Comparison of nanofiltration efficiency with GAC adsorption and air stripping processes for CHCl₃ removal from Tehran drinking water

The effectiveness of nanofiltration (NF) was compared with granular activated carbon (GAC) and air stripping (AS) using a packed column in water treatment for the removal of chloroform (CHCl₃), which is a basic indicator of trihalomethane (THM) compounds in many water resources. Pilot GAC and AS columns were designed and set up with nanofiltration polyamide and cellulose acetate blend spiral-wound modules with MWCO of 300 Da and 600 Da. The study was carried out for the two cases of deionized and chlorinated Tehran tap water. CHCl₃ concentrations for both inlet and outlet samples were detected by gas chromatography (GC) and using electron capture detector (ECD). Results showed that the maximum CHCl₃ removal efficiencies for NF 300 Da, NF 600 Da, GAC and AS packed columns under various operating conditions were 87.8%, 85%, 87.4% and 97.6% for deionized water and 86.1%, 72.3%, 85.1, and 91.2% for chlorinated Tehran tap water, respectively. Although NF, GAC and AS showed acceptable performance for CHCl₃ removal from drinking water, NF was significantly more effective (p<0.05), providing simultaneously a higher flow rate and simpler operating conditions. This method may be considered for conventional water treatment plant finishing water.