AWWA ACE94128

Nanofiltration is an effective alternative for the removal of natural organic matter (NOM) and control of disinfection byproducts (DBPs) in finished drinking water. The efficacy of DBP precursor removal is, to a large extent, membrane and water quality specific. In the waters containing bromide, a shift to the brominated DBPs occurs after chlorination of membrane-filtered water. For the two low pressure hollow fiber NF membranes (400 to 800 MWCO) studied, higher bromoform concentrations were observed after chlorination of the permeate as compared to the raw water. However, use of lower MWCO spiral wound membranes (200 to 300 daltons) controlled the formation of brominated DBPs. The high MWCO (100,000 daltons) UF membrane alone was ineffective for removal of substantial concentrations of precursor materials. The use of alum or PAC as in-line pretreatments to UF enhanced the removal of NOM. However, alum fouled the membrane employed as evidenced through increases in transmembrane pressure. PAC did not compromise membrane operation, even at high doses; rather, it may have acted as a fouling inhibitor.