Treatment of wood industry wastewater by combined coagulation-flocculation-decantation and fenton process

In the present research, the efficiency of turbidity and chemical oxygen demand (COD) reduction from the wood industry wastewater (WIW) by the use of a combined coagulation-flocculation-decantation (CFD) - Fenton process was studied. Firstly, the performance of three coagulants such as ferric chloride (FeCl3), aluminum sulphate (alum), and polyaluminum chloride (PACl) was evaluated. The polyacrylamide (PAM) was used as a flocculant. The results showed that the polyaluminum chloride had a high removal efficiency. The COD reduction of 84.1% and turbidity removal of 82.0% of were obtained in coagulation-flocculation-decantation (CFD). Secondly, Fenton process was optimized, by the use of a response surface methodology (RSM), with application of a central composite design (CCD). The maximum turbidity and COD removal obtained by this process were 94.1% and 72.5% respectively, under optimal conditions ([Fe2+] = 250 mg/L, [H2O2] = 500 mg/L, pH 3.5, time 60 min). The kinetics of COD and turbidity removal were determined by the model of first order. In conclusion, the combination of coagulation-flocculation-decantation (CFD) - Fenton process presented as a remarkable method for wood wastewater treatment. Practitioner points A combination of coagulation-flocculation-decantation and Fenton process was introduced for the wood industry wastewater treatment. A designed experimental approach for treatment of wood industry wastewater using a Fenton process was studied. The yields of COD, BOD5, N-NO3, P-PO4, and dye removal were obtained according to the standard limits in Iran.