Our planet is gifted with water and this uniqueness has created various diversity of living species. We are extremely fortunate to be a part of our blue planet Earth. Well, we know ninety-seven percent is usually seawater and three percent is freshwater, seawater is unfit for consumption as drinking water. Of course, we know the reason, the presence of sodium chloride ( salt) in seawater. The ocean contains about 35,000 ppm of salt. Before getting into the main idea of the topic, let’s actually see what’s desalination all about.
Desalination is a process that takes away mineral components from saline water I.e. removal of salts and minerals from sea . These process is usually driven by either thermal ( in case of distillation) and electrical ( in case of reverse osmosis).
The methods used in desalination are:
Thermal distillation– oldest and simplest method. Seawater is filtered to remove the larger impurities. It is then heated to produce vapour in the vessel that collects the salts. The vapour is subsequently condensed and converted to a mineral-free liquid.
Reverse osmosis- The seawater is carefully filtered through several layers of sand or charcoal to eliminate micro algae, suspended particles leaving behind the salt. The water is then fed under high pressure, through a semi-permeable membrane that traps the salt. For every two litres of seawater, reverse osmosis produces one litre of freshwater and 1 litre of brine. The brine is discharged into the sea.
Electrodialysis– membrane bases process that uses an electric field to filter out the salt. It uses very little energy but is limited to the treatment of low salinity water.
In this process there lies a few drawbacks, the first one being the energy cost. In my last article, I spoke about energy conservation and methods regarding it, so we can understand the energy cost now. Desalination plants often need large quantities of heat to evaporate the seawater. Waste heat is also produced as a by-product during the generation of electricity. Even in the reverse osmosis process, electricity is required to operate the pumps and compressors that draw and move the seawater through the membranes.
The energy requirement is huge, and we mainly use fossil fuels which are non-renewable energy. Well, we know the consequences of using it. The rise of renewable sources has opened up new opportunities and we need to maximize it sooner. Advanced nuclear power should be a way to desalinate the ocean water without burning fossil fuels and causing environmental impact. The initial cost of nuclear power may be high, but it’s returns and benefits are worth it.
The Second drawback is the cost of running desalination process. Energy cost is usually higher call of its working and requirement. It required huge investment for setting up the entire plant and running it , maintenance costs all involves heavy cost.
The major drawback is the brine production. The primary by-product is brine, which is pumped back to the ocean and current regulations requite costly outfall systems to ensure the adequate dilution of salt. The brine sinks to the seafloor and wrecks havoc on ecosystems, cratering oxygen levels, and spiking salt content.
It can also be loaded but heavy metals and chemicals like the anti-foul-ants used in the process get accumulated and discharged to the environment in concentrations that can potentially have damaging effects on the ecosystem. Dilution May help with the hypersalinity problem but doesn’t get rid of chemical toxins. Moreover, did this charge can also contain elements like uranium. The water can also get contaminated.
How can we reduce brine then ? Well ,Some of the methods have been adopted to reduce the concentration of brine, but not fully enough to balance the ecosystem and get rid of consequences. Since, the this charge contains elements, we can try to turn brine into a source of revenue. Reverse osmosis (RO)Is cheaper and more efficient. Advances in membrane technology means facilities require less pressure and energy to filter sea water. As a result of which, RO produces less Brine. Moreover, converting the brine can be economically and ecologically beneficial, converting it into useful products followed by chemical process an electrolysis can produce The desired product. It can be converted to sodium hydroxide and hydrochloric acid . The acid could be used for cleaning parts of the desalination plant and also, used in chemical production as a source of hydrogen.
Some of the facts of desalination plants are:
- Currently, the world produces more than 100 billion litres ( about 27 billion gallons) which leaves a similar volume of brine.
- The top three desalination countries are Saudi Arabia, with 17 per cent of global output, United Arab Emirates (UAE) with 13.4 per cent and the United States ( US) with 13 per cent.
- It takes about 2 gallons ( 8 litres) of seawater to make 1 gallon ( 4 litres) of freshwater.
- Desalination plants operate in more than 100 countries.
Recent innovations in ocean desalination process
- Many new technologies based on machine learning, the sensor has been used.
- Many companies and startups have taken initiatives.
- Scientists are trying to turn renewable energy which reduces the cost of the process as well as the energy cost.
- Small prototypes plant has started running on photovoltaic power, and Dubai is currently working on a project to power all of its desalination with solar energy by 2030.
Ocean desalination plants are very vital, as they can prevent water scarcity. If new innovations, technologies, renewable energy, a decrease in brine concentration, and converting to useful products can be obtained. No worries about the future. Let’s all hope that ocean desalination drawbacks will be resolved soon and make a world reliable, sustainable, and a safer place.
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