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.
