Exploring Mechanistic Insights Into Coagulation-flocculation-aided Adsorption Design: a Comprehensive Study On the...

Industrial wastewater treatment is crucial for environmental protection and public health. This study aimed to investigate the efficiency of the coagulation-flocculation-aided adsorption (C/F-A) system utilizing aluminum salt (AS) coagulant and characterized acid-activated kaolin clay adsorbent (KC) for the removal of pollutants from vegetable oil processing industrial wastewater (VOPIW). The objectives were to optimize the operational parameters of the C/F-A system, evaluate the adsorption capacity of KC, analyze the removal mechanisms, and assess the feasibility of scale-up for industrial applications. Batch experiments were conducted at 25 °C and pH 6-8 to determine optimal conditions for turbidity and total suspended solids (TSS) removal. The Smoluchoski kinetic model and various isotherms (Redlich-Peterson, Elovich, and Dubinin-Radushkevich) were employed for mechanistic analysis. Optimal conditions of 0.2 g/L dosage, pH 6, and 12 min settling time resulted in 96% turbidity and 97% TSS removals. Significant reductions were achieved for various pollutants, including Cu (84%), Fe (80%), Mn (85%), Pb (71%), and Al (98%). The sorption capacities of KC for various pollutants were determined, with the highest recorded for Cu at 35.47 mg/g C. Scale-up analysis was conducted to meet WHO effluent discharge requirements resulting in organic loading corresponding to TDS (2.94 × 10⁹ mg/day), DO (5.1 × 10⁸ mg/day), BOD (4.33 × 10⁸ mg/day), and COD (3.99 × 10⁸ mg/day). The mechanistic parameters confirmed an optimum sweep-flocculation constant, 6.2 × 10^-3 L/g·min, and half-life, 101 min^-1. The study highlighted the effectiveness of the C/F-A system using KC for removing contaminants from VOPIW, suggesting its potential as a cost-effective and sustainable method for industrial wastewater treatment, thereby aiding environmental protection.