Improving the Performance of UF Membrane Processes Using Electropositive Filtration to Polish Backwash Water

This paper and presentation cover results on the ability of an electropositive filter to remove organic and inorganic debris (nanoparticles, silica colloids, humic acid, and polysaccharides) from ultrafiltration (UF) filtrate and quantify the resulting improvements to process performance from using the polished water to backwash the membranes. The removal and fouling characteristics of these materials were investigated using three different process streams: 1) bench-scale dead end filtration; 2) bench-scale hollow-fiber (cross-flow) filtration; and 3) a pilot-scale hollow fiber UF membrane test unit that included two parallel treatment trains. One train received the polished backwash water while the second did not. The analysis includes an economic assessment of the performance impacts as well as hard data on removal capacities for the aforementioned foulants. Conclusions are presented on the feasibility and engineering hurdles that remain regarding the implementation of electropositive filtration into full-scale membrane filtration systems.

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