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In the recent past there has been an increase in the population. Living standards have changed and in the industrial and agricultural sector expansion has been exhibited. The trend is expected to continue in the future. This has called for more demand of fresh aqua making it a rare commodity. Focusing on the seawater technologies has been of assistance to combat this shortage.
97% of earth aqua reservoir is marine. While another 2% is locked in ice caps and glaciers. Only less than 0.5% of the earth total supply is available. These are supply from rivers, lakes and underground reservoir. Sea water is not suitable for human consumption and for industrial or agricultural purposes. Removing salt from the unlimited supply of this resource, desalination has emerged as an important source of fresh water.
The desalination process involves separation of the resource into two streams. A fresh stream containing a low concentration of dissolved salts and a concentrated brime stream. The above process requires some form of energy to desalinate and several different technologies are utilized. Over the years a variety of innovations have been developed on the basis of thermal distillation, membrane separation, freezing, electro dialysis, etc. On commercial basis the two most important technologies are based on the MSF and RO technologies although it is viewed that the two processes together with MED (multiple effect distillation) will be dominant and competitive in the future.
So what are some of the technologies used? Multiple-stage flash distillation is one of them. This one is based on the principle of flash evaporation. The resource is evaporated by reducing the pressure as opposed to raising temperature. The economies of the MSF heating technology are achieved by regenerative heating where the sea water flashing in each flash chamber or stage gives up some of its heat to its counterpart going through the flashing process.
Another form of distillation in the multiple effect, also the MED. Is considered very efficient thermodynamically. It occurs through a series of evaporators known as effects. And applies the principle of lowering the pressure in the different effects. Its economic level is dependent on the number of effects. There are different tubes used. Some submerged, horizontal and others vertical. Has been applied in the Middle East. Its utilization is still low as compare to the MSF but gradually increasing.
Another form of distillation is the vapor compression. Where compression of vapor is the means of heating the incoming aqua. This is made possible by application of two methods. Use of mechanical compressor hand in hand with steam jet. It is built in the principle that boiling point is reduced with reduction of pressure. In small scale units of desalination this method is highly used.
RO, also known as reverse osmosis, is highly used. Where osmotic pressure is overcome through application of outer pressure which is more compared with the sea water osmotic pressure. It therefore flows in reverse direction in respect to direction of the natural flow. Dissolved salts are left behind as it concentration increases. Previous development have come up in aiding the reduction of cost operation of RO plants. They include development of efficient membranes that also last longer and energy recover devices.
There are many other innovations being used in desalination. Others include freezing, solar evaporation and potabilization. But they tend not to be commonly used as compared to the rest.
97% of earth aqua reservoir is marine. While another 2% is locked in ice caps and glaciers. Only less than 0.5% of the earth total supply is available. These are supply from rivers, lakes and underground reservoir. Sea water is not suitable for human consumption and for industrial or agricultural purposes. Removing salt from the unlimited supply of this resource, desalination has emerged as an important source of fresh water.
The desalination process involves separation of the resource into two streams. A fresh stream containing a low concentration of dissolved salts and a concentrated brime stream. The above process requires some form of energy to desalinate and several different technologies are utilized. Over the years a variety of innovations have been developed on the basis of thermal distillation, membrane separation, freezing, electro dialysis, etc. On commercial basis the two most important technologies are based on the MSF and RO technologies although it is viewed that the two processes together with MED (multiple effect distillation) will be dominant and competitive in the future.
So what are some of the technologies used? Multiple-stage flash distillation is one of them. This one is based on the principle of flash evaporation. The resource is evaporated by reducing the pressure as opposed to raising temperature. The economies of the MSF heating technology are achieved by regenerative heating where the sea water flashing in each flash chamber or stage gives up some of its heat to its counterpart going through the flashing process.
Another form of distillation in the multiple effect, also the MED. Is considered very efficient thermodynamically. It occurs through a series of evaporators known as effects. And applies the principle of lowering the pressure in the different effects. Its economic level is dependent on the number of effects. There are different tubes used. Some submerged, horizontal and others vertical. Has been applied in the Middle East. Its utilization is still low as compare to the MSF but gradually increasing.
Another form of distillation is the vapor compression. Where compression of vapor is the means of heating the incoming aqua. This is made possible by application of two methods. Use of mechanical compressor hand in hand with steam jet. It is built in the principle that boiling point is reduced with reduction of pressure. In small scale units of desalination this method is highly used.
RO, also known as reverse osmosis, is highly used. Where osmotic pressure is overcome through application of outer pressure which is more compared with the sea water osmotic pressure. It therefore flows in reverse direction in respect to direction of the natural flow. Dissolved salts are left behind as it concentration increases. Previous development have come up in aiding the reduction of cost operation of RO plants. They include development of efficient membranes that also last longer and energy recover devices.
There are many other innovations being used in desalination. Others include freezing, solar evaporation and potabilization. But they tend not to be commonly used as compared to the rest.
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