SUITABILITY OF THERMALLY TREATED SEDIMENTS FOR ATTENUATION OF MICROPOLLUTANTS

The transport behavior of micropollutants in groundwater depends on a multitude of factors such as physico-chemical conditions of the groundwater, sediment characteristics, and properties of the compounds. Especially the sediment composition has a major influence on the transport behavior of micropollutants in groundwater. This is of particular interest at managed aquifer recharge sites where the occurrence of micropollutants is relevant for drinking water production. The aim of this study was to evaluate the attenuation of micropollutants by thermally treated sediments while maintaining the original hydraulic characteristic. Column studies were performed using natural and thermally treated sediments from an infiltration basin of the Berlin area. Thermal treatment was performed to modify the organic carbon content of the sediments. In one experiment the sediment was heated up to 550°C, in two other experiments the sediment was treated at 200°C, and for comparison, one sediment remained untreated. The treatment took place at atmospheric oxygen content. There was no further surface activation of the sediment after thermal treatment. Retardation and degradation was evaluated for the compounds primidone, carbamazepine, and sulfamethoxazole.

Heating the sediment to 550°C led to a reduction in organic carbon (0.06 wt-%) compared to the treatment at 200°C, where organic carbon (0.17 wt-%) was in the same range as for the untreated sediment. The treatment at 200°C led to a higher retardation of the carbamazepine and primidone, compared to the treatment at 550°C and the sediment without treatment. For sulfamethoxazole no differences in transport characteristics were observed for the different sediments.