Abstract:
Relaxation or backwashing is obligatory for effective operation of membrane module and intermittent aeration is also helpful for nutrients removal. In Phase I- effects of different filtration modes on membrane fouling behavior and treatment in membrane bioreactor (MBR) operated at three modes i.e., 12, 10 and 8 minutes filtration and 3, 2, and 2 minutes relaxation corresponding to 6, 5 and 4 cycles/hour respectively. Various parameters including trans-membrane pressure, specific cake resistance, specific oxygen uptake rate, nutrients removal and sludge dewateriabilty were examined to optimize the filtration mode. TMP profiles showed that, MBR (8+2) with 8 minutes aeration ON and 2 minutes OFF, reduced the fouling rate and depicted long filtration time in MBR, treating synthetic wastewater. MBR (12+3) was more efficient in organic and nutrients removal while denitrification rate was high in MBR (8+2). Dewaterabilty of sludge was high in MBR (12+3) due to longer filtration time. In Phase II- Rhodococcus sp. (BH4) entrapped in sodium alginate beads with effective volume of 0.1% of bioreactor, were used for the degradation of AHLs. QQ-MBR (with quorum quenching beads) experienced less biofouling as compared to C-MBR (without beads), leading to significant decrease in AHLs concentration in QQ-MBR. Soluble EPS production was found to be less in QQ-MBR wh. TMP profile of C-MBR was steeper than QQ-MBR, having short filtration duration, hence profound biofouling was observed in C-MBR. No AHL was detected in the extract of QQ-MBR, while presence of C8HSL in C-MBR was confirmed using high performance liquid chromatography and bioassay. AHLs degradation along with EPS reduction increased the dewaterabilty in terms of capillary suction time and improve the specific cake resistance in QQ-MBR. Efficiency in terms of organics and nutrients removal was found to be same in both MBRs.
