TRATAMENTO DE EFLUENTE DE LAVAGEM DE VEÍCULOS AUTOMOTORES

Abstract

The vehicle washing activity involves the generation of an effluent with specific characteristics, because during washing process detergents and shampoos are used to change the properties of this type of effluent. In this process, all impurities that are impregnated in the vehicle are carried along with the effluent, so it has a high concentration of organic matter, settleable solids and oils and greases. This study aims to evaluate the Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), oils and total and mineral greases removal efficiency, as well as sedimented solids and pH, from two wastewater treatment plants coming from the washing process of light and heavy vehicles. The studied stations consist of a primary treatment system (box separating sand and oil) and subsequent secondary treatment; station 1 has the steps of coagulation, flocculation, sedimentation, anaerobic biological filter, filter filled with sand, and filter filled with activated coal; station 2 consists of flotation electrocoagulation, anaerobic biological filter, filter filled with sand, and filter filled with activated coal. At the station 1 were carried twenty-one effluent collection samples, one at entrance and another at the exit of the sand and oil separator and activated coal filter output, at station 2 were carried out nine effluent collection samples, at the entrance and exit of the sand and oil separator and activated coal filter output, the samples were submitted for analysis to a laboratory certified by ISO / IEC 17025 and accredited by INMETRO. The test results were compared to the reference values established by present legislation. The wastewater at the exit of both stations showed concentrations of the parameters analysed below the reference values and potential reuse in the same company, due to being free of solid and oil particles, enabling to be used to make the first washing of vehicles and using clean water only to perform the final rinsing of vehicles, or it can be used to perform the washing of the station supply track where it operates.