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ISRN Chemical Engineering
Volume 2012 (2012), Article ID 275371, 8 pages
http://dx.doi.org/10.5402/2012/275371
Research Article

Heterogeneous Photocatalytic Degradation of Dairy Wastewater Using Immobilized ZnO

Department of Chemical Engineering, Engineering School of Lorena, University of São Paulo (USP), Estrada Municipal do Campinho, s/n°, Bairro do Campinho, 12600-000 Lorena, SP, Brazil

Received 4 June 2012; Accepted 16 July 2012

Academic Editors: M. A. Oturan and I. Poulios

Copyright © 2012 Gisella R. Lamas Samanamud et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This work evaluated the efficiency and systemic application of heterogeneous photocatalytic degradation for dairy wastewater under advanced oxidation process (AOP) utilizing solar radiation and immobilized ZnO as measured by total organic carbon (TOC). The AOP system consisted of a semibatch reactor and glass tank operated with an initial volume of 3 L of dairy wastewater. ZnO was immobilized on a metal plate of 8 0 0 × 2 5 0  mm and used as a catalyst bed. Evaporation rate was considered when effective degradation of the photocatalytic system was determined. The AOP utilized Taguchi’s L8 orthogonal array. The entry variables were pH, reaction time, initial organic load in the effluent, and ZnO coating thickness on the catalyst bed. When optimized, an effective TOC degradation of 14.23% was obtained under variable values of pH 8.0, a metal-plate coating of 100 micrometers (μm) ZnO, and total reaction time of 180 min.