Optimization of coagulation-flocculation process for wastewater treatment from vegetable oil refineries using chitosan as a natural flocculant

Abstract

Vegetable oil refinery wastewater (VORW) is a significant source of refractory pollutants necessitating efficient treatment prior to discharge. This study investigates the treatment of VORW via coagulation-flocculation using ferric chloride (FeCl₃) as a coagulant and chitosan as a natural flocculant. Central Composite Design (CCD) is employed to optimize the treatment process and assess the interplay of experimental factors. The study evaluates turbidity, COD, and polyphenols as responses, with pH, FeCl₃ concentration, chitosan dosage, and agitation time as independent factors.

The results showed that the optimal conditions identified include pH 6, FeCl3 dosage of 1.6 g/L, chitosan dosage of 13.4 mg/L, and agitation time of 26 min, resulting in 100 % turbidity removal, 86 % COD reduction, and 90 % polyphenol removal. The analysis of variance indicated that the established models were significant and that they are characterized by a good fit (R² in the order of 0.95, 0.96, and 0.96 for turbidity, COD, and polyphenols, respectively).

These findings highlight the efficacy and sustainability of the coagulation-flocculation process with chitosan, offering a practical, rapid, and cost-effective solution for VORW treatment and environmental preservation.