Lab-Scale Investigation of Fenton and Photo-Fenton Processes for Removal of Pollutants from Textile and Dye-Intermediate Industrial Wastewater, Ahmedabad Industrial Estate, Gujarat, India

This study investigates the physico-chemical characteristics and treatment efficacy of effluents from the Ahmedabad Industrial Estate, Gujarat, India, employing two Advanced Oxidation Processes: Fenton and Photo-Fenton. The study focused on a comprehensive suite of parameters, including pH, colour, turbidity, Total Suspended Solids, Total Solids, Total Dissolved Solids, Chemical Oxygen Demand, Biochemical Oxygen Demand, Chloride, Ammoniacal Nitrogen, Nitrate, Sulphate, and Phosphate. Experiments were conducted on 1-litre effluent samples at three volumetric ratios of ferrous ion to hydrogen peroxide: 1:10, 1:20, and 1:30. The Photo-Fenton process followed an identical protocol, with the addition of continuous UV light exposure to accelerate reaction kinetics. The results consistently demonstrated that pollutant removal efficiency correlated positively with the reactant ratio, with the 1:30 ratio yielding the highest performance across all parameters. Colour removal reached 74.11%, turbidity 83.62%, and TSS 72.49%. COD reduction was more modest, ranging between 9.09% and 31.97%. This stream showed significant susceptibility to Fenton oxidation. COD removal was remarkably high (up to 97.89%), while turbidity and TSS removal reached 98.50% and 92.60%, respectively. The inclusion of UV radiation enhanced the breakdown of pollutants, particularly in complex dye-intermediate matrices. TDS removal was notably improved, reaching 75.39%. Colour removal spanned 28.88% to 71.25%, with TSS reduction hitting 92.72%. This process proved highly efficient for organic degradation, achieving up to 96.61% COD removal. TSS removal peaked at 94.37%, confirming the process's viability for solid-liquid separation and organic mineralization. A recurring trend across both treatments was a negative removal value for sulphate. This is attributed to the addition of ferrous sulphate as a catalyst, which naturally increases the residual sulphate concentration in the effluent. While this is a by-product of the chemical dosing, it is a critical factor for post-treatment management. The study confirms that dye-intermediate effluents are generally more responsive to these oxidative treatments than textile effluents. The transition from the 1:10 to the 1:30 ratio consistently improved performance, suggesting that optimizing the peroxide dosage is paramount for maximum pollutant mineralization. Both Fenton and Photo-Fenton oxidation processes are highly effective, sustainable solutions for the pre-treatment of industrial wastewater in the Ahmedabad region. By leveraging the high oxidative potential of the hydroxyl radical, these methods offer a robust pathway for reducing the environmental footprint of textile and dye-intermediate manufacturing. Given the high removal efficiencies observed—particularly at the 1:30 ratio—these AOPs represent a viable, eco-friendly strategy to meet stringent discharge standards and promote water circularity in industrial zones.