Algae Removal by Flotation

Abstract

The importance of algae is discussed. Algae are a significant source of oxygen on Earth due to its capability of photosynthesis. Further they are an efficient biological system for converting solar energy into plant life, a source of energy for higher life. However, at high concentrations, called blooms, they can contribute tastes and odors, and even toxins to the surrounding water. They are best removed before they reach a water treatment plant (WTP) where they may rupture and release their taste and odor oils. Algae at both low and high concentrations may be removed by dissolved air flotation (DAF). Even very high concentrations from wastewater treatment lagoons and algae culture ponds are efficiently removed. The recovered algae have many economical uses. When alum or iron salts are added to improve coagulation for algae removal, phosphorus is also removed, thereby lessening productivity in a lake or stream. The development of algae culture ponds heated by waste heat from a nearby power plant, combined with CO2 and NOX from fossil fueled power plants' atmospheric discharges, could reduce atmospheric pollution and even global warming. The algae produced and removed can serve as an energy source. A case study is described for the application of a DAF system for upgrading a small drinking WTP. Examples are shown for the separation of algae from wastewater treatment plant lagoons. The use of DAF for separation of algae is an important factor in our lives.