Tratamento físico-químico de água de lavagem de veículos por flotação por ar dissolvido visando o reúso

Abstract

Nowadays in the industrial sector, some methods and procedures are discoursed about the use of available water to minimize environmental costs and avoid the non-compliance with stricter environmental laws. In this context, transport companies are using strategies such as water reuse for vehicle washing, saving potable water for other purposes and reducing expenses related to excessive water consumption. Thus, the present work focus in analysing the physicochemical treatment system through Dissolved Air Flotation (DAF) of a bus company in the city of Londrina/Paraná. For this project, the coagulant tannin, considered effective in flotation tests and a non-toxic substance was used. Twelve FAD tests were performed using different pH and tannin concentrations by means of Central Composite Design (CCD). The variables tested were electrical conductivity, pH, apparent colour, COD and Turbidity and were used as parameters of efficiency of the proposed treatment process. By means of these results, it was established an optimum point with the later analysis of the efficiency of suspended, total and volatile solids; Surfactants and Total Nitrogen (NTK). The study concluded that the use of a pH close to 6.5 proved to be more effective at a concentration of tannin between 60 to 95 mg.L-1. It was also concluded that the flotation time exerts influence on the removal, due to the transport of flocs to the treated effluent with the use of rates greater than 70 m3.m-2.d-1.