One of the major challenges of the developing world remains finding a supply of pure water for everyone. A new kind of water filter can remove both chemicals and germs, and even produce hydrogen for fuel.
Clean water for daily living is a challenge in many countries on every inhabited continent of the world. The statistics about the availability of water are shocking:
- Worldwide, 650 million people don't have any regular access to clean water. They are forced to collect water from water holes, puddles of rainwater, from farm runoff, and even from cesspools for drinking, washing clothes, and household purposes. Usually women and girls are given the task of collecting water for the rest of the family. They may have to walk as much as six hours a day to and from water holes carrying 10 liters of water in containers carefully balanced on their heads. These containers weigh 10 kilograms, or about 22 pounds.
- Worldwide, 2.3 billion people don't have access to a toilet. In much of India and Africa, women have to wait until dark falls before they can relieve themselves outside, in the open. Men typically make their toilets in broad daylight. The feces may be collected from city streets, but it is allowed to accumulate where it falls in rural areas. Disease results.
- Worldwide, 500 thousand infants every year die of diarrhea contracted from contaminated water.
- In the developing world, one out of two hospital admissions is for diarrhea.
- The most cost-effective investment in infrastructure is providing clean water. Increased productivity repays the investment in clean water by a factor of 400 percent.
The challenge of providing clean water in much of the world is that the vast water purification facilities common in advanced countries are simply too expensive for many developing countries.
Available funding covers water purification at a family by family level, with very small filtration units the best alternative. However, small filtration units, whether they are put to use in the developing world for everyday use on in the more advanced countries by campers, hikers, and summer cottage owners, also pose some challenges.
- Water filters tend to accumulate bacteria. Even worse, they accumulate the kinds of bacteria that form biofilms, sticky surfaces that bind millions of bacteria together. This enables the bacteria to accumulate in the filter. When they contaminate drinking water, they become the kinds of bacteria that are very hard to treat with antibiotics, and especially likely to cause skin infections (after they pass out of the digestive tract).
- Much available water is salty or brackish. The ideal water filter would take out salt and pollutant chemicals as well as bacteria.
- Water needs to taste and smell good as well as to be good for you. Water filters should take out odors and off tastes.
In addition to all of these properties, the water filter needs to be inexpensive. It cannot be made with, say, platinum, even though platinum is an excellent catalyst for many purification processes.
Just such a filter has been developed in Singapore. Led by Dr Darren Sun, a team of scientists at Singapore’s Nanyang Technological University have spent the past five years developing a material known as Multiple-Use Titanium Dioxide. Titanium dioxide is a very familiar, very well known substance also used in sun block. (It's the kind of sunblock that leaves your nose looking white.) The Singapore scientists modified titanium dioxide crystals into nanofibers.
Purifying Water With A Super-Filter
What's the advantage of using nano-fibers in a water filter? The primary challenge in designing any water filter has always been that the pores have to be large enough to let water through, but small enough to keep bacteria in the filter. Then there has to be a way to clean the filter so that the bacteria do not accumulate into a sticky film that not only slows down the filtration process but also helps them survive.
Nano-fibers can be "spun" so that they have predictable spaces between the individual fibers. Crystalline water filters tend to clump so that more water can pass through them, but more impurities and germs pass through, too. In laboratory tests, nano-fiber water filters compared to traditional filters are:
- About twice as useful for getting rid of organic compounds that cause discoloration of water and undesirable tastes and smells, as well as
- About 250 percent more efficient at removing toxic chemicals, such as the cleaning compound toluene or the benzene found in automobile fuels.
These are great results, but Russian scientists have taken the process one step further.
Three scientists with the Russian Academy of Sciences have worked with titanium dioxide nano-tubes using sunlight as a catalyst for further cleansing of water. When the titanium dioxide filter is exposed to sunlight, they have discovered, it is capable of:
- Removing bacterial colonies even if the source water contained 1 million colonies per ml.
- Removing chemical impurities even if the source water contained 1 mg/liter, or about 1,000 up to 1,000,000 times greater contamination than safe water standards permit.
Trillions of bacteria and nearly all chemicals can be removed from every liter of water as long as the filter is activated by sunlight. This makes it possible to remove the E. coli and Salmonella bacteria that cause hundreds of thousands of deaths every year. It enables the removal of agricultural chemicals and household cleansers that cause slow development of cancer all over the developing world. Best of all, the filter can be recharged over and over again as it is exposed to sunlight. Exposure to sunlight not only helps make water clean, it keeps the filter clean.
Titanium dioxide is non-toxic. It's safe to apply to your skin, and it's even used as a natural whitening agent in many foodstuffs. There is titanium dioxide in chewing gum designed to brighten your teeth, and it's also used a stabilizer in some brands of candy. There are tiny amounts of titanium dioxide in processed dried coconut, Marshmallows, Mentos, and packaged vanilla frosting.
Titanium dioxide is already used in air filters, and it's used in the some of the best water filters for home swimming pools. If you are buying water filters from an online vendor like Amazon, just enter the term "titanium dioxide" in your search. You will be directed to products that contain this amazing substance that can keep the water you use Everyday cleaner, fresher, and toxin- and germ-free.
- Fisichella M, Berenguer F, Steinmetz G, Auffan M, Rose J, Prat O. Intestinal toxicity evaluation of TiO2 degraded surface-treated nanoparticles: a combined physico-chemical and toxicogenomics approach in caco-2 cells. Part Fibre Toxicol. 2012 May 31. 9:18. doi: 10.1186/1743-8977-9-18. PMID: 22650444
- Tsydenova O, Batoev V, Batoeva A. Solar-Enhanced Advanced Oxidation Processes for Water Treatment: Simultaneous Removal of Pathogens and Chemical Pollutants. Int J Environ Res Public Health. 2015 Aug 14.12(8):9542-61. doi: 10.3390/ijerph120809542.
- Photo courtesy of pinksherbet: https://www.flickr.com/photos/pinksherbet/5685106294/
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- Photo courtesy of dino_kuznik: www.flickr.com/photos/dino_kuznik/8458221276/
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