ABSTRACT
The harmful substances, defined as trihalomethanes [THMs], were found to be formed during the disinfection of drinking water when chlorine was used as the disinfectant. In this research, the effectiveness of granular activated carbon [GAC] and air stripping [AS] packed column for the removal of chloroform [CHCL3] [as THMs basic indicator compound in many resources] in range of 50 to 300 micro g/L, from drinking water was studied. Pilots of GAC and air stripping columns were designed and set up. The study was carried out for the two cases of deionized and chlorinated Tehran tap water. Also the effects of flow rate, chloroform and TDS concentrations were considered in both treatment systems. Gas chromatography [GC] with electron capture detector [ECD] was used for determination of chloroform concentration in inlet and outlet samples. The obtained data were analyzed by SPSS and non-parametric KruskaI-Wallis method. Results showed a positive correlation between the flow rate and chloroform concentration, and removal efficiencies. The average of variations of removal efficiencies for AS and GAC columns with deionized water samples were, 89.9%, 71.2% and for chlorinated Tehran tap water were 91.2% and 76.4%, respectively. The removal of feed residual chlorine in these columns with 0.5, 0.8 ppm was 100%, respectively and re-chlorination for finishing water was recommended. Results showed AS to be considered more effective in chloroform removal for conventional water treatment plants as a finishing process
Subject(s)
Water , Carbon , Air , TrihalomethanesABSTRACT
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