Post-treatment of effluent household cleaning by conventional and catalytic ozonation

Abstract

Wastewater produced during the production process of a cleaning and disinfectant industry located in
the urban area of Uberlandia, state of Minas Gerais, Brasil, underwent an oxidative treatment process
with O3/pH7, O3/pH3, O3/pH10, O3/pH3/Fe2+, O3/pH3/Fe3+, O3/pH3/Mn2+, O3/pH10/activated coal 1g/L
e O3/pH10/activated coal 2g/L. The results were evaluated in terms of the removal percentage of two
parameters: DQO and true color. The oxidative process utilizing homogeneous catalytic ozonation in
the form of O3/pH3/Fe3+, was the most efficient both for residual water discoloration, as well as, for the
organic matter oxidation. This maybe due to a better catalyst interaction with the chemical substances
found in the matrix analyzed. Result supported by the current literature in this area, which states that
the reacional mecanism of the ozonation process is yet not entirely stablished, but varies considerably
with the type of metallic content employed and its interaction with the matrix compounds. The maximum DQO removal efficiency was 7,5% in 90 minutes of ozonation, possibly due to the production of ozonation
sub_products. The maximum true color removal was 59% in 90 minutes of ozonation. Thus, the results
indicate the importance of the contact time between bubbles of ascending ozone and residual water, in
the ozonation process.