Investigating the fate of saxitoxins in biologically active water treatment plant filters

Abstract

The saxitoxins are potent neurotoxins, which can be produced by freshwater cyanobacteria. This study assessed the fate of five saxitoxins variants through biologically active laboratory filters containing media sourced from the filters beds of two water treatment plants (WTPs). Decreases in the concentration of the less toxic variants coincided with increases in the concentrations of the more toxic variants through the filters containing anthracite sourced from two different WTPs. No changes in toxin concentrations were evident through parallel filters containing sand. The results strongly suggest that organisms within the biofilm of the anthracite filters possessed the ability to biotransform the saxitoxins variants, which has important implications for drinking water treatment, particularly since this has the potential to increase the toxicity of the filtered water.