Activated carbon filters remove AOX

Activated charcoal filters remove AOX

Many sectors require a sophisticated wastewater purification system to meet the applicable discharge standards. The smart removal of AOX also needs to be addressed. Using activated carbon filters ensures that biological treatment plants are not overloaded and can perform in an extremely efficient way.

AOX is the collective name for adsorbable organic halides. Both biodegradable and non-biodegradable contaminated elements could be present in rainwater, washing water, process water or other sources. Wastewater that contains AOX may often only be discharged if the amount of AOX is below 1 mg/l.

Non-biodegradable AOX is present in such things as wastewater from paint, varnish and coating products, and presents a challenge for quite a number of sectors. It is not possible to eliminate these adsorbable organic halides using a biological treatment plant. The installation of a mobile activated carbon filter before the biological treatment can resolve the problem simply and completely, enabling peak concentrations to be adsorbed adequately and the discharge to remain below the maximum permitted levels.

Activated carbon does not work selectively: as well as AOX, it also removes adsorbable COD. Once the filter is fully saturated with COD, displacement effects occur: the better adsorbable AOX is removed preferentially, enabling the removal of the penetrating COD to take place using biological purification.

Mobile activated charcoal filters are also effective during physico-chemical purification, which is also applied in processing liquid waste. After the coagulation and flocculation process of such a purification plant (in which non-biodegradable COD is removed), the Mobicon systems act as a control filter to reduce AOX concentrations to the absolute minimum. In both cases (pre-treatment of biological purification or control function for physico-chemical purification) our mobile activated carbon units act as a cost-efficient solution for the removal of low AOX concentrations. Once they have reached the saturation point, Desotec ensures that these filters are replaced quickly.


At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. All molecules that were adsorbed on the activated carbon at the customers’ site, are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislationby an incineration and neutralisation setup. The entire installation and it's emissions are under continuous on-line monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.