Redução da toxicidade da vinhaça : tratamento combinado coagulação/floculação/fotocatálise

• Autor(a) principal: Souza, Renata Padilha de
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/3810
• topic: Vinhaça; Tratamento; Coagulação; Floculação; Fotocatálise; Radiação UV; Brasil.; Vinasse; Coagulation/Flocculation; Photocatalisys; UV radiation; Brazil.; Engenharias; Engenharia Química

By virtue of the high ethanol production in the country, the waste generated, vinasse becomes a major environmental problem. Only in the first half of April 2010, Brazil was responsible for producing 756,700 tons of sugar and 710.00 million liters of ethanol, 92.40 million liters of anhydrous ethanol and 617.60 million liters of hydrated ethanol, totaling about 9.23 billion liters of vinasse. Its final disposition, which proved more economical and efficient from the standpoint of agriculture, and therefore, has become widespread and adopted by the majority of the ethanol industries, was the use in fertilization/irrigation in sugarcane fields. This practice has not yet been adequately evaluated because in the vinasse composition, besides the presence of minerals which are important for the production of sugarcane, there are toxic organic compounds, mainly phenol derivatives, which are difficult to be degraded. Traditional methods of treatment are not able to eliminate these compounds or make them less toxic. Vinasse is acid and has high values of COD (chemical oxygen demand) and BOD (biochemical oxygen demand). Its treatment before being released to the soil is therefore necessary. Research shows risks of change in quality of subterranean water where vinasse is disposed. The problems are soil salinity, metal leaching to the subterranean water,unbalance of nutrients and reduction of soil alkalinity. So vinasse treatment before final disposal is necessary. In this work, vinasse was concentrated by coagulation/flocculation. The clarified effluent was then treated by photocatalysis. Photocatalytic degradation of vinasse in naturaand diluted with water, was also studied. The coagulation/flocculation tests were done using tannins and FeCl3 as coagulants. Photocatalytic tests were carried out employing UV radiation, to evaluate the presence of catalysts: TiO2 P25, TiO2 Kronos, ZnO and Fe2O3/TiO2 (suspended) and TiO2 Kronos supported on glass slides. The influence of heat treatment on the properties of the catalysts and the efficiency of the coagulants was also evaluated, as well as reaction time and power of UV irradiation. Analyses of color, turbidity, pH, COD and toxicity and UV-Vis spectrophotometry were done. The results showed that the natural coagulant removes about 50% COD, 85% color and up to 97% turbidity. Photocatalysis combined with coagulation / flocculation removes 67% of COD in 48 h of irradiation in the presence of TiO2 photocatalyst P25. These treatments also reduce the toxicity of clarified vinasse from 77.8% to 13.3% (mortality of Artemia salina).