Characteristics of TOC Treatment for Industrial Wastewater Treatment -Characteristics of Industrial Wastewater TOC Treatment Status and TOC Treatment by Ozone and Advanced Oxidation Process-

Abstract

Objectives:As the organic pollutant indicator is changed from COD<sub>Mn</sub> to TOC and the demand for TOC treatment of industrial wastewater increasing, the current situation of TOC treatment of wastewater discharge facilities of each industrial category is analyzed, and it is intended to consider the possibility of residual TOC treatment by ozone and advanced oxidation process.Methods:To review the TOC treatment situations of wastewater discharge facilities of each industrial category, the field survey data (46 sites) by Environment Ministry and Korea Environment Corporation were analyzed according to inflow TOC concentrations, direct/indirect discharge type, and main treatment process of wastewater treatment facilities. To review the characteristics of TOC treatment by ozone and advanced oxidation processes, previous studies and the results of field pilot tests conducted by ozone companies were comprehensively analyzed.Results and Discussion:The TOC treatment level varies depending on the inflow TOC concentrations to each industrial wastewater treatment facility, direct/indirect discharge type depending on the location of the wastewater treatment facilities, and the main treatment process of the wastewater treatment facility. In particular, the TOC removal rate differed by more than 20% depending on the presence or absence of biological treatment. The wastewater treatment facilities that require additional treatment of residual TOC were divided as follows (1) when the facility has biological treatment as main process, increasing unexpected inflow TOC load in treatment facilities or the condition of the biological treatment become worsen. (2) when the facility has phy-chemical treatment as main process, increasing unexpected inflow TOC load. (3) extending the replacement cycle of activated carbon to save maintenance cost. The advance oxidation process decomposes easily by OH radicals through the radical substitution of unsaturated hydrocarbons and aromatic compounds, so the removal rate of TOC by the O<sub>3</sub>+H<sub>2</sub>O<sub>2</sub> advanced oxidation pilot test was 14.7~93.5%, higher than that of ozone oxidation. The specific ozone consumption per TOC removal amount (O<sub>3</sub>/ΔTOC) by O<sub>3</sub>+H<sub>2</sub>O<sub>2</sub> advanced oxidation is 8.5~22.5mgO<sub>3</sub>/mgTOC, which is 1/5 of that of ozone oxidation only. In addition, comparing ozone demand by COD<sub>Mn</sub> and TOC removal, ozone demand of O<sub>3</sub>+H<sub>2</sub>O<sub>2</sub> advanced oxidation to remove TOC is 2.7 to 4.3 times compared to that by O<sub>3</sub> oxidation to remove COD<sub>Mn</sub>.Conclusion:In order to reduce residual TOC from industrial wastewater effluent, it is necessary to secure stability of the existing main treatment process in preparation for load fluctuations, and the technologies research on complex advanced oxidation processes, hybrid advanced oxidation processes, and pretreatment technology to reduce ozone demand is needed for economical field application.