Comparison of coagulation–Fenton oxidation and coagulation–adsorption processes in textile and chemical industry mixed wastewater

BACKGROUND In this study, the treatment of mixed wastewater from textile and chemical industries using coagulation followed by Fenton oxidation or adsorption processes was investigated. In the coagulation process, the effects of pH and coagulant dosage were examined using polyaluminium chloride, FeCl3 and alum. The effects of Fe2+ and H2O2 concentrations, pH and oxidation time on Fenton oxidation of coagulated mixed industrial wastewater were also investigated. In the adsorption process, the effects of pH, adsorbent dosage and adsorption time were evaluated using coconut‐based activated carbon (Coconut‐AC) and coal‐based activated carbon (Coal‐AC). RESULTS In coagulation, 68.5% chemical oxygen demand (COD), 63.1% total organic carbon (TOC) and 94.3% color removal were achieved with FeCl3 at pH 5 and a coagulant dose of 600 mg L−1. Coagulation–Fenton oxidation resulted in 95.7% COD, 84.1% TOC and 99.0% color removal with 1500 mg L−1 Fe2+ and 6000 mg L−1 H2O2 at pH 3. In the coagulation–adsorption process, 97.5% COD, 95.5% TOC and 99.5% color removal were obtained using Coconut‐AC with an adsorbent dosage of 40 g L−1 at pH 3, while 92.3% COD, 82.4% TOC and 99.2% color removal were obtained with Coal‐AC at pH 3 and an adsorbent dosage of 30 g L−1. CONCLUSION Effective treatment of mixed industrial wastewater from the textile and chemical industries can be achieved more quickly using Coconut‐AC for adsorption following coagulation. Conversely, the same removal efficiencies can be reached over a longer duration with Fenton oxidation after coagulation. © 2024 Society of Chemical Industry (SCI).