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Treating industrial wastewater for ‘a better and cleaner world’

Professor Laichang Zhang

World leaders are sounding the alarm over a global water shortfall that could displace large swaths of people unless countries dramatically change how they use the resource. As reported in March 2018 by the United Nations and the World Bank, 40 percent of the world’s population is currently affected by intense water scarcity, putting the planet’s life-sustaining ecosystems at risk.

Industrial pollution is a major factor in the dwindling supply of clean water worldwide, a pending crisis that researchers at Edith Cowan University (ECU) are not taking for granted. A team led by Laichang Zhang, a professor from ECU’s school of engineering, has developed a crystalline alloy that can strip impurities from industrial wastewater in minutes.

Resembling a simple piece of aluminium foil, the high-tech strip of iron – an extension of Zhang’s previous work developing metallic glasses – removes dyes, heavy metals, and other pollutants created by widely used manufacturing processes.

“Mining and textile production produces huge amounts of contaminated wastewater,” says Zhang. “This along with population growth results in significant environmental problems. We aim to use metallic glasses to make a better and cleaner world.”

An inexpensive type of water treatment

Modifying the internal structure of iron-based alloy has resulted in a new type of crystalline alloy that Zhang says can treat one ton of wastewater for just $15. In their initial research, ECU’s team of scientists at the university’s campus in Perth, Australia, changed iron’s atomic structure to form metallic glass, named for the molecular underpinnings that resemble glass rather than the everyday transparent material.

Compared with the disordered atomic structure of metallic glass, however, the crystalline alloy’s ordered structure allows for the kind of fast electron movement desired in wastewater treatment, as those quick-moving subatomic particles are able to bind with dye or heavy metal molecules and leave behind useable water.

Fast electron transportation from our materials leads to an effective conversion of contaminants into harmless substances or a fast breakage of the chemical structure of pollutants,” says Zhang. “That is to say, the faster an electron transfers, the higher contaminant removal efficiency is.”

Bearing in mind the expense of designing new metallic glass favourable for wastewater purification, ECU researchers devised an alternative that considered the cost of manufacturing and processing materials as well as expenditure for the water treatment itself.

As ECU’s research evolved, university scientists produced partially crystalline metallic glasses at a much lower cost than earlier iterations. The crystalline alloy can also be used up to 30 times without losing its effectiveness, providing a superior substitute to commercial iron powder commonly employed to treat wastewater. Not only does the powder have a single use, says Zhang, it leaves behind an iron sludge that must be purified and safely stored.

“Reusability gives crystalline metallic glasses high economic value in industrial wastewater treatment, and the low amount of metal leaching from them makes it so they can avoid secondary pollutants,” Zhang says.

The metallic glass developed by Professor Laichang Zhang can strip impurities from wastewater in minutes.

Tackling a global crisis

The U.N. and World Bank report, based on two years of research, states that 700 million people are in danger of being displaced by water scarcity within the next 10 years. Meanwhile, more than two billion people are compelled to drink unsafe water, and more than 4.5 billion people do not have safely managed sanitation services.

Globally, agriculture accounts for 70 percent of all water consumption, compared with 20 percent for industry and 10 percent for domestic use. But in industrialised nations, industries consume more than half of the water available for human use. Manufacture of biofuels alone has substantial impact on water demand, as between 1,000 and 4,000 litres of water are needed to yield a single litre of biofuel. According to observers, having less available water risks increased disease, economic breakdown, and even violent conflicts over water access.

Although metallic glass has been studied for decades, few researchers have concentrated on its catalytic properties – defined as chemical reactions altered by the introduction of a new substance, or catalyst – in the area wastewater treatment. The global shortage of potable water, particularly in industrialised urban centres, has exerted pressure on scientists to help curtail the dangers posed by high-yield manufacturing operations.

While presenting the U.N. report last March, Netherlands prime minister Mark Rutte said, “We must work to tackle global water crises now. There is no other option.”

Zhang agrees with this assessment, focusing his work mostly on organic pollutants such as dyes and phenolic compounds derived from industrial activities. The researcher also studies heavy metals, applying his overall findings to industries producing textiles, leather, and pharmaceuticals.

ECU is currently working with industry partners to further improve the crystalline alloy’s effectiveness to reduce its cost in use and manufacture. An Australian drilling-services company is among ECU’s collaborators, along with a U.S. energy concern and Chinese chemical corporation. These enterprises understand the necessity of reusing polluted water from both a business and humanitarian standpoint, says Zhang.

“Fresh water is not only a source of drinking water, but it also supports industrial activities and agricultural irrigation,” he says. “But available fresh water resources are being reduced day by day, so our research for removing pollutants from wastewater is receiving wide attention and interest.”

In 2019, Zhang hopes to upgrade the alloy’s efficiency in different catalytic environments. Answering this question could, among other benefits, increase the substance’s industrial scale.

“Investigating metallic glass in wastewater treatment is interesting, not only because it can bring a better and cleaner environment, but the properties of metallic glass also need to be studied in-depth to further understand unknown application fields,” says Zhang.

Zhang has published 180 journal papers based on his investigations, bringing attention and accolades to the hard work taking place at ECU.

“Our achievements can stimulate the research environment by letting us focus on (the alloy’s) practical applications and solve problems with social concerns,” says Zhang. “This is a positive trend for the university.”


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