Effects of Total Dissolved Solids on Pressure Drop and Net Driving Pressure in Different Designs of Brackish and Seawater Reverse Osmosis Systems

Reverse osmosis is considered one of the best methods for water treatment. Thus, reverse osmosis units are frequently used in the water treatment process. This study investigates and simulates the effects of total dissolved solids on pressure drop and net driving pressure in seawater and brackish water reverse osmosis systems. The results showed that with increasing total dissolved solids, the total net driving pressure increases in both simple and hybrid single-stage designs for brackish and seawater systems and two-stage simple and hybrid brackish systems. In both simple and hybrid designs, the amount of net driving pressure is higher in the first stage than in the second stage, and the amount of pressure drop in the second stage is more than in the first stage. Results also showed that in the simple and hybrid single-stage seawater system, unlike the brackish water system, an increase in TDS reduced the pressure drop in both simple and hybrid designs. In addition, upstream membranes have a higher net pressure drop and net driving pressure than downstream membranes.