Effects of filtration modes on membrane fouling behavior and treatment in submerged membrane bioreactor

• Longer filtration duration observed for 8 min filtration and 2 min relaxation mode.
• Low specific cake resistance was found in MBR(8+2) and high in MBR(12+3).
• Short filtration and relaxation cycles corresponded to less membrane fouling.
• High microbial activity of MBR sludge is responsible for rapid fouling rate.

Relaxation or backwashing is obligatory for effective operation of membrane module and intermittent aeration is helpful for nutrients removal. This study was performed to investigate 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 min filtration and 3, 2, and 2 min 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 dewaterability were examined to optimize the filtration mode. TMP profiles showed that MBR(8+2) with 8 min filtration and 2 min relaxation 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).