Fenton oxidation as a practical primary treatment for raw paper mill wastewater: A real case study

Abstract The pulp and paper industry generates high‐strength wastewater with elevated chemical oxygen demand (COD) and recalcitrant organics that are difficult to be treated by conventional methods. This study evaluated the practicality of the Fenton advanced oxidation process as a treatment technology for raw industrial paper mill wastewater, addressing the gap in previous optimization studies that mainly used synthetic or pre‐treated effluents. The effects of H 2 O 2 concentration (50–70 mmol/L), Fe 2+ dosage (4–8 mmol/L), pH (2–6), and reaction time (120–240 min) were investigated and optimized using response surface methodology (RSM). An optimum COD removal of 86.10% could be obtained under the following reaction conditions: 60.80 mmol/L H 2 O 2 , 6.98 mmol/L Fe 2+ , pH 3, and 209 min. In addition to COD reduction, the total organic carbon (TOC) decreased from 111.20 mg/L in the raw effluent to 36.40 mg/L after treatment, indicating significant organic matter mineralization rather than simple phase transfer. Post‐treatment sludge characterization by inductively coupled plasma mass spectrometry (ICP–MS) and field emission scanning electron microscopy (FE–SEM/EDX) showed an iron‐rich matrix containing Zn, Ni, Pb, As, and Sn, indicating the sludge should be managed as scheduled hazardous waste under Malaysian regulations. To enhance resource circularity, the Fenton sludge was chemically reduced with Na 2 SO 3 , achieving 76.90% conversion of Fe 3+ to Fe 2+ . The regenerated Fe 2+ yielded 60.80% COD removal in a subsequent Fenton cycle under optimized conditions. Overall, the results demonstrated the feasibility of Fenton oxidation as a primary treatment technology for real paper mill effluent while offering a viable route for partial iron recovery.