Reverse Osmosis in Water Treatment
Reverse osmosis is a method of water treatment that eliminates water contaminants when pressure is applied to the feed/unfiltered water through a selectively permeable membrane. In reverse osmosis, the water flows from the region of high concentration of contaminants to the area with lower contaminants across the semi-permeable membrane. The chemistry of reverse osmosis is seen in the sense that the solvent (water) is forced from regions of high solute (contaminants) through the semipermeable membrane, to the low concentration (low contaminants) by application of pressure that is above the osmotic pressure. Reverse osmosis is highly efficient in the provision of highly purified water. Therefore, the process has been widely used in the production of clean drinking water (Potluri & Rao 2006).
Reverse osmosis has basic stages that enhance the removal of contaminants and the production of high-quality water. After the elimination of the contaminants, the water formed is referred to as permeate while the concentrated water left behind is called brine. Firstly, the feed water is passed through the sediment filter that removes the solid particles such as dust and dirt. Secondly, the filtered water is passed over the carbon filter. The carbon filter is used to eliminate organic compounds such as volatile organic compounds (VOCs). Carbon filters also remove chlorine and water contaminants that cause awful taste and odor. Finally, the water is taken through the semi-permeable membrane that removes the solid and dissolved contaminants up to 98%. After passing through the semi-permeable membrane, the purified water is collected in storage tanks for consumption (Cingolani, Fatone, Frison, Spinelli, & Eusebi, 2018)
Reverse osmosis is an effective method of water treatment that eliminates both dissolved and undissolved water contaminants. Reverse osmosis removes main water contaminants such as fluoride, salts, sediments, chlorine, arsenic, herbicides, and arsenic. However, reverse osmosis has a major weakness in the sense that it cannot be used to remove bacteria and viruses. For this reason, further disinfection of water after reverse osmosis through other methods is advised. Therefore, ultraviolet radiation is used for elimination of the viruses and bacteria in water (Torii, Hashimoto, Do, Furumai, & Katayama, 2019).