Removal Efficiency and Fate of Chlorinated Paraffins (CPs) in a Municipal Sewage Treatment Plant near a Typical Petrochemical Park

Thisstudy provides a scientific assessment of the secondaryenvironment risks of CPs caused by reclaimed water and sludge disposal. Water resources play an important role in industrial,agricultural,and public activities. Chlorinated paraffins (CPs) in wastewater generatedby these activities provide an important source of CP contamination.In this study, the occurrences of short-chain chlorinated paraffins(SCCPs) and medium-chain chlorinated paraffins (MCCPs) were simultaneouslystudied in a typical sewage treatment plant (STP) near China'ssecond-largest oil production base over a 1-year period. High levelsof SCCPs and MCCPs (3809 & PLUSMN; 670 and 4803 & PLUSMN; 478 ng/L) werefound in the influent due to receiving 75% of industrial wastewater.C-14-CPs was the predominant congener group, accountingfor 37% of the total CP concentrations. The dissolved removal efficiencyof CPs was 83.5%. Mass balance results demonstrated that 3.2% of theinitial CPs was found in the final effluent, and 66.3% of the initialCPs was found in the dehydrated sludge, while 30.4% of the initialCPs was lost due to the biodegradation and volatilization. This indicatedthat sorption onto sludge was the main fate of CPs in wastewater treatment.High mass fractions of CPs were found in the final effluent and dewateredsludge in the winter season due to the low biodegradation, biotransformation,and volatilization.