Kinetics of Simultaneous Ammonium and Phosphate Recovery by Natural Zeolite

Abstract

Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be developed. This study represents the basis of an extension of the ion-exchange-loop-stripping process (ILS), which is a combined stripping and ion exchange process using natural zeolite for nitrogen recovery. In batch experiments with a special zeolite filled stirrer, the mechanism and kinetics of simultaneous ammonium and phosphate recovery by natural zeolite were determined. Zeolite loadings of 6.78 mg PO43− g−1 were reached and after regeneration, phosphate recovery rates up to 75% of the initial concentration were achieved. The speed of phosphate precipitation is mostly controlled by the pH value of synthetic wastewater. Phosphate removal in simultaneous experiments does not affect ammonium sorption onto zeolite. These findings and the different removal mechanisms of ammonium and phosphate lead to versatile applications in wastewater treatment and reveal great potential of natural zeolite in simultaneous nutrient recovery processes.

Treatment of Agricultural Waste Using a Combination of Anaerobic, Aerobic, and Adsorption Processes

“…Moreover, the increase in the initial ammonium concentration has been reported to enhance the phosphorus removal rate, while a shift in the value of pH from 8 to 9 resulted in a much faster and more efficient rate. On the other hand, ammonium sorption to zeolite was less efficient, due to the shifted NH 3 /NH 4 + equilibrium [36]. Another study claimed that the natural Ca-loading of the applied zeolite may be responsible for not completing CaP-precipitation and P-loadings are limited by the available Ca-cations in the zeolite structure [37].…”