big, in the range of 30%-43%. While for the propionic acid, the percentage for R4 went up and then down, and in the other bioreactors, the trend kept increasing to about 20%. However, semi-aerobic treatment had a good efficiency for the degradation of organic matter. The volatile solids were significantly reduced from 50.5% to 17%, 18%, 21% and 22% with the sequence of R4>R2>R3>R1. The trend of settlement was observed by R4>R2>R1>R3, with about the 50% of the initial waste depth.