Nitrogen (N) and phosphorus (P) are crucial elements for life. Reactive forms of N (such as ammonium) and inorganic P (or phosphate) are widely applied as fertilizers to promote the growth of plants. A significant portion (&gt;80% in certain cases) of N and P applied to farmland is lost in water. The runoffs from agriculture as well as other anthropological discharges from municipal and industrial wastewaters cause the enrichment of N and P in rivers and lakes. This leads to eutrophication, threatening the survival of aquatic species and jeopardizing sources of clean water. Traditionally, chemical precipitation is used to remove these contaminates during wastewater treatment. Although feasible for implementation, the struvite derived from direct chemical precipitation is usually contaminated by toxic substances, deemed inappropriate for reuse, and dumped in landfills. Alternatively, ion exchange represents a promising approach toward the recovery of the N and P from wastewater. Recent research has turned to zeolites due to their structural robustness, tunable and selective adsorption properties, employment of naturally abundant elements and environmental compatibility. We have demonstrated the ability of ZSM-5 sorbents to recover ammonium from solution. Modification of ZSM-5 with transition metals produces positively-charged active sites that enable the recovery of phosphate. Kinetics and sorption capacity has been systemically studied with fittings into different transport models and isotherms, enabling the proposal of ion-exchange mechanisms. Optimization of zeolites for nutrient recovery were examined by investigating the effects of zeolite frameworks with various geometries and pore morphologies as well modifications with different metal cations.

Recovery of nitrogen and phosphorus nutrients via metal-exchanged zeolites

255th National Meeting (2018)

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