For the survival of humans, animals industries and agricultural sector, fresh water has always been a vital commodity. With the increase in each of the above factors makes an increase in its supply in the future important. As it is becoming a scarce commodity. There are various seawater technologies that have come up which aided significantly in achieving the objective.
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.
This process entails separation of sea water to two streams. Fresh one with very small concentration of salts dissolved and one with highly concentrated brime. Various forms of energy are required for the success and thereby emergence of different innovations. Different technologies based on different means of achieving this. But not all have a potential future. The MSF, RO and MED have been prophesied to be the dominant means although currently MSF and RO are the widely used.
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 method based on distillation is multiple effect distillation. Considered to thermodynamically efficient. It involves the sea water being undertaken through effects, these are a chain of evaporators. The effects use the law of reduction of pressure. Its economic efficiency is determined by the number of effects. This technology has been recently applied in the Arabian region but in comparison to its counterpart MSF it is still not very utilized although it is rising steadily.
We also have vapor compression distillation. Where through the vapor compression heating the sea water takes place. It applies the principle of reducing pressure in order to lower the boiling temperature. The heat absorbed from the condensation of vapor is utilized in heating the incoming marine aqua. This is achieved by use of steam jet. A compressor can also be used. This method is common in desalination units which run on small scale.
Reverse osmosis, commonly referred to as RO, is where the osmotic pressure is overcome by applying external pressure higher than the osmotic pressure on the sea water. Thus it flows in the reverse direction to the natural flow across the membrane leaving the dissolved salts behind with an increase in salt concentration. Over the past decade a number of developments have been made to help reduce the operating cost of RO plants. These are the development of membranes that can operate efficiently with longer duration and the use of energy recover devices.
Methods such as solar evaporation, freezing and potabilization are used but not as often as the ones described above.
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.
This process entails separation of sea water to two streams. Fresh one with very small concentration of salts dissolved and one with highly concentrated brime. Various forms of energy are required for the success and thereby emergence of different innovations. Different technologies based on different means of achieving this. But not all have a potential future. The MSF, RO and MED have been prophesied to be the dominant means although currently MSF and RO are the widely used.
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 method based on distillation is multiple effect distillation. Considered to thermodynamically efficient. It involves the sea water being undertaken through effects, these are a chain of evaporators. The effects use the law of reduction of pressure. Its economic efficiency is determined by the number of effects. This technology has been recently applied in the Arabian region but in comparison to its counterpart MSF it is still not very utilized although it is rising steadily.
We also have vapor compression distillation. Where through the vapor compression heating the sea water takes place. It applies the principle of reducing pressure in order to lower the boiling temperature. The heat absorbed from the condensation of vapor is utilized in heating the incoming marine aqua. This is achieved by use of steam jet. A compressor can also be used. This method is common in desalination units which run on small scale.
Reverse osmosis, commonly referred to as RO, is where the osmotic pressure is overcome by applying external pressure higher than the osmotic pressure on the sea water. Thus it flows in the reverse direction to the natural flow across the membrane leaving the dissolved salts behind with an increase in salt concentration. Over the past decade a number of developments have been made to help reduce the operating cost of RO plants. These are the development of membranes that can operate efficiently with longer duration and the use of energy recover devices.
Methods such as solar evaporation, freezing and potabilization are used but not as often as the ones described above.
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