How does desalination alleviate water scarcity?
Problem: Water covers 70% of the earth’s surface but only 1% of it is fit for drinking for humans hence, we are in a situation of water scarcity as the population grows this will only get worse.
Solution: So, we use desalination process to make salty sea water fit for drinking.
What is desalination ?
Desalination is the process of removing salt and other impurities from seawater or brackish water, making it suitable for human use or irrigation. This is done through methods like distillation or membrane filtration to produce freshwater from saline water sources, addressing water scarcity in arid regions or areas with limited access to freshwater.
Desalination Plant
A desalination plant is an industrial facility designed to extract salt and other impurities from seawater, producing freshwater suitable for various purposes such as drinking, irrigation, and industrial processes. These plants typically utilize either distillation methods, such as multi-stage flash distillation, or membrane filtration techniques like reverse osmosis, to separate salt and impurities from the water.
The largest water desalination plant (By capacity) is located at Shoaiba on the Red Sea Coast of Saudi Arabia, hosts a total of 8 desalination facilities and is operated by the The Saline Water Conversion Corporation (SWCC), with a total desalinated water production capacity of 2,998,000 cubic meters per day as verified on 7 December 2023.
The Shoaiba plant uses a Multi-Stage Flash Distillation (MSF) process.
Membrane filtration method
Membrane filtration method is based on osmosis, in a desalination plant using membrane filtration method five major steps are followed:
- Sea water intake: Saline sea water is taken from the sea slowly so it does not damage the aquatic life.
2. Screening: Screening of water Filters out seaweed and other ocean debris.
3. Ultrafiltration: The water the passed through series filters which consist of 7000 tiny straws with holes that are smaller than a human hair capable of rejecting viruses and bacteria.
4. Reverse osmosis: The process of movement of solvent through a semipermeable membrane from the solution to the pure solvent by applying excess pressure on the solution side is called reverse osmosis.
Here the water is pressurized which takes a lot of energy to do so and pressurizing of water is one the major things which makes membrane method unsustainable due to its high energy requirements.
5. Water treatment: Water obtained from the reverse osmosis process is treated with similar to the way we treat traditional water sources like ground water. Minerals are added and the water is disinfected to stabilize it ad make it safe for drinking.
Alternate method of desalination: Boiling of Sea water (Distillation)
Salty sea water is boiled and condensed water vapour is released which is used as fresh water, this is method is neither easy nor cost effective.
Since water has an extremely high specific heat capacity it needs a large amount of energy to get it to boil, all this heat energy comes from fossil fuels which leads to global warming and which will then cause an increase in amount of water that needs to be desalinated.
This method will also give out ultra-heated highly salinized brine (solution of sodium chloride (NaCl) and water (H2O)).
Hence this method is not at all sustainable.
Membrane method is also not efficient if looked from a long-term perspective but it is certainly more efficient than boiling of sea water.
Problem with desalination plants
There are more than 18,000 desalination plants operating across the globe. But, those plants provide less than a percent of global water needs even though they consume a quarter of all the energy used by the water industry. The oceans are a nearly unlimited resource of water but in order to make it safe for drinking we have to treat and desalinate the salty sea water but the technology used by us is not efficient when the output is taken into consideration.
Oneka on desalination
Oneka is a Canadian company develops and commercializes autonomous desalination systems that use the power of the waves to make fresh water, it is located in Sherbrooke, Quebec
Oneka Technologies turns seawater into fresh water in an innovative and sustainable way by harnessing wave energy. Over the years, they have developed great expertise in the exploitation of wave energy and are now able to offer high-performance and reliable patented solutions to their customers.
Oneka’s water quality is adjusted to meet the World Health Organization standards and/or local water standards.
The Benefits of Oneka sea water desalination technology
All-in-one solution, Zero GHG emissions, Zero electricity, Zero land space, Eco-friendly brine Safer water intake, Promotes growth of marine life, Scalable & modular system
They currently offer 3 different raft sizes: Ice cube, Iceberg and Glacier.
Oneka Iceberg
The Iceberg-class unit was developed to deploy commercial-scale projects for coastal communities, industries and resorts. One unit can provide water for 100 to 1500 people per day depending on consumption.
Unit Specifications:
Production capacity: up to 50 m3 (13k US gal)/day/unit (The production depends on wave height. The optimal quantity of buoys is calculated in order to meet water needs.)
Dimensions: 5 m x 8 m (16 ft x 26 ft)
Weight: 11,000 kg (23,000 lbs)
Oneka IceCube
From their larger scale desalination units, they downsized their most advanced technology to provide plug-and-play desalination buoys, the IceCube-class units, for humanitarian and natural disaster relief applications.
Unit Specifications:
Production capacity: 1 m3 (265 US gal) /day/unit
Dimensions: 1.5 m (5 ft)
Weight: 350 kg (772 lb)
Oneka Glacier
The Glacier-class buoy, currently under development, represents a major breakthrough for Oneka. It is capable of producing up to 500 m3 of fresh water per unit per day. Its deployment will meet the water needs of municipalities and large coastal industries, with the aim of significantly increasing local freshwater supplies.
Frequently Asked Questions:
The organization acknowledges that new technology is raising many questions in the minds of individuals. Here is the link to the answers of questions they received most frequently. — www.onekawater.com/faq
