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Behavior, Fate, and Mass Loading of Short Chain Chlorinated Paraffins in an Advanced Municipal Sewage Treatment Plant
journal contribution
posted on 2013-01-15, 00:00 authored by Lixi Zeng, Huijuan Li, Thanh Wang, Yan Gao, Ke Xiao, Yuguo Du, Yawei Wang, Guibin JiangSewage treatment plants (STP) are an important source
of short
chain chlorinated paraffins (SCCPs) to the ambient environment through
discharge of effluent and application of sludge. In this work, a field
study was conducted to determine the behavior and possible removal
of SCCPs during the sewage treatment process in an advanced municipal
STP in Beijing, China. SCCPs were detected in all sewage water and
sludge samples, and 97% of the initial mass loading in raw sewage
was found to be associated with suspended matter. The total concentrations
in raw influent, tertiary effluent, and dewatered sludge were 184
± 19 ng/L, 27 ± 6 ng/L, and 15.6 ± 1.4 μg/g dry
weight (d.w.), respectively. The dissolved concentrations of total
SCCPs (∑SCCPs) significantly decreased during mechanical, biological,
and chemical treatments. SCCP homologue profiles in aqueous phase
were distinctly different from those in solid phase. Along the treatment
process, the relative abundance of shorter chain and lower chlorinated
congeners gradually increased in sewage water, but no obvious variations
of homologue profiles were found in sludge. Mass flow analysis indicated,
the removal efficiency in aqueous phase for ∑SCCPs was 82.2%,
and the congener-specific removal efficiencies were positively related
to their solid–water partition coefficients (Kd). Mass balance results indicated that 0.8% and 72.6%
of the initial SCCP mass loading were ultimately found in the effluents
and dewatered sludge, respectively, while the remaining 26.6% was
lost mainly due to biodegradation/biotransformation. It was suggested
that the activated sludge system including basic anaerobic–anoxic–aerobic
processes played an effective role in removing SCCPs from the wastewater,
while the sorption to sludge by hydrophobic interactions was an important
fate of SCCPs during the sewage treatment.