Long-term evaluation of a UF pilot plant for potable water production

The results of a 15 m(2) low-pressure capillary membrane UF pilot investigation are presented. The plant has been operating for 20,000 h using the same set of prototype membrane modules, and continues to produce 10-15 m(3)/D of high-quality potable water. Sub-standard surface water from the Theewaterskloof impoundment, normally used for irrigation, was supplied as the feed to the plant. The membrane filtration system removes > 95% turbidity, 92-97% apparent colour, 97-99% iron, and 60-85% natural organic matter. All faecal and other coliform bacteria are also removed while the heterotrophic plate count is reduced to an acceptable level. A 15-20% average specific flux loss was observed, and the membrane life is estimated to be > 5 years.