Poor management of human activities has caused serious impacts to ecosystems, thus affecting their quality and maintenance of environmental conditions. One problem that has been dogged in recent decades is the final disposal of waste generated in the sewage treatment process, particularly sewage sludge, which may contain toxic substances like heavy metals and organic substances, as well as pathogenic microorganisms. A viable alternative for the allocation of sewage sludge is its application in agriculture as soil reconditioning. However, accumulation of heavy metals in soils with sewage sludge may cause harmful effects to the associated biota and to human health. Another factor to be considered is the possible leaching of toxic substances into groundwater and the river systems around the sludge disposal area. The use of microorganisms in the biodegradation process seems to be a promising approach to reducing the toxicity of sewage sludge. To better assess the potential toxicity of sewage sludge, different tests using different bioindicators should be carried out. The aim of this project is to analyze the toxic, cytotoxic, genotoxic and mutagenic potential of sewage sludge, before and after the process of biodegradation by microorganisms, using test systems like Salmonella typhimurium, Allium cepa, Eisenia fetida and mammalian culture cells. The sewage sludge to be assessed will be collected at the Sewage Treatment Station of Rio Claro - SP. The tested samples will correspond to raw sludge (100%) and soil / sludge mixtures at proportions of 10% and 50% of mud for E. fetida and A. cepa. Assays with S. typhimurium, A. cepa and mammalian culture cell will be performed with the solubilized raw sludge and different soil / mud solubilized mixtures. Samples of sludge submitted to biodegradation for 2, 6 and 12 months will also be evaluated using the same tests to verify the effectiveness of biodegradation by microrganisms in the decomposition of toxic substances in sludge sewage.
News published in Agência FAPESP Newsletter about the scholarship: