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Effect of HRT and Support Media on Acidogenic Process by Rotational Drum Fermentation System

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

Citation:  Paper number  026135,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.10945) @2002
Authors:   Yutaka Kitamura, Wei Zhong Jiang, Noriaki Ishizuka
Keywords:   pH, acidogenic process, hydrolysis constant, stirring media, volatile acid (VA) inhibition, volatile solid degradation ratio, un-ionized VA, ionized VA, VA spectrum

The effects of hydraulic retention time (HRT) and the stirring media in the fermentor on RDFS acidogenic process were evaluated via system parameters involving volatile acid (VA) production and volatile solids (VS) degradation under mesophilic conditions. Two sequential experiments were conducted using a bench-scale RDFS. The first set of experiments was performed at HRTs of 15, 20, 25, and 30 days. A first order hydrolysis rate constant of 3.710-3 d-1 was calculated at pH values of 4.3 ~ 4.8. VS degradation and total VA (as acetic acid) ranged from 6.7 to 10.4 %, and 13.3 to 16.0 g/L, respectively. Results of the second set of experiments showed that the stirring media accelerated the hydrolysis and acidification processes, with Kh values of 5.3~7.210-3 d-1, and the VA spectrum was also influenced. The combined results indicate that pH values have an important effect on the distribution of un-ionized VA and ionized VA. At the same time, accumulation of VA, especially un-ionized VA, inhibits the hydrolysis process regardless of the type of stirring media in the fermentor.

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