YOUNG PROFESSIONALS Wei Wei and Lan Wu UTS researchers making waves

The Centre for Technology in Water and Wastewater (CTWW) at the University of Technology Sydney (UTS) is

“I HAVE ALWAYS cared about environmental problems since childhood and have had a continuous passion for waste and wastewater treatment,” said CTWW researcher Lan Wu.

CTWW, under the leadership of Professor Long Nghiem, has grown from strength to strength since its establishment. It seeks to develop water and wastewater technologies that can be applied in residential, commercial, and industrial environments. The current research themes include:

• Wastewater treatment and re-use technologies

• Water supply and alternative water sources

• Water resource management and catchment modelling

• New materials and membrane processes

The research focuses on the development of innovative technologies. These new technologies should deliver abundant recycled, desalinated, and harvested stormwater supplies. The new technology is aimed at regenerating and modernising existing water infrastructure in a cost-effective, safe, and reliable way without needing to rebuild from the ground up.

Wastewater researchers

The focus on wastewater treatment and reuse technologies has highlighted the work of one research team. The team, led by Professor Bing-Jie (Bruce) Ni, has spent significant time working to reduce nitrous oxides and methane emissions. It has also developed the first fundamental understanding of the biotoxicity of microplastics and nanoplastics. Another area of research is developing technology to gain renewable liquid bioenergy from sewage sludge. The team

Researchers such as PhD candidate Wu and ARC Decra Fellow and Lecturer Wei Wei are working to improve the situation for the world. Both of them are originally from mainland China and have a deep appreciation for improving how the world deals with wastewater.

“Waste and wastewater treatment is a serious issue in China, especially after policies were implemented to improve people’s living quality. This was achieved by becoming a global hub for manufacturing,” said Wu. Wu is working on her PhD under Dr Wei. She is focusing on the reclamation of nitrous oxides for a new source of renewable energy and converting organic wastes to liquid bioenergy. Wei’s research is looking at ways to reduce sewage sludge and do something with it.

“I have been working in environmental biotechnology, wastewater/sludge treatment and environmental toxicology,” she said. “My research focuses on developing and applying innovative and sustainable techniques to achieve sewage sludge reduction. I want to transform waste from a troublesome pollutant to a valuable resource with maximised energy recovery. I’m also looking at how to mitigate the adverse influences of emerging contaminants (e.g., microplastics, nanoplastics) on energy recovery in wastewater/ sludge treatment systems.”

Reclaiming liquid bioenergy from sludge

According to Wei, Australia’s energy consumption is growing by about two per cent per year. While that does not sound like much, much of this growth is sourced from natural, non-renewable sources.

“Wastewater treatment plants (WWTPs) in Australia annually produce around 360,000 dry tons of carbon-rich sewage sludge,” said Wei. “It typically represents a substantial, but largely untapped renewable energy resource. Treatment facilities that re-direct sewage sludge from waste to renewable energy resources can bring strong economic, social and environmental benefits to Australia.” Her group has developed an innovative technology to gain renewable and high-value liquid bioenergy (medium chain fatty acids) from sewage sludge. The technology allows for easy collection, storage, and transportation. It can be applied in existing anaerobic sludge fermentation infrastructure, as well as to develop new applications in a range of industries for addressing Australia’s escalating energy demands.

Nitrous oxide emissions

One fugitive emission that many people do not think about is the group of nitrous oxides (NOx). Nitrous oxides represent about 10 per cent of all emissions from WWTPs. Partial or complete denitrification removes nitrogen from sewage and municipal wastewater. New technologies can reduce the amount of carbon and energy are at the cutting edge of new technology in wastewater treatment.

required for denitrification.

“The idea to look at this area came from Professor Ni,” said Wu. “We wanted to investigate ways to use nitrous oxide emitted from WWTPs as a renewable source of energy. There was a lot of focus on the role of nitrogen monoxide (NO) in producing nitrous oxide. It’s a challenging pathway, but we looked at how coal is used to power big chunks of Australia. Once we have a lot of nitrous oxide, it can be burnt with methane. It burns with more energy than methane being burned with oxygen. That makes it significantly better for the wastewater industry.”

This technology, once further developed, provides opportunities for energy self-reliance across the country. It also eliminates the need to use ammonia for the process, which is better for the Australian fertiliser industry.

“I have used the fermentation process. It’s an established technique for WWTPs, and we can collect methane emissions. By combining methane with nitrous oxide for combustion, we can generate more energy than existing technologies,” she said.

Biochar to fight microplastics

Microplastics, and nanoplastics, have become an issue for most countries and the environment. The environmental risks associated with micro- and nanoplastics are continuing to grow. While there has been plenty of discussion about the impact microplastics have on humans and animals, there has been less research done on the impact of microplastics on microorganisms.

“Our studies found microplastics induced toxicity toward anaerobic microorganisms during wastewater treatment,” said Wei. “This biotoxicity decreases wastewater treatment efficiency. Considering the negative impacts of these microplastics, it is important to find effective ways to reduce the direct contact between microplastics and microorganisms in wastewater. If we can do that, we can alleviate and mitigate more of the negative impacts of microplastics.”

To do this, Wei’s research group looked at biochar. It’s a promising carbon absorbent that comes from the pyrolysis process.

“Biochar has excellent pore structures and functional oxygencontaining functional groups. There are other mineral elements as part of biochar,” she said. “Sludge, as the byproduct of wastewater treatment plants, could be utilised as the initial feedstock of biochar formation. This would not only lessen the costs of wastewater treatment plants but also transform waste into functional materials. We have demonstrated that biochar is capable of mitigating the inhibition of microplastics on wastewater treatment efficiency.”

What’s next?

Wu is working towards her PhD, focusing on renewable energy from sludge. Once she gets her doctorate, Wu wants to optimise the bioenergy outputs from food waste.

“There’s enormous potential for the industry to work with our research,” said Wu. “There has been considerable interest in

Australia in producing mediumchain fatty acids and long-chain alcohols. It would improve the monetary value of organic wastes and facilitate the establishment of a bio-based economy within Australia. Food waste is a carbonrich and abundantly produced waste across Australia, which can also be utilised as a promising substrate for bioenergy production.”

Wei is working with industry partners to ensure that her research goes somewhere.

“The sewage sludge-to-energy work is ongoing. I need to further optimise the sludge management and wastewater treatment plant operations. Ideally, we will find a method to efficiently recover liquid bioenergy from wastewater and reduce our carbon footprint eventually towards net zero emissions from wastewater management. I will also look at new and emerging challenges of sewage sludge treatment for the water sector as a whole.”

The research has the potential to turn wastewater into highly valuable products.

Dr Wei Wei is studying biochar and how it reduces the toxicity of microplastics.

For more information, visit www.uts.edu.au/research/ centre-technology-water-andwastewater