Water analysis : high temperature instead of toxic chemicals

The decomposition of organic substances always consumes oxygen. At the same time, the oxygen demand during degradation is an indication of the degree of pollution of water with organic substances. Therefore, the so-calledChemical Oxygen Demand (COD)is an important parameter in water analysis: in the case of the standardized wet-chemical method (according to DIN 38409-41) and in rapid tests (according to DIN 38409-1), the COD gives the The amount of oxygen that would be required if only oxygen would serve as the oxidizing agent in the chemical oxidation of all oxidizable compounds contained in the water.

So far, however, this determination is problematic: Firstly, the substances dichromate and mercury used represent a danger to the environment. On the other hand, the use of 150 ° C hot chromic-sulfuric acid is a hazard for laboratory employees. Animproved, chemical-free and thus environmentally friendly and user-friendly processis the result of thejoint project LATECOD, which is funded by the Federal Ministry of Education and Research (BMBF). Itspartnersare theBerliner Wasserbetriebe- the largest integrated water and wastewater disposal company in Germany - and the measuring instrument manufacturerLAR Process Analyzers AG.

LATECOD continues to develop a chemical-free high-temperature process based on thermal oxidation of the sample at 1,200 ° C with subsequent detection of oxygen consumption. The process has been extensively studied in various applications and comparative analyzes and control measurements performed. The adaptation to the system, as well as sample preparation was carried out in cooperation with Berliner Wasserbetriebe. The calculations showed that that It would also be worthwhile for the user to compare the procedures with those of the DIN rapid test: With around two samples a day, the comparatively high investment costs pay for themselves after around two years.

The Federal Ministry of Education and Research (BMBF) is supporting the joint project LATECOD ("Testing and Evaluation of a Laboratory Device for Determining the Chemical Oxygen Demand without Potassium Dichromate by means of the High Temperature Method) within the Measure" SME Innovative: Resource Efficiency and Climate Protection " BMBF Program "Research for Sustainable Development" (FONA3).