CONCLUSIONS
The swine waste treatment system in this study is effective in treating highly concentrated swine waste(4-g%). At an HRT of 32 days, 75*9-78.9% of TCOD can be removed and biogas production rate of 0.72-O+@ m3/m3/day can be achieved in the anaerobic treatment units. The diluted liquid portion from raw and anaerobically digested swine
wastewater can also be effectively treated by the aeration (HRT = 3 days) and polishing
(HRT = 4 days) units. The overall removal efficiencies of 89-95.4% of TCOD, 80.3-85-l% of T-N and 81.2% of T-P can be achieved by this treatment system at the overall HRT of 39 days. The system is economically feasible for the treatment of swine wastewater generated from centralized pig farms. A profit can be made with an operation of more than 830 pigs if produced methane gas and digested sludge can be fully utilized. If HDPE material is used for the anaerobic digester, a profit can be made with an operation of more than 227 pigs for small producers.