Comparison of Nanofiltration and GAC Adsorption Processes for Chloroform Removal from Drinking Water

Abstract

In this research, the Chloroform (CHCl3) removal effectiveness of two water treatment systems including membrane technology and granular activated carbon (GAC) adsorption were studied. Two bench-scales were designed and set up: 1) Nanofiltration (NF) spiral-wound modules and 2) GAC adsorption column. Chloroform was considered as trihalomethanes (THMs) basic indicator compound. The inlet and outlet CHCl3 concentrations were detected by gas chromatography (GC) with electron capture detector (ECD). The study was carried out for the two cases of spiked deionized water with CHCl3 and chlorinated Tehran tap water. Flow rate, CHCl3 and total dissolved solids (TDS) concentrations were considered in both treatment systems and the transmembrane pressures for membrane pilot, as the basic variables affecting removal efficiencies. Results showed that CHCl3 rejection coefficients for NF 300 Da, NF 600 Da and GAC Column, with various operation conditions had a range of 55.2% to 87.8%, 78% to 85% and 41.4% to 74.1%, respectively. It was found that removal efficiencies for NF 600 Da were lower than those of NF 300 Da and GAC column. The obtained data were analyzed by SPSS and non-parametric Kruskal-Wallis method. Results showed a positive correlation between the flow rate, CHCl3 concentration and chloroform rejection coefficients and the TDS concentration had no significant effect on chloroform removal efficiencies.