Desalination is the process of removing salt and other minerals from seawater to make it drinkable. It is an increasingly popular solution to water scarcity, as it can provide fresh water in areas with limited access to clean water.
While desalination has long been used in coastal areas around the world, its popularity has grown in recent years as freshwater becomes increasingly scarce. The process is not without its critics, who argue that it is expensive, energy-intensive, and poses ecological problems.
Despite these concerns, desalination remains a promising solution to the planet’s water crisis, and many countries are investing in the technology. Here’s a closer look at how desalination works and why it could be a vital part of the solution to the world’s water scarcity crisis.
How it works
Seawater desalination is the process of removing dissolved minerals from seawater to make it suitable for human consumption. The most common desalination method is reverse osmosis, which involves forcing seawater through a semipermeable membrane.
The pores in the membrane are tiny enough to allow water molecules to pass through but exclude larger salt molecules. As a result, freshwater can be collected on the other side of the membrane while the salt concentration in the seawater increases.
While reverse osmosis is the most common method of seawater desalination, other ways, such as distillation or ion exchange, can also be used.
There are two main methods of desalination: reverse osmosis and thermal distillation. Reverse osmosis uses a semipermeable membrane to filter out salt and other impurities from water – like PFAS; RO removes PFAS highly effectively at up to 97%. Thermal distillation, on the other hand, uses heat to evaporate water, leaving behind salt and other minerals.
Pros and cons
There are many advantages to seawater desalination, including the following:
- It is a renewable source of freshwater.
- It can be used to combat water scarcity in coastal areas.
- It does not require chemicals or other pollutants to operate.
- It produces drinking water that is safe and clean.
- It helps to preserve natural freshwater resources.
- It can be used in emergencies to provide clean drinking water.
- It can be used to improve water quality for marine life.
However, while seawater desalination offers a potential solution to the problem of freshwater shortages, it is not without drawbacks.
One of the biggest challenges is the high cost of setting up and operating a desalination plant. According to the World Bank, the average cost of producing freshwater from seawater is about US$1.50 per cubic meter—four times more expensive than traditional sources such as groundwater or surface water.
In addition, desalination plants require a lot of energy to operate, contributing to greenhouse gas emissions.
There are also ecological concerns. Some experts have argued that de-sal plants cause disturbances to marine habitats when they suck ocean water for treatment. The process ends up sucking out fish, fish larvae, eggs, and plankton, killing them instantly in most cases.
Additionally, desalination can also lead to the build-up of brine, a highly concentrated solution of salt and other minerals. If the brine is not properly treated and disposed of, it can damage marine ecosystems.
Finally, desalination produces brine—a highly concentrated waste product that must be appropriately disposed of. For these reasons, seawater desalination is not always the best solution to the problem of freshwater shortages.
Averting a water crisis
Worldwide, the demand for water is growing at an unsustainable rate. According to the UN, by 2025, 1.8 billion people will live in areas with severe water shortages, and two-thirds of the world’s population will face acute water stress.
One way to ease the pressure on our freshwater supplies is to turn to seawater desalination. Although it is a relatively expensive process, it is becoming increasingly cost-effective as technology improves.
Moreover, desalination can positively impact the environment by reducing the need for wastewater treatment facilities. Wastewater treatment takes a lot of energy and chemicals, which damages ecosystems. Desalinating seawater can help us to avoid these negative impacts and safeguard our planet’s limited freshwater resources.
Some of the biggest desalinating countries in the world include Saudi Arabia, the United Arab Emirates, Kuwait, Israel, Qatar, and Australia. These countries have all invested heavily in desalination to combat water scarcity.
Seawater desalination is a technology that is constantly evolving. Among the newest developments is membrane distillation, which uses heat and pressure to remove salt from water. This method is more energy-efficient than traditional reverse osmosis, producing water almost entirely free of impurities.
Another promising new technology is nanofiltration, which uses tiny pores to filter out salt and other particles. Nanofiltration membranes are durable and can be reused many times before needing replacements. In the future, seawater desalination could play a vital role in meeting the world’s demand for fresh water.
With technological advances, desalination plants will become more efficient and less expensive to operate. As a result, this vital technology will become increasingly accessible to communities around the globe.
The planet is facing a water crisis. And while there are many factors contributing to this, one of the biggest is the ever-growing demand for fresh water. With the world population projected to reach 9.7 billion by 2050, it’s clear that we need to find a way to increase the supply of fresh water to meet this demand.