Affiliation:
1. HUN-REN Centre for Energy Research, Konkoly-Thege M. út 29-33, 1121 Budapest, Hungary
Abstract
The long time (2 h) required for measurement, expensive chemicals (Ag2SO4), and toxic reagents (K2Cr2O7, HgSO4) limit the application of the standard method for measuring the oxygen equivalent of organic content in wastewater (chemical oxygen demand, COD). In recent years, the COD has increasingly been replaced by the total organic carbon (TOC) parameter. Since the limit values of the pollution levels are usually given in terms of the COD, efforts are being made to find the correlation between these parameters. Several papers have published correlation analyses of COD and TOC for industrial and municipal wastewater, but the relationship has not been discussed for individual chemicals. Here, this relationship was investigated using 70 contaminants (laboratory chemicals, pharmaceuticals, and pesticides). The calculated COD values, in most cases, agreed, within ~10%, with the experimental ones; for tetracyclines and some chloroaromatic molecules, the measured values were 20–50% lower than the calculated values. The COD/TOC ratios were between 2 and 3: for macrolides, they were ~3; for fluoroquinolones and tetracyclines, they were ~2. The molecular structure dependence of the ratio necessitates the establishing of the correlation on an individual basis. In advanced oxidation processes (AOPs), the ratio changes during degradation, limiting the application of TOC instead of COD.
Funder
International Atomic Energy Agency
National Research, Development and Innovation Office of Hungary
Subject
Chemistry (miscellaneous),Analytical Chemistry,Organic Chemistry,Physical and Theoretical Chemistry,Molecular Medicine,Drug Discovery,Pharmaceutical Science
Reference44 articles.
1. Anagnostopoulos, A., Hjort, M., and Vaiopoulou, E. (2023, December 16). Assessment of Chemical Oxygen Demand/Total Organic Carbon (COD/TOC) ratios in refinery effluents. Report: Environmental Science for European Refining, no. 16/22. Brussels, 2022. Available online: https://www.concawe.eu/publications/?_sft_topic=manufacturing-water-wastewater-emissions&_sft_publicationscategory=report.
2. Relationship, importance, and development of analytical techniques: COD, BOD, and, TOC in water—An overview through time;SN Appl. Sci.,2023
3. OECD (1992). Guidelines for the Testing of Chemicals Ready Biodegradability Section 3, OECD. Test No. 301.
4. (1998). Water Quality. Determination of the Biochemical Oxygen Demand after N Days (BOD[n]) of Water-Part 1: Dilution and Seeding Method with Allylthiourea Addition. Standard No. DIN EN 1899-1:1998.
5. Analytical approaches for determining chemical oxygen demand in water bodies: A review;Li;Crit. Rev. Anal. Chem.,2018