CP-1997-05
An on-farm swine waste treatment system for odor control, byproduct recovery and treated wastewater reuse in Hawaii.
Yang P.Y., C. Gan, D.G. Paquin, and T. Liang
A prototype of swine waste treatment system for 240- to 240-pig operation was investigated for its potential for odor control, byproduct utilization, and treated wastewater reuse. It was found that the high solid portion of the swine waste rangine from 4% to 8% total solids could be treated and stabilized by the anaerobic process with a hydrulic retention time (HRT) of 32 days. The diluted liquid portion from raw and anaerobically digested swine wastewater could be effectively treated by the aeration and sedimentation units with an HRT of 3 and 4 days, respectively. The overall removal efficiency of 89.0% to 95.4% for total chemical oxygen demand, 82.3% to 88.5% for total Kjedahl nitrogen, and 81.2% for total phosphorous could be achieved. The treated effluent could be reused for irrigation of pastures without any odor problems. Also, it meets the requirements of the wastewater reuse criteria, R-3, issued by the Hawai’i Department of Health. An economic analysis was conducted by calculating the net present worth. It was found that the capital cost for equipment is the major expense item for the proposed treatment system. The reuse of biogas as energy and sluge as fertilizer was determined to be the key factor in turning the treatment system into a profit operation. Also, it was found that the farm operation would require more than 830 pigs for the swine waste treatment system to achieve a breakeven point. Thus this treatment system could result in a profit by centralizing the hog operation and by fully utilizing the produced methane gas and digested sluge.