Advancements in technology have brought about numerous environmental challenges, with pollution being one of the most severe issues. This pollution can come in various forms, such as air pollution from exhaust fumes and soil and water pollution from fertilizers and other chemical residues. Despite improvements in wastewater management in developed countries, there are still concerns about the presence of “forever chemicals” or PFASs in tap water. Recent data from the US Geological Survey revealed that 45% of tap water samples in the US contained traces of PFAS. So, why are these chemicals a problem, and why should we consider using ultrasound technology?
Understanding “Forever” Chemicals
Commonly referred to as “forever” chemicals, per- and polyfluoroalkyl substances (PFAS) are chemical compounds known for being highly resistant to environmental degradation and can persist in the environment for extended periods, sometimes lasting hundreds to thousands of years. Examples of these long-lasting chemicals include persistent organic compounds (POPs) like PCB, DDT, and brominated flame retardants, often found in nonstick pans and stain-resistant fabrics. The US Environmental Protection Agency (EPA) has identified over 9,000 PFAS substances.
These chemicals pose risks as they can accumulate in ecosystems and the food chain, causing harm to human health and biodiversity once released into the environment. Various studies have linked PFAS to cancer, reproductive issues, and immune system problems. This raises the question: how can we eliminate a nearly indestructible substance once it enters food chains and water systems?
Exploring Ultrasonic Cleaning as a Solution
In an attempt to address the issue of PFAS contamination, researchers at Ohio State University have proposed the use of ultrasonic cleaning as a sustainable solution. This innovative approach aims to eliminate the need for oxidizing chemicals traditionally used for PFAS removal.
The study, published in The Journal of Physical Chemistry A, delves into the potential of ultrasonic cleaning by emitting frequencies lower than those used in medical imaging. This type of ultrasound generates cavitation bubbles by compressing and stretching the liquid solution, reaching temperatures of 10,000 degrees Kelvin. This intense heat breaks down the carbon-fluorine bonds of PFAS, leading to harmless residues. Laboratory experiments have shown promising results in removing smaller PFAS compounds within a short timeframe.
Although the technology may not be feasible on a large scale due to energy consumption, there is a possibility of developing domestic ultrasonic water purification systems, expanding its practical applications beyond the laboratory setting. Additionally, this technology has shown efficacy in removing pharmaceuticals from tap water in previous studies.
Other PFAS Elimination Methods
While US researchers explore ultrasonic cleaning, a team at the University of British Columbia has developed an advanced silica filter system capable of absorbing up to 99% of PFAS in water. The PFAS are then eliminated through electrochemical and photochemical processes, showcasing the potential for widespread application in remote or domestic settings.
Various methods have been explored in recent years to obtain safe drinking water, ranging from large-scale technologies like fog harps to domestic systems that generate drinking water from the air. Reverse osmosis desalination technologies remain prevalent for providing drinking water in arid coastal regions without access to river water or aquifers.
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