摘要:
多环芳烃(PAHs)在水环境中可以通过化学或微生物作用转化成其衍生物(SPAHs),而SPAHs可能具有更强的毒性和“三致性”从而危害人体健康。为探明污水厂中PAHs和SPAHs的存在性及不同二级处理和再生水处理工艺对它们的去除效果,对北京及广东共4座污水处理厂中PAHs及SPAHs进行了检测,同时对再生水进行了健康风险评价。结果显示:从进水浓度来看,4座污水处理厂中,低环芳烃浓度(191.8~394.2 ng·L-1)明显高于高环芳烃(89.3~108.2 ng·L-1);SPAHs中氧取代物(O-PAHs)总浓度(253.8~322.2 ng·L-1)高于甲基取代物(MPAHs,44.3~220.4 ng·L-1)。不同二级处理工艺对PAHs的去除率为43.7%~58.2%,对SPAHs的去除率为45.8%~52.1%。不同再生水处理工艺对PAHs和SPAHs去除率差别较大,PAHs的去除率范围为1.8%~41.1%,SPAHs的去除率范围在2.35%~25.9%。结果表明,目标物的去除以生物降解为主,此外,吸附在固体颗粒上,随颗粒沉淀去除也是主要途径之一。通过对污水厂再生水的风险评价,苯并[a]芘(BaP)和二苯并[a,h]蒽(DBA)2种强致癌物TEQ浓度均高于1,其致癌风险较大,安全性有待提高。
Abstract:
Polycyclic aromatic hydrocarbons (PAHs) in aqueous environment can be transformed to substituted polycyclic aromatic hydrocarbons (SPAHs) by chemical or microbial process, which are more toxic and carcinogenic, thus endangering human health. In order to investigate the removal efficiency of PAHs and SPAHs during different biological treatment process and water reuse process, target compounds from 4 wastewater treatment plants in Beijing and Guangdong Province were investigated, and health risk assessment were made for reused water. Results indicated that low-ring aromatic hydrocarbon concentrations were significantly higher (191.8-394.2 ng·L-1) than that of high-ring aromatics (89.3-108.2 ng·L-1) in the influent from the four wastewater treatment plants. The total concentration of oxygen substituted PAHs (OPAHs) (253.8-322.2 ng·L-1) was higher than that of methyl substituted PAHs (MPAHs, 44.3-220.4 ng·L-1). The removal efficiencies of PAHs during different biological treatment processes were 43.7% -58.2%, while the removal efficiencies for SPAHs were 45.8% -52.1%. The removal efficiencies of PAHs and SPAHs in different water reclaimed processes were different, with PAHs in the range of 1.8% -41.1% and SPAHs in the range of 2.35% -25.9%. The results showed that the removal of the targets mainly depends on biodegradation, and adsorption on solid particles and removing with the particle deposition was also one of the major pathways. The results of risk assessment for reused water indicated that the toxic equivalent quantity (TEQ) of two carcinogens, benzo[a] pyrene (BaP) and dibenzo[a, h] anthracene (DBA), were both higher than 1, which meant that the carcinogenic risk of reclaimed water was relatively high. From this aspect, the safety of the reclaimed water should be taken more consideration.
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