| Abstract |
| The anaerobic process has been usually operated under mesophilic and thermophilic conditions. If the aerobic digestion under normal temperature gains a result similar with the process under high temperature, it can lower the treatment cost of wastewater needed. The purpose of this study is to determine optimum HRT on each mixing ratio securing economical efficiency by comparing treatment characteristics according to mixing ratio of livestock wastewater and food wastes. The pH range in reactors was 8.35~8.55 and average alkalinity of effluent was 12,480 mg/L in HRT 30 days, 12,440 mg/L in HRT 40 days, 12,420 mg/L in HRT 50 days and 12,070 mg/L in HRT 60 days. This is out of common alkalinity concentration in anaerobic reactor for stable operation, but any obstacle was not shown. Therefore, the others such organic loading rate are considered more important under the high pH and alkalinity conditions. It was thought that methanogens were inhibited from high pH and ammonia, given the high VFAs concentrations more than 2,500 mg/L. But because high alkalinity pH drop wasn`t arisen. It was estimated that methanogen was inhibited from high pH and total ammonia nitrogen, it was operated under the "inhibited steady state". COD concentration was not big difference in HRT 40, 50 and 60 days, but VFAs concentration was low in HRT 50 days in case of mixing ratio 5:3 and HRT 40 days in the event of mixing ratio 5:2 and 5:1, it was thought that activity of methanogen was high. |
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| Key Words |
| Low temperature, anaerobic, Livestock wastewater, food waste, methane |
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