Advanced numerical kinetic model for predicting COD removal and optimisation of pulp and paper wastewater treatment by Fenton process

Abstract

ABSTRACT In the present study, a kinetic model has been developed to predict the chemical oxygen demand (COD) removal efficiency of Fenton process for the treatment of pulp and paper mill (P&P) wastewater. In order to investigate the effects of main parameters including Fe(II) dosage, H2O2 dosage, and pH, 45 experiments have been carried out at three levels for each parameter, and thus COD removal efficiency has been obtained. The Fenton process was simulated by using 10main reactions, and the model was solved numerically according to a specific algorithm. All the pollutants in the P&P wastewater were assumed to be a pseudo-material, andapparent kinetic constant (k**)was calculated using a developed iterative method. The results of the numerical model indicated that the proposed model had a great potential to predict COD removal efficiency for P&P wastewater by Fenton in comparison to the first and second-order kinetic models. Accordingly, R-squared (R 2), Root Mean Square Error (RMSE), and Mean Relative Error (MRE) of the numerical kinetic model were 0.93, 4.296 × 10−7, and 0.035, respectively, implying remarkable accuracy of the numerical model. Furthermore, at the optimum point of Fenton process,which was pH: 3,[H2O2]:0.015 Molar, and [Fe(II)]: 0.015 Molar, the COD removal efficiency of P&P wastewater reached 78%. As the basis of the numerical model was established according to mechanisms of Fenton process, the results demonstrated the great performance of the advanced kinetic model in the estimation of the COD removal efficiency, the behaviour of effective parameters such as pH, H2O2, and Fe(II) along with their effects on k**, and Fe(III) accumulation during Fenton process.