Application of micellar enhanced ultrafiltration for nutrients removal Original Research Article

The feasibility of micellar-enhanced ultrafiltration to remove nutrients, nitrate and phosphate, was investigated with a cationic surfactant, cetlypyridinium chloride (CPC). The effects of surfactant molar ratios on the rejection of nitrate and phosphate and flux decline were studied. In the nitrate/phosphate/CPC system, as the molar ratio of nitrate: phosphate:CPCincreasedfrom 1:0.06:1.06to 1:0.06:3.18andto 1:0.06:5.30,therejectionofnitrateincreased from 77% to 84% andto 92%, while phosphate rejection increased from 83% to 87% and 95%, respectively. The rejection ofCPC increased as the molar ratio increased, and the concentration of CPC in the permeate was negligible because the size of the CPC micelle was lager than the pore size of the membrane, which indicated that the secondary pollution by surfactants might be insignificant. The reduction of permeate flux induced by the addition of a surfactant was due to the gel layer formed on the surface of the membrane.