Effect of Potassium Inhibition on the Thermophilic Anaerobic Digestion of Swine Waste
Abstract:The inhibition effects of high potassium concentration on thermophilic anaerobic digestion of swine waste were studied. A continuous stirred tank reactor (CSTR), operated at a hydraulic retention time of 10 days and chemical oxygen demand loading of 7.2 to 7.5 g/L/d, was used to digest swine waste and cultivate thermophilic anaerobic microorganisms. To evaluate the toxicity of potassium, batch inhibition tests were also conducted. Without acclimation to potassium, the inhibition threshold beyond which methane production decreased significantly was 3 g K +/L. Volatile fatty acids accumulation was observed during the decline of methane production. Propionic acid was the dominant fatty acid, indicating that propionic acid utilizers were more sensitive to potassium inhibition than acetoclastic methanogens. To test the effect of acclimation on potassium inhibition, the potassium concentration in the CSTR was increased to 6 and 9 g K +/L. Acclimation to 6 g K +/L increased the tolerance of anaerobic inocula to potassium inhibition without significantly reducing the methanogenic activity. The inhibition threshold was increased from 3 g K +/L for unacclimated inocula, to 6 g K +/L for inocula acclimated to 6 g/L of potassium. Acclimation of inocula to 9 g/L potassium further increased the inhibition threshold to 7.5 g K +/L. However, the overall methanogenic activity in the last case was lower than that of unacclimated and 6 g K +/L acclimated inocula.
Document Type: Research Article
Publication date: 2007-06-01
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Water Environment Research� (WER�) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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