Effect of biological contact filters (BCFs) on membrane fouling in drinking water treatment systems

Abstract

Membrane fouling is a serious problem in drinking water treatment systems. Biological contact filters (BCFs) are often used as a pretreatment to remove ammonia, dissolved organic matter (DOM), and metal ions such as iron and manganese. In this study, the effect of BCF as a pretreatment for membrane fouling was evaluated using a laboratory-scale mini module consisting of a mini BCF column and a mini MF column. Initially, it was confirmed that the main foulant was a biopolymer (at low concentration) in the raw water. Subsequently, the biopolymer concentrations in the BCF influent and effluent were measured with the excitation emission matrix (EEM) fluorescence spectroscopy and the liquid chromatograph organic carbon detector (LC-OCD). The fouling potential of the BCF influent and effluent was also measured to evaluate MF membrane fouling rate. The results demonstrate that application of the BCF reduced the biopolymer concentration of the effluent and reduced membrane fouling. The effect of BCF was also established in an actual drinking water treatment plant. It was found that optimizing the contact time of raw water with the BCF was crucial to reduce membrane fouling.