New ways to extract value from wastewater inspired by plants

Australian National University (ANU) scientists are drawing inspiration from plants to develop new techniques to separate and extract valuable minerals, metals and nutrients from resource-rich wastewater.

ANU researchers are adapting the ‘membrane separation mechanism’ of plants so they can be incorporated into new wastewater recycling technologies. This approach offers a sustainable solution to help manage the resources needed for global food, energy and water security by providing a way to harvest, recycle and reuse valuable metal, mineral and nutrient resources from liquid waste.

The technology could benefit a range of industries such as agriculture, aquaculture, desalination, battery recycling and mining. It could also help companies rethink their approach to waste management by creating ways to extract value from wastewater. The research also has implications for flood and drought prone areas across Australia.

Global wastewater is estimated to contain three million metric tons of phosphorus, 16.6 million metric tons of nitrogen, and 6.3 million metric tons of potassium. Recovery of these nutrients from wastewater could offset 13.4 percent of global agricultural demand for these resources.

Ammonia and hydrogen molecules, among others, embedded in wastewater could supply electricity to 158 million households.

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“The world’s wastewater contains a jumble of resources that are incredibly valuable, but only in their pure form. A big challenge facing researchers is figuring out how to efficiently extract these valuable minerals, metals and nutrients while maintaining their purity,” said Associate Professor Caitlin Byrt, ANU plant scientist.

“The Australian mining industry, for example, generates more than 500 million tonnes of waste per year, and this waste is rich in resources such as copper, lithium and iron. But currently liquid waste is only a problem; it cannot be thrown away and cannot be used. It’s just waste unless each resource can be extracted in its pure form.

“This is particularly the case in the battery recycling space; you have this huge, rich source of lithium inside spent batteries, but we can’t yet extract it or reuse it efficiently. Harvesting resources from industrial and urban waste is a key step towards transitioning to a circular green economy and building a sustainable future, as well as reducing our carbon footprint.”

Researchers have investigated the specialized molecular mechanisms that help plants recognize and separate different molecules of metals, minerals and nutrients contained in the soil, allowing them to sort the good from the bad – an essential biological process necessary for their growth and development.

“Resources such as boron, iron, lithium and phosphorus are used in battery technologies, and plants are masters at sequestering these types of resources,” Associate Professor Byrt said.

Ammonia, a compound used to create fertilizers and an essential material in crop production, is another key resource that scientists want to extract from liquid waste solutions.

“Fertilizer costs are skyrocketing, putting a lot of pressure on Australian farmers to afford these higher prices, yet we’re wasting huge proportions of these molecules and that’s causing problems for the environment,” Associate Professor Byrt said.

“Ammonia is also a critical molecule for storing hydrogen fuels. So as we continue to develop the hydrogen fuel industry, there will be an increase in demand for ammonia used as a storage molecule, because that way the hydrogen fuel industry will be able to transport the stored hydrogen around and ultimately use it as a potential fuel source for cars and other technologies.”

Associate Professor Byrt said advances in precision separation technology could also offer security to flood- and drought-prone communities across Australia by providing them with portable, safe and reliable access to clean drinking water in the face of worsening weather conditions as a result of climate change.

“Clean water and the security of nutrient sources support agricultural productivity. Developing technologies to sustainably manage these resources is critical to food security in Australia and globally,” she said.

Reference: De Rosa A, McGaughey S, Magrath I, Byrt C. Molecular membrane separation: Plants inspire new technologies. The new phytologist. 2023. doi: 10.1111/nph.18762

This article has been republished from the following materials. Note: Material may have been edited for length and content. For further information, please refer to the specified source.

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