INFLUENCE OF ANTI-FOULING BACTERIA ON PERFORMANCE EFFECIENCY AND MEMBRANE FOULING OF SUBMERGED MEMBRANE BIOREACTOR

Abstract

Wastewater reclamation with membrane bioreactor (MBR) technology seems to be a feasible option but membrane biofouling is a critical operational problem that hinders the rapid commercialization of MBRs. Naturally bacteria have the ability to produce signals i.e. N-acyl homoserine lactones (AHLs) which helps them to communicate with each other and form colonies under favorable environmental conditions and produce bacterial byproducts like soluble microbial products (SMP)resulting in biofilm formation on the membrane surface and reduction in membrane permeability. To reduce this natural behavior of microbial interaction, introduction of quorum quenching mechanism in MBR i.e., disruption of signal molecules can significantly decreaseAHLs presenceand extracellular polymeric substance (EPS) production causing reduction in membrane biofouling.In the present study, potential quorum quenching bacteria were screened using a biosensor, Pseudomonas aeruginosa QSIS2 (lasIrhlI double mutant harboring pLasB-SacB1) and applied in MBR. Three lab-scale MBRs in continuous mode were operated in parallel under similar operating conditions. Two QQ-MBRs were inoculated with different QQ bacterial consortium entrapped within polymeric beads. Performance efficiency in terms of membrane permeability, transmembrane pressure (TMP) build up and biofouling retardation rate of QQ-MBRs was investigated and compared with Control-MBR. Both QQ-MBRs experienced three times less biofouling as compared to Control MBR leading to significant decrease in acyl homoserine lactones (AHLs) concentration. Similarly, polysaccharide and protein concentration also significantly decreased in the biocake of QQ-MBRs thereby resulting extension in the time required to reach the TMP of 30 kPa, compared to Control-MBR. More than 90, 45 and 49 % of COD, NH4-N and PO−3 4 -P removal efficiencies further elucidate that QQ bacterial consortium may efficiently reduce membrane bio fouling by maintaining the performance intact.