VIRUS REJECTION BY ULTRAFILTRATION MEMBRANES AND LOW PRESSURE REVERSE OSMOSIS MEMBRANES

Abstract

Fifteen types of ultrafiltration membranes and low pressure reverse osmosis membranes were examined in terms of virus rejection by using several types of coliphages: None of the tested pieces of membranes was complete barrier against Qβ, which is the smallest virus used in this study. Logarithmic rejection coefficient Φ ranged from 3 to 6 for Qβ. Higher rejection was observed for T4, MS2 and two types of indigenous coliphages compared to the Qβ case. Neither molecular weight cutoff value of ultrafiltration membranes nor salt rejection of reverse osmosis membranes had significant relation to rejection of virus. T4 virus which has 80nm of diameter leaked through some of the tested membranes. These phenomena imply membranes have abnormally larger pores which are not included in the main pore size distribution. The velocity variation method was tested to obtain real rejection of virus from observed rejection data. Smaller value of exponent in the laminar flow mass transfer equation than 0.33 was adequate in the case of larger solutes and high flux. Real rejection coefficient of Qβ was estimated 2 to 3 of Φ higher than the observed rejection coefficient.