Streaming potential and SEM-EDX study of UF membranes fouled by colloidal iron

摘要

Destabilization-flocculation is often used as a pretreatment before ultrafiltration of drinking water and secondary wastewater effluent.The fouling of ultrafiltration membranes by colloidal iron hydroxide-oxide has been studied by measuring the pore streaming potential of a series polysulfone type UF membranes with 10 KDa-50KDa NMWCO.SEM-EDX was carried out on the fouled membranes and the iron distriubtion in and on the fouled membrane w as determined.Fouling of the membranes as measured by flux reduction was usually accompanied by a positive change in zeta potential and iso-electric point (IEP) of the membrane.Severity of fouling seems to correlate with the presenceof some pores of size larger than part of the iron colloid particle size distribution.SEM-EDX confirmed presenceof iron within those membranes (20KDa) suffering the most foling.An initially large change in zeta potential was seen even after relatively small amounts of solution were filtered through the membrane.A control experiment showed this is not due to iron adsorption equilibrium,but should probably be attributed to fouling.