OPTIMIZING NITROGEN RECOVERY FROM SOURCE-SEPARATED URINE
Maritza Flores-Marquez1, William Tarpeh2.
1University of California, Merced, Merced, CA, 2University of California, Berkeley, Berkeley, CA.
To reduce the eutrophication of aquatic environments that stem from the excess nitrogen not removed at waste water treatments plants, ion exchange cartridges are being developed to incorporate into source-separating toilets for the recovery of nitrogen from urine. Comprising 1% of waste water volume, urine contains the majority of excreted nutrients such as nitrogen, potassium, and phosphorous. The nitrogen that may be recovered by these cartridges is in the form of ammonium, resulting from the hydrolysis of urea from fresh urine. Resins of interest for the design of the ion exchange cartridge include clinoptilolite and faujasite (natural occurring minerals) and Dowex 50 and Dowex Mac 3 (synthetic materials). To determine the efficiency of each resin to adsorb ammonium, 24-hour batch experiments with an ammonium chloride solution were performed to generate equilibrium adsorption isotherms. Preliminary results demonstrate that Dowex Mac 3 adsorbed larger quantities of ammonium as nitrogen than the other resins. This may indicate that Dowex Mac 3 may be the ideal resin to include in the ion exchange cartridge design. However, further studies involving synthetic urine and actual urine must be conducted to confirm this. The effective design of these ion exchange cartridges will lead to the alternative production of ammonium-based fertilizers from the recovered nitrogen in the form of ammonium from urine.