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International Journal of Chemical Engineering
Volume 2013 (2013), Article ID 393467, 5 pages
Research Article

The Application of a Surface Response Methodology in the Solar/UV-Induced Degradation of Dairy Wastewater Using Immobilized ZnO as a Semiconductor

1Department of Chemical Engineering, Engineering School of Lorena, University of Sao Paulo (USP), Estrada Municipal do Campinho, s/n°, Bairro do Campinho, 126020-810 Lorena, SP, Brazil
2Department of Civil and Environmental Engineering, University of Texas at San Antonio (UTSA), One UTSA Circle, San Antonio, TX 78249, USA
3Departament of Production Engineering, Sao Paulo State University (UNESP), 12516-410 Guaratingueta, SP, Brazil

Received 30 May 2013; Accepted 15 August 2013

Academic Editor: Antonia Pérez de los Ríos

Copyright © 2013 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.


An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 μm of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process.