Stuart Khan is a Professor in the School of Civil and Environmental Engineering with expertise in water treatment processes. His passion for recycling water started very young, when an ocean sewage outfall was earmarked for one of his favourite spots: Look At Me Now Headland near Coffs Harbour.

How did you get into wastewater treatment processes?

My background is in science and I even started a PhD in chemistry before switching directions. The change happened in 1998 when I met a visiting professor from the U.S. here in UNSW’s School of Civil and Environmental Engineering. He was looking at Cryptosporidium (a disease carrying parasite) and other microbial contaminants in drinking water.

Because chemical contaminants in drinking water was an emerging field of interest, and one that fascinated us both, we developed a PhD project looking at how pharmaceuticals and hormones pass through humans into wastewater treatment plants, and how they might be removed. It was really quite cutting edge. I was one of the first people looking at these sorts of contaminants in wastewater and drinking water in this part of the world at the time.

 Professor Stuart Khan (right) is a leading expert in the area of water treatment processes

When did you start working at UNSW?

After my PhD I worked at the University of North Carolina, and then the University of Wollongong, but returned to UNSW in 2005 to work on a project looking at how antibiotics end up in wastewater and how best to remove them. We also looked at the development of antibiotic-resistant bacteria in sewage treatment plants.


What are you working on at the moment?

One of our big projects is focused on a process called advanced oxidation. This is pretty much the final step in a recycled water system that will ensure the purified water is safe enough to drink. It’s an important project in a couple of ways. It helps guarantee the safety of recycled water supplies, but it also builds the confidence of drinking water regulators who are, first and foremost, concerned with protecting public health.


Is recycled water being used for drinking water in other countries?

There has always been an element of this in what we call de facto water recycling, where cities discharge their treated wastewater into rivers, those rivers flow downstream, and a town or city downstream will take the same water out again and use it as their drinking water supply. But the type of water recycling I tend to work on is more intentional and requires a lot more attention to water quality and treatment processes. This has been a worldwide growth area in the last 20 years, including Australia. There are large water recycling projects underway in both Perth and Brisbane.


What has kept your interest up over the last two decades?

It really goes further back than that. One of the things that motivated my initial interest in recycled water was growing up in Coffs Harbour in the 1980s and early 1990s, where there was a big debate about an ocean outfall that was being constructed near the pristine environment of Emerald Beach and Look At Me Now Headland.

Surfers and environmentalists were opposed to it and people started questioning the status quo and asking whether something more productive could be done with the wastewater instead. Interestingly, one outcome of that debate is that a lot of sewage gets recycled now and supports a thriving blueberry industry.

From a personal point of view, I realised we should stop thinking about wastewater as a waste disposal problem and start thinking about it as an opportunity. This early experience led to my passion for better water management in urban environments which has continued ever since.

Professor Stuart Khan with his former PhD students at the Old Bar sewage treatment plant collecting samples to understand how some contaminants vary in concentration over a 24-hour period.  

Are you heartened by what you’re seeing in terms of water management in Australia, or do you feel the country has a long way to go?

It’s a slow process. Unfortunately, terrible as they are, droughts tend to be a motivator. During the Millennium Drought, everyone started to think a lot more about water, but then it rained and funding dried up. Now we are in another big drought there is a lot more interest, particularly in regional towns around NSW who are actively looking for ways to make better use of wastewater.

Some of our big cities, however, have a long way to go. In Sydney, for example, about 80% of wastewater is discharged straight into the Pacific Ocean. I suspect that this will change in the near future, particularly when we start to run out of water.


What’s one of your fondest memories from your time at UNSW?

It’s hard to pinpoint one, but something that springs to mind was taking some PhD students to a wastewater treatment plant at Old Bar on the mid coast of NSW. We camped so we could characterise the variability of the wastewater over a 24-hour period and had people on shifts collecting samples. I’m not sure that too many sewage treatment plants would let you do that these days, but it was fun at the time.


What do you enjoy most about working at UNSW?

The people I work with. One recent initiative, which has been a fantastic development, is the UNSW Global Water Institute which has brought together all the water expertise from all the different schools and faculties across the University. The diversity of skills and knowledge has provided exponential benefits in terms of better understanding some of the water problems we face.


What are the most important skills engineers need to thrive today?

Understanding the fundamentals is essential, but even more important are things like communication skills, creativity and teamwork. A niche skill is a really great thing too. Having a particular way of looking at, or doing things, makes you a very important team member.

Lastly, having a driving passion is hugely valuable. If you have a world view of things (as I feel I developed when I witnessed what happened with the ocean outfall at Look At Me Now Headland), and believe you can make a real difference in a particular area, that is always something that will lead to great outcomes.