The impact of conventional water treatment processes on cells of the cyanobacterium Microcystis aeruginosa

Cyanobacteria can produce toxins, tastes and odors which significantly impa ir water quality. Removal of intact cyanobacterial cells with their intrace llular compounds during water treatment would potentially reduce the concen tration of taste, odor and toxic cell metabolites present in the treated wa ter. In this study, the effect of conventional water treatment processes us ing aluminum sulphate (alum) on the integrity of cells of toxic Microcystis aeruginosa was evaluated using both jar tests and pilot plant studies. Rem oval of M. aeruginosa cells by alum flocculation using a jar test apparatus indicated all cells were removed without damage to membrane integrity. Thu s the chemical treatment and mechanical action did not damage the cultured M. aeruginosa cells and, more importantly, did not result in additional rel ease of cell metabolites above background concentrations. For pilot plant e xperiments, which consisted of coagulation/flocculation-sedimentation-filtr ation, most of the cells were removed intact and no additional microcystin was found in the finished water. (C) 1999 Elsevier Science Ltd. All rights reserved.