Trihalomethane formation potential of organic fractions in secondary effluent
XUE Shuang , ZHAO Qingliang , WEI Liangliang , JIA Ting
DOI:
Received July 24, 2007,Revised September 05, 2007, Accepted , Available online
Volume 20,2008,Pages 520-527
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Organic matter is known to be the precursor of numerous chlorination by-products. Organic matter in the secondary e uent from
the Wenchang Wastewater Treatment Plant (Harbin, China) was physically separated into the following fractions: particulate organic
carbon (1.2–0.45 m), colloidal organic carbon (0.45–0.1 m), fine colloidal organic carbon (0.1–0.025 m), and dissolved organic
carbon (DOC) (< 0.025 m). Moreover, < 0.45 m fraction was chemically separated into hydrophobic acid (HPO-A), hydrophobic
neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N), and hydrophilic fraction (HPI). The chlorine reactivity of these
organic fractions obtained from both size and XAD fractionations were evaluated. The structural and chemical compositions of the
HPO-A, HPO-N, TPI-A, and TPI-N isolates were characterized using elemental analysis (C, H, O, and N), Fourier transform infrared
spectroscopy (FT-IR), and proton nuclear magnetic resonance spectroscopy (1H-NMR). Results showed that DOC was dominant in
terms of total concentration and trihalomethane formation potential (THMFP), and there was no statistical di erence in both specific
THMFP (STHMFP) and specific ultraviolet light absorbance among the 0.45, 0.1, and 0.025 m filtrates. HPO-A had the highest
STHMFP compared to other chemical fractions. HPO-A, HPO-N, TPI-A, and TPI-N contained 3.02%–3.52% of nitrogen. The molar
ratio of H/C increased in the order of HPO-A < HPO-N < TPI-A < TPI-N. The O/C ratio was relatively high for TPI-N as compared
to those for the other fractions. 1H-NMR analysis of the four fractions indicated that the relative content of aromatic protons in HPO-A
was significantly higher than those in the others. The ratio of aliphatic to aromatic protons increased in the order of HPO-A < HPO-N <
TPI-A < TPI-N. FT-IR analysis of the four fractions showed that HPO-A had greater aromatic C==C content whereas HPO-N, TPI-A,
and TPI-N had greater aliphatic C–H content. TPI-N contained more oxygen-containing functional groups than the other fractions.
