Estudo da eficiência do tratamento biológico de efluentes através da otimização de parâmetros físico-químicos auxiliados pelo planejamento fatorial de experimentos

Abstract

The industries effluents treatments was employed in order to reduce the organic material until appropriate level, and subsequently, returns it to the environment, without damages, or reuse itself in the same process. The slaughter-house industry is characterized by consuming a large amounts of water in the production processes, producing a wastewater with high concentrations of organic material, that can be verified by high levels of Biochemical Oxygen Demand (BOD5) and high levels of Chemical Oxygen Demand (COD). Increasingly, these companies search new techniques that are less harmful to the environment in order to eliminate or minimize the impacts. Thus, considering the importance of slaughter-house industry to the economy for Presidente Prudente-SP region and the environmental impact of this activity, the present study was done to optimize the wastewater treatment produced by these industries. To perform this study the concentration of nutrients, pH and oxygen concentration were systematic changed to gain a greater efficiency in the biological wastewater treatment system, employing a factorial design study. The wastewater treatment was carried out in a bench scale through an aerobic biological reactor. Analyzes were performed to characterize the effluent from the reactor by kinetic profiles and the obtain results were employed in the experimental design. These COD and BOD data were used as responses in the experimental design. It was verified an average COD removal of 79.3% and an average BOD5 removal of 76.7% for BOD5. All experiments represent a first order kinetics, and the maximum removal rate reaches 99%. This study demonstrated that a correct variation of nutrient concentration, pH and oxygen concentration values can optimize the organic matter removal.