Decomposition and Recapture of Ammonium Bicarbonate Draw Solution

A laboratory scale technology that mimics a simple distillation and condensation system was used for decomposition and recapture of an ammonium bicarbonate draw solution. To analyze the recapture performance for this specific application and the influence of system parameters, a test matrix was implemented to address the mass transfer and kinetics involved in the recapture process using 1M, 2M, and 3M ammonium bicarbonate draw solutions. Also, CHEMCAD was used to design a conceptual distillation and condensation recapture and recovery system for a 1000 gpd pilot-scale system. The UNIQUAC model and Pitzer method were used for the simulation of the NH3-CO2-H2O ternary system. Effluent quality for the simulation was specified to contain less than 1% of NH3 and CO2. The unit cost of product water was estimated to be $0.12/gal for only the recovery system. The results herein have practical significance to a full-scale Forward Osmosis process. A highly efficient draw solution of ammonium bicarbonate can be reconstituted; however, the current suite of experiments did not address the impact of using a reconstituted solution within the Forward Osmosis system