I was invited to be interviewed for the ABC Radio National Program ‘In Conversation’. Of course, the main topic of discussion was potable water recycling. If you’re interested, you can listen to the interview
online here. Or if you prefer to skim for the controversial parts, the transcript is below...
I can’t quite believe that I suggested that there was a good case for damming the Mary River, -I must have been nervous!
Robyn Williams: Good evening, Robyn Williams with In Conversation, and this time a wet one; it's about the paradox of planet water. Now let's be serious, if you saw us from space you'd hardly want to call us the planet earth when such a very small fraction of it isn't blue; it should be the planet water, shouldn't it? And the paradox, well, that is the fact that so little of this water, barely 2%, is freely available for drinking, washing or putting in your vase. So much water, so little to drink, as the poet remarked.
And to obtain more we need the science, not least the science and technology of recycling, and don't forget that it's the same water going around and around from millennia. Here's In Conversation producer Nicky Phillips with Dr Stuart Khan at the University of NSW.
Nicky Phillips: Stuart, there's a fairly big debate at the moment going on in south east Queensland about recycled water, there's going to be a recycled water plant in use as of February next year. But 12 months ago it was quite a distressing situation with the water suppliers in Brisbane and the Gold Coast. Can you tell us just how bad the situation was?
Stuart Khan: Yes, I think in around March last year, March 2007, the Queensland government had released some projections on where their water supply would be and they were really quite startling projections. They were assuming that Queensland would stay on very, very tight water restrictions, level 5 water restrictions and that the inflows to the dams would be the same as they were in 2006/2007, which of course didn't turn out to be the case; we've had much better rain than that. But looking at those projections, they were looking at situations of pretty much running out of water, being less than 5% of capacity of the dams by around about this time, or early next year if they did not go ahead and build a number of major pieces of infrastructure—including the indirect potable water recycling scheme that they're building and also including the desalination plant down at the Gold Coast at Tugun River, as well as the new dams they are building on the Mary River. So without building all three of those components to the water supply system, really it was looking like a serious situation to running out of water. And even with those, the possibilities of having very, very low water supplies ongoing into the future were quite stark. So there was a lot of pressure on the Queensland government to do something.
Nicky Phillips: So that the indirect potable reuse centre is going ahead?
Stuart Khan: Yes, it's recycled water, it's water I think from I think six waste water treatment plants around south east Queensland, of which the water is then taken to three new advanced water treatment plants where they undergo advanced treatment processes including membrane filtration through a reverse osmosis membrane, and advanced oxidation, which is an oxidative process that breaks down any remaining chemicals that may make it through the reverse osmosis process.
Then some of it going to power stations, two major power stations in south east Queensland, Swanbank and Tarong power stations, and the left over water available from that will then be used to recharge Brisbane's main drinking water supply, which is at Lake Wivenhoe, or Wivenhoe Dam. And from there of course it will be mixed with the natural inflows of water into that dam, flow around 40 kilometres downstream to the Mount Crosby water filtration plant where it will then be treated at the conventional drinking water treatment plant, undergoing filtration and chlorination before being redistributed back as a clean drinking water source to the residents of south east Queensland.
Nicky Phillips: For all the hysteria that surrounds recycled water, do people realise that they drink unplanned potable reused water?
Stuart Khan: I think awareness of that fact is increasing because of the debate surrounding planned indirect potable water use. Unplanned water recycling is a situation where we have waste water treatment plants, sewerage treatment plants, discharging conventionally treated waste water that was never meant for drinking and not prepared in a way that's supposed to be suitable for drinking into rivers, or into catchments upstream of where other towns will take their drinking water supplies from that particular river.
So there are examples all over Australia of unplanned indirect potable water areas and there are examples all over the world. Some of the classic Australian examples are in Sydney. We have...our drinking water supply is Warragamba Dam and we have influence coming into that dam from sewerage treatment plants such as Lithgow sewerage treatment plant, commonly Goulburn discharges its water into the Wollondilly River which then flows down and becomes part of our drinking water supply. I think at the moment there is so little water available in Goulburn that they are actually reusing most of that water themselves for irrigation.
Those are two of the sewerage treatment plants that end up as part of Sydney's water supply. In Queensland the water that's already flowing into Lake Wivenhoe comes from a number of sewerage treatment plants including at Esk, Lowood, the list goes on and it's the same all over the world. It's a normal situation and it's called unplanned indirect potable water reuse.
Nicky Phillips: Opponents of recycled drinking water suggest that there could be dangerous bacteria or virus outbreaks but I'm assuming that that could also happen in non-recycled water?
Stuart Khan: Yes it can also happen in non-recycled water and it does also happen in non-recycled water. There's a professor in Canada actually called Steve Hrudey who released a very, very interesting book about four years ago called Safe Water Drinking. The book was essentially a review of all of the water borne illness outbreaks that had occurred in developed countries in the last 10 or 20 years and there are many examples. So we've seen outbreaks from organisms like cryptosporidium and giardia which are protozoan organisms causing illnesses in cities like Milwaukie in the US and very famously Walkerton in Canada where a number of people died because of those outbreaks. And they are conventional drinking water treatment processes, they are not water recycling schemes, they are drinking water treatment processes which in hindsight had been shown to be relatively poorly managed or not optimally managed and it shows us the importance of really taking a lot of care and a lot of attention in the way we manage risks associated with drinking water production and drinking water distribution. Because the risks are real, there are real possibilities of people becoming ill and people dying if things are not done properly.
Nicky Phillips: So what are the advantages of using recycled water?
Stuart Khan: Well there are a few advantages of using recycled water, in fact if you actually look at the way that we've started to use recycled water in Australia the major driver in the 1990s was environmental protection. We started to have the development of the EPAs, the state based EPAs around Australia which started to impose tighter restrictions on pollution that could be discharged. And so that put a lot of pressure on water utilities to start finding alternative ways of disposing of the water. And we started to see water recycling projects that included things like watering lots, and lots of golf courses around Australia are watered by recycled water and airports, and we started to see a little bit of industrial use but essentially they are ways of avoiding discharging water into rivers and streams.
But then in the last decade the driver really changed because since about 2000/2001 when we went into a long term El Nino phase on the east coast and we saw some similar evidence of climate change on the west coast of Australia the driver for all water management in Australia became finding new sources for drinking water supplies for major cities, or preserving those drinking water supplies for major cities. So we started looking at opportunities to recycle water in a way that would take pressure off current drinking water supplies and we started to see a lot of new industrial water recycling developments.
Now a lot of the low-hanging fruit, so as to speak, has been picked and a lot of those easy industrial processes have been identified and we are starting to see that the next best way to be able to preserve water supplies, actually to use that water as an indirect process for refilling our drinking water catchments. So that requires a lot more investment in the way that we treat water to ensure that we are treating water to a very, very high quality suitable for a drinking water source. A lot of change in the way that we manage recycled water once it becomes the drinking water supply. We recognise that new guide lines are required in Australia which have been developed and endorsed by the National Health and Medical Research Council that impose a very strict risk assessment and risk management regime on the way that water is prepared, delivered and managed in general in terms of understanding what could go wrong in the processes of supplying that water and how those problems can be avoided.
The philosophy that has generally been imposed is a multiple barrier of philosophy where if you have a human error, if you have a problem in the water treatment process, or a water supply process that there's a large degree of redundancy built into the system where there are subsequent barriers that can handle that water and produce high quality water anyway even if things go wrong upstream. So it gives us the opportunity to be able to deal with problems as they come up but still be able to produce a very reliable supply of drinking water into our catchments.
Nicky Phillips: So if it's so reliable why do you think the public is so concerned? Is it still that we haven't got over the yuk factor of recycled water?
Stuart Khan: Yes, that's a big question and there's a lot of research going on trying to understand the way we think about water, trying to understand why we have a yuk factor, so as to speak. I mean the yuk factor is real, it's not some way of criticising people who take a less rational approach to their attitudes towards water. My own opinion is that it's something that we evolved with and the yuk factor actually served us very, very well. It tells us that keeping away from our own faecal excrements etc. is a really, really good idea and we're repulsed by the idea of going close to it. And that's because people who did get too close to human excrements in the past were more likely to catch diseases and less likely to survive. And there's evolutionary pressure there for us to exhibit that kind of behaviour, or not to exhibit that kind of behaviour.
So it's a real leap for us to be able to go from a real natural instinct to not want to have anything to do with our own bodily excrements and waste water that carries those excrements to suddenly actually being able to say we can treat that water very, very well, very reliably, to a very, very high quality and to produce a much cleaner water that what we are currently drinking. I think that's a leap for a lot of people including myself but the fact is it can be done, it is done, there's plenty of evidence for it, there are plants across the USA that are doing exactly that and there's no reason why we can't do it just as well in Australia.
Nicky Phillips: As well as the public's concerns about recycled water it's also got scientists debating. Now microbiologist Peter Collignon and town planner Patrick Troy have been quite vocal in their opposition to recycled water. Is it a subject that has divided scientists or is it just a few people speaking out against it?
Stuart Khan: I think without wanting to put words in the mouths of other people my understanding of most of the comments that have been made by people such as Professor Collignon are that there's a general acceptance that these water treatment plants, advanced water treatment plants can be built and designed to do a great job, to produce very clean water. And when they're doing what they are supposed to be doing they do indeed produce very clean water. I think the major concern that has been expressed is how reliable is that, can things go wrong, and what happens if things do go wrong? That's probably the area where there is a bit of division in the scientific community with a number of people taking the position that the risk management regime that's been imposed by the new Australian water recycling guidelines is a very effective regime, it's a regime that's been adopted from the food industry largely. I think that the concept that if things go wrong it will necessarily lead to human health implications is wrong.
Generally if we're talking about reverse osmosis membranes for example if a reversals osmosis membrane breaks down what generally happens is you can't supply the water, you can't get water through the membrane if it's not working properly and that water needs to be discharged. So you run a risk there of course of not being able to produce the water that you want to produce but you don't produce water that's of a lower quality, that water remains either there at a very high quality or not available at all. One of the comments that I've heard recently that Professor Collignon made on the radio was that he was suggesting that major developments in public health in the last 200 years have really come about because people have learnt to separate their drinking water supplies from their waste water discharges.
It's actually factually incorrect, because we've never been able to separate drinking water supplies from waste water discharges and usually when people are thinking about major advances in the control of cholera and other water borne diseases we are thinking about situations like London in the 1800s where there were endemic cases of typhoid and cholera and largely they were related to waste water being in the drinking water supply. However we never, ever were able to really separate them, the London drinking water supply, a large part of it comes from the Thames River and there are 380 sewerage treatment plants that discharge water into the Thames River and it becomes part of the London water supply.
What we've done is we've increased treatment, we've improved the treatment of that water, we've developed techniques like media filtration, flocculation, coagulation, activated carbon absorption, disinfection most importantly and chlorination and it's these processes that have been effective in making sure that water, even though it hasn't been separated from our drinking water resource and is our drinking water sources and even though it is recycled water it's actually safe to drink. So it's not about separation it's about treatment and I would go so far as to say that those major public health advances of the 1800s, the people we can thank for those are not the medical profession at all, it's the engineers, it's the water treatment engineers that have provided safe drinking water to cities like London that really should get the credit for the major advances in public health.
Nicky Phillips: Another aspect of your research is on hormones in water. Have we always been concerned with hormones or organic material in water or is this just come up because of the recycled water debate? I mean hormones are excreted by everyone in their urine, is it just because we are now talking about using recycled water that it's an issue?
Stuart Khan: Yes, the fact that we're talking about water recycling has definitely raised the profile of the issues associated with chemicals like hormones in water in the community. However, the issue itself of being concerned about trace organics such as hormones in water certainly precedes potable water recycling schemes and is much more relevant really to environmental systems because that's where we've actually seen impacts. In about the mid 90s was when people started to ask questions about what was going on in some environmental systems people were catching fish that were showing very unusual qualities and these were referred to as herm fish because they had some part male and part female qualities. The reason for that was not clear at the time but from some investigations that took place in the UK it was traced back to the impact of chemicals that were coming from the sewerage treatment plant being discharged into rivers in the UK. Largely they were hormones but there were also lots of other industrial chemicals and some natural chemicals that mimic the effect of hormones. What they found is that if they put fish in a cage in a river just downstream of a sewerage treatment plant discharge those fish eventually exhibited those qualities of being feminised.
And it was related back to the presence of the particular hormones such as oestrogen, a hormone called 17 beta oestradiol which is a natural oestrogen and a hormone called ethanol-oestradiol which is a synthetic oestrogen that's used in the contraceptive pill. That was traced back to discharges from very poorly treated sewerage that was being discharged into rivers in northern England. Since the 1990s a lot of research has been done in that particular area looking at different organisms, different types of fish in different places around the world and we see now that it's a worldwide phenomenon.
Nicky Phillips: What about its effect on humans, have there been any research on that?
Stuart Khan: Yeah, it's a controversial topic on which it's definitely true to say that the scientific community is divided but there have been suggestions that exposure to different chemicals, not necessarily hormones themselves, but other chemicals that mimic the action of hormones, plasticisers, industrial chemicals, polychlorinated biphenyls etc. have caused similar types of effects in humans, or at least effects related to our sexuality or to our endocrine systems. The main focus has been on sperm counts and sperm mobility and there are been a few epidemiological studies that have suggested that male sperm counts have been decreasing around the world over the last two decades and that evidence has more of less been brought together with observations of endocrine disrupting chemicals, hormones etc. in wild life. People are essentially putting two and two together and saying well you know we're seeing effects on humans, we know that these chemicals have effects on animals; could the chemicals be responsible for the effects that we are seeing on humans?
And that's a perfectly valid hypothesis that they may well be. However, the general scientific consensus is that we haven't actually been able to identify a conclusive link between the presence of these chemicals in our environment and effects on humans even though I think it's well accepted that we keep on looking and we keep on researching the issue we will find links.
Nicky Phillips: Hormones are very small, are they easily removed from water?
Stuart Khan: Yes, there are a number of different treatment processes that we use that are very effective for removing hormones from water, even conventional waste water treatment plants can be very effective if they are designed and operated well. Some studies that were undertaken recently in Queensland show that it's related to how we manage the activated sludge process, the biological process and if that sludge process is managed in a way that optimises the removal of organics we can end up with water where we cannot measure hormones in the effluence at all. And in fact that is very consistent with a lot of studies that are now being undertaken around Australia. But poorly operated waste water treatment plants we can definitely measure concentrations of hormones down around the milligram per litre concentration but well operated plants are very effective in removing those.
Then if we're talking about advanced water recycling processes reverse osmosis is extremely effective for rejecting any additional hormones that may be present or may not be present, they offer a multiple barrier essentially for the removal of any hormones that may theoretically be present in effluence going into an advanced water recycling treatment plant. And then, if you're talking about drinking water, an advanced drinking water treatment plant where you are actually using advanced oxidation as is the case in south east Queensland as a subsequent treatment process, then advanced oxidation is extremely powerful again at degrading hormones. So I think it's important to be clear that hormones in sewerage doesn't equal hormones in recycled water. One is a source water to a water recycling scheme and the other is a final product of water and of course the millions and billions of dollars that we are spending in between is supposed to achieve something and what it achieves is effective removal of a lot of trace organic chemical contaminants.
Nicky Phillips: So has there been any research on the effect of hormones or hormone-like chemicals on the Australian environment?
Stuart Khan: Very little, in fact there was a meeting in Canberra about 12 months ago that scientist from all around Australia came together and we decided to put together a document called the Black Mountain Declaration and put together a document that describes the consensus is on the implications of hormones and hormone like chemicals in the Australian environment. And it was well agreed that there's reasons to be concerned because when we've done surveys of Australian rivers we find that you'll see similar concentrations to those concentrations that have been reported from Europe. However, nobody has really gone out and done a systematic survey of impacts on Australian native species and we've not seen these sorts of feminisation processes that we've seen across Europe and across the USA in Australia. But it's because we're not looking and I think that's a key part of the Black Mountain Declaration is that we require research, it's a research priority to start saying well, you know we have all the evidence to suggest that there will be impacts to Australian wildlife if we can actually be bothered to get out there and look for it. That's an important part of our research agenda now.
Nicky Phillips: Now I understand your background is in chemistry, why did you get involved in water treatment?
Stuart Khan: I was working at Sydney University, I'd actually started a PhD in organic chemistry at Sydney University which I didn't end up finishing, but I was looking around for an alternative option for a PhD at the University of NSW and I was introduced to a professor that was a visiting professor from the US. And he had a background in microbial water treatment, or water engineering, looking at organisms like cryptosporidium and giardia.
My background being in chemistry, we sort of came together over a cup of coffee and we talked about what each of us could bring to a particular PhD project and we decided that the issue was just emerging in the time, in the mid to late 90s, that people were starting to report early occurrences of pharmaceuticals and hormones in water and so we were keen to have a look at whether the water treatment processes that my PhD supervisor was studying looking for microbes could actually have an effect on some of the organic chemicals as well.
And so we ended up doing a large number of surveys at some sewerage treatment plants in Sydney, looking at removal through conventional waste water treatment processes and there was also a pilot water recycling plant that was available up in Queensland at the time that we did some surveys looking at the removal of pharmaceuticals through processes like reverse osmosis and micro filtration, ozonation, advanced oxidation etc. which turned out to be some of the earlier studies on the removal of those chemicals by advanced water recycling processes. There are plenty, plenty more of them now that are much more comprehensive than the ones I ran ten years ago but that's very much what sparked my interest in the whole area of advanced water treatment.
Nicky Phillips: What do you like the most about studying water treatment?
Stuart Khan: I love chemistry, I love understanding how chemicals react to each other, how chemicals are removed, how chemicals are degraded by biological processes and physical processes, that's my interest. I am also interested in risks associated with chemistry and toxicology, I love discovering new pollutants I like what's actually a headache to a lot of people finding new pollutants, new byproducts from treatment processes that we are using and getting a good handle on the significance of those by-products and those chemicals and if they do present a risk to human health, if they can be degraded by different processes, or if we can prevent forming some of the by-products in the first place by operating processes in a different way. Anything to do with chemicals in water I'm generally interested in it.
Robyn Williams: Dr Stuart Khan at the University of NSW. And what exactly goes ahead in Queensland is as much to do with politics now as it is to do with science. He was with Nicky Phillips. Next week at this time I shall be In Conversation with the distinguished mathematician Freeman Dyson from Princeton.
Freeman Dyson: Sea level rises may or may not have anything to do with global warming, it's not at all clear. Sea level rise has been going on much longer, long before global warming and it probably has very little to do with human activities. All we know for sure is that sea level has been rising steadily for about 10,000 years and we'll have to do something about that.
Robyn Williams: Freeman Dyson at the Institute for Advance Studies at Princeton— that's next week on the Galapagos, climate and much else. I'm Robyn Williams.
