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Enhanced Phosphorus Removal in Swine Manure Using Aerated Batch Reactors

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

Citation:  Paper number  024097,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.9539) @2002
Authors:   Pius M. Ndegwa, Jun Zhu, Ancheng Luo, Douglas W. Hamilton
Keywords:   Aeration treatment, pH, oxidation-reduction potential, swine manure, and phosphorus

This study compared three schemes of soluble orthophosphates reduction from liquid manure during batch-aeration: solids-liquid separation before aeration (referred to as pre-aeration solids-liquid separation), solids-liquid separation in the middle of aeration (referred to as mid-aeration solids-liquid separation) and no solids-liquid separation at all (control). From the results of this study, mid-aeration solids-liquid separation resulted in more orthophosphate being converted to non-soluble species, which are amenable for removal by the subsequent solids-liquid separation: 84%, 87%, and 92%, for the control, pre-aeration solid-liquid aeration, and mid-aeration treatments, respectively. The mid-aeration solids-liquid separation further improved the overall actual removal of total phosphorus in a subsequent removal of the sludge from the liquid after an overnight sedimentation process: 80% against 70% and 66% for pre-aeration solids-liquid separation and control, respectively. The pH change was found to have a significant effect on reduction of soluble orthophosphates as observed from the fitted 3rd order regression equation with a high correlation coefficient of 0.99. Maximum rate of reduction of soluble orthophosphates in the manure occurred at approximately the pH of 7.0. The oxygen transfer efficiency was also significantly improved by the solids-liquid separation treatment implying that, significant energy saving is possible for pro-longed aeration. This is an important element in the post-aeration treatment for ensuring that phosphorus already removed from the solution stays in the sludge and is not released back into solution if removal of the sludge does not immediately follow scheduled-aeration treatment.

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