The Danish drinking water resource is increasingly polluted by pesticides, especially BAM and atrazine. Activated carbon filtration is an obvious technology that is used worldwide, but primarily for treatment of surface water, whereas Danish drinking water supply is based on groundwater. The purpose of the project has therefore been to investigate the opportunities for using activated carbon (AC) filtration to remove the pesticides BAM (2,6-Dichlorobenzamide) and atrazine from Danish groundwater. The main objective of the study was to determine the AC capacity, which is an expression for the amount of pesticide which can be bound to a certain amount of AC and maintain the outlet concentration below a certain, given value. The AC capacity was investigated for three different types of activated carbon (Chemviron Filtrasorb F400, Norit ROW 0.8, and Lurgi, Hydraffin CC 8 x 30). Experimentally three different approaches were used: Column experiments at bench-scale (near-realistic scale (one meter scale)), small-scale column test (centimetre scale) and adsorption isotherm test (batch test with suspended AC). In general this project showed that AC adsorption is a suitable method for removal of BAM from groundwater. Furthermore, the capacities for BAM unexpectedly were in the same order of magnitude as capacities for atrazine. It was expected that the adsorption of BAM onto activated carbon would be considerably lower compared to that of atrazine, because of the more polar structure of BAM (hydrophobicity). The capacity for BAM and atrazine did not vary significantly with the different types of activated carbon or groundwater investigated in this study. Modelling of break-through curves with the program AQUASIM of tracer experiments carried out in the bench-scale columns and of pesticide adsorption in bench-scale columns and small-scale columns has shown a potential for model-based scaling. It is possible to model sorption of BAM in both bench-scale columns and small-scale columns with isotherm data for BAM (Kd=1.15 m3/g AC). By modelling of the tracer experiments from the bench-scale columns, it is possible to estimate mass transfer parameters necessary for modelling the breakthrough profiles of BAM.
|Effective start/end date
|01/01/2000 → 31/12/2005
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