Algae are a problem in both municipal and industrial plants. In municipal drinking water, source water containing algae and its breakdown products can cause deleterious taste and odours in the drinking water. In impounded water bodies such as lakes, ponds, fountains and reservoirs algae is an aesthetic problem, and in industrial plants algae blooms can cause performance issues in cooling and process water systems.
Algae may be present as single cell or colonial planktonic algae which include diatoms and many species of green and blue-green algae, or filamentous algae such as, Chara, and Nitella. In general filamentous algae are more difficult to treat and may require higher dose rates of a suitable algae control agent.
Chlorine dioxide has been shown to be effective in controlling algae growth. Chlorine dioxide is believed to attack the pyrrole ring of the chlorophyll. This cleaves the ring and leaves the chlorophyll inactive. Since algae cannot function without chlorophyll metabolism, they are destroyed. The reaction of chlorine dioxide with algae and their essential oils forms tasteless, odourless substances.