Biofouling mitigation and microbial community dynamics in the membrane bioreactor by the indigenous quorum quenching bacterium Delftia sp. JL5.

ABSTRACT

The quorum quenching (QQ) strategy has attracted increasing attention in membrane bioreactor (MBR) fouling control. However, the applicable QQ strain remains limited. This study investigated the antibiofouling performance of a new indigenous QQ bacterium, Delftia sp. JL5 (JL5) in MBR. JL5 produces intracellular acylase that irreversibly degrades N-acylhomoserine lactones (AHL), inhibited biofilm formation of quorum-sensing bacteria from activated sludge. During 120 days of operation, immobilized JL5 substantially delayed MBR biofouling by 2.1 and 2.9 times, at a flux rate of 30 L/(m2·h) and 20 L/(m2·h), respectively. A slower flux rate was favorable for effective mitigation of JL5 biofouling. JL5 reduced the AHL and extracellular polymeric substances of biocake without affecting the efficiency of waste removal. The presence of JL5 significantly changed the microbial structure of the membrane biocake, but not the activated sludge. Collectively, high activity, durability, and acid tolerance credited JL5 as a promising strain for QQ-MBR.