As the critical parameter, the operating conditions are able to define the system efficiency of forward osmosis (FO) process. In other words, to reach the optimal performance, the effective operation of FO process can be achieved by working on these optimal design parameters. In this work, to simulate the influence of each initial condition on FO process performance, sensitivity analysis technique was introduced to developed dynamic FO model, focused on both single and a mixture of two organic acid feed solutions, by NH4Cl as draw solution. As functions of operating variables, the FO membrane rejection and concentration performance of the system could precisely be defined via Levenberg-Marquardt algorithm. The simulation results demonstrated that sensitivity analysis techniques can be practically applied as a guideline to design and modify any comparable FO processes by optimizing operating parameters to achieve the desirable performance in terms of both minimizing cost and maximizing efficiency. (C) 2018 Elsevier Ltd. All rights reserved.