Response of membrane bioreactor to feed starvation shock load

Abstract

The impact of feed starvation condition on the biological characteristics and the performance of an aerobic submerged Membrane Bioreactor (MBR) system was investigated. The synthetic wastewater treated in MBR under steady-state condition showed 95% removal of COD, 98% removal of TOC and suspended solids, 88% of TKN removal and 30% removal of phosphate. The system was subjected to a feed starvation shock load for five days and the response of the system in the process of recovering back to pre-shock steady-state condition was studied. After five days of shock loading, the effluent quality deteriorated showing traces of substrate leakage in effluent, large fraction of biomass wash off and reduction in microbial activity inside the reactor. The biological solids in the reactor reduced gradually from 15 g/L to 6 g/L, which took around a month for the biomass to revert back to its normal growth phase. The system required seven days to recover back to steady condition. Overall, the study showed a faster recovery of organic, solid, nutrients removal; however, the system took a month to regain the amount of biomass lost during feed starvation shock load.