Aplicação de processo oxidativo avançado baseado em fotocatálise heterogênea (TiO2/UVsolar) para o pré-tratamento de afluente lácteo

Abstract

The aim of this work was to evaluate a pretreatment system for dairy wastewater based on an advanced oxidative process (AOP). An AOP treatment based on photocatalysis was applied to reduce the organic load in dairy effluents obtained from the dairy process, such as cream, yoghurt and pasteurized milk. Titanium dioxide was used as a semiconductor. It was finely distributed and fixed with poliuretanic ink on a flat metallic plate where the effluent was circulated on its catalytic bed fixed at a 23º angle. This AOP process was exposed to direct solar radiation. Some process factors were analyzed: pH influence (5 or 7), reaction time (120 or 180 min), TiO2 photocatalytic activity (anatase or rutile) and initial organic load in the effluent (In natura or 1:1 v/v of effluent water). The best conditions for AOP process were determined through an experimental design (24-1). Process efficiency was obtained through chemical oxygen demand (COD) tests. The best conditions for AOP were: reaction time of 180 min; TiO2 anatase; pH 5 and In nature effluent with percentage removed COD (%CODrem) above 54.77 ± 1.66 %, representing a COD reduction from 3782.5 ± 37.6 mg.L-1 to 1710.4 ± 0.3 mg.L-1 and the reduction of total organic carbon of 983.6 ± 37.6 mg.L-1 in 606.8 ± 2.0 mg.L-1.