Engineering solutions for the reduction and removal of toxin-producing cyanobacteria from waterways

Cyanobacterial blooms constitute a serious threat to the sustainability and the safety of water resources around the world. Excessive growth of toxin-producing cyanobacteria and long lasting episodes of blooms are believed to have increased in frequency and magnitude in the last decade due to increased nutrient loading from watersheds to lakes, reservoirs, rivers and estuaries. Long term and sustained effort focused on the reduction of point and non-point
source nutrient export have only resulted in a relatively small reduction in eutrophication in some areas in the world. It is essential that more direct action is taken to apply active treatment to reduce and remove algal blooms and their toxins especially in key waterways such as drinking water supplies or fish rich waters, among other environments. In this talk, a series of experiments will be presented to demonstrate the short term benefit from the application of an in situ treatment to control internal loading of phosphorus. In contrast, a
more active treatment consisting of the controlled addition of hydrogen peroxide, a low cost technology, is presented to show a net reduction in the occurrence of cyanobacteria and their toxins. An overview of the advantages, including rapid reaction and low cost, and the limitations of such treatments will be discussed.