Treatment of vegetable oil refinery wastewater with biodegradability index improvement

Abstract

The vegetable oil refinery wastewater (VORWW) creates an environmental problem in terms of threat to aquatic life due to high organic and inorganic content. These refinery plants produce a large quantity of wastewater with high chemical oxygen demand (COD) and biological oxygen demand (BOD). In this research, HC was evolved as a recent treatment option for the treatment of VORWW. Various parameters like inlet pressure, pH, temperature and H2O2 dose were tested during experimentation to determine BOD, COD, and BI (BOD/COD ratio). Using the hydrodynamic cavitation (HC) reactor biodegradability index (BI) of 0.69 and COD reduction up to 71.8% were obtained. In this same condition BOD increases by 14.4%, which helps to increase BI at optimum conditions of 120 min reaction time, operating temperature 20 °C, inlet pressure 8 bar, pH-4 and H2O2 dose of 25 g/L. It was found that the operating pressure of 8 bar in the HC reactor gives the maximum BI (BOD/COD ratio). The obtained optimum conditions of HC were used in the Ultrasonic cavitation reactor for the degradation of VORWW. In the 80 min of treatment COD reduced by 73.2%, which is highest as compared to HC. Similarly, BOD increases by 12.7% in just 80 min of treatment. The final obtained BI is 0.71, COD of 5984 mg/L and BOD 4270 mg/L which seems good as compared to HC.