Environmental Engineering Laboratory, Departament d'Enginyeria Quimica, Universitat Rovira i Virgili, Av. Països Catalans 26, 43007 Tarragona, Catalonia, Spain.
Sci Total Environ. 2012 May 15;425:99-109. doi: 10.1016/j.scitotenv.2012.03.018. Epub 2012 Apr 6.
Chemical and ecotoxicological properties of 28 sewage sludge samples from Spanish wastewater treatment plants were studied in order to assess their suitability for agricultural purposes. Sludge samples were classified into five categories according to specific treatment processes in terms of digestion (aerobic/anaerobic) and drying (mechanical/thermal). Composted samples, as indicative of the most refined process, were also considered. Sludges were subjected to physical-chemical characterization, being the sludge stabilization degree respirometrically assessed. The concentrations of seven metals (Cd, Cr, Cu, Pb, Zn, Ni, Hg) and organic substances (phenolic compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated naphthalenes, polybrominated diphenyl ethers, and perfluorinated compounds) were determined. Finally, two ecotoxicological tests were performed: i) Microtox® toxicity test with Vibrio fischeri, and ii) root elongation test with Allium cepa, Lolium perenne and Raphanus sativus seeds. Significant differences were found in the following parameters: dry matter, electrical conductivity, nitrogen, organic matter and its stability, phytotoxicity and ecotoxicity, depending on the sludge treatment. In turn, no significant differences were found between categories in the concentrations of most metals and organic pollutants, with the exception of free phenolic compounds. Furthermore, no correlation between total heavy metal burden and ecotoxicity was observed. However, a good correlation was found between phenolic compounds and most ecotoxicological tests. These results suggest that sludge stability (conditioned by sludge treatment) might have a greater influence on sludge ecotoxicity than the pollutant load. Composting was identified as the treatment resulting in the lowest toxicity.
为评估西班牙污水处理厂 28 个污水污泥样品是否适合农业用途，研究了这些样品的化学和生态毒理学性质。根据消化（好氧/厌氧）和干燥（机械/热）的具体处理过程，将污泥样品分为五类。还考虑了堆肥样品，作为最精细处理过程的代表。对污泥进行了物理化学特性分析，并通过呼吸测定评估了污泥稳定度。测定了七种金属（Cd、Cr、Cu、Pb、Zn、Ni、Hg）和有机物质（酚类化合物、多环芳烃、多氯联苯、多氯萘、多溴二苯醚和全氟化合物）的浓度。最后，进行了两项生态毒理学测试：i）使用发光菌 Vibrio fischeri 的 Microtox®毒性测试，和 ii）使用洋葱、黑麦草和萝卜种子的根伸长测试。发现以下参数存在显著差异：干物质、电导率、氮、有机物及其稳定性、植物毒性和生态毒性，这取决于污泥处理方式。反过来，除了游离酚类化合物外，大多数金属和有机污染物的浓度在各分类之间没有发现显著差异。此外，重金属总负荷与生态毒性之间没有观察到相关性。然而，发现酚类化合物与大多数生态毒理学测试之间存在良好的相关性。这些结果表明，污泥稳定性（受污泥处理条件的影响）可能对污泥生态毒性的影响大于污染物负荷。堆肥被确定为毒性最低的处理方法。
