Since the early 1990s, AOX has been an integral part of wastewater monitoring. It was developed as a sum parameter to describe the amount of (non-polar) chlorinated hydrocarbons. This type of substance can be easily enriched on activated charcoal. After combustion of this charcoal in an oxygen atmosphere, the resulting chloride is collected in an absorption
solution. The content of chloride can then be determined by various techniques.
