Research Article Assessment of Trihalomethane Formation in Chlorinated Raw Waters with Differential UV Spectroscopy Approach

Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this study, the changes in UV absorbance of water samples were characterized using defined differential UV spectroscopy (DUV), a novel spectroscopic technique. Chlorination experiments were conducted with water samples fromTerkos Lake (TL) and Büyükçekmece Lake (BL) (Istanbul, Turkey).Themaximum loss ofUVabsorbance for chlorinatedTL andBL rawwater sampleswas observed at a wavelength of 272 nm. Interestingly, differential absorbance at 272 nm (ΔUV 272) was shown to be a good indicator of UV absorbing chromophores and the formation of trihalomethanes (THMs) resulting from chlorination. Furthermore, differential spectra of chlorinated TLwaters were similar for given chlorination conditions, peaking at 272 nm.The correlations between THMs and ΔUV 272 were quantified by linear equations with R2 values>0.96. The concentration of THMs formed when natural organic matter is chlorinated increases with increasing time and pH levels. Among all THMs, CHCl 3 was the dominant species forming as a result of the chlorination of TL and BL raw water samples. The highest chloroform (CHCl 3), dichlorobromomethane (CHC