Chitosan is extracted from chitin and is nature’s second most abundant natural biopolymer next to cellulose. Chitin is the structural material found in crustacean shells such as shrimp, crabs, and lobsters. Chitin is also found in fungi cell walls and the exoskeletons of insects. Chitin and chitosan are natural components of biochemical degradation processes occurring naturally in the earth’s soil and water. Like chitin, chitosan is found to exist naturally in the environment (water and soil) because it is a biodegradation product of chitin.
Chitosan acetate has been used in water treatment for more than three decades. It has the unique ability to absorb dissolved oil and grease from water, chelate (bond with) heavy metals, and flocculate suspended sediment. Chitosan-based water treatment has been used for decades in various industrial and municipal applications and commercial aquarium clarification. The U.S. Environmental Protection Agency has approved chitosan for use in drinking water treatment and for use in the agriculture industry.
Storm water treatment with Chitosan, at proper dose rates, is highly effective in reducing turbidity levels by greater than 95% when used with sand filtration systems. Chitosan’s efficacy lies in its ability to make small suspended soil particles stick together to become larger and denser. The larger and denser floc particles can be easily removed through settling and/or sand filtration. The cationic (positive charge) nature of chitosan molecules interact with the predominately anionic (negative charge) sediment particles in storm water. As these opposite charges attract, the chitosan molecules can bind with numerous soil particles. Avoid over dosing, which can cause the opposite of the intended effect. An excess of cationic material can cause the floc that initially formed at a lower dose to break apart.