Biochar (Activated Carbon) Used in Water Treatment Systems to Remove Micropollutants
According to the Swiss Federal Office of the Environment (FOEN), the quality of surface waters has improved considerably since the 1970s. Toxic substances have disappeared or were banned. However, inputs of micropollutants (trace compounds) are posing an increasing challenge for the protection of bodies of water. This is due, on the one hand, to the daily use of a large number of these compounds and, on the other hand, to the fact that even low concentrations of micropollutants can cause damage to aquatic organisms. According to current knowledge, the concentrations detected in surface waters do not harm human health. However, various studies clearly suggest that pesticide pollution is a key factor influencing the widespread lack of species diversity observed in bodies of water.1
Of the many pilot projects conducted in German speaking regions and the advanced methods of purification realised to date in municipal sewage treatment plants, the use of ozone and of activated carbon have proven feasible for the targeted elimination of micropollutants. These two process technologies can remove a wide range of micropollutants from waste water to a comparatively large extent. In addition, they are easy to integrate into the existing purification process of a sewage treatment plant. Both process technologies require an additional downstream stage to post-treat the waste water subsequent to the “micropollutants stage”. When using powdered activated carbon, this additional stage removes the powdered activated carbon particles that are laden with micropollutants to the greatest possible extent and, when using ozonation, it removes the resulting degradation/transformation products.2