Feasibility on Immobilized Cells in Anaerobic Digestion of Domestic Wastewater
Date Issued
2014
Date
2014
Author(s)
Lin, Rong-Yi
Abstract
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.
Subjects
都市廢水
固定化細胞
厭氧醱酵
甲烷
Type
thesis
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