Comparative study on wastewater pollution reduction: dissolved air flotation versus acidic flotation and pH effects

Vegetable oil refineries produce large quantities of wastewater containing organic matter, oils, and greases, creating a significant source of pollution, eutrophication, and esthetic deterioration of aquatic ecosystems. The present study aimed to improve flotation techniques for the separation of oil and water by demonstrating the impact of pH on the removal of chemical oxygen demand (COD), oils and greases (O&G), turbidity, and polyphenols from vegetable oil refinery wastewater. Acidic flotation was studied in different pH ranges (1-7), and its treatment efficiency was compared with that of dissolved air flotation. The results obtained showed that acidic flotation, optimized at a pH of 3, resulted in a significant reduction of 93.33% in chemical oxygen demand (COD), 99.24% in oils and fats, and 99.86% in turbidity, and removal of 97.95% of polyphenols and 95.58% of absorbance at 254 nm. Dissolved air flotation, however, also showed promising results, with a reduction of 61.04% of COD and 89.1% of oils and fats, 96.77% of turbidity, 77.29% of polyphenols, and 58.78% of absorbance at 254 nm. The results of this study highlight the effectiveness of acidic flotation at pH 3 as a high-performance treatment technique for vegetable oil refinery wastewater, offering exceptional pollution removal efficiencies.