Application of TOC Standards for Managing Refractory Organic Compounds in Industrial Wastewater

The aim of this study is to understand the limitation of organic pollutant indexes (BOD5, CODMn, CODCr) and estimate to set the TOC standard by comparing oxidation rates of BOD5, CODMn, CODCr and TOC based on the 487 organic compounds and 11 effluents from industrial wastewater containing various and unknown organic compounds. The range of ratio of theoretical oxygen demand (ThOD) to theoretical organic carbon (TOCt) was 0.00~5.33 and average ratio of classes of organic compounds was 2.68~3.70. According to classes of organic compounds, the average ratio of O 2/C was 1.2 (range : 1.02~1.39). The order of oxidation rate for 15 organic compounds was TOC (90.7%) > CODCr (88.8%) > BOD5 (54.4%) > CODMn (30.8%) indicating the lower oxidation rate of BOD5 and COD compared with TOC. The ranking for average oxidation rate was CODCr > CODMn > BOD5 indicating that BOD5, CODMn could be underestimated comparing with ThOD of organic compounds in case of industrial wastewater containing high concentration of refractory organic compounds. Most of the relationships between organic pollutant indexes and TOC were higher than 0.9. The ratio of TOC to organic compound indexes decreased in the order : COD Cr (3.4) > CODMn (1.9) > BOD5 (0.7).