Comprehensive evaluation of mineral adsorbents for phosphate removal in agricultural water

Phosphorus (P) is one of the essential macronutrients for agricultural production. Accelerated crop production to meet the global food demand has led to the accumulation of P in agriculture soils through over-use of fertilizers. Phosphorus loss to the aquatic environment through surface runoff and subsurface transport is known to contribute to the occurrence of eutrophication and hypoxia. The reduction of dissolved P in agricultural drainage water has been one of the primary goals among agro-environmental communities. In recent years, advancement in material science allowed us to improve the adsorbent technology to remove nutrients in wastewaters. Numerous studies showed adsorbent specific-P adsorption capacity that can be sensitive to changes in physicochemical conditions of wastewaters (e.g., pH, solid/solution ratio, interfering ions, ionic strength, flow rate). This chapter provides a comprehensive review of inorganic adsorbents (e.g., anion exchange resins, calcium and magnesium oxides, hybrid anion exchange resins, layered double hydroxides, metal oxyhydroxides, zerovalent iron, and zirconium and lanthanum oxides) that have been demonstrated to remove dissolved P from synthetic and natural wastewaters. Important criteria (e.g., adsorption capacity, stability, and cost efficiency) for selecting adsorbents for P removal in agricultural waters and the future perspective are discussed.