Comparison between rejection characteristics of natural organic matter and inorganic salts in ultra low pressure nanofiltration for drinking water production

Comparisons between rejection characteristics of natural organic matter and inorganic salts by nanofiltration in a very low operational pressure (<0.5 MPa) are demonstrated here. A nanofiltration pilot plant has been operated at the Tamagawa water purification plant, which is located downstream on the Tama River, Japan. The molecular weight distribution and concentration of natural organic matter that account for trihalomethane formation potential, and concentrations of various inorganic salts have been measured in the raw water from the Tama River, microfiltration pretreated effluent and nanofiltration production during 6-months operation of the pilot plant. This paper discusses the water quality and rejection mechanism of natural organic matter and inorganic salts. In addition, the steric-hindrance pore (SHP) model and the Nernst-Planck equation have been used to evaluate membrane pore structures and rejection of ionic solutes, respectively.