Department of Biology, Institute of Biosciences, São Paulo State University (Unesp), Av. 24-A, 1515, 13506-900 Rio Claro, SP, Brazil.
Department of Analytical Chemistry, Institute of Chemistry, São Paulo State University (Unesp), Rua Professor Francisco Degni, 55, 14800-060, Araraquara, SP, Brazil.
Ecotoxicol Environ Saf. 2018 Jan;147:550-557. doi: 10.1016/j.ecoenv.2017.09.009. Epub 2017 Sep 15.
Sewage sludge (SS) obtained after sewage treatment process may contain several toxic substances. Bioremediation can decrease the toxicity of the sludge, mainly when it is associated with stimulant agents, such as sugarcane bagasse (B). Samples of pure SS (SSP); SS+B; SS+Soil; and SS+B+Soil were bioremediated for 1, 3, and 6 months (T1, T2, and T3, respectively). After each period, the cytotoxic, genotoxic, and mutagenic potentials of the solid samples and their respective aqueous extracts (aqueous eluate and percolate water) were evaluated by the Allium cepa test. A microbiological analysis of the samples was also performed after each period tested. All solid samples of SS+B (in T1, T2, and T3) and the solid sample of SSP (treatment T3) showed a significant decrease of cell division (cytotoxic effects). The aqueous eluate extracts of SS+B (T1 and T3) and SSP (T2 and T3) induced cytotoxic effect. The solid sample of SS+B (T2 and T3) and aqueous extracts of SSP (T1) were genotoxic, indicating a harmful effect of SS on A. cepa, even after 6 months of bioremediation. There was an alternation in the microbial community both in diversity and in abundance, with the predominance of nonfermenting gram-negative bacilli. The tested bioremediation periods were not sufficient for the complete detoxification of SS, and the use of B did not seem to contribute to the degradation of the pollutants to inert compounds. These data emphasize that a specific relationship should exist between the sludge characteristic and the biostimulating agent used to promote a more efficient bioremediation. These results suggest the necessity to study longer periods of biodegradation and the use of other decomposing agents for greater safety and sustainability for the agricultural use of this residue.
污水处理厂（SS）在污水处理过程中可能含有多种有毒物质。生物修复可以降低污泥的毒性，特别是当它与刺激剂（如甘蔗渣（B））结合时。对纯 SS（SSP）；SS+B；SS+土壤；和 SS+B+土壤进行了为期 1、3 和 6 个月（T1、T2 和 T3）的生物修复。每个时期后，通过葱属植物试验评估固体样品及其各自水提取物（水浸提液和渗滤液）的细胞毒性、遗传毒性和致突变潜力。每个测试期后还对样品进行了微生物分析。在 T1、T2 和 T3 中，所有 SS+B 的固体样品和 SSP 的固体样品（处理 T3）均显示细胞分裂（细胞毒性作用）显著减少。SS+B 的水浸提液提取物（T1 和 T3）和 SSP（T2 和 T3）诱导细胞毒性作用。SS+B 的固体样品（T2 和 T3）和 SSP 的水提取物（T1）具有遗传毒性，表明 SS 对 A. cepa 具有有害影响，即使在生物修复 6 个月后也是如此。微生物群落的多样性和丰度都发生了变化，优势为非发酵革兰氏阴性杆菌。测试的生物修复期不足以使 SS 完全解毒，并且 B 的使用似乎并没有有助于将污染物降解为惰性化合物。这些数据强调，在促进更有效的生物修复时，污泥特性和生物刺激剂之间应该存在特定的关系。这些结果表明，需要研究更长时间的生物降解和使用其他分解剂，以提高该残留物用于农业的安全性和可持续性。
