Hydrodynamic Cavitation for Vinasse Treatment: Optimization Using the Taguchi Method and Phytotoxicity Evaluation

Abstract

The operational factors that maximize the removal of color, polyphenols and chemical oxygen demand in vinasse were evaluated by hydrodynamic cavitation with orifice plates, and the phytotoxicity of the treated effluent was analyzed under optimal conditions. A Taguchi experimental design with three operating factors was used: treatment time (20 and 60 min), orifice plate diameter (1 and 1.5 mm) and number of orifices (6 and 9) with the signal-to-noise (S/N) ratio of 'Larger is better'. The experiments were carried out at an inlet pressure of 4 bar and a controlled pH of 2. Phytotoxicity was evaluated with optimal factors in Raphanus sativus L. (radish) seeds. The results showed that optimal conditions were achieved with a treatment time of 20 min and the use of a 6-orifice plate of 1.5 mm diameter each orifice. These conditions allowed a reduction in COD by 44.19%, color intensity by 33.96% and polyphenol content by 90.25%. Under these conditions, the germination rate of radish seeds in cavitated vinasse reached 104.10%, indicating a significant decrease in toxicity. Hydrodynamic cavitation has been proven to be effective in vinasse treatment, combining high removal of contaminants and improvement in the environmental viability of effluent.