Desalination technology: The ultimate weapon to fight against water crisis

By: Muhammad Daniyal Kamal

We all think that the water we drink or use for different purposes is unlimited. Based on a report by World Wildlife Fund (WWF), two third of the population all over the world will experience water scarcity by 2025. This is because of the droughts that are driven by global warming.

The question arises; How can we get over this massive coming water crisis?

The answer is, there is a sea of desalination technologies that have been developed and are on their way to be launched. For instance, the solar domes in deserts or the nano-membrane filters most of the seawater in minutes, making it drinkable.

Let’s get started to find out! How nanotech can help us to win our war against the water crisis?

As the surface freshwater is running out and it has become difficult to get to aquifers because of the expensive technology to extract. The majority of countries have their eyes on seawater, as it is quite good because our Earth contains 97% water as marine water.

Desalination plants have been increased gradually over the last forty years. Basically, desalination is a process that takes away the mineral salts from water. This has been achieved by the technique named Reverse Osmosis (RO). Here a semipermeable membrane is being used that traps all the salts from the seawater making it purely drinkable. For example, desalination technology is being used by Dubai, a city in United Arab Emirates (UAE). Dubai gets 90% of its freshwater through desalination. But this process comes with a price that we have to pay.

It is an energy-demanding process. The desalination process needs high pressure to run efficiently, as stated in a report by Dubai Electricity and Water Authority. This means the use of fossil fuels to balance out the high pressure which is required. It as a result, leads to 76 million tons of CO2 emissions per year through desalination plants all over the world. We could come up with a prediction that by 2040, these emissions will skyrocket to 500 million tons of emissions per year. We will have to look for a low-carbon alternative to lessen the CO₂ emissions.

Also, this desalination process has another environmental concern. It produces a very toxic solution named as “brine” as a byproduct, as explained in an article published in Scientific American. This byproduct then gets dumped up into the oceans which is threatening our local marine ecosystems. The salts then settle down into the deep water, which then consumes the oxygen. It kills marine animals, published in an article by BBC News. Now, the RO could produce up to 2 liters of brine for every liter of clean water which has been produced.

To combat this, Saudi Arabia is working on a cheaper and cleaner desalination technology. Saudi Arabia will then be listed among the top nine countries which will be facing the problem of water stress by 2040. As it is working on desalinating the Red Sea to make fresh water, as revealed in NEOM.

Furthermore, Saudi Arabia becomes the first country that is using solar technology to make the first-ever solar dome at Neom. Neom will be a mega-city that Saudi Arabia is developing along the country’s Northern Red Sea Coast.

The design is based on concentrating solar power technology, essentially contributing to the large mirrors that will focus the sunlight onto a glass of semi-sphere.  By doing this, it will follow the principle of the greenhouse effect. The whole process could be read further at the website Solar Water PLC. This will then vaporize the seawater which is contained in the giant metallic pod. It will then pump all the steam out and will perform the process of condensation. This will make clean water. This plan will rely on solar energy, based on the ideas of developers. It will contribute to being carbon neutral.

Here, a question arises. What will happen to the waste being produced?

The salts which will be extracted, contribute to making the battery components and for fertilizers too.

Solar domes are not the only alternatives to RO. There are also new materials being used for distillation, which are more energy efficient.

One of the technology is membrane distillation, which uses microporous membranes. These microporous membranes are used to separate the two solutions at different temperatures. In the case of water, we will be having seawater and freshwater. The temperature gradient on the membranes leads to an increase of vapor pressure difference. It allows the water vapors to pass through the membranes. Green engineers have developed a nanofiber membrane that desalinates seawater with an efficiency of 99.9%. Water scarcity could prove to be lethal for our society. We have to value our freshwater and utilize it with complete responsibility. But the use of these sustainable desalination technologies will prove to be vital.

The writer is a student of Quaid-i-Azam University, Islamabad. Currently, He is an intern at Pakistan Environmental Protection Agency (Pak-EPA). He can be reached at [email protected]