Combined natural flotation and chemical precipitation for the treatment of vegetable oil refinery wastewater

Vegetable oil refineries, while playing a crucial role in food and industrial production, are also responsible for generating significant quantities of wastewater. The complex composition of this wastewater, including contaminants, causes significant environmental impact, particularly on aquatic ecosystems. This study aims at improving the effectiveness of wastewater treatment from vegetable oil refineries. It examines a combined method, starting with natural flotation and continuing with chemical precipitation using caustic soda (NaOH). Natural flotation presents a good removal efficiency of turbidity, chemical oxygen demand (COD), nitrate ions (NO₃⁻), Total Phosphorus (TP), and polyphenol of 97.3%, 38.5%, 78.6%, 97.7, and 91.6%, respectively. Chemical precipitation reduces turbidity, COD, nitrates, ammonium, color, polyphenols, and absorbance at 254 nm by 99%, 25%, 83.2%, 96%, 38.3%, 62.2%, and 52.9%, respectively. The study shows that treatment by natural flotation followed by precipitation is a simple and efficient means for small and medium-sized companies to reduce the pollution impact of wastewater.