| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 101 === A 5L continuous stirred anaerobic bioreactor couple with a 1.2L crossflow membrane bioreactor (AnMBR) with solids retention time (SRT) infinite days were setup for treating synthetic low-strength wastewater at hydraulic retention times (HRTs) of 2, 1 and 0.5 days using sequencing batch reactor (SBR) processing. At startup condition, shorter HRT or higher influent COD concentation increased biogas production due to higher organic loading rate (OLR) or enhanced dominance of methanogenics. Higher OLR or higher influent COD concentration offer enough organic matters that lead to greater methane content and methane production, therefore, it can also result better methane yield. The chemical oxygen demand (COD) removal averaged 98 ± 2% corresponding to an average permeate COD of 8 ± 6 mg/L was achieved at 0.8 kg COD/ m3‧d OLR and 12 hours HRT and averaged methane yield was 0.21 L CH4/ g COD. MF flat sheet membrane completely retain biomass as well as further remove soluble COD present after biological treatment to produce a high quality effluent. At temperature 30 ± 5℃, approximately 40% of COD was not available for methane recovery as a result of the COD loss by dissolved methane and untreated COD. The fraction of methane recovered decreased from 76 to 60%, with the decrease of HRT from 1 day to 12 hours. Optimal methane production is 1.04 L per day at 400 mg/L influent COD concentration. No obvious fouling happened during the operation because of short duration time and clean effluent from the anaerobic bioreactor. Transmembrane pressure (TMP) was below 2 Kpa while flux was between 4 to 4.2 L/ m2‧h (LMH). Each cycle of SBR operation needs at least 2 hours for completed mixing and reaction in this system.
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