Effect of pH by Manganese Salts and Natural Organic Matter on Nanofiltration Membrane Fouling

Abstract

This research aimed to determine the removal performance of manganese affected from solution pH of combined manganese salts with natural organic matter (NOM) using commercial nanofiltration (NF) membrane. The filtration experiments were tested under a dead-end filtration test cell. Variational factors used in this study were the types of manganese salts (i.e. manganese chloride (MnCl2), manganese sulfate (MnSO4), and manganese nitrate (Mn(NO3)2)) with the solution pH of 3, 5, and 7, and ionic strength of 0.01 mol/L. Water samples were prepared with NOM concentration of 10 mg/L, while the operating pressure was operated constant at 60 psig. Experimental results found that the MnSO4 salt provided the highest manganese removal efficiency of 95%, while the removal efficiencies of MnCl2 and Mn(NO3)2 were about 84.86% and 70.7%, respectively. Solution fluxes were not significantly different. In the presence of NOM concentration of 10 mg/L, solution pH of 3–7, it was found that low solution pHs for all conditions provided the highest manganese removal. The removals of NOM were relatively high more than 97%. The mathematical fouling model was done with cake filtration model (CFM) due to NOM accumulation on NF membrane surface.