Evaluation of Concentration Polarization Due to the Effect of Feed Water Temperature Change on Reverse Osmosis Membranes

Abstract

Water is a necessary resource for life development. Its excessive consumption has a negative impact, generating scarcity problems worldwide. Desalination is an alternative to solve these problems; its objective is to reduce the concentration of total dissolved solids to levels suitable for consumption. The most widely used desalination technology is reverse osmosis, which works by means of semipermeable membranes; however, lack of knowledge or wrong operation cause phenomena such as concentration polarization, which reduces the effective area for mass transfer in the membrane, increasing the energy consumption of the process. The objective of the present study is to evaluate the concentration polarization (β) of the concentration in reverse osmosis membranes by varying the temperature in the feed water (23, 25.5, 28, and 35 °C) for different concentrations (5000 and 10,000 mg L−1) in order to reduce its impact on energy consumption (kWh m−3). The results show that as the temperature increases, the specific energy consumption decreases for both concentrations. In the 5000 mg L−1 tests, the specific energy consumption decreased by 0.590 kWh m−3, representing 12.5%. For 10,000 mg L−1 tests, the specific energy consumption shows a reduction of 0.72 kWh m−3, which represents a percentage decrease of 14.54%.

Keywords

• desalination
• concentration polarization
• reverse osmosis
• water scarcity