| Summary: | 碩士 === 國立交通大學 === 環境工程系所 === 98 === The membrane bioreactor (MBR) is a new technology for wastewater treatment, in which membrane filtration is combined with the conventional activated sludge process. The advantages of MBR over conventional treatment include small footprint and less sludge production. Moreover, MBR produces superior effluent quality, capable of meeting more stringent future discharge limits and wastewater reclamation goals. One of the major disadvantages of MBR is membrane fouling, which is related to the critical flux. Membrane fouling leads to the permeate flux decline, making more frequent membrane cleaning and replacement necessary which increases operating costs. Several factors can contribute to membrane fouling, out of which operation parameters and sludge characteristics are reported as the foremost. Therefore, for a successful MBR operation it is essential to quantify the effect of membrane-flux and the wastewater characteristics on the performance of MBR. In the present study is to confer the effects of membrane flux on the performance of a pilot-scale membrane bioreactor treating industrial low C/N wastewater.
From the result of bench study, the low C/N wastewater can be degraded NH3-N even when SRT was operated under 8 days. The conditions of MBR pilot were under HRT at 1.92 hrs, membrane flux at 5.95, 7.14 and 8.93 L/m2-h (LMH), SRT at 12 and 10 days. The average TSS, COD, BOD5 and NH3-N concentrations in the influent of MBR pilot were 60, 75, 46 and 40 mg/L, respectively. As a result of MBR operation, TSS, COD, BOD5 and NH3-N were removed maximally of 89, 82, 90 and 95%, respectively. It was found that the effect of pretreatment using coagulation and flocculation on MBR performance was insignificant. The trans-membrane pressure (TMP) is found to increase with increase in membrane-flux. The lowest fouling rate of 5.33x1011m-1d-1 associated with a highest permeate/membrane-area ratio of 12.86 m3/m2 was obtained under SRT of 10 days and flux of 7.14 LMH. Based on the experimental results, a SRT of 10 days with a flux of 7.14 LMH is selected for the pilot-scale MBR operation.
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