RESUMO

The application of ozonation has been increasing in recent years, the main disadvantage of this type of treatment being related to the by-products, which can have toxic and carcinogenic properties, and therefore should be studied further. In this study, the combined treatment of ozonation and subsequent biological degradation with a biofilm, to reduce the color and chemical oxygen demand (COD), was investigated. The experimental part of the study consisted of two phases. The first phase was the ozonation process, the results obtained demonstrated that the ozonation of Remazol Black B dye at pH values of 3-11, was effective, partially oxidizing and completely decolorizing the effluent, even at relatively high concentrations of the dye (500 mg/L). Color removal efficiencies greater than 96% were obtained in all cases. The degradation kinetics of ozone is a pseudo-first-order reaction with respect to the dye concentration. It was possible to verify that the ozonation process as a pre-treatment increases the dye degradation efficiency. For the biological treatment, an increase in ozonization time increased the dye concentration reduction in hydrolyzed dye synthetic effluent. The toxicological results of the tests with Daphnia Magna showed that there is an increase in toxicity after ozonization and a decrease after submitting the ozonized synthetic wastewater to biological treatment with a biofilm.

Assuntos

Compostos Azo/isolamento & purificação , Biodegradação Ambiental , Corantes/isolamento & purificação , Oxidantes Fotoquímicos/química , Oxigênio/química , Ozônio/química , Indústria Têxtil , Animais , Bactérias/química , Bactérias/metabolismo , Biofilmes , Calibragem , Cor , Daphnia , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Naftalenossulfonatos , Espectrofotometria Ultravioleta

RESUMO

This work simulated numerically the n-pentane separation of a mixture of iso-pentane, n-pentane and nitrogen, using an adsorption column with zeolite 5A. The mathematical model equations of the mass and heat transfer in the adsorption column are presented, as well as the boundary and initials conditions, beyond some hypotheses and considerations. The Volume Finite Method was used in the discretization of the equations to get the system of algebraic equations and posterior development of the computational algorithm. The numerical results using the Differencing Central (CDS) and Upwind (UDS) interpolations were compared with experimental results found in the literature. The influence of the partial pressure in the adsorption column performance was also analyzed.