Wednesday, October 29, 2008

Living and breathing recycled water today

Today was one of those days where recycled water seems to permeate every aspect. I woke up early wanting to write a blog article on an urban water-themed textiles exhibition that I saw last night (more on that soon).

However, I was quickly distracted by an online news article from the Australian. The article titled ‘Recycled sewage 'will have bugs'’ quoted Prof Patrick Troy from the Australian National University (ANU) raising his concerns about the safety of recycled water. I plan to write an article examining those concerns soon too.

By 8 am I was picked up from home by a colleague for a drive out to Western Sydney to collect some water samples from a pilot-scale water recycling plant at St Marys. This is part of Sydney Water’s ‘Replacement Flows Project’, which I will also write a blog about someday!

Straight after the 9 am news, I took a phone interview with the local ABC Radio program in Ballarat, Victoria. Some members of the Ballarat community have called for a debate on indirect potable water recycling as a means for addressing the city’s water shortages. I may be exaggerating, but I think I spoke for about half an hour about the issues as I see them. I may have raised a few eyebrows by giving the opinion that reverse osmosis would not be a simple technology to implement in such a location (due to the need to dispose of the waste stream) and that I thought alternative treatment processes such as activated carbon treatment were probably more appropriate in that circumstance. I didn’t get around to discussing the likely existing value of the water (treated effluent) as it is currently used or disposed of, but clearly that will also be an important issue to consider.

Still on our way to St Mary’s I received my first of three calls for the day from Queensland. A briefing note on Patrick Troy’s comments was being prepared for Premier Anna Bligh and there was an interest in identifying the source of a figure (8 per cent) which had been quoted. I wasn’t immediately sure of the source, but was able to provide an opinion on a few other aspects of the article.

After collecting our samples from St Mary’s, I returned to my desk and sent a quick email to Patrick Troy. Troy responded that the figure was taken from a research paper that I had previously read by Queensland scientist, Andrew Watkinson. I called Andrew and ascertained that the study that was alluded to in The Australian was undertaken at an industrial water recycling plant (not one designed or managed for a potable water supply). I’ll write some more about the relevance of the findings from that study in a subsequent blog.

By the late afternoon, I read the following article from ABC news in Queensland:

Bligh says academic ill-informed on water claims
ABC Online, 29 October 2008.

Queensland Premier Anna Bligh has dismissed the credentials of an academic who has cast doubt on the safety of recycled water.

Australian National University Professor Patrick Troy says it is impossible to remove all biological waste molecules before the water is added to south-east Queensland dams next year.

Ms Bligh says she has had fresh advice from Government scientists.

"I'm very disappointed with ill-informed comments by somebody who has no expertise in the field of water treatment, from someone whose expertise is in town planning," she said.

"His claims relate specifically to current water treatment of sewage, not to the water treatment that will be done in our recycling project."

The State Government will begin pumping tertiary-treated recycled water into dams early next year.

But Professor Troy says there is no guarantee on the osmosis technique.

"Although this reverse osmosis technique is a step up, the fact remains that it's not absolutely guaranteed," he said.

"The fact is that we don't know what the long-term effect will be of the operation of these systems."

I spent the remainder of the afternoon trying to focus on a review of quantitative methods for water recycling risk assessment that I am currently preparing for the National Water Commission. But that’s another topic that I really must catch up and write a decent blog post on one of these days...


Anonymous said...

Is there a water recycling plant (designed or managed for a potable water supply) in Australia that is available for study?

Stuart Khan said...

Hello Anonymous,

It is a fair point that there was not such a plant available when Watkinson’s research was undertaken in 2006. However, yes, there is now. The most established one is at Bundamba and there are two others about to come online at Luggage Point and Gibson Island. There are also pilot-scale plants operating in Perth and Sydney.

The Bundamba plant has been operating for over a year now. I am aware that there has been extensive chemical testing and that the results of this have been very positive. However, I have not actually seen them since they are not yet publically available. It will be helpful when they are.

Anonymous said...

You may want to read the Australian again today. Diseases Expert Professor Peter Collginon has again rejoined the debate to set a few facts straight!,25197,24573902-5006786,00.html

Anonymous said...

Is there anywhere else in the world millions of people are drinking recycled water, where the % of recycled water is comparable to the % expected in SEQ? According to the Australian - "Nowhere in the world is the proportion of drinking water that is recycled sewage anything like 10 or 25 per cent. There's never been a population of this size that has been subjected to this.",25197,24572253-5006786,00.html

Anonymous said...

Interesting.... "University of Queensland vice-chancellor Paul Greenfield, who heads an expert government advisory panel on recycled water, said that it was not possible to guarantee the safety of recycled water."We can only talk about improbabilities," Professor Greenfield said.",25197,24573902-5006786,00.html

Stuart Khan said...

The question regarding the proportion of water sourced from recycled supplies is an interesting one. However, I don’t think these are numbers that I can easily obtain for most schemes around the world.

In some cities, the fact that a very large proportion of their water supply has come from sewage treatment plants discharging upstream is patently obvious. For example, there are around 380 sewage treatment plants that discharge daily into the Thames River catchment upstream of London. There is no additional advanced water treatment for such ‘unplanned indirect potable water recycling’ schemes.

The City of Berlin sources much of its water supply from the Spree, which can be comprised of up to 70% treated municipal effluent (from sewage treatment plants) during dry periods.

However, I don’t think these figures on proportions or percentages are as relevant as they may first appear. If water is unsafe at 100%, it is not going to be that much safer at 10% or 1%. Safe water management requires much greater margins of safety which render the differences in 1%, 10% or 100% relatively insignificant.

Anonymous said...

Can prions associated with BSE/vCJD (mad cow) be detected and removed from recycled water?

Anonymous said...

Greg Cary (4BC Brisbane) talks to Professor Peter Collignon Microbiologist at the Australian National University School of Medicine.

Stuart Khan said...


I am no expert on prions. However, the same question is addressed in the Queensland Water Commission document "Purified Recycled Water for Drinking: The Technical Issues". See Box 6.2. “Can I get mad-cow disease from drinking water?” on pages 179-180.

Anonymous said...

Hi Stuart, I heard you today on 4BC responding about the Recycling of Brisbane water and I reckon there are a number of questions the radio host won't ask and when prompted completely ignores. The Winvanhoe and Somerset Dams have a combined catchment of some 8000 sq kms. This is where most of the Sth East Qld's water comes from. In this 8000 sq km area there are some large communities all of which have sewage treatment and some if not all of the out flow from the treatment plants flows into the Dam Catchment Area. The area has inumerable wild life none of whom are toilet trained, likewise livestock and domestic animals. Almost all of the rural duellers use some for of septic system. There is also some farming which no doubt has chemical and pesticide run off. I got this direct from the SEQ Water web site.
We have been using this water for more than 50 years and there have been no alarms or health warnings yet.
I asked SEQ Water what the percentage purified recycled water would be of the total held in Wivanhoe and they didn't know.
When the "frighteners" were asked about singapore's recycled water, they always says "oh they only have 1% recycled water", well our recycled water will only be a small percentage of the overall total. I appears to me that the media will pick up on anything with a hint of controvesy and ignore the real issues to keep the story "live". SE Water respondents don't really explain how the process works and so the media debate goes on and on. Next time you get the opportunity will give them a couple of chorts ones in the ribs and put them straight.

Stuart Khan said...

Thanks for your comment, Anonymous.

Of course, you are correct in stating that there are already many sources of pollution (including sewage treatment plants) in Brisbane’s drinking water catchment. While that does give some indication that Brisbane’s current drinking water treatment (at Mt Crosby) is effective, I don’t think it is a justification for any actions that might further compromise water quality or safety.

And yes, of course I agree that the main interest of much of the media is “a good story”. I can’t blame them for that, but I am at least glad that the media and the community as a whole are interested and engaged in debating the important issues of urban water management. I may refrain from giving anyone the ‘couple of [short?] ones in the ribs’ :-)

Anonymous said...

Thanks Stuart for all the time and energy that you must have spent on this site ... I feel you bring a level head and sense of humor to this often emotive issue. I found your site while searching for information on Recycled Sewage Water. Most concerning to me, about drinking water containing recycled waste, is the use of government pledges from a "team of experts" and spin to state the case that drinking this water is safe, over publicly available studies, facts and data - on the water actually being recycled in SEQ - over a nice long period of time.

Stuart Khan said...

Thanks Anonymous,

I think that’s one of the nicest comments I have received on this blog in more than two years. I agree that a lot more publically available facts and data from the SEQ plants would be extremely helpful for all of us to make informed decisions.

The Bundamba advanced water treatment plant has been operating for more than a year now, -supplying water for power generation. I would love to have access to the bucket-loads of analytical data that I know has been collected during that time... Hopefully it will eventually be made publically available.

Ellen said...

Hi Stuart,
Great site! You are obviously very knowledgable on this topic.
In the debate about the use of recycled water for human consumption, I haven't noticed any discussion on the use of this water for irrigation of fresh food crops. Recycled water currently props up the horticulture industry in Werribee, Victoria. Can you please refer me to any research on this topic?
Ellen Fox

jphellowell said...

Hi Stuart,

I am currently undertaking a final yr project for my master of architecture...the project I am pursuing a community based recycling center at Toronto, Lake Macquarie.

Have you had any experience in that geographical area before?


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