Name: Course: Instructor: Institution: Date of Submission: Abstract This project is about the aspect of reverse osmosis which occurs when an external pressure of higher magnitude than the osmotic pressure is applied to a system and changes the original direction of the fluid flow across a given semi-permeable membrane. The key concept in this study is to investigate the desalination of salt water through the aspect of characterization of reverse osmosis separation module. Membrane separation apparatus was used to attain the objective. The method used to describe the flow of both the solute and the solvent across the semi-permeable membrane was the Solution-Diffusion Model. The results showed us that as the flux of the solute was on the increase, the concentration of the feed-permeate across the semi-permeable membrane were also increasing. Conversely, an increase in the salt concentration was indicative of a decrease in salt rejection and vice versa. Additionally, the design problem was shown to be as a result of the direct costs which at the same time were negatively affected by the inflation rates. The inflation rate of an estimate of 2.0408115 since 1998 increased the total cost to 2893145.1 from the initial 1417644.45. In conclusion, the quality and the quantity of the water that is in production in reverse osmosis was dependent on variables such as the system recovery, feed water pressure and also the changes brought in feed water quality.