Milestone in COD Analysis

The German standard methods for examination of water and waste water specify the use of potassium dichromate for the determination of the chemical oxygen demand (DIN 38409-41). In 2013, the European Parliament and the Council for Registration, Evaluation, Authorisation and Restriction of Chemicals, called REACH, have adopt a ban that prohibits the use of this dangerous and mutagenic chemical. Hence, alternatives for a clean and safe COD analysis are needed.

Since years, total organic carbon (TOC) measurements are used for the correlation from TOC to COD. However, one time defined correlation factors are only suitable for constant water matrices. If the waste waters' composition varies, then the TOC-correlation method does not provides reliable measurement results.

Another COD analysis method is the correlation using the parameter total oxygen demand (TOD). Since the TOD indicates the oxygen demand of water as the COD does, it is a preferable alternative to the TOC-COD correlation. The TOD is a reliable and reproducible parameter that easily correlates to the COD. In the US it is standardized by ASTM D6238 and commonly used.

LAR Process Analysers have developed an innovative online as well as laboratory COD analyser using the TOD-correlation. Based on the high temperature combustion method at 1,200°C, LAR's COD analyser completely oxidises the samples compounds. Afterwards, the needed oxygen demand is measured – without the use of any hazardous chemicals. The safe and clean measurement takes place in less than 3 minutes. The online analyser QuickCOD_ultra is used established since years. During ACHEMA 2015, LAR presented their innovative laboratory COD analyser QuickCOD_lab to the general public for the first time.