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 (FeCl 3 ), 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 ([Fe 2+ ] = 250 mg/L, [H 2 O 2 ] = 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, BOD 5 , N‐NO 3 , P‐PO 4 , and dye removal were obtained according to the standard limits in Iran.