The Opportunities and Challenges of Desalination

Bringing Freshwater to the Remotest Parts of the Globe

The Llobregat River winds through Barcelona from the Serra del Cadi to the south of the city, where it meets the Mediterranean Sea. While its water comes from a fresh source, somewhere in the municipality of Suria, the deeper waters become saltier. Though treating the water gave the residents drinkable water during the 1950s, it would become clear that desalinating the Llobregat River was a better solution.

During the early 2000s, the Catalan Government conceived the Spanish National Hydrological Plan to supply safe drinking water in the Barcelona metropolitan region. With the Aguas Ter Llobregat (ATLL) assigned to design and construct the plant, Barcelona’s Sea Water Desalination Plant now runs alongside the mouth of river Llobregat and provides tap water to the 1.3 million inhabitants in the area. Today, the plant produces about 200,000m³ of water per day, making it the largest reverse osmosis (RO) desalination plant in Europe.

Desalination is becoming one of the partial solutions to the lack of water quantity and quality, especially in areas that don’t have immediate access to fresh bodies of water or regularly experience drought. Countries like Saudi Arabia, UAE, and Israel already have more than one plant, filtering and treating water in labs larger than the one found in Barcelona. Without their plants, these countries may have to rely on imported supplies as their primary source.

The steady industrialisation of this industry has led to more investments in research and increasing development of desalination equipment. Just in 2020, the coronavirus outbreak has driven the interest and demand of clean water sources in many parts of the globe. While the pandemic may have hampered further manufacturing of new technology, the value for the global water desalination market rose to USD 13.12 billion and is projected to increase by 7.1% in 2028.

With this projected increase, there are evident advantages to desalination.

The Opportunities: Water Management for the Future

Safety of desalination process

With decades’ worth of research and testing, the desalination process is proven to filter out toxins when performed correctly. And it doesn’t need a large-scale application with sophisticated tools. Individuals may use the same distillation technology to treat undrinkable water during emergencies. Whether desalination provides a viable drinking source regularly or a one-time occasion, it is a proven technology founded on widely accepted scientific concepts.

Before desalination became a solution to treating saltwater, early scientists studied and practised distillation. In Aristotle’s Meteorologica, he has correctly observed that when saltwater turns into vapour, it does not remain salty when it condenses. Based on this definition, desalination became the modern application of distillation.

Purifying freshwater from seawater began in the 1930s, where plants still used distillation-based materials to treat water. This involved heating technologies, multistage flash distillation, multiple-effect distillation, and mechanical vapour compression, processors. Large-scale machines in the Middle East will heat the water, then condense the vapours to extract desalinated water.

However, thermal desalination costs a lot of money and consumes tonnes of energy.

Later in the late 1950s, it was discovered that reverse osmosis (RO) membrane distillation strategies are more energy-efficient solutions. From polymeric cellulose films to asymmetric cellulose membranes, these new materials had low permeabilities that separate the salt from the sea or brackish waters. During its earlier stages, the RO membranes were yet to be applied to large-scale desalination plants.

It was in 1980 when Cadotte patented the three-layer thin-film composite (TFC) membranes that met the industry standard. This innovation uses three layers that allow water to flow through (high permeability) while filtering out the salts and other solutes (high water selectivity). This technology is now called interfacial polymerization, a scientific standard that still stands today in the RO membrane manufacturing industry.

With the changes in formulation, manufacturing, and processes, energy consumption and recovery have drastically improved. Modern desalination technology is now more sustainable and easier to implement for seawater, brackish water, and even wastewater treatment.

More recent advances to desalination membranes include channel-based transport, where biological cell membranes have protein channels that transport water faster and more efficiently. With more materials, technologies and growing interest to improve this industry, more experts are testing new sustainable solutions.

Now that companies and governments have access to reverse osmosis technology, saltwater is easier to process and requires less chemicals and desalination equipment is easier and cheaper to install.

Aside from this, desalination is also another way to restore natural marshes, rivers, and deltas. If these plants use reverse osmosis technologies that don’t pollute the water with harmful chemicals to create drinking water, freshwater marine life can be preserved and protected.

Long-term solution for food supply chains

In a bid to raise awareness and compassion, the United Nations released an article on world hunger and starvation. Due to the rapidly changing climate, many people lack access to their basic needs. Last 2017, humanity witnessed many food shortages and droughts throughout the globe. While natural calamities happen for varied reasons, people normally suffer from malnutrition, low immunity, and chronic hunger, often resulting in high mortality rates. During the two-year famine in Somalia last 2011, the United Nations reported that around 260,000 people died from lack of food supplies, water access, and international aid. While installing desalination plants won’t solve the problems overnight, having potable water can give impoverished families the chance to survive for another day.

As weather patterns are also changing, drought is becoming another environmental problem in different parts of the globe. While some cities are experiencing more rainfall and are at risk of flooding, other places go for extended periods without rain. Temperatures are constantly growing higher, with summers more severe. With climate change growing more erratic, experts say that droughts will become more frequent, intense, and long-lasting. In the future, droughts will not only pose a long-term problem for Middle Eastern and African countries but also parts of the United States and Europe. During the harshest climates, having access to desalinated water can help those who need it the most. Although it’s not always a tailor-fit solution in every situation, water is one of humanity’s basic needs and a critical component for survival.

For several land-locked states that have to share the same water supply to irrigate their crops, generate electricity, and create drinking water, desalination can provide a better alternative. Cases like the Acheloos River in Europe and the Colorado River in the US show us that reservoirs and dams have lower water levels today than in the year 2000. Despite the lowering supply, the demand for freshwater remains at an all-time high. Using desalination methods can change this issue and prevent any political wrangling and water diversion talks.

Water movement as sustainable energy source

Desalination plants can also become a source of renewable energy. When water starts flowing into the facility, the water movement is strong enough to turn hydropower turbines. Scientists and experts can leverage this opportunity and install these turbines at the inlets to generate power for the surrounding communities or even for the facility itself. This type of technology is already applied at dams and water reservoirs and already yields favourable results.

So far, about 24% of the world produces and uses hydropower and their primary source of electricity. As hydroelectric power plants are already the most efficient renewable energy source, these desalination facilities can also become a reliable domestic source of energy.

Fresh water becomes more accessible

Water is one of humanity’s basic needs. People need it to get through our daily routine, when they cook, drink, bathe, and clean. On a larger scale, it stabilises economies and allows trade. By 2020, The Middle East and Africa will have a 40% share of global revenue for water desalination equipment. Brought about by an increase in population, many nations in these continents will support infrastructure to bring potable water to conflict-hit areas. In Asia Pacific countries such as India, China and Bangladesh are experiencing a depletion in groundwater supply from increased irrigation for agriculture. With the right desalination strategy, these countries may commission or manufacture the equipment they need.

When there is a consistent supply of freshwater, everyone benefits.

In line with that, desalination now becomes a long-term solution when creating water reserves for the next generations. Many plants already have the foundations: hydropower facilities, storage reservoirs, and manmade lakes. When lakes or rivers dry up, this solution can keep dying ecosystems alive.

Water independence for rural municipalities

Many communities without immediate access to freshwater still depend on their neighbouring cities or states for consistent water supply. There is a global trade in water to help other countries meet the needs of their people. With the need to provide water security, the US, China, India, Brazil, Canada, Australia, Indonesia, and Germany are major water exporters to different parts of the globe.

Instead of using taxpayer funds to buy freshwater from another city or country, these can be invested by putting up desalination plants to help small towns produce their water supply.

Economic opportunities for different industries

As the desalination method also produces a high salt concentration, many industries can take this waste and use it in several ways. The icing industry can take the byproduct and use it for de-icing or even transportation. This can boost the local economy of the area, providing jobs for more people.

The Challenges: By-products and Waste Disposal

Chemical waste disposal and brine management

While the main output is fresh drinking water, desalination also churns out several byproducts that need to be disposed of properly to keep people and their environment safe. The primary byproduct of the entire process is brine, liquid with high concentrations of salt. This is often pumped back out to sea, where it sinks to the seafloor and negatively affects the ecosystem, oxygen levels, and salt content. When the sodium levels of seawater increase, marine creatures are ill-equipped to manage the sudden change. Too much salt in the water will also decrease the oxygen levels, causing both aquatic flora and fauna to suffocate and die.

Apart from brine, chemicals are also used to treat the water to make it safe enough to drink. Some facilities use hydrogen peroxide, chlorine, and hydrochloric acid during the pre-treatment and cleaning process. After this, the chemicals must be disposed of properly to prevent them from entering the water table and causing more damage.

Negative impact to marine life and ecosystem

Often chemical discharges or brine dumping around a desalination plant can negatively affect the smallest creatures in the food chain. Phytoplankton forms the base of all marine life, normally eaten by zooplankton, small fish, and crustaceans. Without these microscopic algae, the food levels are reduced and can impact the entire ecosystem.

There is also a widespread concern for entrapment when a desalination facility brings in water for processing. Marine life like plankton and small fish can get trapped among the membranes, endangering their life.

There are also times when the water released by the facility can be harmful to human health, as well. If the chemicals were not disposed of properly, the chemical byproducts can leach into the water table and expose people and plumbing systems to acidic waters. When the pH balance of the water is too high, it can mix with other harmful elements in some plumbing systems and poison you.

High energy consumption

While desalination technologies have come a long way and have made several improvements, these plants still need a significant amount of power. During the past few years, scientists have been scrambling to find more sustainable and renewable sources of energy to prevent climate change from worsening.

Expensive desalination technology

Though desalination pumps and filters are available for a single household living in a coastal community, these materials can cost approximately USD 5,000. This is only telling of how much countries or businesses need to invest when they want to fund an industrial or national plant. When looking at the desalination models in the Middle East, a gallon of water can cost up to USD 6.50. The cheapest ones in the United States cost about USD 1.10 per gallon.

And consumers won’t only be paying for the water. The cost of access for the average consumer can be 70% to 75% higher than what they normally pay. City planners will have to consider this when constructing a facility that is experiencing water scarcity.

When everything is accounted for, the practice of desalination and reverse osmosis membranes are not widespread enough to cheapen the cost of the technology and expertise needed.

Sustainability: Cooperation Against Climate Change 

Glen Engineering is experienced in desalination piping solutions for more than two decades. We not only make sure that our products and processes meet the highest standards of quality control, but we also ensure lower costs. 

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