water with dye

Wood-based material cleans up toxic water using only the Sun

Image credit: Dreamstime

A method to purify contaminated water using a material derived from trees could improve water quality in countries with poor treatment technologies.

The material, which was developed by researchers at Chalmers University of Technology in Sweden, could also combat the widespread problem of toxic dye discharge from the textile industry.

According to the World Health Organisation (WHO), there are currently over two billion people living with limited or no access to clean water.

The new material is based on cellulose nanocrystals which have an extremely high absorption capacity.

“We have taken a unique holistic approach to these cellulose nanocrystals, examining their properties and potential applications. We have now created a biobased material, a form of cellulose powder with excellent purification properties that we can adapt and modify depending on the types of pollutants to be removed,” said Gunnar Westman.

The researchers show how toxic dyes can be filtered out of wastewater using their material and the treatment requires neither pressure, nor heat and uses only sunlight to catalyse the process.

“Imagine a simple purification system, like a portable box connected to the sewage pipe. As the contaminated water passes through the cellulose powder filter, the pollutants are absorbed and the sunlight entering the treatment system causes them to break down quickly and efficiently,” Westman added.

“It is a cost-effective and simple system to set up and use and we see that it could be of great benefit in countries that currently have poor or non-existent water treatment.”

India is one of the developing countries in Asia with extensive textile production, where large amounts of dyes are released into lakes, rivers and streams every year. The consequences for humans and the environment are serious.

Water contaminant contains dyes and heavy metals and can cause skin damage with direct contact and increase the risk of cancer and organ damage when they enter into the food chain. Nearby vegetation is also affected in several ways, including the impairment of photosynthesis and plant growth.

So far, laboratory tests with industrial water have shown that more than 80 per cent of the dye pollutants are removed with the new method and the researchers believe they can improve this.

“Going from discharging completely untreated water to removing 80 percent of the pollutants is a huge improvement, and means significantly less destruction of nature and harm to humans,” Westman said.

“In addition, by optimising the pH and treatment time, we see an opportunity to further improve the process so that we can produce both irrigation and drinking water. It would be fantastic if we can help these industries to get a water treatment system that works, so that people in the surrounding area can use the water without risking their health.”

Cellulose nanocrystals could also be used for the treatment of other water pollutants than dyes. In a previous study, the research group has shown that pollutants of toxic hexavalent chromium, which is common in wastewater from mining, leather and metal industries, could be successfully removed with a similar type of cellulose-based material.

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