| Aromatic ester is a type of synthetic compounds,which mainly includes parabens?PBs?and phthalate esters?PAEs?.PBs as preservative and PAEs as plasticizer are used in personal care and plastic products respectively,which are chemicals that humans are often exposed to and can produce hazards to the endocrine system and the natural environment.With more chemicals entering our daily life,PBs and PAEs can cause more serious hazards to human beings and the natural environment as being discharged into municipal wastewater.Municipal wastewater treatment plant is the receiver and emission source of pollutants from people's living.So it is necessary to systematically study the distribution and removal mechanism of PBs and PAEs in municipal sewage.The present study focused on dissolved PBs and PAEs in a municipal wastewater treatment plant with inverted A2/O in Guangzhou,used solid phase extraction?SPE?as the pretreatment method,and detected 5 PBs with LC-MS/MS and 15 PAEs with GC-MS.By the determination of the concentration of PBs and PAEs,the present study characterized the profile and seasonal variation of PBs and PAEs,and tried to find the main removal pathway of PBs and PAEs in the sampled wastewater treatment plant?WWTP?,as well as assessed the risk of PBs and PAEs in the effluent.The results are summarized as follows:?1?The total concentrations of five parabens??5PBs?were widely ranged from 94.20ng·L-1 to 956.53 ng·L-1 with a mean value of 528.16 ng·L-1 in the influent while ranged from0.89 to 14.72 ng·L-1 with a mean value of 5.99 ng·L-1 in the effluent.In the influent,the predominant PBs were MeP,EtP and n-PrP,and both n-BuP and BeP were minor?<2%of?5PBs?.PBs showed the highest average influent concentration in spring,while the lowest one was found in autumn,and the former was 5.7 times as high as the latter.Besides,the biggest seasonal variation was observed in MeP among five parabens.Seasonal variation was observed in paraben distribution to some extent,but the predominant individuals were MeP,EtP and n-PrP consistently.?2?The average removal efficiency of?5PBs was 98.6%in the sampled WWTP.The average removal efficiencies of three predominant individuals?i.e.,MeP,EtP and n-PrP?were over 98%.The most critical stage of?5PBs removal was during influent and pre-anoxic with an average removal efficiency of 98.4%,possibly resulting from biodegradation,adsorption and dilution.PBs were further removed in the following biological treatment.The effect of season variation on the removal efficiencies of PBs was limited.The annual receiving and emission flux of PBs were 424.12 kg and 4.82 kg,respectively.The ecological risk of PBs was considered as low in effluent.?3?The total concentrations of 15 phthalate esters(?15PAEs)were ranged from 1.67-8.88?g·L-1 with a mean value of 5.34?g·L-1 in the influent while ranged from 0.88-1.97?g·L-1with a mean value of 1.38?g·L-1 in the effluent,below the concentration of the discharge standard in China.In the influent,the predominated individuals of PAEs were DEP and DBP,accounting for 35%and 30%of?15PAEs,respectively.PAEs showed the highest average influent concentration in winter,while the lowest one was found in summer,and the former was 1.7 times as high as the latter.Besides,the biggest seasonal variation was observed in DEP.Seasonal variation was observed in PAEs distribution to some extent.?4?The average removal efficiency of?PAEs was 70.9%in the sampled WWTP.The average removal efficiency of DMP and DEP were 97.8%and 99.0%,respectively,while that of DIBP,DBP and DEHP were 45.2%,55.3%and 49.5%,respectively.The most critical stage of?15PAEs removal was during influent and pre-anoxic with an average removal efficiency of 64.9%.Certain level of effect on the removal efficiency of PAEs caused by season variation was observed.The annual receiving and emission flux of PAEs were 4288 kg and1108 kg,respectively.The ecological risk of PAEs was considered as medium with the main contributor of DEHP in effluent.The present study revealed the distribution and removal mechanism of parabens and phthalate esters in WWTP and provided an important reference to evaluate the removal efficiency of aromatic ester in WWTP. |
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