Recent Advances in Technologies for Phosphate Removal and Recovery: A Review
Mallikarjuna N. Nadagouda, Gaiven Varshney, Vikas Varshney, Charifa A. Hejase
Abstract
Phosphorus is a nonrenewable resource, yet an essential nutrient in crop fertilizers that helps meet growing agricultural and food demands. As a limiting nutrient for primary producers, an excess amount of phosphorus entering water sources through agricultural runoff can lead to eutrophication events downstream. Therefore, to address global issues associated with the depletion of phosphate rock reserves and minimize the eutrophication of water bodies, numerous studies have investigated the removal and recovery of phosphates in usable forms using various chemical, physical, and biological methods. This review provides a comprehensive and critical evaluation of the literature, focusing on the widely employed adsorption and chemical precipitation for phosphate recovery from various wastewaters. Several experimental performance parameters including temperature, pH, coexisting ions (e.g., NO3–, HCO3–, Cl–, SO42–), surface area, porosity, and calcination are highlighted for their importance in optimizing adsorption capacity and struvite crystallization/precipitation. Furthermore, the morphological and structural characterization of various selected adsorbents and precipitated struvite crystals is discussed.