| Treatment Process |
Relative Effectiveness |
| Intracellular Cyanotoxins Removal (Intact Cells) |
|
| Pretreatment oxidation |
Avoid pre-oxidation because often lyses cyanobacteria cells releasing the cyanotoxin to the water column. |
| Coagulation/Sedimentation/Filtration |
Effective for the removal of intracellular toxins when cells accumulated in sludge are isolated from the plant and the sludge is not returned to supply after sludge separation. |
| Membranes |
Study data is scarce; it is assumed that membranes would be effective for removal of intracellular cyanotoxins. Microfiltration and ultrafiltration are effective when cells are not allowed to accumulate on membranes for long periods of time. |
| Flotation |
Flotation processes, such as Dissolved Air Flotation (DAF), are effective for removal of intracellular cyanotoxins since many of the toxin-forming cyanobacterial are buoyant. |
| Oxidation Processes |
Avoid because often lyses cyanobacterial cells releasing the cyanotoxin to the water column. |
| Extracellular Cyanotoxins Removal |
|
| Membranes |
Depends on the material, membrane pore size distribution, and water quality. Nanofiltration and ultrafiltration are likely effective in removing extracellular microcystin. Reverse osmosis filtration would likely only be applicable for removal of some extracellular cyanotoxins like cylindrospermopsin. Cell lysis is highly likely. Further research is needed to characterize performance. |
| Potassium Permanganate |
Effective for oxidizing microcystins and anatoxins. Further research is needed for cylindrospermopsin. |
| Ozone |
Very effective for oxidizing extracellular microcystins, anatoxin-a and cylindrospermopsin. |
| Chloramines |
Not effective |
| Chlorine dioxide |
Not effective with doses used in drinking water treatment. |
| Chlorination |
Effective for oxidation extracellular cyanotoxins as long as the pH is below 8, ineffective for anatoxin-a. |
| UV Radiation |
Effective of degrading microcystins and cylindrospermopsin but at impractically high doses. |
| Activated Carbon |
PAC: Most types are generally effective for removal of microcystin, anatoxin-a and cylindrospermopsin, especially wood-based activated carbon.
GAC: Effective for microcystins but less effective for anatoxin-a and cylindrespermopsins. |
