AWWA ACE56151

The potential for the cyanobacterial hepatotoxins, microcystin-LR and nodularin, to adversely effect human health was recently highlighted by the death of 50 patients in a Brazilian hospital who received microcystin contaminated water as a part of their renal dialysis treatment. There is a need in developing countries and in remote communities for a low cost, easily maintained toxin removal strategy. Bank filtration, the natural and/or artificial movement of water through aquifer material, is a possible candidate technique to remove cyanobacterial toxins from drinking water supplies. Once present in the environment the toxins can be transported through the soil water ultimately entering an aquifer, degraded by micro-organisms or bound to organic and/or mineral fractions of the soil material. Several studies have investigated the persistence of cyanobacterial toxins in the environment. However, the methods did not enable any conclusions to be made regarding processes influencing adsorption, as the soil properties were not quantified and toxin recovery methods from soil particles were not validated. A detailed understanding of the factors that influence the fate of a particular contaminant is required to enable the assessment of the efficiency of bank filtration as a removal strategy for cyanobacterial toxins. More specifically, the purpose of this study was to: examine the type of adsorption processes occurring with microcystin-LR and nodularin in a wide range of soils; to determine water quality parameters influencing adsorption; and, to assess the potential for soil microflora to degrade the toxins. Includes 16 references, tables, figures.