Degradation of microcystin-LR through biological sand filters

Cyanobacteria are a global problem as they are able to produce compounds which can compromise the quality of potable water. Of major concern are the microcystin toxins which in dissolved form are not well removed by conventional water treatment processes. This study showed that microcystin-LR (MCLR) could be effectively removed from water using laboratory biological sand filters with complete removals observed under a range of conditions, including various sand and water combinations, different initial MCLR concentrations, and also two different temperatures. Molecular techniques allowed for the isolation of a bacterium, from the biofilm of one of the filters, which was shown to contain mlrA, a gene previously documented to be involved in the biodegradation of MCLR. This gene was also identified within the biofilm of two additional filters strongly suggesting that the removal of MCLR through the filters was through biological action. © 2007 ASCE.