Mechanistic model of electrocoagulation process for treating vinasse waste: Effect of initial pH

Abstract

Electrocoagulation (EC) is widely applied to treat wastewaters. Vinasse is a bioethanol waste containing high Chemical Oxygen Demand (COD) and having low power Hydrogen (pH) level. Application of EC for treating vinasse has been studied by other authors, but development of mechanistic models has not been conducted yet. Because of the complex reactions in EC, building a mechanistic model is very interesting. The effect of initial pH in EC on COD removal of the vinasse was investigated and then the measured data was modeled. In the model, reactions in EC process consisted of adsorption, flocculation, entrapment, sedimentation and flotation. Measured data obtained through experiment included COD, total dissolved Fe, scum and sludge per real time during EC process. Increase in initial pH from 4.35 to 6.00 increased the kinetic constants of k1 (adsorption), ke (entrapment) and ksc (flotation). Furthermore, some mathematical equations between the initial pH and the kinetic constants were successfully founded so that the EC performance for other initial pH (in range of 4.35–6.00) could be predicted. Meanwhile, ratio between removed COD to total operating cost for initial pH of 4.35, 5.00 and 6.00 after EC process for 60 min was 0.0570, 0.0506 and 0.0636 g-COD IDR−1 respectively.