One solution to the world’s water pollution problems could be something you can’t taste, touch, see, smell, or hear. Especially hear. Ultrasound, the range of frequencies beyond the limits of human hearing, is starting to emerge as an effective water treatment that is more sustainable than chemical dosing. Researchers are discovering that ultrasound performs well on algae, and that’s only the beginning. Ultrasound can remove a variety of pollutants in water, including those that affect the taste of America’s favorite fish, the catfish.
Ultrasound and Algae
For a number of years now, companies like LG Sound have been promoting ultrasound as a sustainable, energy efficient, chemical-free way to reduce and manage algae in stored water settings, from ornamental ponds up to large industrial water storage facilities. The right frequency simply breaks up the cellular structure of the algae without harming other aquatic life. In practice, it’s somewhat more complicated. According to Duddy Heviandi Oyib, special projects manager and chief biologist of LG Sound, responses to ultrasound depend on the unique properties of each body of water. That includes the water’s current condition in terms of pollutants, as well as its size and depth. Still, the results are impressive.
Ultrasound and Catfish
The USDA has been focusing on reducing off-flavor in catfish, caused by their unique tendency to absorb and express pollutants in their environment. It’s part of a broader program to improve marketability, which also includes reducing mortality rates in farmed catfish. Conventional treatment of tanks and ponds consists of substances like diuron, sodium chloride, hydrogen peroxide, titanium dioxide, and copper, but aside from their expense any one of these can lead to a cycle of greater dependency. So far, the results of ultrasound promise a more sustainable approach. Researchers at the UDSA’s Stoneville, Mississippi unit found that an ultrasound regimen decreased bacterial biomass by 60% in tanks, without impacting fish growth. In production ponds, ultrasound also demonstrated an ability to change the density of algae.
Ultrasound and Other Pollutants
Catfish aren’t the only happy campers when it comes to the ultrasound treatment. Ultrasound can also remove mercury from sediment, and it could help get rid of pharmaceutical pollution in water supplies. Choosing Ibuprofen as a test case, an international team of ultrasonics researchers based in Switzerland demonstrated that a two-hour ultrasound treatment eliminated 98% of the drug.
Researchers at Ohio State University have found that ultrasound could remove one roadblock to the use of ceramic filters, which are being developed as an alternative to chemical water supply treatment. Composed of tiny channels separated by membrane, ceramic filters are fine enough to catch bacteria and viruses, but they eventually become clogged and need to be cleaned. Ultrasound could keep ceramic water filters clean while they are in operation, eliminating the expense and complications of off-line cleaning.
According to the Defense Technical Information Center, ultrasound could even be used to disinfect bacteria in ballast water, helping to solve the problem of invasive pollution from global ocean transportation.
Ultrasound and Wastewater
Researchers at Harvard have found that ultrasound can reduce the presence of heavy metals in sewage sludge. LG Sound’s work on the Chem-Free wastewater treatment project in Europe has also demonstrated the potential for ultrasound to improve the foundational process of sewage treatment – biodegradation – by stimulating the bacteria to speed up their activity.
Water and wastewater treatment can both require enormous amounts of energy, and ultrasound offers a means to reduce that load. With economists are debating whether some breakthrough technology is needed to solve our energy problems, it won’t be long before ultrasound makes itself heard.
Image: Biology Big Brother on flickr.
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