Research project BAK

Development and technical testing of a biological filtration methodology based on activated carbon for the removal of organic chlorinated compounds from contaminated groundwater

Project description:

The treatment of organically contaminated water is an upcoming task worldwide. Both for resource protection and for water production, there is a recurring need to clean contaminated groundwater and surface water. In the field of groundwater remediation, the main pollutants to be treated worldwide are chlorinated hydrocarbons (CHCs) in addition to petroleum hydrocarbons (MHCs). The optimization of groundwater purification measures in the case of CHC pollution is of outstanding importance in the context of water treatment. Here, activated carbon filters continue to represent an essential component of purification systems, especially for groundwater contaminated with organic pollutants. They are convincing due to their robustness and simplicity and generally enable reliable compliance with the purification targets to be achieved. Negative aspects are the high consumption of activated carbon and the short service life. In classical two-stage groundwater purification plants, on average 50% of the operating costs are accounted for by the activated carbon. An extension of the service life of the activated carbon through the targeted stimulation of biological degradation processes in the activated carbon filter contains an enormous savings potential. Both suppliers of water purification plants and those responsible for the treatment of polluted water are showing considerable interest in making activated carbon technology, which is convincing for its robustness and simplicity, more effective.

The BAK project served to develop a completely new approach to the use of activated carbon filters as a purification process. The basic feasibility of such an approach was demonstrated on a laboratory scale (projects SAFIRA I and II). The basic principle of the process was that the activated carbon retains the pollutants only temporarily, but they are degraded microbially on the activated carbon. The activated carbon filter thus becomes a means of active pollutant removal. The preliminary work at IAK and TZW Karlsruhe had shown that simultaneous adsorption and microbiological degradation of pollutants on the activated carbon can lead to considerable extensions of the service life and thus to a significant reduction in the consumption of activated carbon. However, considerable development was still needed to make these processes safe and predictable and thus economically applicable.

The objective of the project was to demonstrate the technical feasibility of the BAK process and to extend the service life of activated carbon filters. In plants where water with low contamination is treated, much higher service life extensions can be achieved. Using the example of Bitterfeld, it was to be shown for which pollutants the process can be used, that it ensures effective cleaning and with what savings in activated carbon this methodology is associated.