IMPROVED OZONATION IN AQUEOUS SYSTEMS

A method of catalytic ozonation in an aqueous system using hydrogen peroxide (H2O2) as a catalyst has been developed. In aqueous solutions or organic compounds including refractory organics such as acetic acid (sodium salt), acetone, etc., the addition of H2O2.accelerates the ozone reaction to reduce total organic carbon (TOC) in all cases. The reaction rate and efficiency were dependent on pH, and on the concentration of H2O2 and TOC in the reaction system. The catalytic ozonation was used to reduce chemical oxygen demand (COD) in effluents from the electro-deposition process. A 100 ton/day plant built for the treatment of the electrodeposition process effluent combined the catalytic ozonation process with the processes of biological treatment, chemical coagulation, flotation, and filtration. The catalytic ozonation reduced the COD in the filtration effluent from 70 mg/1 to less than 10 with dosing of 200 mg/1 of ozone (consumption of 180 mg/1) and 45 mg/1 of H2O2. The power required for the ozonation process was 4.8 kwh/ton, and the operating cost was about half the regenerating cost encountered in activated carbon treatment for the same COD reduction. A pilot plant study on an oxygen recycling ozonation system capable of producing 400 g/h of ozone showed that the total power required for generating 1 kg of ozone was 9.5-10.9 kwh. The adoption of such a system in such a plant is expected to cut operating costs by about 40%. 0191-9512/79/020119-13$02.00/0 International Ozone Association. © 1979, Taylor & Francis Group, LLC. All rights reserved.