Experimental assessment of the efficacy of microfiltration and ultrafiltration for Cryptosporidium removal

Abstract

In order to evaluate the efficacy of microfiltration and ultrafiltration for Cryptosporidium oocyst removal, a bench-scale experiment was carried out using two 0.2m2 molecules, MF (nominal pore size 0.25μm) and UF (nominal cut-off MW 13,000 daltons) in cross-flow mode at an oocyst level of 106/L. Both of the membranes eliminated the oocysts from the influents with removal efficiency estimated to be >7 log10. As for the MF, an additional experiment was conducted at a much higher oocyst level up to 108 oocysts/L in both cross-flow and dead-end modes and which achieved >7 log10 removal, although some oocysts appeared in the filtrate in both modes. Based on these results, microfiltration and ultrafiltration are conclusively considered to be excellent processes for drinking water treatment as a single process that produces safe (an annual risk 10−4) water from highly polluted source waters.