Effect of biological activated carbon pre-treatment to control organic fouling in the microfiltration of biologically treated secondary effluent

Biological activated carbon (BAG) filtration was investigated as a pre-treatment for reducing the organic fouling of a microfiltration membrane (0.1 mu m polyvinylidene fluoride) in the treatment of a biologically treated secondary effluent (BTSE) from a municipal wastewater treatment plant. BAC treatment of the BTSE resulted in a marked improvement in permeate flux, which was attributed to the effective removal of organic foulants and particulates. Although the BAC removed significantly less dissolved organic carbon than the granular activated carbon (GAG) treatment which was used as a control for comparison, it led to a markedly greater flux. This was attributed to the effective removal of the very high molecular weight substances such as biopolymers by the BAG through biodegradation and adsorption of those molecules on the biofilm. Size exclusion chromatography showed the BAG treatment led to approximately 30% reduction in these substances, whereas the GAG did not greatly remove these molecules. The BAG treatment led to a greater reduction of loosely-attached and firmly-attached membrane surface foulant, and this was confirmed by attenuated total reflection-fourier transform infrared spectroscopy analysis. This study demonstrated the potential of BAG pre-treatment for reducing organic fouling and thus improving flux for the microfiltration of BTSE. (C) 2014 Elsevier Ltd. All rights reserved.