When engineer and researcher Professor Denis O’Carroll first came to the Water Research Centre (WRC), he only intended to stay for a short time. 

At the time, he was based at Western University in Ontario, Canada, but he was immediately impressed by the UNSW research environment, as well as the WRC’s facilities and expertise.

“I was here on sabbatical in 2011 and 2012, and I really enjoyed working in the Water Research Laboratory at Manly Vale and the Water Research Centre at Kensington,” he says.

“The breadth and depth of knowledge that my colleagues have is unbelievable.

“And then UNSW has all kinds of great structures, great facilities, great labs and great tools in those labs, so it’s very highly ranked in the water [research] space.”

In 2015, Professor O’Carroll made the move permanent, transferring to the WRC as an ARC Future Fellow.  Back then, his research was focused on nanotechnology as it relates to water engineering, including developing nanometals for contaminated site remediation, and investigating the outcomes and ecotoxicity of nanoparticles released from commercial products.

“Starting with the nanometal work, [we used that] to clean up contaminated sites,” says Professor O’Carroll, now the Deputy Head of School (Research) at the UNSW School of Civil and Environmental Engineering.

“There are also microbial communities in the ground, [so we were interested to understand] how the nanometals worked with the natural microbes to work synergistically to clean up the contaminants in the ground.”

Over the years, his interests have expanded into the cooling effects of green walls and green roofs and, more recently, into investigating the fate and mitigation of per- and poly-fluoroalkyl substances (PFAS).

Also known as ‘forever chemicals’ because they take decades to break down, PFAS are a growing threat to the environment and to human health. They’re found in all kinds of everyday products, from cosmetics to pizza boxes, which means they’ve also made their way into the soil, the groundwater and our bodies in ever-growing quantities.

“[PFAS] can be contaminants, so we look at where they go in the environment and [how] they change or modify the environment, [as well as how we can clean them up],” Professor O’Carroll says.

“We took our knowledge that we gained in the nano[metal] work and brought that to PFAS — we’re [using] some of the same types of background chemistry to treat [them].”

What draws all of Professor O’Carroll’s work together is his commitment to using engineering to address pressing challenges facing the environment, as well as his “marvellous” team of researchers.

“I’m interested in water broadly, and typically [in] water quality and looking at contaminants in water — where they go, how we can clean them up,” he says.

“And then [I’m also] interested in climate change and how we could develop ways to mitigate [its impacts] in urban areas.”

He’s currently winding up a $1.1 million ARC special research grant, awarded in 2019, to develop cost-effective methods to treat large quantities of PFAS-contaminated water. 

He’s also working with industry partners, including Property New South Wales and Viral Pacific to deliver novel chemical remediation solutions to PFAS contamination at commercial and government-owned sites.

Next year, Professor O’Carroll will commence a $400,000 ARC Discovery project to investigate contaminants of emerging concern, including PFAS, and the drivers that determine their fate in the environment.