Title: Sequential phases in the anaerobic degradation of swine manure
Abstract: A mass balance model was used to calculate the amount of substrate degraded during batch fermentations of swine manure (16–23% total solids). Three phases could be identified. In phase I, the methane production rate was low and decreasing. The concentration of short-chain fatty acids increased, and pH and Eh decreased. Initially, there was a high rate of substrate degradation, which decreased. Forty-two per cent of the methane originated from CO2 reduction, due to a high production of H2 and acetate but a low conversion of acetate to CH4. In phase II, the methane production rate and pH increased, and the acetate and then the butyrate concentration decreased. The rate of substrate degradation was initially low, but rose to a maximum late in phase II. Only 11% of the methane originated from CO2 reduction, due to a low production of H2 but a high utilization of the acetate which had accumulated in phase I. In phase III, the methane production rate reached a maximum and declined. The concentration of acetate decreased, propionate increased, and butyrate was absent. Thirty-seven per cent of the methane originated from CO2 reduction. The low concentrations of fatty acids suggest that hydrolysis and fermentation of substrate were the main factors limiting the methane production.
Publication Year: 1986
Publication Date: 1986-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 2
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