- 學位論文
固定化細胞於都市廢水厭氧處理之可行性
Feasibility on Immobilized Cells in Anaerobic Digestion of Domestic Wastewater
摘要
固定化細胞係將微生物侷限於一特定的空間或特殊的材質之中，在操作反應槽時可避免菌種的流失。本研究以厭氧消化結合固定化細胞技術處理低濃度的廢水並生產甲烷。開始時以人工廢水為基質進行試驗，採漸進的方式逐步減小水力停留時間(HRT)，最後再以都市廢水測試厭氧處理的可行性。本研究的菌種為養豬場的厭氧污泥，製成包埋式(Entrapped)固定化細胞後，以100%的填充率(Packing ratio)置入槽中，反應槽的有效工作體積(Working volume)為3 L，操作溫度為37±1 °C。反應槽起動時，HRT為10天，進流的人工廢水濃度為475 mg COD/L。當反應槽穩定之後，HRT漸減為5天、3天、1.56天、1天、12小時及6小時，進流濃度則維持不變。在此試驗期間，於HRT 6小時、有機負荷(OLR) 1.9 g COD/L/d時有最大的甲烷產率0.357 L CH4/L/d，甲烷成分亦達約80%。然後再將HRT和進流人工廢水濃度分別減半為3小時，及接近都市廢水的237 mg COD/L，即維持有機負荷與HRT 6小時相同的條件進行測試，結果顯示COD去除率差異不大，甲烷成分則降至60%，甲烷產率(MPR)也大幅下降至0.121 L CH4/L/d。可知進流基質的有機物濃度過低時，較不利於沼氣生產。最後再以取自台北市內湖汙水處理廠之原廢水以HRT 3小時進行測試，試驗結果顯示出流水質可達放流水標準，穩態時平均COD去除率、GPR、MPR及甲烷成分則分別為87.5%、0.31 L/L/d、0.198 L CH4/L/d及63.67%，證實應用厭氧固定化細胞處理都市廢水並生產甲烷確實可行。
並列摘要
Immobilized-cell is a technique which the microbial cells are confined within a limited space, so that active cells will not be washed out during operation of the reactors. In this study, anaerobic digestion was integrated with immobilized cells for the treatment of low concentration wastewater and methane production. In the beginning, the artificial wastewater was used as substrate and several tests were conducted by gradually decreasing the hydraulic retention time (HRT). At last, the domestic wastewater was used as substrate to evaluate its feasibility for anaerobic treatment. The innoculum of this study was the anaerobic sludge of a pig farm. After fabrication of the entrapped-type immobilized cells, they were placed in a reactor with 100% packing ratio. The reactor had an active volume of 3 L, and was operated at 37±1 °C. To start up, the reactor was operated at an HRT of 10 days and fed with the artificial wastewater with a concentration of 475 mg COD/L. After reaching the steady state, tests of different HRT of 5, 3, 1.56, 1, 0.5 (12 hrs) and 0.25 (6 hrs) days were conducted, while the influent COD concentration were remained the same. Among these tests, the maximum methane production rate (MPR) of 0.357 L CH4/L/d and 80% of methane component was achieved at 6 hrs HRT and 1.9 g COD/L/d organic loading rate (OLR). To simulate the domestic wastewater, the HRT and influent concentration were then reduced to 3 hrs and 237 mg COD/L, respectively, but had the same OLR as the test of 6 hrs HRT. Results showed that the COD removal efficiency had no significant difference, but the methane component reduced to 60%, and the MPR dramatically decreased to 0.121 L CH4/L/d. It seemed that the biogas production was adversely affected due to the low organic concentration of substrate. In the last test, with 3 hrs HRT, the influent used was the raw wastewater from Neihu WWTP, Taipei. Experimental results showed the effluent could meet the governmental effluent standard, and the COD removal efficiency, GPR, MPR and methane component at steady state were 87.5%, 0.31 L/L/d、0.198 L CH4/L/d and 63.67%, respectively,. Therefore, feasibility of application of the immobilized-cell for anaerobic treatment of the domestic wastewater and biogas production was successfully proved.