In-Situ Observation of Biofouling Growth in a Submerged Membrane Bioreactor using CLSM

Abstract

Biofouling is one of the primary hurdles unavoidable in the operation of membrane bioreactors. Thedistribution and roles of cake layers in biofouling have been extensively investigated. Transparent exopolymerparticles perform a variety of biological functions, which has a substantial impact on particle distribution as it ispresent ubiquitously in wastewater. Fouling was seen in this investigation to be the result of the deposition ofparticulate, colloidal or soluble material within the pores or on the membrane surface. The distribution ofbiofouling on the membrane surface and in the cake layer was investigated using a membrane bioreactoroperating at a membrane flux of 10 L/m2h, with the initial concentration of mixed liquor suspended solids of10g/L treating actual sewage. Confocal laser scanning microscope and field emission scanning electronmicroscope were employed to divulge the mechanism of fouling in the membrane bioreactor. The transmembrane pressure and membrane flux were observed throughout the membrane operation. As the foulingprogressed, a membrane sample was taken and examined. During the membrane bioreactor operation process,the outcome of the fluorescent staining of the foulant was depicted. In the initial stage, humic-like substancescontribute to membrane fouling. Highly concentrated protein-like compounds dominated the fouling behavior.Over time, a protein-controlling cake layer was formed. It can be concluded that in the long-term stage, proteinwas significantly linked with irreversible fouling.