Â鶹ÒùÔº

Arsenic is a natural component of Earth's crust and highly toxic in its inorganic form. The element is a cause of a global public health crisis, as it is present in groundwater and the drinking water consumed daily by millions of people in countries such as Bangladesh, China, India, Mexico and Pakistan.

Long-term exposure to high levels of inorganic arsenic can cause cardiovascular disease and cancers of the bladder and lungs. But now, scientists from Denmark have developed a new treatment that turns arsenic-rich groundwater waste into useful raw materials.

While current methods to clean arsenic from groundwater are successful, they create another problem—an arsenic-rich sludge that requires complex, specialist and expensive disposal methods. The residue is also a major environmental and health hazard if not disposed of properly.

In a study, in the journal Science Advances, Kaifeng Wang and Case van Genuchten at the Geological Survey of Denmark and Greenland detail a two-step process to convert the hazardous sludge into a raw material for electronics, batteries and semiconductors.

Transforming a deadly contaminant into a valuable resource

First, the sludge is washed in a strong alkali solution that pulls arsenic out of the waste by breaking the chemical bonds between arsenic, phosphate and iron oxides that had been added in the cleaning treatment.

This releases dissolved arsenic and phosphorus into the liquid. Next, the researchers heat the solution and add a common, safe chemical called thiourea dioxide. This converts dissolved arsenic into pure, solid, metallic arsenic nanoparticles. The remaining phosphates can be easily recovered separately by treating them with calcium.

"This work can catalyze the previously unimaginable scenario that the same contaminant resulting in 'the largest mass poisoning in human history' can be transformed to a commodity that provides increased economic welfare to local communities," wrote the researchers in their paper.

Scaling up challenges

The process is still at the lab scale, and the key challenge for scaling up the technology is developing the most cost-effective and efficient method of operating. This includes practical ways for recycling and reusing the chemicals so local treatment plants don't have to keep buying them.

Once the challenges are met, communities could find ready markets for their extracted arsenic. This is because the element is classified as a Critical Raw Material (CRM) in places like the US and Europe, meaning it is important economically. For example, metallic arsenic is needed for semiconductors and clean energy technologies.

© 2025 Science X Network