Total recycle strategy of phosphorus recovery from wastewater using granule chitosan inlaid with γ-AlOOH.

Eutrophication which caused by excessive phosphorus in aquatic environment is a worldwide problem. Phosphorus is a nonrenewable resource widely used in agriculture and industry. Therefore, the development of economical methods for phosphorus capture and reuse from wastewater is urgently needed. In this study, a novel granule chitosan inlaid with γ-AlOOH on its structure (γ-AlOOH@CS) was prepared for phosphate removal with a recycle manner. Results showed that γ-AlOOH@CS exhibited a fast phosphate removal of 0.5 h for half adsorption capacity. The material presented a high adsorption capacity of 45.82 mg/g, the adsorption capacity maintained stability at pH 4-6, and favorable selectivity was observed when compared with other common anions. Column experiment was also performed well in treatment of the simulated wastewater. Isotherms and thermodynamics studies indicated that phosphate adsorption onto γ-AlOOH@CS was heterogeneous, spontaneous and exothermic. In material recycle experiment, by using NaOH solution as solvent and phosphoric acid as precipitant under hydrothermal reaction conditions, the products of chitosan, aluminum phosphate and sodium dihydrogen phosphate were obtained, with their purity reaching the industrial standard. Meanwhile, chitosan can be reused for new γ-AlOOH@CS preparation. This study provides a total recycle strategy of phosphorus removal from wastewater.