有机废弃物之厌氧消化.doc

有機廢棄物之厭氧消化-前處理及溫度之影響 Anaerobic digestion of organic waste-effects of pretreatment and temperature 研究生: 楊易霖 Yi -Lin Yang 指導教授: 郭文健 Wen-Chien Kuo [摘要]the two-phase continuously-stirred flow tank reactor CSTR . Hydrolysis pretreatment under different temperatures was evaluated. Operating conditions of different organic loading rates OLR and hydraulic retention time HRT were also investigated. When different temperatures 55 and 70℃ were tested for effect of thermal pre-treatment for 24 hours, results showed that the highest hydrolysis rate under 55 and 70℃ were 28.02% and 34.62 %, respectively. Under both tested temperatures, the majority of hydrolysis reaction occurred at the first 5 hours. For acidification test, without artificial pH control in the system, the total volatile fatty acids TVFAs were found to increase with reaction time. It took about 16 hours for the system to reach a stable condition, and the TVFA levels were increased more than 600 mg/L of COD within 10 hours. In the CSTR experiments, system went through a pre-treatment of hydrolysis and acidification for 6 hours before subsequent methanogenesis. For the mesophilic system, the highest loading was operated under an OLR of 3 kg COD/m3-d and a HRT of 10 days. The highest COD removal efficiency was 90%, with a daily gas production of 3~4 L/day and a methane percentage of 40%. On the other hand, the thermophilic system was operated under an OLR of 5 kg COD/m3-d and a HRT of 5 days, and the highest COD removal efficiency was 94.4%, with a gas production of 3~4 L/day and a methane content about 50%. Kinetic study of kitchen wastes using chemostats showed that the maximum specific utilization rate k of the mesophilic system was 1.28 mg COD/mg VSS Activity-d, while the thermophilic one was 3.54 mg COD/mg VSS Activity-d. This verified the fact that thermophilic one had a must higher substrate utilization rate than the mesophilic one when treating kitchen wastes. Considering factors such as COD remo