Desalination after reverse osmosis makes water drinkableDiego Hall
February 21, 2012 — 1,034 views
The process of desalination is used for separating the salt from sea water and then the water can be used for various purposes. The content of salt in water varies and the classification is based on that. In the process of desalination, the water is divided into two or three streams, depending on the level of salinity that is present in the water. This is very effective for providing potable water in the coastal areas. The coastal areas have large supplies of water but that water cannot be used for any purpose. Thus water in those areas has to be desalinated and only used thereafter. Reverse osmosis water is one of the many effective ways that are employed for desalination process. It is quite possible to remove insoluble ingredients from water by various filtering processes, but elements like salt dissolve in water and thus it is not that easy to remove salt from water. Processes like reverse osmosis water and electrodialysis are the most common ways of desalination.
After desalination through the process of reverse osmosis water, the water becomes fit for use not only for industrial and agricultural sectors but also for the domestic sector. Brine is the most common by-product that is obtained after desalination of water. The entire process of reverse osmosis water undergoes four steps. All these steps are equally important for proper desalination of water. These steps are as follows:
- Pretreatment of the saline water – In reverse osmosis, the water is passed through a semi permeable membrane and the preparation for that has to be done in advance. The feed water needs to undergo some pretreatments so that the insoluble particles are separated and removed and become compatible with the semi-permeable membrane. The pH level of the water is also adjusted. A threshold inhibitor is also put so that there is no problem of scaling, which are usually caused by calcium sulphate or other chemicals of the same kind.
- Adjusting the pressure for reverse osmosis water – In the process of reverse osmosis water for desalination, adjusting the pressure plays a pivotal role. The pressure of the feed water which is already pretreated is increased so that it becomes adequate for the semi-permeable membrane as well for the amount of salinity of the sea water.
- Separating the brine from the fresh water – This is the most important step in the desalination process through reverse osmosis water. The water is passed through the semi-permeable membranes and two streams are kept as outlets. One outlet is for the fresh water and the other is for the concentrated brine. How much ever good the membranes might be, some little amount of salt gets passed through the membranes.
- Stabilization and post treatment of the water – The process of desalination gets complete with stabilization and post treatment of the water. This is the last step in the process of reverse osmosis water. Before being recommended as suitable for drinking, the pH level of the water has to be adjusted and all the unwanted gases removed from the water. After this the water becomes fit for drinking as well as for other purposes.