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

Citation:  Pp. 590-595 in the Ninth International Animal, Agricultural and Food Processing Wastes Proceedings of the 12-15 October 2003 Symposium (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003.  701P1203.(doi:10.13031/2013.15298)
Authors:   Z. Hu, C. R. Mota, F. L. de los Reyes III and J. Cheng
Keywords:   Intermittent aeration, nitrogen removal, nitrification, denitrification, optimization

A continuous-flow intermittent aeration (IA) process has been studied for nitrogen removal from anaerobically-pretreated swine wastewater. Hydraulic retention time in the IA tanks was 3 days and biosolids retention time was around 20 days. In the IA process, aeration was controlled to provide alternating aerobic and anoxic conditions for nitrifying and denitrifying bacteria, respectively. The alteration of aeration to non-aeration of 1 h to 1 h and 1 h to 3 h was tested in the first phase of this study to investigate the effect of aeration cycle and aeration-to-non-aeration ratio on the performance of the IA process. Over 80% nitrogen removal was observed in the IA tanks. The operation with longer non-aeration period (1-h aeration followed by 3-h non-aeration) resulted in lower nitrate- and nitrite-nitrogen concentrations than with shorter non-aeration period (1-h aeration followed by 1-h non-aeration). In the second phase, the aeration to non-aeration ratios of 1 h to 1 h, 1 h to 3 h (old tanks), 0.5 h to 1.5 h, 0.5 h to 2 h and 1h to 4 h (new tanks) were tested for the purpose of optimization. The mixed culture from the old tanks was used as inocula for the new tanks. Again, over 80% nitrogen removal was consistently obtained from all tanks after three months of operation. The experimental results have indicated that the IA process is an effective way for nitrogen removal from swine wastewater.

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