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Enhancement of hydrolysis and acidification of solid organic waste by a rotational drum fermentation system with methanogenic leachate recirculation

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2007 ASAE Annual Meeting  077120.(doi:10.13031/2013.22881)
Authors:   Ling Chen, Wei Zhong Jiang, Baoming Li, Yutaka Kitamura
Keywords:   leachate from methanogenic process, cascade process, hydrolysis rate constant, volatile solid degradation ratio, VA spectrum

A cascade process of a rotational drum fermentation system with leachate recirculation from a methanogenesis to the acidogenic reactor was constructed to enhance the hydrolysis and acidification of solid organic waste. Using fresh soybean meal as substrates, two process configurations-Cascade processes 1 and 2, without and with leachate recirculation, respectively-were employed to perform the experimental estimation under mesophilic condition and a total HRT of 20 days. An apparent first-order hydrolysis rate constant of 9.0×10-3 /d for Cascade process 1 at pH values of 4.5-4.6 and 15.8×10-3 /d for Cascade process 2 at pH of 4.6-5.2, were obtained. The apparent VS degradation ratios ranged from 16.5% to 21.1% and total VA (as acetic acid) from 14.5 g/L to 16.7 g/L. Occupying ratios for ionized VA decreased from 40.5% to 35.3% for Cascade process 1 and increased to 68.5% for Cascade process 2. However, occupying ratios of acetic acid decreased from 96.1% to 94.3% for Cascade process 1 and to 72.6% for Cascade process 2 whereas propionic acid and butyric acid ratios increased in acidogenesis of Cascade process 2. The leachate recirculation promoted hydrolysis of substrate in Cascade process 2, where apparent hydrolysis rate constant and VS degradation ratio were higher than that of Cascade process 1.

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