Experimental analysis on the synergistic effect of combined use of ozone and UV radiation for the treatment of dairy industry wastewater

Abstract

The present study focused on the various advanced oxidation processes; Ozone, UV radiation, O<sub>3</sub>/H<sub>2</sub>O<sub>2</sub>, O<sub>3</sub>/UV, UV/H<sub>2</sub>O<sub>2</sub> and O<sub>3</sub>/UV/H<sub>2</sub>O<sub>2</sub> for treatability of dairy industry wastewater. With this aim, the trials were carried out in cylindrical reactor fortified with UV radiation and Ozone injection. Efficiency of the treatment process was evaluated considering Chemical Oxygen Demand (COD), lactose reduction and process parameters were determined to be reaction time, pH, circulation rate, and H<sub>2</sub>O<sub>2</sub> dosage. 32.5%, 35.2% , 25%, 83% COD and 40.6%, 43.6%, 38.2%, 80% lactose reduction efficiency were obtained under the operating conditions for O<sub>3</sub>/H<sub>2</sub>O<sub>2</sub>, O<sub>3</sub>/UV, UV/H<sub>2</sub>O<sub>2</sub> and O<sub>3</sub>/UV/H<sub>2</sub>O<sub>2</sub> processes, respectively. As per this outcome, UV/H<sub>2</sub>O<sub>2</sub>/O<sub>3</sub> process gave more than 65% of COD and 52.36% of lactose reduction efficiency than other hybrid processes. Optimum conditions for UV/H<sub>2</sub>O<sub>2</sub>/O<sub>3</sub> process (pH = 5, time = 180 mins, circulation rate = 50 mL/h and H<sub>2</sub>O<sub>2</sub> dosage of 0.5 mL) resulted in 88% of COD and 93.4% lactose reduction.