Improving Access to Clean Water and the Role of Nanotechnology

Access to clean, safe drinking water is thought to be a basic human right. Yet, according to the World Health Organization (WHO), over 785 million people across the globe are without access to a basic drinking-water source. This has researchers around the world researching and developing a series of water treatment solutions and applications using nanotechnology.

Current WHO statistics are damning, making this an issue that must be addressed urgently as it is thought that around 2 billion people are using a contaminated water supply. In addition, over 485,000 people die each year from diarrhoeal related illnesses and diseases such as polio, typhoid, and cholera are once again being transmitted as a further consequence. Based on current trends and data, it is thought that by 2025 half of the total global population will be living in water-stressed or water-scarce areas.

 

While there are a wide-range of effective water purification methods and techniques including boiling, filtration, oxidation, and distillation, these often require high amounts of energy. Other treatment processes may include the use of chemical agents which is only possible in areas with an infrastructure that is up to par.

The more affordable and portable devices currently available are not always fit for purpose as they cannot guarantee 100% removal of harmful viruses, bacteria, dust, and even microplastics. So, it is thought that nanotechnology could offer affordable and accessible clean water solutions to the world’s most vulnerable populations.

Nanotechnology is a process that involves manipulating and controlling matter on the atomic scale. In the process of water purification, this involves using nanomembranes to soften the water and eradicate biological and chemical contaminants as well as other physical particles and molecules.

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What’s more is that nanotechnology is portable and can be incorporated into existing commercial devices which increases the likelihood that nanotech solutions could become a feasible option for areas of the developing world and places with limited infrastructure.

In recent years scientists have improved on conventional methods that use coagulants by taking their cues from nature, notably the ocean dwelling Actinia organism. Traditional coagulants, such as aluminum sulfate and other metallic salts can pull out larger contaminants by causing them to group together and settle. However, this method is not effective for smaller particles and molecules and often requires additional methods to ensure the water is clean. Thereby increasing the cost and use of energy as several techniques are required to ensure the water is safe.

Using nanocoagulants, scientists were able to synthesize organic and inorganic matter to replicate the structure of the Actina sea anemone. The researchers produced a reversable core-shell that can catch larger particles as well as the smaller ones when it turns inside-out. This is also a one-step process which removes the need for additional technologies and opens up the potential for minimizing water purification costs.

Another viable method of water purification currently in development that makes use of nanotechnology includes utilizing magnetically active nanoparticles to extract chemicals from water. The process enables the removal of toxins from drinking-water contaminants attracting nanoparticles that consist of magnetic phases. This solution would also be low-energy and could provide an economic advantage as well as health and environmental benefits.

Other proposals for nanotech solutions include using nanoparticles to break down microplastics and a rapid nano-filter that can clean dirty water 100 times faster than current methods. Researchers are also aware that most water purification methods require access to a constant electricity supply, but this can be a significant obstacle in places with limited infrastructure or areas damaged by extreme weather conditions.

One such approach is the creation of a self-sustaining biofoam that conducts heat and electricity by combining bacteria-produced cellulose with graphene oxide. The graphene-fused foam draws water up to the surface via the cellulose layer which accelerates evaporation. This results in a layer of freshwater which can be easily collected and is safe to drink. The biofoam is also lightweight and relatively inexpensive to manufacture making it an attractive alternative to conventional methods.

Thus, as the need for clean, safe water is very much still an urgent global issue, nanotech solutions offer new and essential possibilities for the water treatment industry. The next phase of development is the scaling up of nanotechnologies to improve access to clean water. Perhaps then the future can be one that offers a new hope to the expanding global population experiencing water-stressed and water-scarce conditions.

Re-Posted from AZ NAno – David J. Cross MA

COULD TECHNION RESEARCHERS SOLVE THE WORLD’S WATER CRISIS?

 

The World Health Organization (WHO) estimates that by 2025, about half of the world’s population will live in areas where there is a shortage of clean drinking water. Is it possible that the solution to the global water crisis is, literally, right under our noses? Technion researchers have developed a model for a system that separates the moisture naturally present in the air around us and converts it into drinking water. The patented system, and how it can help prevent the water crisis that awaits the world, was recently presented by Associate Professor David Broday of Technion’s Faculty of Civil and Environmental Engineering at a seminar on water, energy, treatment, and recycling.

“Water is available and free to everyone”

Associate Professor Broday, who developed the system together with his colleague Associate Professor Eran Friedler, explains that the idea is to take advantage of a resource that is constantly and abundantly present around us.

“The atmosphere is everywhere, and there is humidity everywhere,” says Broday. “No atmosphere is completely dry; there is humidity even in the air of the arid Sahara Desert. In fact, the amount of moisture in the atmosphere is equal to the amount of fresh liquid water in the world (i.e. not accounting for glaciers). This is a huge amount of water freely available to everyone with no restrictions.”

Harvesting moisture from the air is not new, and there are several companies around the world that have already developed technologies around this concept. This existing technology, says Broday, is similar to a domestic air conditioner that cools air that comes from the outdoors, uses the cold air, and discards the water condensed during the cooling process. In the case of moisture harvesting technology, it is the air that is discarded and the water that is used. “The existing technology actually takes air and cools it to extract the moisture from it,” explains Broday. “It is brought to a state where the moisture condenses on a cold surface and drips from it, then it is collected and used for drinking.”

But, says Prof. Broday, there is a problem with this technology. “Air is composed not only of moisture but also of other gases like oxygen and nitrogen, and this technology invests in cooling them along with the humidity,” he explains. “Air volume contains only 4 to 5 percent humidity, at best, which is a very small part. A lot of energy is invested in cooling something of which more than 90 percent doesn’t get used at all. This is an ineffective use of energy. This process is expensive to begin with, and in effect most of the energy goes towards cooling material that we are not at all interested in.”

With their system, the researchers propose to optimize this process by separating moisture from the air before cooling it. Doing so will make it possible to invest energy in cooling only the moisture itself and converting it into available water.

 

Global Maps for ‘Water from Air Resources

 

The Technion system is also a radical departure from attempts by others who are trying to develop membranes that will separate the moisture out of the air (like the desalination process in which membranes separate salt from seawater).

“The alternative we are proposing is based on the use of an absorbent substance called a desiccant, which is a highly concentrated saline solution that naturally absorbs the moisture from the air when it comes into contact with it,” Broday explains. “The idea is to use this material to absorb a large amount of moisture from the air, and to cool the moisture only after this has been accomplished.”

“Our system is composed of several stages,” he explains. “In the first stage, it will circulate air to transfer moisture from the air to the dessicant, which is in a liquid state. This cycle is repeated over and over again, as the dessicant collects more and more moisture from the air. In the second stage, we transfer a small portion of the dessicant to another part of the system, where we produce conditions that cause the desiccant to release the moisture. This moisture is then condensed and turned into water. For this to happen, we need to cool it down – this is the third stage, which is actually similar to what happens in existing systems; but unlike them, at this stage we cool 100 percent humidity rather than air, only a fraction of which is relevant to our needs.”

Drinkable water in the middle of the desert

According to the researchers, their proposed system isn’t just more energy-efficient. It also provides cleaner water. After cooling, the water collected in the system should be suitable for immediate drinking, as opposed to existing technologies in which air is cooled in its entirety. “If the air spinning in a system – in addition to moisture – contains disease-causing bacteria, when it is cooled and the water condenses, the bacteria in the air may also find their way into the water,” Broday explains. “This means this water may require purification to make it fit for consumption.­­­­

“In our system, the air does not meet the cooling coils at all – only the moisture that is separated from it. As a result, even if the air contains substances we do not want to reach the water, they are absorbed into the dessicant but not released in the next stage,” he says. “Even if bacteria, dust, and the like have accumulated, because it is a very concentrated salt solution, it simply dries up. So the resulting moisture would be clean, and the water, pure. Of course they would be tested, but the need for water treatment processes would probably be much smaller, which is expected to lower the price of using it.”

Using the system would not be without cost, and the researchers emphasize that their method of producing water is more expensive than desalination.

“Where water can be desalinated – that is, in proximity to a source of water such as a sea or brackish lakes – desalination is the preferred option,” explains Broday. “Economically speaking, it makes sense to desalinate and produce a system for transporting water to places that are up to about 62 miles away. Any further than this, and the cost of transportation becomes more expensive than the cost of desalination. There are also towns located close to rivers where water is suitable for use. But when we take all of these out of the equation, there are quite a few places in the world where desalination and direct use are not economically viable.”

The Technion researchers’ system has not yet been built, but they have already performed simulations with a model to see how the system would function in different climatic and humidity conditions. “We wanted to see whether the system can be used in areas where the air is arid,” says Broday, “for example in the Sahara Desert, and in Yemen, which is currently experiencing a severe hunger crisis and lack of drinking water.” He says the system is both relatively small and allows for distributed production of water that does not depend on one source from which the water must be piped to all the other localities.

“We strongly believe in the idea and the preliminary results,” says Broday. “But we still have to put the theory into practice. That’s the next stage.”

The Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and a key to Israel’s renown as the world’s “Start-Up Nation.” Its three Nobel Prize winners exemplify academic excellence. Technion people, ideas and inventions make immeasurable contributions to the world including life-saving medicine, sustainable energy, computer science, water conservation and nanotechnology.

American Technion Society (ATS) donors provide critical support for the Technion—nearly $2.5 billion since its inception in 1940. Based in New York City, the ATS and its network of supporters across the U.S. provide funds for scholarships, fellowships, faculty recruitment and chairs, research, buildings, laboratories, classrooms and dormitories, and more.

Eco-Friendly Desalination using MOF’s could Supply the Lithium needed to Manufacture Batteries required to Mainstream EV’s

A new water purification (desalination) technology could be the key to more electric cars. How?

“Eco-Friendly Mining” of world’s the oceans for the vast amounts of lithium required for EV batteries, could “mainstream” our acceptance (affordability and accessibility) of Electric Vehicles and provide clean water – forecast to be in precious short supply in many parts of the World in the not so distant future.

Humanity is going to need a lot of lithium batteries if electric cars are going to take over, and that presents a problem when there’s only so much lithium available from conventional mines.

A potential solution is being researched that turns the world’s oceans into eco-friendly “Lithium supply mines.”

Scientists have outlined a desalination technique that would use metal-organic frameworks (sponge-like structures with very high surface areas) with sub-nanometer pores to catch lithium ions while purifying ocean water.

The approach mimics the tendency of cell membranes to selectively dehydrate and carry ions, leaving the lithium behind while producing water you can drink.

While the concept of extracting lithium from our oceans certainly isn’t new, this new technology method would be much more efficient and environmentally friendly.

Instead of tearing up the landscape to find mineral deposits, battery makers would simply have to deploy enough filters.

It could even be used to make the most of water when pollution does take place — recovering lithium from the waste water at shale gas fields.

This method will require more research and development before it’s ready for real-world use.

However, the implications are already clear. If this desalination approach reaches sufficient scale, the world would have much more lithium available for electric vehicles, phones and other battery-based devices. It would also reduce the environmental impact of those devices. 

While some say current lithium mining practices negates some of the eco-friendliness of an EV, this “purification for Lithium” approach could let you drive relatively guilt-free

Reposted from Jonathan Fingas – Engadget

Technology could make treatment and reuse of oil and gas wastewater simpler, cheaper – University of Colorado + MIT + Rice Universities (NEWT)

Oil and gas operations in the United States produce about 21 billion barrels of wastewater per year. The saltiness of the water and the organic contaminants it contains have traditionally made treatment difficult and expensive.

Engineers at the University of Colorado Boulder have invented a simpler process that can simultaneously remove both salts and organic contaminants from the wastewater, all while producing additional energy. The new technique, which relies on a microbe-powered battery, was recently published in the journal Environmental Science Water Research & Technology as the cover story.

“The beauty of the technology is that it tackles two different problems in one single system,” said Zhiyong Jason Ren, a CU-Boulder associate professor of environmental and sustainability engineering and senior author of the paper. “The problems become mutually beneficial in our system—they complement each other—and the process produces energy rather than just consumes it.”

The new treatment technology, called microbial capacitive desalination, is like a battery in its basic form, said Casey Forrestal, a CU-Boulder postdoctoral researcher who is the lead author of the paper and working to commercialize the technology. “Instead of the traditional battery, which uses chemicals to generate the electrical current, we use microbes to generate an electrical current that can then be used for desalination.” 

This microbial electro-chemical approach takes advantage of the fact that the contaminants found in the wastewater contain energy-rich hydrocarbons, the same compounds that make up oil and natural gas. The microbes used in the treatment process eat the hydrocarbons and release their embedded energy. The energy is then used to create a positively charged electrode on one side of the cell and a negatively charged electrode on the other, essentially setting up a battery.

Because salt dissolves into positively and negatively charged ions in water, the cell is then able to remove the salt in the wastewater by attracting the charged ions onto the high-surface-area electrodes, where they adhere.

Not only does the system allow the salt to be removed from the wastewater, but it also creates additional energy that could be used on site to run equipment, the researchers said.

“Right now oil and gas companies have to spend energy to treat the wastewater,” Ren said. “We are able to treat it without energy consumption; rather we extract energy out of it.”

Some oil and gas wastewater is currently being treated and reused in the field, but that treatment process typically requires multiple steps—sometimes up to a dozen—and an input of energy that may come from diesel generators.

Because of the difficulty and expense, wastewater is often disposed of by injecting it deep underground. The need to dispose of wastewater has increased in recent years as the practice of hydraulic fracturing, or “fracking,” has boomed. Fracking refers to the process of injecting a slurry of water, sand and chemicals into wells to increase the amount of oil and natural gas produced by the well.

Injection wells that handle wastewater from fracking operations can cause earthquakes in the region, according to past research by CU-Boulder scientists and others.

The demand for water for fracking operations also has caused concern among people worried about scarce water resources, especially in arid regions of the country. Finding water to buy for fracking operations in the West, for example, has become increasingly challenging and expensive for oil and gas companies.

Ren and Forrestal’s microbial capacitive desalination cell offers the possibility that water could be more economically treated on site and reused for fracking.

To try to turn the technology into a commercial reality, Ren and Forrestal have co-founded a startup company called BioElectric Inc. In order to determine if the technology offers a viable solution for oil and gas companies, the pair first has to show they can scale up the work they’ve been doing in the lab to a size that would be useful in the field.

The cost to scale up the technology also needs to be competitive with what oil and gas companies are paying now to buy water to use for fracking, Forrestal said. There also is some movement in state legislatures to require oil and gas companies to reuse wastewater, which could make BioElectric’s product more appealing even at a higher price, the researchers said.

MIT – Toward Cheaper Water Treatment for Oil & Gas Operations

MIT spinout makes treating, recycling highly contaminated oilfield water more economical

Also Read: Nanotechnology Enabled Water Treatment or NEWT: Transforming the Economics of Water Treatment: Rice, ASU, Yale, UTEP win $18.5 Million NSF Engineering Research Center

 

 

 

Explore further: New contaminants found in oil and gas wastewater

More information: “Microbial capacitive desalination for integrated organic matter and salt removal and energy production from unconventional natural gas produced water.” Environ. Sci.: Water Res. Technol., 2015,1, 47-55 DOI: 10.1039/C4EW00050A

Provided by: University of Colorado at Boulder

Genesis Nanotechnology ~ “Great Things from Small Things”
YouTube Video: Genesis Nanotechnology Nano Enabled Water Treatment; Quantum Dots from Coal & More

NSF and Stony Brook University: New Nanotechnology to produce sustainable, clean water for developing nations: Video

This technology would enable communities to produce their own water filters using biomass nanofibers, making clean water more accessible and affordable.

The world’s population is projected to increase by 2-3 billion over the next 40 years. Already, more than three quarters of a billion people lack access to clean drinking water and 85 percent live in the driest areas of the planet. Those statistics are inspiring chemist Ben Hsiao and his team at Stony Brook University. With support from the National Science Foundation (NSF), the team is hard at work designing nanometer-scale water filters that could soon make clean drinking water available and affordable for even the poorest of the poor.

Traditional water filters are made of polymer membranes with tiny pores to filter out bacteria and viruses. Hsiao’s filters are made of fibers that are all tangled up, and the pores are the natural gaps between the strands. The team’s first success at making the new nanofilters uses a technique called electrospinning to produce nanofibers under an electrical field.

Hsiao’s team is also looking to cut costs even further by using “biomass” nanofibers extracted from trees, grasses, shrubs — even old paper. Hsiao says it will be a few years yet before the environmentally friendly biomass filters are ready for widespread use in developing countries, but the filters will eliminate the need to build polymer plants in developing areas. Ultimately, those filters could be produced locally with native biomass or biowaste.

The research in this episode was supported by NSF award #1019370, Breakthrough Concepts on Nanofibrous Membranes with Directed Water Channels for Energy-Saving Water Purification.

Watch the Video: New Nanotechnology to Produce Sustainable, Clean Drinking Water for Developing Nations

NSF and Stony Brook University: New nanotechnology to produce sustainable, clean water for developing nations

This technology would enable communities to produce their own water filters using biomass nanofibers, making clean water more accessible and affordable – Follow the Link below to Watch the Video.

The world’s population is projected to increase by 2-3 billion over the next 40 years. Already, more than three quarters of a billion people lack access to clean drinking water and 85 percent live in the driest areas of the planet.

Those statistics are inspiring chemist Ben Hsiao and his team at Stony Brook University. With support from the National Science Foundation (NSF), the team is hard at work designing nanometer-scale water filters that could soon make clean drinking water available and affordable for even the poorest of the poor.

Traditional water filters are made of polymer membranes with tiny pores to filter out bacteria and viruses. Hsiao’s filters are made of fibers that are all tangled up, and the pores are the natural gaps between the strands. The team’s first success at making the new nanofilters uses a technique called electrospinning to produce nanofibers under an electrical field.

Hsiao’s team is also looking to cut costs even further by using “biomass” nanofibers extracted from trees, grasses, shrubs — even old paper. Hsiao says it will be a few years yet before the environmentally friendly biomass filters are ready for widespread use in developing countries, but the filters will eliminate the need to build polymer plants in developing areas. Ultimately, those filters could be produced locally with native biomass or biowaste.

The research in this episode was supported by NSF award #1019370, Breakthrough Concepts on Nanofibrous Membranes with Directed Water Channels for Energy-Saving Water Purification.

Watch the Video Here: New Nanotechnology for Sustainable, Clean Water for Developing Nations

MIT: Silk-based filtration material breaks barriers: Engineers find nanosized building blocks of silk hold the secrets to improved filtration membranes

A scanning electron micrograph shows a free-standing Bombyx mori silk nanofibril membrane.

Image courtesy of the researchers.

When the Chinese first discovered silk, its superior quality and properties were thought so special, it was reserved exclusively for clothing the emperor, his relatives, and dignitaries. And for more than two millennia, the mechanisms of silk production were a highly guarded secret.

Fast forward to today: MIT and Tufts University researchers have discovered additional hidden secrets of silk, called nanofibrils, which, when expertly extracted and reassembled, can be manufactured into advanced filtration membranes. The researchers’ new silk-based filtration technique was recently described and published in the paper, “Ultrathin Free-Standing Bombyx mori Silk Nanofibril Membranes” in the journal Nano Letters.

The paper reveals how silk nanofibrils (SNFs), a key nanocale building block of natural silk, can lead to new naturally-based filters that are more effective, less expensive, and “greener” compared with traditional commercial products. This discovery could portend new production methods and supply chain economics for anyone that uses the new filter membranes, including water treatment facilities, food manufacturers, and life sciences organizations.

The researchers included Department of Civil and Environmental Engineering (CEE) graduate student Kai Jin; CEE postdoc Shengjie Ling; Markus J. Buehler, head of CEE and the McAfee Professor of Engineering; and Professor David L. Kaplan, chair of the Tufts Department of Biomedical Engineering.

“There has been a renewed focus recently on developing these types of ultrathin filtration membranes which can provide maximum flow-through while retaining molecules or pollutants that need to be separated from the flow,” Ling says. “The challenge has always been to create these new ultrathin and low-cost devices while retaining mechanical strength and good separation performance. Cast silk fibroin membranes aren’t an option, because they do not have porous structure and dissolve in water if not pretreated. We knew there had to be a better way.”

An insurmountable challenge — until now

The researchers spent many months sharing ideas, working and reworking calculations, and experimenting in the lab. Their effort to find just the right solvent to dissolve the silk fibers into their most elemental compounds without destroying the samples was one of their greatest challenges.

“We devoted a lot of time developing the method for extracting the nanofibrils from the natural silk fibers,” Ling says. “It’s a novel approach, so we had to use trial and error before we eventually found success. It was such a good feeling to realize in tangible results what was calculated.”

Their work — a collaborative effort among civil, biomedical, and computational engineering, and materials science — found the solution in this new free-standing ultrathin filtration membrane and its innovative, advanced production technique.

Infinitesimal, but mighty

Natural silk fibers, which are made of pure protein, are renowned for their incredible lightness, strength, and durability. The silk nanofibrils used by the researchers were exfoliated from domesticated silkworm-produced fibers. It is the special character of the silk nanofibrils that helps the innovative membranes retain their exquisite structure and superior physical properties.

Historic methods to extract or prepare these nanofibers have not always worked. The illustration in the slideshow above shows the researchers’ unique four-step approach that proved effective by overcoming prior hurdles. The first two steps were used to exfoliate the silk nanofibrils from the silk fibers by degumming, washing, drying, and incubating them at a constant temperature, before placing them in water and stirring or shaking them to remove any undissolved silk. The third step involved using ultrasonic waves to extract the silk nanofibrils, which remained stable over several months. Scanning electron micrograph imagery showed the silk nanofibrils had a diameter and contour length similar to the diameter of a single nanofibril strand. In the last step and final process, they assembled the silk nanofibrils into the ultrathin membranes using a vacuum filtration process.

Success came in meeting and exceeding three important membrane attributes: thickness (40-1,500 nanometers with narrowing pore sizes of 12-8 nm); superior water permeation, known as flux; and excellent broad-spectrum separation performance for most dyes, proteins, and nanoparticles. All of these mechanical superiority results are critical to industry, especially for use in pressure-driven filtration operations, even at high applied pressures.

Whether purifying waste water for drinking, or capturing the minuteness of blood clots in the human body, these new silk-based membranes offer significant advanced operational efficiencies. And one piece of silk nanofibrils membrane averages only $0.05-$0.51 compared with $1.20 per piece of commercial filtration membrane.

Silk nanofibrils used in manufacturing hold other important benefits, too. As the by-products of silkworms, innovative manufacturers who leverage silk’s natural properties can enhance their industrial ecology and produce less environmental stress. And once the filters are replaced, the used ones biodegrade, leaving no lasting impact.

A keen eye for detail

Controlling the thickness of membranes and pore size distribution is especially important for filters to work effectively, so the researchers made sure the interconnected membrane pores produced in the lab were uniform and without cracks or pinholes.

In addition, they noted the new membrane’s rejection of protein and gold nanoparticles in flow was higher than that of membranes with similar thickness. Protein molecules, colloids, nanoparticles, small molecules, and ions were all used to assess size-selectivity.

The researchers experimented frequently with water fluxes through membranes of different thicknesses (40-60 nm).

“What really surprised us,” says Jin, “is that one flux was faster than that of most commercial materials, in fact, more than 1,000 times higher in some cases.” The result proved better than fluxes of the most advanced ultrathin membranes.

Other findings showed remarkable flexibility, ease of use and sustainability. For example, the new membranes could be removed without adhering to the supporting substrate, they appeared homogeneous, were transparent with structural color on the surface, could be cut and bent without damage, and probably most important, did not dissolve in water — a critical role in most filtration processes. And because silk nanofibrils are negatively charged at neutral pH, more positively charged molecules can be taken up by the membranes via electrostatic interactions.

“These natural silkworm membranes have remarkable separation efficiency on par with current synthetic technologies,” says Professor Kristie J. Koski of Brown University’s Department of Chemistry, who was not involved in the research. “As a non-toxic, flexible, and tunable membrane, they have great potential for purification and recycling especially in applications where synthetic alternatives are not an option such as in biological systems.”

Professor Thomas Scheibel of The University of Bayreuth in Germany, who also was not associated with the study, adds: “The filter efficiency is one of the most important parameters of filter materials. This parameter is mainly influenced by the structure of the filter material. Nano silk filters are consistently filled and therefore enable the retention of quite small particles. New filter devices based thereon should allow lowering the overall energy consumption in water as well as in air filtration at constant or even higher filter efficiencies than existing ones.”

The team’s discovery reflects ways in which silk’s hidden secrets can advance civilization in multiple new ways.

Marilyn Siderwicz | Department of Civil and Environmental Engineering

KAUST University: Partnering for sustainable fresh water production: Video

Published online Jun 7, 2016

Combining methods for water desalination results in low-cost, highly efficient water production.

Innovative solutions to improve the efficiency of water desalination are a major focus in countries such as Saudi Arabia, where fresh water for industrial, agricultural and human use is scarce. A research partnership between KAUST and the National University of Singapore has won global acclaim for its unique and efficient yet low-cost method of conducting desalination called hybrid multi-effect adsorption desalination.

In a world of dwindling freshwater supply, how can we meet the demands of a growing population? This video explains a new hybrid process which can double the freshwater output of traditional thermally-driven desalination without requiring additional energy. Developed by the King Abdullah University of Science and Technology (KAUST) and the National University of Singapore (NUS), this desalination method is now being piloted for wider implementation by MEDAD, a KAUST-supported startup company. For more information on the new hybrid technology.

Video explains the hybrid process of adsorption desalination using animations.

© 2016 KAUST

The collaboration has resulted in two desalination pilot schemes—one at KAUST itself and the other at a second location also in Saudi Arabia—as well as a spin-off company called MEDAD that will help to commercialize the hybrid desalination technology. The project is led by Kim Choon Ng from the University’s Water Desalination and Reuse Center. Ng has devoted his career to finding ways of reducing the cost of desalination through novel technologies.

Traditional desalination techniques use membranes and pressure to separate salt and other minerals from seawater, but these techniques are expensive, energy intensive and inefficient.

“Desalination is particularly complicated in the challenging environment of the Gulf, where high salinity, silt levels and increased water temperatures make working with the seawater quite difficult,” Ng said. “The frequent occurrence of hazardous algal blooms has also contributed to high pre-treatment costs and severe fouling of membranes. These elements combine to considerably increase the overall unit cost of producing desalinated water.”

Ng and his team recognized that the only viable option to overcome these challenges was to base their system on thermal desalination rather than membrane-based techniques.

They investigated a combined technique and utilized an existing industrially-proven method called multi-effect distillation (MED). This involves spraying saline water over the outer surfaces of a series of tubes (or stages) arranged in a tower. At the top of the tower, saline water is fed in and heated by a steam-driven compressor. The resulting water vapor is collected while the salt is left behind. This process is repeated over subsequent stages, and the vapor from each stage is channeled through the tubes to the bottom of the tower, where it condenses to generate fresh water as it cools.

Ng’s team combined MED with a thermally-driven process called adsorption desalination (AD), which uses low-cost silica gel adsorbents with a very high affinity for water vapor. The researchers adapted the last stage of MED so that the vapor uptake is carried out by AD.

The water vapor is attracted to designated adsorption gel beds while the remaining gel beds undergo desorption, removing the water and preparing the silica gel for the next round. Crucially, there are no major moving parts in the AD cycle, meaning it uses far less energy than some other techniques, and it can run on waste heat from other industrial processes.

“The best part about AD is that it can be run at low temperatures and low pressures,” explained Ng. “In fact, we can run cycles at only 7°C and at a pressure of 2 kPa. This presents a unique opportunity to exploit the renewable energy resources that the Kingdom has—namely solar and geothermal energy—to run the system. Also, because we are producing cooling as part of the process, we can link into air-conditioning systems.”

Simulations on the hybrid MEDAD system indicate that it could double or even triple desalinated water production. Experiments conducted at the pilot plant at KAUST have already increased fresh water production by more than 50 percent. This represents the highest water production ever reported for a desalination technique and earned the team a GE-Aramco “Global Innovation Challenge” award in January 2015. The breakthrough also helps extend the lower end of the temperature range at which the system can operate, which has been a major limitation with MED in the past.

“This represents a major leap forward in water production using thermally-driven cycles, and it is attributed to the excellent thermodynamic synergy between MED and AD cycles,” noted Ng. “We believe it can be developed fully to an extent where the energy efficiency of desalination can meet the target needed for sustainability.”

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The technology has been licensed by the NUS Industry Liasion Office, part of the NUS Enterprise, and the University’s Innovation and Economic Development Office, to MEDAD.

 

Kim Choon Ng and Muhammad Wakil inspect the MEDAD hybrid desalination pilot at KAUST.

© 2015 KAUST

Kim Choon Ng (left) explains the hybrid cycle to visitors at KAUST, including Ahmad Khowaiter from Saudi Aramco (center), Dr. Abdulrahman from the Saline Water Conversion Commission (SWCC) (right) and Dr. Ahmed Al Arifi from SWCC (far right).

© 2015 KAUST

 

“Swarming” Microbots (with Graphene layer) to Clean Polluted Water

A new study shows that a swarm of hundreds of thousands of tiny microbots, each smaller than the width of a human hair, can be deployed into industrial wastewater to absorb and remove toxic heavy metals. The researchers found that the microbots can remove 95% of the lead in polluted water in one hour, and can be reused multiple times, potentially offering a more effective and economical way to remove heavy metals than previous methods.

The researchers, Diana Vilela, et al., have published a paper on the lead-adsorbing microbots in a recent issue of Nano Letters.

“This work is a step toward the development of smart remediation system where we can target and remove traces of pollutant without producing an additional contamination,” coauthor Samuel Sánchez, at the Max-Planck Institute for Intelligent Systems in Stuttgart, Germany; the Institute for Bioengineering of Catalonia in Barcelona; and the Catalan Institution for Research and Advanced Studies in Barcelona.

Heavy metal pollution in water is a common problem stemming from industrial activities, including the manufacturing of batteries and electronics, as well as mining and electroplating. These activities produce metals such as lead, arsenic, mercury, cadmium, and chromium, all of which pose a safety hazard to living organisms and the environment.

In the new study, the researchers focused specifically on removing lead from wastewater by designing tube-shaped microbots with three functional layers. The outer layer of graphene oxide adsorbs the lead from the water. The middle layer, nickel, makes the microbots ferromagnetic so that their direction of motion can be controlled by an external magnetic field. The inner layer, platinum, gives the microbots the ability to self-propel themselves through water. When hydrogen peroxide is added to the wastewater, the platinum decomposes the hydrogen peroxide into water and oxygen microbubbles, and ejecting the microbubbles from the back of the microbot propels it forward.

 Magnetic guidance of a microbot. Credit: Vilela, et al. ©2016 American Chemical Society

Watch the Video Here: 

http://phys.org/news/2016-04-microbots-polluted.html

When the microbots are finished adsorbing the lead, a magnetic field can be used to collect them all from the water. Then the microbots are treated in an acidic solution to remove the lead ions, which can later be recovered and reused. The microbots can also be reused for further lead clean-up.

“This is a new application of smart nanodevices for environmental applications,” Sánchez said. “The use of self-powered nanomachines that can capture heavy metals from contaminated solutions, transport them to desired places and even release them for ‘closing the loop’—that is a proof-of-concept towards industrial applications.”

In the future, the microbots could even be controlled by an automated system that magnetically guides the swarm to accomplish various tasks.

“We plan to extend the microbots to other contaminants, and also importantly reduce the fabrication costs and mass-produce them,” Sánchez said.

The combination of self-propelled robots with functional layers also opens the doors for similar designs that could have applications in areas including drug delivery and sensing.

Explore further: New system may one day steer microrobots through blood vessels for disease treatment

More information: Diana Vilela, et al. “Graphene-Based Microbots for Toxic Heavy Metal Removal and Recovery from Water.” Nano Letters. DOI: 10.1021/acs.nanolett.6b00768

Journal reference: Nano Letters

Examining Global Water Scarcity: Why Canada Cannot Export Its Water

Summary

Editor’s Note: This is the 10th installment of an occasional series on water scarcity issues around the world that Stratfor will be building upon periodically.

Despite being “water rich,” Canada will experience increasing regional water stress as demographics and climate variability threaten the natural resources in the country’s prairie. Suggestions about the possibility of Canada exporting water will emerge sporadically, as they have in the past. But such plans are highly unlikely to come to fruition, both because public opinion opposes the commoditization of water and because the exporting water would not be profitable. While Canada will continue to protect its freshwater resources, it will not turn them into a traded commodity.

Analysis

Canada’s wealth of resources and comparatively small population allow the government to capitalize on the export of a number of goods, including oil, natural gas, fertilizer and wheat. But although Canada holds roughly 7 percent of the world’s renewable freshwater resources and less than 1 percent of the total global population, water is not poised to become another exported commodity — even as other areas of the world continue coping with water stress and water scarcity.

Canadian citizens generally view access to water as a basic human right and oppose attempts to sell it for profit. In addition, logistical difficulties and economic infeasibility — not only in Canada, but globally — ensure that bulk transfers of water across long distances will remain rare.

Canada’s Deceptive Abundance

The amount of renewable fresh water available to each Canadian citizen is more than 80,000 cubic meters per year. Even other countries that are not typically considered water stressed have far less water available per citizen. For example, the United Kingdom’s annual per capita water availability is just over 2,300 cubic meters per year, and the United States has just over 9,500 cubic meters per person.

However, Canada’s surfeit of water is greater on paper than it is in reality. The country’s water prices are among the lowest in the Organization for Economic Cooperation and Development, encouraging overuse of the resources. Moreover, as in the United States, Canada’s water is not equally distributed. The majority of Canada’s population lives in the southern part of the country, but 60 percent of the country’s renewable water drains to the north, so access to water resources is limited. In fact, some areas of Canada are already experiencing some degree of water stress.

The prairie provinces of Alberta, Manitoba and Saskatchewan are typically more arid than other parts of the country. An expansion of agricultural and industrial activity in the region, along with population increases in recent decades, has led to greater water stress in parts of these provinces, and the pressure is expected to increase in coming decades. Agricultural and extractive industrial activity can be expected to continue in the region even as existing resources dwindle. Glaciers that feed the headwaters of many of the major rivers in the region have shrunk by roughly 25 percent in the past 100 years. Increasing temperatures and more frequent droughts are predicted, likely further increasing the strain on the water supply.