Bacterial Quorum Quenching for the Control of Membrane Biofouling in MBR for Wastewater Treatment

Recently, enzymatic quorum quenching has proven its potential as an innovative approach to biofouling control in the membrane bioreactor (MBR) for advanced wastewater treatment. However, practical issues on the cost and stability of enzymes are yet to be solved, which requires more effective quorum quenching methods. In this study, interspecies quorum quenching by bacterial cell was elaborated and proved to be efficient and economically feasible biofouling control in MBR. Two strains of indigenous quorum quenching bacteria, Rhodococcus sp. BH4 and Pseudomonas sp. 1A1, which were isolated from a real MBR plant, were selected for the application to the biofouling control in MBR. Firstly, various characteristics of strain BH4 and 1A1 were investigated to elucidate their behaviours in the mixed liquor of MBR. AHL degradation rates of two strains were tested by using a reporter strain, Agrobacterium tumefaciens A136. Secondly, a ‘Microbial-vessel’ was designed to encapsulate the quorum quenching bacteria using a microporous hollow fiber membrane. The effect of biofouling inhibition by the Microbial-vessel was evaluated over 90 days of MBR operation. Finally, the quorum quenching bacteria were entrapped in free-moving beads to gain the physical washing effect as well as the quorum quenching effect on the biofouling control in MBR. Successful control of biofouling in a laboratory scale MBR suggests that the biofouling control through the interspecies quorum quenching could be expanded to the plant scale of MBR and various environmental engineering systems with economic feasibility.