Use of a hybrid treatment system for vinasse bioremediation and evaluation of its toxicity by histological and molecular analysis

In an attempt to reduce the use of fossil fuels, for economic, geopolitical and environmental reasons, ethanol is presented as one of the main energy alternatives. Vinasse is one of the subproducts of alcohol production from sugarcane (Saccharum sp.) and due to its abundance in organic matter it has been used as fertilizer in the soil presenting good results over the years, since it promotes improvement in soil fertility by means of availability of some elements for plants. However, this substance presents significant pollutant power due to its high concentration of organic matter and it can reach water resources through percolation, reaching groundwater, and/or runoff, reaching the surface waters. The use of treatment systems, such as stabilization, filtration and phytoremediation to treat wastewater from different sources has become particularly interesting since they are highly effective biogeochemical systems to reduce the impact of wastewater pollution. Therefore, the present study had as aim to develop a hybrid treatment system with the purpose of bioremediating vinasse, changing its physical and chemical characteristics as an attempt to reduce the environmental impact of this residue. To verify the efficacy of the proposed treatment, physicalchemical tests of the vinasse were carried out before and after treatment and also tests with bioindicators to analyze their toxicity were applied. In order to analyze the toxicity of bioremediated vinasse, the histopathology of gill and liver, investigation of molecular mechanisms (qPCR, HSP70, TBARS) that indicate cell stress in tilapias and the analysis of amphipods swimming behavior were used as biomarkers.The results obtained through the physicochemical analyzes showed a significant improvement in the composition of the vinasse, besides prove the efficiency of water hyacinth into phytoremediation. These results were corroborated by toxicity analyzes, since the analyzed organs of the fish exposed to bioremediate vinasse did not show significant alterations. In addition, the analyzes of amphipods swimming behavior indicated that although the vinasse was submitted to a hybrid treatment system, it maintained the capacity to disturb the aquatic environment, however, when compared to raw vinasse, in natura, it was observed toxicity. Thus, we can conclude that the proposed treatment method was efficient in reducing the pollutant potential of vinasse, making the use of this residue safer. (AU)