Nanofiltration and reverse osmosis thin film composite membrane module for the removal of dye and salts from the simulated mixtures

Nanofiltration (NF) and reverse osmosis (RO) thin film composite polyamide membrane modules were used to remove the color from the contaminated solution mixture. The feasibility of membrane processes for treating simulated mixture by varying the feed pressures (100–400 psi) and feed concentrations was studied to assess the separation performance of both NF and RO membranes. It was found that the efficiency of NF and RO membranes used in the treatment of colored water effluents was greatly affected by the presence of salts and dyes in the mixture. Color removal by NF with a high rejection of 99.80% and total dissolved solids (TDS) of 99.99% was achieved from RO by retaining significant flux rate compared to pure water flux, which suggested that membranes were not affected by fouling during the simulated wastewater process operation. The effect of varying concentrations of Na2SO4 salt and methyl orange (MO) dye on the performance of spiral wound membranes was determined. Increasing the dye concentration from 500 to 1000 mg/L resulted in a decrease of salt rejection at all operating pressures and for both concentrations of 5000 and 10,000 mg/L as the feed TDS. Increasing the salt concentration from 5000 to 10,000 mg/L resulted in a slight decrease in dye removal.