Runoff from construction sites and farms drains into local bodies of water and is a major source of suspended solids, heavy metals & minerals, hydrocarbons, and other pollutants that chitosan binds to.
The demand for safe & clean ways to treat wastewater from industrial factories, mines, and sewage will only continue to grow with the world’s population.
Because chitosan is safe and nontoxic, the flocs or “sludge” generated in treatment can be recycled as a protein, lipid, and/or dye concentration, adding economic value to wastewater byproducts. The US Food Drug Administration (FDA) approves the use of chitosan in these processes.
Chitosan is an ideal eco-friendly flocculant for water clarification applications due to its ability to bind to a variety of organic and inorganic particulates .
Removal of suspended solids, dyes, heavy metals, and other pollutants is facilitated with chitosan in solution at acidic, neutral, and alkaline pH conditions [2,3].
Aggregation and flocculation by chitosan occur because of the unique pH-sensitive and strong hydrophilic nature of chitosan. Chitosan can then be removed via filtration or sedimentation; leaving clarified water behind without any residual toxic chemicals .
Other Uses for Chitosan in Water Treatment
The removal of microorganisms from suspension presents a challenge in beverage manufacturing, algal biomass production, and water treatment. Chitosan has been shown to bind directly to the outer cell wall of microorganisms in a range of pH conditions [5,6].
 Guibal, Eric, et al. “A review of the use of chitosan for the removal of particulate and dissolved contaminants.” Separation science and technology 41.11 (2006): 2487-2514.
 Bhatnagar, Amit, and Mika Sillanpää. “Applications of chitin-and chitosan-derivatives for the detoxification of water and wastewater—a short review.” Advances in Colloid and Interface Science 152.1 (2009): 26-38.
 Guibal, Eric. “Interactions of metal ions with chitosan-based sorbents: a review.” Separation and purification technology 38.1 (2004): 43-74.
 Renault, François, et al. “Chitosan for coagulation/flocculation processes–an eco-friendly approach.” European Polymer Journal 45.5 (2009): 1337-1348.
 Divakaran, Ravi, and V. N. Sivasankara Pillai. “Flocculation of algae using chitosan.” Journal of Applied Phycology 14.5 (2002): 419-422.
 Cheng, Yu-Shen, et al. “The impact of cell wall carbohydrate composition on the chitosan flocculation of Chlorella.” Process Biochemistry 46.10 (2011): 1927-1933.