Deo Randhir P, Halden Rolf U
The Biodesign Institute at Arizona State University, Center for Environmental Biotechnology, 1001 S. McAllister Avenue, P.O. Box 875701, Tempe, AZ 85287, USA.
J Environ Monit. 2010 Feb;12(2):478-83. doi: 10.1039/b919076g. Epub 2009 Nov 25.
Accurate quantification of organic wastewater compounds (OWCs) is essential for assessing their removal efficiency in wastewater treatment plants (WWTPs) and for calculating discharge rates into effluent-receiving surface waters. In this study, we undertook a theoretical evaluation of the effect of sorption and sample filtration on data quality. Filtration of samples, while commonly practiced, may preclude a potentially significant fraction of chemical mass from both chemical measurements and mass flow analyses for WWTPs. Sorption theory dictates that analyte losses from sample filtration are notable for hydrophobic organic compounds (HOCs) featuring a pH-dependent logarithmically transformed organic carbon-water distribution coefficient (log D(OC)) of > or =3.0. Among a total of 33 organic wastewater compounds considered, the extent of sorption to filterable materials ranged from 22% for bisphenol A diglycidyl ether (BADGE) to 99% for di-(2-ethylhexyl)phthalate (DEHP). Sample filtration also was demonstrated to have a profound impact on the outcome of chemical fate and behavior studies. When the chemical mass residing on filterable particulates was considered, the concentration spread (range) doubled between maximum and minimum concentrations reported for raw wastewater. Furthermore, removal efficiencies of WWTPs calculated for HOCs increased by as much as 62% just by changing the method of accounting. We conclude that some of the data spread reported in the literature concerning chemical mass loadings, contaminant concentrations in raw sewage, and removal efficiencies of similarly designed WWTPs is driven not by actual differences in sewage composition, geographic locations and treatment units but by sample processing protocols and the method of mass accounting.
准确量化有机废水化合物（OWCs）对于评估其在污水处理厂（WWTPs）中的去除效率以及计算排入受纳地表水的排放率至关重要。在本研究中，我们对吸附和样品过滤对数据质量的影响进行了理论评估。样品过滤虽然是常用做法，但可能会排除污水处理厂化学测量和质量流量分析中潜在的大量化学物质。吸附理论表明，对于pH依赖性对数变换有机碳-水分配系数（log D(OC)）≥3.0的疏水性有机化合物（HOCs），样品过滤导致的分析物损失显著。在所考虑的总共33种有机废水化合物中，对可过滤材料的吸附程度范围从双酚A二缩水甘油醚（BADGE）的22%到邻苯二甲酸二（2-乙基己基）酯（DEHP）的99%。样品过滤还被证明对化学归宿和行为研究的结果有深远影响。当考虑存在于可过滤颗粒上的化学物质时，原废水报告的最大浓度和最小浓度之间的浓度范围（跨度）增加了一倍。此外，仅通过改变计算方法，为HOCs计算的污水处理厂去除效率就提高了多达62%。我们得出结论，文献中报道的关于化学物质负荷、原污水中污染物浓度以及类似设计的污水处理厂去除效率的一些数据差异，不是由污水成分、地理位置和处理单元的实际差异驱动的，而是由样品处理方案和质量计算方法驱动的。
