Comparison of the use of functional porous organic polymer (POP) and natural material zeolite for nitrogen removal and recovery from source-separated urine

Recovering nitrogen from source-separated urine can offset fertilizer production, reduce the energy consumption associated with wastewater treatment, and help prevent certain pollutants from entering into wastewater treatment plants. This study evaluated the performance of a newly designed porous organic polymer (POP) for removing ammonium (NH4+) from synthetic hydrolyzed urine in comparison with natural clinoptilolite in terms of adsorption capacity (isotherm), adsorption rate (kinetics), regeneration rate, and adsorbent cost. NH4+ removal from hydrolyzed urine using the POP was rapid with a capacity of 74.96 mg/g, which is about five times higher than clinoptilolite (15.42 mg/g). In addition, the predicted capacity of both adsorbents decreased with the number of cycles using an integrated adsorption-regeneration model, but remained at about 83.4% and 21.6% of the pristine POP and clinoptilolite after 24 cycles, respectively. The POP had a higher adsorbent cost than clinoptilolite, however, it can be competitive to clinoptilolite with multiple uses if its production can be scaled up.