Abstract

Distillery effluent leads to extensive surface water and groundwater pollution. Removal of various contaminants and color from this type of effluent has attracted great attention from environmental and aesthetic point of view. Distillery Wastewater (DWW) is hard to dispose due to its dark brown color, high ash content, low pH, undesirable viscosity, hydrophilicity, and high levels of Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). The treatment of DWW has become challenging with conventional treatment methods. With this, a unique hybrid treatment method utilizing a dual coagulation process followed by photo-Fenton oxidation under UV-C light irradiation was investigated for their combined treatment capabilities on the removal of COD, TSS, turbidity, and color from bioethanol DWW. The experimental design used a sequential experimentation approach based on the optimum result on the following sequence of optimizations: i) dual coagulant dosage using Aluminum Chlorohydrate (ACH) and Polydiallyldimethylammonium Chloride (PolyDADMAC); ii) dual coagulation settling time; iii) photo-Fenton H₂O₂ concentration; and iv) photo-Fenton UV-C exposure time. The optimum dosage for the dual coagulation process is 90% ACH:10% PolyDADMAC with 5 h of settling yielding color and COD removal of 47.75% and 92.56%, respectively. Subsequently, 245 × 10^-3 mol/L of H₂O₂ concentration with a UV-C exposure time of 5 hours is optimum for the photo-Fenton process, yielding an overall color and COD removal of 94.25% and 99.81%, respectively.