State Key Laboratory of Urban Water Resources and Environments (SKLUWRE), Harbin Institute of Technology, Harbin 150090, China.
Environ Sci Process Impacts. 2014 Feb;16(2):271-9. doi: 10.1039/c3em00487b.
The uncontrolled release of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs) and the adverse health effects on the public have been of increasing concern. In this study, a lab-scale bioreactor was prepared to analyze the mass distribution of three aromatic (benzene, toluene, and xylenes) and four chlorinated VOCs (chloroform, carbon tetrachloride, trichloroethylene, and tetrachloroethylene) among the air, water and sludge phases in wastewater treatment processes. The VOC distribution through a full-scale WWTP in northern China was further investigated with respect to the effects of seasonal temperature variations and treatment technologies, followed by the cancer risk assessment using a steady-state Gaussian plume model (Industrial Source Complex) to simulate the atmospheric behaviors of the VOCs emitted from the WWTP. It was found that three aromatic hydrocarbons, notably benzene, were more readily released from the wastewater into the atmosphere, whereas the chlorinated compounds except chloroform were mainly present in the water phase through the treatment processes. The primary clarifier was the technology releasing high levels of VOCs into the atmosphere from the wastewater. The extents of volatilization or biodegradation, two important mechanisms to remove VOCs from wastewater, appeared to be determined by the physicochemical characteristics of the compounds, as the influence of treatment technologies (e.g., aeration) and seasonal temperature variations was rather limited. More importantly, the people living in the areas even more than 4 km away from the WWTP were still potentially exposed to cancer risks exceeding the regulatory threshold limit. The findings described the complex nature of VOC emissions from WWTPs and quantitatively indicated that the associated health impacts on the public near the WWTPs could be severely underestimated, whereas their treatment efficiencies by wastewater treatment technologies were overestimated. Instead of fully controlling the VOC release from WWTPs, the identification and abatement of important VOC species with regard to the atmospheric emission and health concerns is one possible alternative approach to effectively minimize the environmental and public health impacts by VOCs released from this particular source.
污水处理厂（WWTP）中挥发性有机化合物（VOCs）的失控释放及其对公众健康的不利影响引起了越来越多的关注。在这项研究中，制备了一个实验室规模的生物反应器，以分析在污水处理过程中，空气中、水中和污泥相中三种芳香族（苯、甲苯和二甲苯）和四种氯化 VOCs（三氯甲烷、四氯化碳、三氯乙烯和四氯乙烯）的质量分布。进一步调查了中国北方一个全规模 WWTP 中 VOC 的分布情况，考虑了季节性温度变化和处理技术的影响，然后使用稳态高斯烟羽模型（工业源综合模型）对 WWTP 排放的 VOC 的大气行为进行模拟，对癌症风险进行了评估。结果发现，三种芳香族烃，尤其是苯，更容易从废水释放到大气中，而氯化化合物除了三氯甲烷外，主要通过处理过程存在于水相中。初次沉淀池是将 WWTP 中的 VOC 释放到大气中的主要技术。挥发或生物降解两种重要的去除废水中 VOC 的机制的程度似乎取决于化合物的物理化学特性，因为处理技术（例如曝气）和季节性温度变化的影响相当有限。更重要的是，生活在距离 WWTP 甚至超过 4 公里的地区的人们仍然可能面临超过监管阈值的癌症风险。研究结果描述了 WWTP 中 VOC 排放的复杂性质，并定量表明，人们对 WWTP 附近的公众健康影响可能被严重低估，而废水处理技术对其的处理效率被高估。与完全控制 WWTP 中 VOC 的释放相反，确定和减轻与大气排放和健康关注有关的重要 VOC 种类是一种有效的替代方法，可以有效降低 VOC 从这一特定来源释放对环境和公众健康的影响。
