Recent developments in polysaccharide-based technologies for phosphorus removal and recovery from wastewater: A review

Abstract

Phosphorus (P) is an essential nutrient for the biological function of both animals and plants, as well as a main constituent of industrial products, including crop fertilizers, detergents, chemicals, pharmaceuticals, food and feed, and construction materials. In recent years, the imbalance between P mining and its excessive, inefficient use has led to resource depletion, runoff and water contamination. P contamination predominantly sources from agricultural, industrial, and domestic waste worldwide. The overabundance of P in water bodies has exacerbated eutrophication and related health problems, affecting aquatic life and posing risks to humans. To address global concerns about the depletion of phosphate rock (PR) reserves and alleviate associated environmental and health hazards, various physical, chemical, and biological methods are currently employed to remove and recover P from wastewater. Among these, adsorption, chemical precipitation, membrane filtration, the use of microorganisms, ion exchange, and crystallization are considered the most widely employed techniques. These conventional methods present several drawbacks, including strict control of operation, limited sensitivity to phosphate ions (PO₄³⁻) at low concentrations, high chemical and energy consumption, poor mechanical and chemical stability, limited scalability, and high costs. Recently, biopolymers, primarily polysaccharide-based technologies, have emerged as sustainable, eco-friendly, low-cost, and innovative alternatives for removing and recovering P from aqueous environments, addressing the prevailing challenges and gaps associated with conventional methods. Polysaccharides and their derivatives exhibit enhanced P removal efficiency, renewability, scalability, high mechanical and chemical strength, and non-toxicity. Although polysaccharides have been widely investigated for wastewater treatment, their involvement and mechanisms in P removal and recovery have not been systematically analyzed. Therefore, this study consolidates recent findings on polysaccharide-based materials, namely cellulose, chitosan, starch, and alginate, for the effective removal and recovery of P, filling an unaddressed area in the literature. The current review also provides a synopsis of current trends and future advancements in polysaccharide-based technologies for the removal and recovery of P. Furthermore, this review serves as a guide to the development of practical and sustainable waste and resource management systems for P, subsequently contributing to the circular bioeconomy.