Mechanism of Membrane Fouling Control by HMBR: Effect of Microbial Community on EPS

Abstract

A hybrid membrane bioreactor (HMBR) employing activated sludge and biofilm simultaneously is proved to represent a good performance on membrane fouling control compared to conventional membrane bioreactor (CMBR) by reducing extracellular polymeric substances (EPS), especially bound EPS (B-EPS). In order to better understand the mechanism of membrane fouling control by the HMBR in regard of microbial community composition, a pilot scale HMBR operated to treat domestic wastewater for six months, and a CMBR operated at the same time as control group. Results showed that HMBR can effectively control membrane fouling. When transmembrane pressure reached 0.1 MPa, the membrane module in the HMBR operated for about 26.7% longer than that in the CMBR. In the HMBR, the quantity of EPS was significantly lower than that in the CMBR. In this paper, soluble EPS was also found to have a close relationship with cake layer resistance. The species richness and diversity in the HMBR were higher than those in the CMBR, and a certain difference between the compositions of microbial communities in the two reactors was confirmed. Therefore, the difference in microbial community compositions may be the direct reason why EPS in the HMBR was lower than that in the CMBR.

Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

“…Therefore, the membrane fouling before the 9th day of GMBR operation might be due to pore fouling by sEPS even without the biofloc attachment. Similar phenomena were repeatedly reported elsewhere [21,22]. The fact that the sEPS in the membrane effluent was only 6% and 3% those in the GMBR mixed liquor before and after the 9th day of a backwash cycle actually indicated such a pore fouling to cake-layer fouling shift within the GMBR backwash cycle (Figure 9B) and corroborated the TMP increase before the biofloc attachment (Figure 10A).…”

Performance of a Double-Filter-Medium Tandem Membrane Bioreactor with Low Operating Costs in Domestic Wastewater Treatment

“…The average SS in the effluent of the filter cloth assembly was 58 mg•L −1 , which aligns with the Wastewater Quality Standards for Discharge to Municipal Sewers (GB/T 31962-2015). The average SS in the final DT-MBR effluent was 5.6 mg•L −1 (Figure 3 Due to the high MLSS, sufficient HRT, and suitable temperature, DT-MBR presented good biodegradation and nitrification performance with average COD and NH4 + -N removals of 91.1% (Figure 4) and 98.4% (Figure 5), respectively, which are similar to those of Liu [10,29] and Münch et al [30]. The aeration tank played a leading role in COD and 4) and 98.4% (Figure 5), respectively, which are similar to those of Liu [10,29] and Münch et al [30].…”

“…The average SS in the final DT-MBR effluent was 5.6 mg•L −1 (Figure 3 Due to the high MLSS, sufficient HRT, and suitable temperature, DT-MBR presented good biodegradation and nitrification performance with average COD and NH4 + -N removals of 91.1% (Figure 4) and 98.4% (Figure 5), respectively, which are similar to those of Liu [10,29] and Münch et al [30]. The aeration tank played a leading role in COD and 4) and 98.4% (Figure 5), respectively, which are similar to those of Liu [10,29] and Münch et al [30]. The aeration tank played a leading role in COD and NH 4 + -N removals, with average removals of 79.3% and 84.9%, respectively.…”

“…Due to the high MLSS, sufficient HRT, and suitable temperature, DT-MBR presen good biodegradation and nitrification performance with average COD and NH4 + -N movals of 91.1% (Figure 4) and 98.4% (Figure 5), respectively, which are similar to th of Liu [10,29] and Münch et al [30]. The aeration tank played a leading role in COD a NH4 + -N removals, with average removals of 79.3% and 84.9%, respectively.…”

“…Additionally, due to the high DO, forming an anaerobic zone inside the activated sludge floc as well as in the local area of the aeration tank is difficult, and the phosphorusaccumulating bacteria were unable to conduct the phosphorus-releasing reaction without the anaerobic conditions. Thus, the phosphorus removal efficiency of DT-MBR was poor, and the average TP removal was only 50.7% (Figure 7), which is significantly lower than those of Liu et al [10,29]. The aeration tank played a leading role in TP removal, with an average removal of 40.4%.…”