What Is Desalination?
With water scarcity being a major issue in Australia and around the world, desalination creates a reliable water supply not dependent upon rain. This incredible technology is now used by many countries to help create a sustainable water source.
But what is desalination? The simple science behind the desalination process is that it removes mineral components, primarily salt, from saline water. Read on to discover whether desalinated water is truly the sustainable source we are hoping for and other considerations.
Is Desalinated Water Safe?
Desalinated water is safe. All drinking water produced by desalination plants must meet strict quality guidelines. In Australia, these are set by the stringent Australian Drinking Water Guidelines (2011). Many desalination plants are fitted with delivery points, so that water authorities may regularly monitor water quality.
Desalinated water is still treated with fluoride, chlorine and other chemicals. These have their own set of issues, including affecting the taste and balance of your water, as well as potential side effects that are damaging to your health, such as electrolyte abnormalities from demineralised water.
Add to this the disinfectants that are put into our water to counteract the bugs, bacteria and organic matter in water pipes and you’re left with impure water and water devoid of beneficial minerals needed to hydrate.
To avoid harmful repercussions, consider choosing an effective benchtop water filter to reduce fluoride, chlorine, nasty chemicals, heavy metals and contaminants from drinking water. As well as the added benefit of using natural mineral stones to replenish the beneficial minerals (magnesium, potassium, chloride & sodium) which are essential in your drinking water for cellular hydration.
Desalination and Water Treatment
Because Australia has severe issues with water scarcity, with many regions lacking any freshwater supply at all, we are at the forefront of desalination. Currently Australia has over 30 desalination plants, with every state in Australia now using desalination plants to help boost water supply.
Australia has desalination plants that follow these basic water treatment processes: coagulation, flocculation, sedimentation, filtration (using either distillation or reverse osmosis desalination method - outlined in more detail below) and disinfection of water.
This turns seawater into drinkable water, which is fantastic. The trouble is, this process alters the natural chemistry of the water, stripping it of beneficial minerals and pumping it with chlorine and many other chemicals. These minerals are removed through the process of reverse osmosis because their molecules are larger than water, meaning the much-needed magnesium, calcium, iron and more might not be present in your drinking water.
Australia has desalination plants that follow these basic water treatment processes: coagulation, flocculation, sedimentation, filtration(using either distillation or reverse osmosis desalination method - outlined in more detail below) and disinfection of water.
This turns seawater into drinkable water, which is fantastic. The trouble is, this process alters the natural chemistry of the water, stripping it of beneficial minerals and pumping it with chlorine and many other chemicals. By using a zazen Alkaline Water System, you revert the water to a purer naturally balanced form in a state ideal for hydration.
Desalination across the Australian States & Territories
The Gold Coast Desalination Plant has the capacity of producing 49 gigalitres of drinking water per year for residents of the Gold Coast, Brisbane, and Logan. Unlike other states, the plant itself is actually located 1.5 kilometres out to sea on what has become artificial reefs that have quickly become the residence of a myriad of sea-dwelling flora and fauna. The water undergoes stringent and frequent testing in order to meet the regulatory standards set out by the Australian Drinking Water Guidelines 2011.
Western Australia (WA)
Western Australia’s Kwinana-based Seawater Desalination Plant has been up and running since opening in 2006, and is responsible for producing 15% of Perth’s water supply. There is a strong focus from operators to protect the surrounding marine environment, with efforts to undertake constant review of key locations, offshore infrastructure inspections, and performance tests on diffuser systems. Through partnerships with local groups, such as the Perth Region Natural Resource Management group, their efforts have prevented widespread erosion and has encouraged native fauna to return to the area after construction was finished. With all of this positivity, the plant still practices reverse osmosis, meaning that while the drinking water may meet minimum drinking guidelines, it is possible needed minerals will be missing when consumed by WA residents.
South Australia (SA)
South Australia also relies heavily on the water source from the ocean. The state has multiple plants with the largest, known as the Adelaide Desalination Plant, located in Lonsdale, boasting a capacity of 100 gigalitres per year. The climate-independent water source is pumped along 11 kilometres of pipeline to storage tanks to be blended with treated water from the reservoir. Nearly 200 billion litres have been produced, with production slowed to a halt in the wetter months (May – August) as the demand for water isn’t as high.
Northern Territory (NT)
Northern Territory does not currently have a desalination plant established. The Territory Government has begun exploring solutions to secure future water supplies in collaboration with the Department of Industry, Tourism and Trade and the Australian Government.
The Victorian Desalination Plant was constructed in 2012 after the rising demand became evident from a growing population and the alarming effects of climate change (culminating in the Millennium Drought in which water storage in the largest reservoir dropped to only 16.5% capacity). It now delivers up to 150 billion litres of drinkable water each and every year (approximately 33% of Melbourne’s annual water demand). Once the plant removes the dissolved salts from the seawater via reverse osmosis, the water is tested for quality at all delivery points whilst travelling through 84 kilometres of two-way pipelines connecting areas throughout Western Port and South Gippsland.
New South Wales (NSW)
Sydney also has been working hard to secure future water supplies for its citizens, especially those in the populous Greater Sydney area. The Sydney Desalination Plant may supply up to 250 million litres of treated drinking water each day, equalling approximately 15% of the area’s water demand. While it is always ready to produce drinking water, the Metropolitan Water Planis only activated for supply once the dam storage dips to below 60% capacity. It is also one of the only plants to be completely powered by renewable energies.
Seawater contains around 130g of salt per gallon. Desalination reduces these salt levels to well below 2g per gallon, the limit for safe human consumption. This desalination process is conducted using two main methods: distillation and reverse osmosis.
Desalination dates back a long way. In the 4th Century B.C., Aristotle is regarded as the first to theorise how to remove salt from seawater. He suggested successive filters, but sadly was unable to invent them in his lifetime.
The first recorded example of desalination came around the year 200 A.D., when sailors were noted for collecting the freshwater steam from boiling saltwater. This began a trend of desalinating seawater with simple pans and boilers on ships.
The sailors’ desalination method of evaporating water, which leaves the salt and other impurities behind, is a primitive form of the distillation method, or thermal desalination, which is still used today, albeit mostly by older desalination plants.
This is because, since the 1950s, reverse osmosis has replaced distillation as the primary method of desalination. In simple terms, reverse osmosis forces seawater through a semipermeable filter membrane at high pressure, allowing water molecules to pass through but leaving the larger salt molecules (and chemicals) behind.
For decades, the major hurdle for reverse osmosis was its cost. However, as technology has proliferated in recent times, seawater reverse osmosis has become more affordable, and thus a much more viable, attractive alternative to distillation.
Over 2000 years after Aristotle originally envisioned the idea, reverse osmosis is now the primary desalination method used globally. The greatest challenge of desalination is the stripping of all minerals from the water, these minerals are required for the body to absorb water for the purposes of hydration.
Desalination Pros and Cons
Providing water to the predicted 10 billion people expected to be alive in 2050 is one of the biggest challenges of the 21st century.
Moreover, water use has been growing twice as fast as population growth, causing more and more communities to suffer water shortages already. This drives the demand (and therefore prices) for freshwater supplies higher, making desalination increasingly attractive.
Providing a climate-independent source of water for critical human needs and economic development (such as agriculture), and providing water security against the effects of climate change, a growing population and drought, are the main desalination advantages.
Desalination works best in countries where rainfall is low, has coastlines (ideally close to major cities where demand is highest), and access to cheap energy and wealth to invest in and maintain desalination.
The first desalination plants in the mid-1960s were hailed as a great solution that would make our oceans drinkable. But extracting salt is not without negative environmental impacts.
Both the reverse osmosis and distillation desalination processes use a lot more energy, and thus produce a lot more greenhouse gases, than traditional water treatment methods.
Reverse osmosis requires large amounts of energy to generate the high pressure that forces the water through the filter. Current methods require about 14 kilowatt-hours of energy to produce 1,000 gallons of desalinated seawater.
The increased energy demand means that desalination is more expensive than traditional water treatment methods too. Depending on local energy prices, 1,000 gallons of desalinated seawater can cost around $3 or $4 USD. By comparison, large-scale municipal seawater desalination projects in Australia cost approximately $1-$4 per kilolitre, with energy use representing 50-70% of total operating costs.
This sounds affordable but is often more expensive than pumping water out of the ground or importing it. The high cost of desalination also means that poorer countries that would benefit greatly from desalination simply cannot afford the infrastructure.
Costs and logistical issues are then further compounded if desalination plants are a long distance from populated areas, as this requires long water pipes to be built and high volumes of water to be transported over large distances.
The environmental cost of desalination is heightened when factoring in the very salty, slushy brine, the by-product of membrane desalination. Roughly 142 million cubic metres (equivalent to 56,800 Olympic swimming pools) is created and returned to the sea every day, together with chemicals used during the desalination process.
Due to its dense concentration, this brine, enough to cover the entire surface of Germany, sinks and spreads along the seafloor, where it can interfere with entire marine ecosystems. As a pollutant, it must be disposed of carefully.
The good news is that breakthroughs in desalination are helping to lower the costs, energy consumption and its environmental impact.
For example, in 2007, Australia's largest scientific research agency joined with nine major universities in a membrane research program to reduce desalination energy costs, as well as maintenance costs associated with gunk sticking to membranes and fouling them up.
Further positive news is that desalination plants are adopting more renewable energy too. For example, Sydney’s Desalination Plant can supply up to 250 million litres a day, which is up to 15% of its city’s water needs. And the plant is 100% powered by renewable energy.
Many other Australian desalination plants are also powered by accredited ‘Green Power’, such as wind energy. But while this is beneficial to the environment, it can result in a significant increase in operating costs, due to the premium attached to renewable energy. But, as renewable energy becomes more affordable, desalination plants should too.
Desalination At Home
Desalination is not just limited to industrial, large-scale plants. In fact, you can desalinate water at home, although these have a number of limitations.
You may have seen a survivalist movie or video where someone puts water in a bowl, places a mug in the middle and covers it to capture the evaporated water and drip into the mug when put in a hot spot (either using the natural sun or any other form of heat).
This rudimentary distillation method is similar to what the sailors used to do. Unfortunately, this bowl and mug method will not produce much water and is better suited for a science fair project than a sustainable source of water.
A solar still employs much the same technique, just with a large hole in the ground as opposed to a bowl, with vegetation added in for extra moisture, and the hole securely covered with a large plastic sheet or similar. Fancy solar stills make use of more sophisticated and carefully constructed entrapments. Again, while this has its merits and charms, it is not a practical solution for most households.
There are also a number of home water distillation systems that imitate desalination plant processes. These home water distillation systems can provide contaminant-free, drinkable water from seawater. However, these types of systems are often very expensive and critically lack the beneficial minerals required to hydrate.
No matter how you get your water, be it desalination or not, the zazen Alkaline Water System can enhance it with electrolytes and key minerals to keep you hydrated and functioning at your fullest.
We hope this has helped you learn more about desalination and the origins of your water. For more information about water and health, head over to our informative blog section.
Water Corporation, Perth Seawater Desalination Plant, https://www.watercorporation.com.au/Our-water/Desalination/Perth-Seawater-Desalination-Plant
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