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. The distribution and roles of cake layers in biofouling have been extensively investigated. Transparent exopolymer particles perform a variety of biological functions, which has a substantial impact on particle distribution as it is present ubiquitously in wastewater. Fouling was seen in this investigation to be the result of the deposition of particulate, colloidal or soluble material within the pores or on the membrane surface. The distribution of biofouling on the membrane surface and in the cake layer was investigated using a membrane bioreactor operating at a membrane flux of 10 L/m2h, with the initial concentration of mixed liquor suspended solids of 10g/L treating actual sewage. Confocal laser scanning microscope and field emission scanning electron microscope 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 fouling progressed, 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 substances contribute 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, protein was significantly linked with irreversible fouling.

Keywords

• Biofouling
• CLSM
• FESEM
• Sewage