Membrane hybrid system combined with a trickling filter and a thin layer of biosand to reduce high levels of organic matter in drinking water in developing countries

The present study develops membrane hybrid system for drinking water that combines a trickling filter (TF) and a thin-layer biosand filter (TBSF) prior to membrane. Two different types of trickling filter (submerged and protruding) were placed before the biosand filter (BSF) with two different sand depths (40 and 3 cm). The effectiveness of the TBSF was measured in terms of the reduction in levels of total organic carbon, turbidity, Escherichia coli, and bacteriophage MS2. The hybrid systems with a TF + BSF + MF membrane showed higher TOC removal and turbidity reduction than hybrid systems only with BSF + MF membrane. The TOC removal and turbidity reduction by the hybrid systems with a TF were much more stable than those of hybrid systems without a TF throughout the operating period despite the changing level of the TOC. The removal of E. coli by hybrid systems with a TF was greater (usually >99.99%) and more stable than that by the hybrid systems without a TF. However, the removal of bacteriophage MS2 by the hybrid systems with a TF was only moderate (∼99%) and not greatly different from that by the hybrid systems without a TF.