State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
Chemosphere. 2021 Oct;280:130745. doi: 10.1016/j.chemosphere.2021.130745. Epub 2021 May 3.
Sewage treatment plants (STPs) are important in densely populated megacities like Hong Kong to control the release of harmful pollutants from households and industries into the receiving water bodies and maintain water quality for supporting various beneficial uses. This study investigated the occurrence of the teratogenic retinoic acids (RAs) and their oxidative metabolites in sewage and sludge of six selected STPs that treat about 87% of all sewage in Hong Kong annually, and compared the removal efficiencies of these compounds from sewage between two major sewage treatment processes, i.e., chemically enhanced primary treatment (CEPT) and secondary (biological) treatment. The total concentrations of the studied RAs in influent, effluent and sludge from the six selected STPs were found between 21.5 and 33.1 ng/L, 12.0-20.4 ng/L, and 4.33-7.02 ng/g dry weight, respectively. The compounds were dominated by all-trans-RA and 13-cis-RA, together accounting for 46.9-65.6%, 38.4-56.7%, and 62.8-82.8% of the total RAs in influent, effluent and sludge, respectively. The studied RAs could not be satisfactorily removed by both treatment processes with removal efficiencies ranging from 25.4% to 47.4% only, without significant difference in their removal between CEPT and secondary treatment. Based on the calculated hazard quotients of all-trans-RA equivalents (0.248-0.521), the treated effluents from all the six STPs exhibited medium ecological risks to the receiving coastal environment. Therefore, continuous monitoring of these compounds and enhancement of treatment technologies of STPs shall be considered in the future to improve the removal efficiencies of these compounds.
污水处理厂（STP）在香港等人口密集的特大城市中非常重要，可控制家庭和工业向受纳水体排放有害污染物，保持水质以支持各种有益用途。本研究调查了 6 家处理香港每年约 87%污水的选定 STP 的污水和污泥中致畸性视黄酸（RAs）及其氧化代谢物的情况，并比较了两种主要污水处理工艺（即化学强化一级处理（CEPT）和二级（生物）处理）对这些化合物从污水中的去除效率。在选定的 6 个 STP 的进水、出水和污泥中，所研究的 RAs 的总浓度分别为 21.5-33.1ng/L、12.0-20.4ng/L 和 4.33-7.02ng/g 干重。这些化合物主要由全反式-RA 和 13-顺式-RA 组成，分别占进水、出水和污泥中总 RAs 的 46.9-65.6%、38.4-56.7%和 62.8-82.8%。这两种处理工艺都不能令人满意地去除这些化合物，去除效率仅为 25.4%-47.4%，CEPT 和二级处理之间没有显著差异。基于全反式-RA 当量（0.248-0.521）的计算危害商数，所有 6 个 STP 的处理出水对受纳沿海环境表现出中等生态风险。因此，未来应考虑对这些化合物进行连续监测并加强 STP 的处理技术，以提高这些化合物的去除效率。
