Decreasing COD in Sugarcane Vinasse Using the Fenton Reaction: The Effect of Processing Parameters

Abstract

An experiment on Fenton degradation of sugarcane vinasse was carried out to determine its effect on the wastewater characteristics. Vinasse, a by-product of distillation in the bioethanol industry, contains high organic matter, as the value of chemical oxygen demand (COD) is >100,000 mg/L and BOD5 is 31,250 mg/L. The Fenton reaction is one of the advanced oxidation process (AOP) methods which has been widely applied for the treatment of wastewater containing organic pollutants and contaminants. This method utilizes hydroxyl radical (•OH) produced from the catalyzing reaction between Fe2+ or Fe3+ and hydrogen peroxide. The effect of pH, the ratio of [H2O2] and [COD], and the ratio of [H2O2] to [Fe3+] were studied in this research to evaluate the Fenton reaction. Results from this experiment showed that treatment of vinasse using the Fenton reaction decreased the COD value to 48.10%, and its biodegradability enhanced almost two times at a pH value of 3.8, a ratio of [H2O2] to [COD] of 0.62, and a ratio of [H2O2] to [Fe3+] of 50 (g/g), which demonstrated that the Fenton treatment was effective to reduce organic matter of sugarcane vinasse. Three kinetic models (first order, second order, and Behnajad–Modirshahla–Ghanbery (BMG) kinetic model) were used to evaluate the degradation of the COD value. On the basis of the value of R2 (coefficient of determination), we suggested that BMG represented the best kinetic model. This study finds that the Fenton treatment is able to mitigate the environmental impacts of sugarcane vinasse.