Desalination is the future scope to satisfy the water needs in future where water scarcity is more, but RO process produce lesser fresh water and ejects more waste water. So is there any alternate process ?
RO is the most cost-effective method the Israeli government by Israel Desalination Enterprises, or IDE Technologies, at a cost of around $500 million, it uses a conventional desalination technology called reverse osmosis (RO) 20 percent of the water consumed by the country’s households.
solar distillation is one of the best cost effective method for convert salt water into pure water
Dear Karthick,
Developed by a team of researchers at Alexandria University in Egypt, the procedure uses a desalination technique called pervaporation to remove the salt from sea water and make it drinkable. Specially made synthetic membranes are used to filter out large salt particles and impurities so they can be evaporated away, and then the rest is heated up, vapourised, and condensed back into clean water. Crucially, the membranes can be made in any lab using cheap materials that are available locally, and the vaporisation part of the process doesn't require any electricity. This means the new method is both inexpensive and suitable for areas without a regular power supply - both factors that are very important for developing countries.
The technique not only desalinates the seawater, it's capable of removing sewage and dirt from it too. The researchers combined expertise in oceanography, chemical engineering, agricultural engineering and biosystems engineering to come up with the solution, and their work has now been published in the journal Water Science and Technology. The technology implemented in the study is much better than reverse osmosis, the technology is currently used in Egypt and most of the countries in the Middle East and North Africa.
With my best regards
Prof. Bachir ACHOUR
Thermal distillation is promising conversion technique for desalination of sea water or brine solution
Dear Karthick Munisamy
Large-scale commercially available desalination processes, with power-to-water
ratios from 0.8 to 10, can generally be classified into two categories.
The first is distillation processes, which include Multi Stage Flash (MSF), Multi Effect Desalination (MED), and Multi Effect Vapour Compression (MED-VC), which require mainly heat plus some electricity for the ancillary equipment.
The second is the Reverse Osmosis (RO) processes, which require electricity to drive a pressure, which forces impure water to pass through special semipermeable membranes, where salt is rejected.
Dear Karthick,
Maybe the following is of help.
Currently, cost-effective large-scale desalination is provided only by reverse osmosis membranes.
A point of attention may be how to quantify and weigh costs of water desalination, including fouling.
Best regards, Hans
RO is most effective technology for desalination. As mentioned by Prof. Bachir Achour, pervaporation desalination is one another technology. Brief description of desalination by pervaporation compare to RO is written below.
In case of pervaporation desalination, non-volatile salt is separated from water using a hydrophilic membrane in the form of vapour at a downstream side. Pervaporation desalination generally shows the more than 99% salt rejection due to non-volatility and low diffusivity of salt. It is also found that salt rejection is quite independent of the concentration of salt in the feed. Dense and hydrophilic nature of pervaporation membrane is also leading to anti-fouling property by preventing the salt deposition on membrane surface. Pervaporation desalination involves the phase change process and does not require to overcome the osmotic pressure of saline water. Pervaporation can be useful to treat highly saline water without needing to create much vapour pressure different across the membrane. For example, the vapour pressure of water with 100 g/l NaCl is about 11.58 kPa at 323 K, which is only 6% lower than pure water, whereas an osmotic pressure difference between them is high as about 10.7 MPa at 333 K and is required to overcome by applying high pressure to reverse the flow during RO treatment. Due to above reason, energy need is not much dependent on salt concentration of the feed water in pervaporation desalination. It can be indicated that pervaporation desalination is feasible to treat produced water from mineral oil and natural gas extraction when salinity is as high as 400 g/l, which makes it difficult for RO process because of the requirement of high hydraulic pressure to overcome osmotic pressure. But to make the pervaporation membrane for use in brackish/sea water desalination(
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