AOX
Also: AOX, adsorbable organic halides
A regulatory parameter measuring chlorinated organic compounds in pulp mill effluent. Tracked to monitor ECF bleaching emissions.
AOX (adsorbable organic halides) is a sum parameter for chlorinated organic substances, measured by adsorbing the compounds onto activated carbon, combusting, and analyzing the halogens released. Pulp mill AOX limits are set by environmental regulators (EU IED, US Cluster Rule).
Modern ECF mills typically discharge 0.1 to 0.4 kg AOX per air-dry tonne of pulp, well below regulatory limits. TCF mills discharge essentially zero AOX.
Related
- Bleaching. Chemical removal of residual lignin from chemical pulp to produce white pulp. ECF (chlorine dioxide) and TCF (oxygen, ozone, peroxide) are the two major systems.