Removal of cyanobacterial toxins (microcystins) and cyanobacterial cells from drinking water using domestic water filters

Toxic cyanobacteria are increasingly found in drinking water reservoirs, with cells and/or dissolved toxins entering the potable water supply. The most commonly observed group of cyanobacterial toxins is the microcystins, and concern about their impact on human health has prompted investigations into remedial treatment methods. This study investigates the ability of domestic water filters to remove cyanobacterial cells and microcystins from drinking water. Cyanobacterial cell were removed by the filter, but the percentage removal (c. 60% of filamentous cells compared to only 10% of single cells) appeared to be dependent on the colony morphology. The removal of four microcystins was assessed and their percentage removal varied little, although microcystins-LR appeared to be removed to a slightly lesser extent. Toxin concentration and the presence of cell components did not affect the amount of soluble toxin removed from water. The performance of three different brands of water filter was compared, assessing the reproducibility of cartridges and their efficiency when both new and at the manufacturers recommended half-life. All brands of water filters investigated were found to remove a proportion of the soluble microcystin; however, none removed all the toxin in a single passage through the filter.