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Cyanotoxin Management Plan

This plan consists of several steps including performing a specific evaluation for vulnerability to the blooms for a specific watershed and water treatment facility; establish means of preparing and observing for potential blooms; testing for cyanotoxins in the raw water and communicating this information to all individuals in the area, and carrying out necessary treatment to destroy the toxins; determining if there are cyanotoxins in the finished water and advising all individuals in the area to carry out necessary treatment to destroy the toxins; and continuing to monitor and treat the finished water to make sure that cyanotoxins do not exceed acceptable levels.

  • Step 1—Develop the necessary information to make decisions on how to best eliminate, mitigate, or treat cyanotoxins by evaluation of the watershed used for obtaining the raw water for the specific water treatment plant. This is done by understanding the characteristics of the water including bacteriological, chemical, and physical qualities; climate and weather conditions during different seasons of the year; and the use of the land that is draining into the watershed and potential nutrient types and levels going into the water from the land.
  • Step 2—If the watershed and raw water are vulnerable to cyanotoxins, determine if there are long-term mitigation strategies which can prevent the blooms from occurring. Conduct constant visual inspections to determine if and when the blooms will occur. There may well be a seasonal variation. Evaluate the existing treatment process of the water from raw water to finished product. Determine if the usual coagulation, clarification, and filtration are effective in removing the cells of the blooms and if frequent backwashing of the filters will make them more effective. Can preoxidation of the raw water cause more cells to disrupt and therefore limit the production of toxins? Can the use of powdered activated carbon at appropriate levels be effective? Can the use of ozone or granular activated carbon in advanced water treatment plants remove the dissolved toxins?
  • Step 3—Consider several techniques of mitigation of the toxins as follows: relocate the intake source of raw water; use an alternate source of raw water; bypass the increased sedimentation from ponds or reservoirs and have the raw water flow directly to the water treatment plant; use ultrasonic treatment to help prevent the blooms from forming; use an algaecide such as hydrogen peroxide which will not contaminate the water itself; add alum to the water which will help precipitate the phosphorus and coagulate the cells; use aeration pumps at the bottom of the water source which will help mix the water and disrupt the algae blooms; and use mechanical mixing to disrupt the blooms.
  • Step 4—Test all finished water before distribution, and if cyanotoxins are present in above recommended levels, retreat the water before use.
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