A pilot-scale forward osmosis desalination system is developed and demonstrated employing ammonium bicarbonate as its draw solute. The system consists of three stages: (1) water permeation through the membrane, (2) draw solute and water separation, and (3) draw solute recovery. In the membrane process, multiple spiral wound membrane elements are connected to investigate the water recovery change according to the membrane area. The draw solution diluted by water permeated through the membrane from the salt water enters a packed column where ammonium bicarbonate is decomposed into ammonia and carbon dioxide. The separation efficiency and energy consumption of the separation column are measured for 120 kg/h fresh water production. Lastly, the draw solutes are then recovered back into the system by absorption with the diluted ammonium bicarbonate solution. The operational results are compared to those from simulation. The results of this study will contribute to facilitating the technical and economical evaluation of forward osmosis desalination systems. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.