The effects of physical cleaning and chemical backwashing on foulant formation in a microfiltration membrane intended for the reuse of wastewater

摘要

Biologically treated water contains a sufficient amount of organic matter and micro-organisms to cause a variety of problems with microfiltration membranes. Membrane fouling caused by these organic materials is difficult to control with a single physical cleaning procedure. In this study, the effect of aeration conditions on chemical backwashing and foulant removal during chemical backwashing was analyzed. The cleaning efficiency improved as the chemical concentration and contact time increased. The chemical backwashing in the aeration condition showed outstanding cleaning efficiency. This indicated that physical cleaning was required during chemical backwashing because it initiated flow inside the submerged membrane tank. The foulant removal analysis indicated that the particle removal rate increased under the aeration condition, based on the turbidity and total organic carbon results, and that the amount of effluent dissolved matter increased as the chemical concentration and contact time increased, based on dissolved organic carbon, and UV radiation at 254nm (UV254) results. The Fourier transform infrared spectroscopy analysis indicated that chemical backwashing under the aeration condition controlled polysaccharides, a major foulant.