Treatment of olive mill wastewater with advanced oxidation methods

There is no common method applied in our country for the treatment of wastewater, which is formed after olive oil production and is known to cause serious environmental hazards if it is discharged to receiving environments without treatment. This wastewater, which is called olive black water, contains high amounts of organic substances, oil-grease and phenolic substances. In this study, various pre-treatment and final treatment types were applied in the treatment of olive black water. In the pre-treatment system, acid digestion (AD, below pH 2) and precipitation with lime (LP, 12.5 pH ) processes were applied, and in the final treatment systems, the Fenton process and UVC ray contact after Fenton and ultrasound after Fenton were applied. As a result of the pre-treatment studies, it has been determined that the precipitation with lime is more successful than the crushing using acid. The removal efficiencies of COD, oil-grease, TOC and phenolic substances obtained at the end of pre-treatments by lime precipitation and acid cracking were 52%, 99.7%, 42%, 13% and 43%, 89%, 30%, 0.30% was determined, respectively. In LP+Fenton and AD+Fenton applications under the optimum conditions, COD, oil-grease and TOC removal efficiencies were determined as 75%, 99.3%, 62% and 66%, 99.4%, 42%, respectively. Accordingly, LP pre-treatment application before Fenton application gave more successful results than AD pre-treatment. COD removal efficiencies by LP+Fenton+UV and LP+Fenton+US applications are 78% and 90%, respectively. Likewise, the COD removal efficiencies by AD+Fenton+UV and AD+Fenton+US were determined as 54% and 77%, respectively. It can be seen that US application gives more successful results in terms of COD removal efficiencies. However, as a result of LP+Fenton+US and AD+Fenton+US applications, the COD, oil-grease and TOC removal efficiencies were determined as 90%, 98.5%, 67% and 77%, 98.4%, 64%, respectively. As a result of LP+Fenton+US application, where the best removal efficiency was obtained, it was determined that the COD concentration was 10.600 mg/L. Although the wastewater obtained as a result of the study has been degreased and made suitable for delivery to the anaerobic treatment plant, it is anticipated that the evaluation of the applied processes as a pre-treatment system may provide advantages for the final treatment plant. Key words: Fenton, Ultrasound, UVC, Lime precipitation, Acid digestion