Journal article
Anaerobic digestion of swine manure: Inhibition by ammonia
A stable anaerobic degradation of swine manure with ammonia concentration of 6 g-N/litre was obtained in continuously stirred tank reactors with a hydraulic retention time of 15 days, at Four different temperatures. Methane yields of 188, 141, 67 and 22 ml-CH4/g-VS were obtained at 37, 45, 55 and 60 degrees C, respectively.
The yields were significantly lower than the potential biogas yield of the swine manure used (300 ml-CH4/g-VS). A free ammonia concentration of 1.1 g-N/litre or more was found to cause inhibition in batch cultures at pH 8.0 (reactor pH), and higher free ammonia concentrations resulted in a decreased apparent specific growth rate.
Batch experiments with various mixtures of swine and cattle manure showed that the biogas process was inhibited when the swine-to-cattle manure ratio was higher than 25:75, corresponding to a free ammonia concentration of approximately 1.1 g-N/litre. Inhibition of the biogas process and, thereby, a reduction of the methane yield followed a four-stage pattern: below a threshold of 1.1 g-N/litre free ammonia, the process was uninhibited; over this concentration, inhibition occurred, forming first a phase with an initial inhibition, then a plateau and then an inhibition stage where the apparent specific growth rate decreased with increasing concentrations of free ammonia. (C) 1998 Elsevier Science Ltd.
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Language: | English |
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Year: | 1998 |
Pages: | 5-12 |
ISSN: | 00431354 and 18792448 |
Types: | Journal article |
DOI: | 10.1016/S0043-1354(97)00201-7 |
ORCIDs: | Angelidaki, Irini |