Scientists from Cardiff University in the UK have developed a point-of-use water disinfection method based on hydrogen peroxide that is millions of times more effective than the current chlorination methods used by public water systems.
In 1908, chlorine was first used in the United States as a major disinfectant. Since then, its popularity has soared and now, approximately 2/3 of public water systems are disinfected with chlorine or chloramines to kill parasites, bacteria and viruses. Chlorine levels up to 4 milligrams per liter, or 4 parts per million, in drinking water are considered safe by the EPA and CDC. At this level, harmful health effects are unlikely to occur. However, more recently, research has shown that chlorine can react with naturally occurring compounds in water to form compounds that, in high doses, can be toxic to humans.
As a result, some commercial providers have switched to hydrogen peroxide as a drinking water disinfectant. In the UK, over 4 million tons of hydrogen peroxide is produced, transported and stored in factories on an annual basis. To handle transport without degradation, stabilizing chemicals are often added to the hydrogen peroxide solution during the production process, but these end up reducing its effectiveness as a disinfectant.
Graham Hutchings and his international team of researchers have overcome this limitation by using a catalyst made from gold and palladium that takes in hydrogen and oxygen to form hydrogen peroxide. In a study published in Nature Catalysis, the team showed that as the catalyst brought the elements together to produce hydrogen peroxide, it simultaneously produced a number of highly reactive compounds—known as reactive oxygen species (ROS)—which the team demonstrated were responsible for the antibacterial and antiviral effect, and not the hydrogen peroxide itself.
The researchers tested the three methods—chlorine, hydrogen peroxide and catalyst-based hydrogen peroxide—against E.coli bacteria. In identical conditions, the catalyst-based method was shown to be 10 million times more potent at killing the bacteria than an equivalent amount of the industrial hydrogen peroxide, and over 100 million times more effective than chlorine disinfection.
Moreover, the catalyst method was also shown to kill bacteria and viruses in a shorter time compared with the other two methods.
As the researchers continue to refine and move toward scale up, the easy-to-use method has the opportunity to revolutionize water disinfection and use.
Currently, an estimated 785 million people lack access to clean water, and 2.7 billion experience water scarcity at least one month a year. Additionally, 2.4 billion people around the world live in locations that have inadequate sanitation, which is often to blame for deadly diseases like cholera, typhoid and rotavirus.
Thus, for many, a simple, inexpensive point-of-care tool that can instantly disinfect water means the difference between life and death.
“We now have proven one-step process where, besides the catalyst, inputs of contaminated water and electricity are the only requirements to attain disinfection,” said Hutchings, chemistry professor at Cardiff Catalysis Institute. “Crucially, this process presents the opportunity to rapidly disinfect water over timescales in which conventional methods are ineffective, while also preventing the formation of hazardous compounds and biofilms, which can help bacteria and viruses to thrive.”