典型污水处理厂中多溴联苯醚的分布特征、迁移及负荷研究

本研究通过对典型污水处理厂各构筑物进行采样分析,研究多溴联苯醚在污水处理厂中的分布、迁移和转化.结果表明,在污水处理厂所有污泥样品中都有PBDEs检出,PBDEs浓度范围在4226.76~9204.14 ng·g-1之间.其中,BDE-209是主导同系物,所占平均比例为83.16%(范围为75.75%~89.48%).该污水处理厂的进水样品中溶解态PBDEs总浓度为183.11 ng·L-1,而出水样品中溶解态PBDEs浓度则降至7.07 ng·L-1,PBDEs的去除率达到96%以上.所有污水样品中BDE-209都是最主要的同系物,所占比例在75.75%~85.68%之间,BDE-99和BDE-47是仅次于BDE-209的另外2种主要同系物.通过对污水处理流程中PBDEs的溶解态和颗粒态分配系数的研究得出,溶解性颗粒物对疏水性有机物在整个污水处理流程中的迁移、转化有重要的影响.该污水厂的日均PBDEs负荷量为21311.2 mg·d-1,污水经初沉池和二沉池处理之后分别有58.07%和39.91%的PBDEs被去除,即一共有97.98%的PBDEs被去除了,最后在出水中只剩2.02%的PBDEs.该污水厂通过出水的日均排放PBDEs的量为430.8 mg,通过脱水污泥日均排放PBDEs的量高达20880.4 mg.土壤在污泥农用之后PBDEs浓度年增加量为25.4μg·kg-1,污泥农用需要百年以上才能达到欧盟的规定限值.

The distribution, migration and mass loading of polybrominated diphenyl ether in a typical sewage treatment plant

In this study, samples from all the processes of a typical sewage treatment plant were analyzed to investigate the distribution and transformation of polybrominated diphenyl ethers (PBDEs). PBDEs were detected in all sludge samples, and the total concentration of PBDEs ranged from 4226.76 to 9204.14 ng·g^-1 with BDE-209 being as the predominant congener (average ratio being 83.16%). The concentrations of dissolved PBDEs in the influent and effluent were 183.11 and 7.07 ng·L^-1, respectively, and the corresponding removal efficiency reached over 96%. BDE-209 was also the predominant congener in the wastewater samples, contributed 83.16% of the total PBDEs (ranging 75.75%~89.49%), and followed by BDE-47 and BDE-99. It was found that the presence of dissolved organic matter affected the mobility of PBDEs during the initial stages of the treatment process. According to the average loading of PBDEs (21311.2 mg·d^-1) of the treatment plant, most of PBDEs might have been removed after the primary and secondary settling tanks with removal efficiencies being 58.07% and 39.91% respectively and about 2.02% PBDEs being discharged with the treated effluent. The resulting mass loading of PBDEs was estimated 430.8 mg·d^-1. The concentration of PBDEs in agricultural soils after the fertilization of sewage sludge was estimated to be 25.4 ng·g^-1, which could meet the limitation of European Union after more than one hundred years.