Thursday, August 30, 2007


I’m currently in Colorado visiting Assoc Prof Jorg Drewes at the Colorado School of Mines (CSM). Jorg is well recognised for his research which has improved the understanding of how trace chemical contaminants are removed from water during various treatment processes. I mentioned some of Jorg’s research previously regarding the membrane rejection diagram developed by Jorg and one of his post-doctoral researchers.

Jorg is also the Director of the new Advanced Water Quality Centre (AQWATEC), which was opened at CSM this week. I was fortunate to be visiting during the week of the official ribbon cutting.

Despite the dodgy acronym, AQWATEC is a great facility for advancing our understanding of water treatment and water recycling processes. A significant amount of effort has been invested in developing pilot-scale water treatment operations. These can be used to examine the impacts that various operational changes may have on treated water quality. Furthermore, these pilot-scale apparatus will be extremely useful for investigations into the optimisation of energy efficiency and membrane life-span.

Pilot-scale rigs in the AQWATEC currently include:

- Reverse osmosis
- Nanofiltration
- Forward osmosis
- Membrane distillation
- Soil transport columns (to simulate soil-aquifer treatment)
- Coagulation/flocculation
- Dual media filtration
- Capacitive deionisation
- Electrodialysis
- Fluidised bed crystallisation
- Activated sludge bioreactor

About 60 people came along to the grand opening including a Colorado Congressman (Ed Perlmutter), the Executive Director of the Awwa Research Foundation (Rob Renner) and representatives of the US Bureau of Reclamation.

Expect to see plenty of quality research coming from the AQWATEC during the next few years.

Monday, August 27, 2007

Tinsel Town Toilets and Taps

Hello from Hollywood.

I’m on my way to visit a colleague in Colorado (more about that later) and am stopped over for the weekend in California. I found a half-decent backpacker’s hostel right next to Hollywood Boulevard, -moments away from mayhem. I only have the weekend here, so have been walking, walking and walking, trying to see what I can while fighting off the jetlag.

Being in California, and doing lots of walking, I feel that I am entitled to eat breakfast in a greasy diner if I want to. So there I was this morning, mopping up some fried eggs (sunny-side up) with toast and slurping back a milkshake cup of weak sour coffee, when I began to flick through a copy of the LA Times. Just a few pages into the lift-out 'Opinion' section, I happened across the following article about indirect potable water recycling in Los Angeles (which includes Hollywood). As they say, expect the unexpected in Hollywood (actually, probably nobody has ever said that, but can’t I invent my own cliché’s if the real ones don’t quite fit?).

Revisiting 'toilet to tap'

This time around, Los Angeles can't afford to let recycled water slip through its fingers.

By Marc B. Haefele and Anna Sklar

Los Angeles Times

August 26, 2007

Los Angeles' water supplies are getting lower. The once-desolate Owens River Valley burst into flower this year because the Department of Water and Power brought less water to the city. Other states are increasing the amount of water they are able to tap from the Colorado River, L.A.'s primary source of water. And this has been the city's driest year on record. In response, Mayor Antonio Villaraigosa has called for greater water conservation to help meet future needs.

Given this scary situation, the DWP earlier this month asked a handful of private contractors how to promote "recycled water planning" and, in the words of DWP representative Carol Tucker, "to explore all options with our stakeholders for recycling water." Tucker insisted that turning sewage into tap water was not part of the plan, and other DWP officials have echoed her message.

But the water agency's request for ideas about recycling was explicit. It spoke of "indirect potable reuse," which means restocking groundwater with purified wastewater.

Sound vaguely familiar?

It should. Los Angeles has been there -- and then backed off. This time it should stay the course.

The new study might cost $1.5 million, but most of the needed equipment already exists. It's called the East Valley Water Reclamation Project.

Built in the 1990s at a cost of $55 million, it was used for a few days then shut down seven years ago. As DWP engineer Bill Van Wagoner put it, "We spent slightly under $1 million per acre foot (of water produced) before we had to shut it off." That comes down to about $2.75 a gallon -- as opposed to the fraction of a cent per gallon usually paid by DWP customers.

The problem? "Indirect potable reuse" got a bad new name: "toilet to tap."

Public hearings on the reclamation project's safety were held in 1995. The Los Angeles City Council then greenlighted it unanimously after the Los Angeles Regional Water Quality Control Board, the state Department of Health Services and the state Environmental Protection Agency also approved the proposal.

It worked this way: Sewage was treated at the Donald C. Tillman Water Reclamation Plant in Van Nuys and then pumped to spreading fields near Hansen Dam, where, over five years, it would filter through sandy soil and gravel into an underground reservoir.

But what should have been an engineering triumph soon became a PR disaster.

For five years after its approval, the reclamation project was largely forgotten. Then came the official DWP announcement of its completion in 2000, just before an open mayoral contest in 2001 that included Valley secession on the ballot. The water agency could not have chosen a more inopportune moment.

The new pipeline, providing enough treated water for 120,000 L.A. homes, was greeted by protest. State Sen. Richard Alarcon, who had approved it when he was a council member, now objected. He was swiftly joined by Gerald Silver, president of Homeowners of Encino, credited with popularizing the "toilet to tap" tag. Opposition snowballed.

Mayoral candidate and Valley council member Joel Wachs, who also had approved the plan in 1995, cried foul in 2000: "Go tell somebody in North Hollywood that they have to drink toilet water but the mayor [Richard Riordan] won't have to drink it in [his] Brentwood [home]."

Wachs was utterly wrong. East Valley groundwater, like all the city's groundwater, is moved from Hollywood to downtown to Silver Lake and even to the Westside, "depending on supply, need and the way the system goes," Tucker said.

At the time, the DWP insisted that the treated water from the Tillman plant was almost potable, and when it reached the water agency's Valley wells, it would have a purity indistinguishable from unpolluted rainwater.

Few listened, however. City Atty. James K. Hahn, planning his own mayoral run, discretely ordered the recycling project shuttered for no other visible reason than the public protest. As mayor, he later reaffirmed his order, and the DWP promptly ran and hid from water recycling.

Back then and now, however, water treated at the city's main Hyperion wastewater plant goes into other cities' water supplies. It flows into aquifers supplying Manhattan Beach, Hermosa Beach, Redondo Beach and Torrance, courtesy of the West Basin Water Recycling Facility. The water supply of thousands of other Los Angeles County residents also includes highly treated wastewater.

This is because modern water-purification technology is considered totally reliable. It uses micro-filtration and reverse osmosis, which pumps water through permeable membranes, and ultraviolet light to remove all contaminants. The "yuck factor" is now completely imaginary.

Orange County just opened its own half-billion-dollar reclamation program -- almost four times the size of the East Valley project -- with minimal public opposition. The secret of this success? Transparency.

"We started telling people from the start that we're purifying sewage water," said Ron Wildermuth, district communications director, for the Orange County Water District.

The district also mounted a substantial public education campaign that should become a model for the DWP's plan to relaunch its own ill-publicized recycling program. By November, Orange County's water reclamation plant daily will supply up to 500,000 people with 70 million gallons of treated water.

Every day, the outflow of L.A.'s treated wastewater -- about 400 million-plus gallons -- amounts to the state's fifth-largest river running into the Pacific Ocean.

In these dry times, it makes perfect sense to stop throwing it away.

Marc B. Haefele is a commentator for KPCC and writes for Citybeat, Citywatch and Nomada magazine of Buenos Aires. Anna Sklar is a former NPR reporter and former public affairs director for the city Department of Public Works. She is the author of "Black Acres," a history of the city sewer system.



If you’re ever in Hollywood, the best thing to see (by far) is the Page Museum at the La Brea Tar Pits. It’s an amazing 40,000 year history of mammoths, bison, sabre-toothed cats and predatory birds becoming trapped in seeping pits of asphalt. The collection of bones retrieved (and still being retrieved) from such a small area is truly amazing. I particularly like the way they have set up the working palaeontology laboratory as part of the exhibit. Internationally significant scientific research, -right in the middle of Tinsel Town!



I was gently elbowing my way along Hollywood Boulevard this afternoon, intermittently glancing down at the stars that line the footpath (okay, sidewalk). Somewhere between Bing Crosby and Ozzy Osbourne, I came across the one below. Please explain...?

Saturday, August 18, 2007

Reverse Osmosis at the WCRWP

The Queensland State Government is currently busy with the construction of the Western Corridor Recycled Water Project (WCRWP). We took a brief overview of the scheme on this blog back in May. However, as I mentioned at the time, the WCRWP is a mega-project and we’d only just skimmed the surface.

Many readers of this blog seem to be particularly interested in reverse osmosis (RO) as an important treatment process of the WCRWP. We’ve previously discussed the important mechanisms by which RO membranes work, the variable rejection that can be expected for various contaminants, the reasons behind why RO is a relatively energy-intensive process, issues associated with membrane biofouling and even the potential alternative process of forward osmosis (FO).

However, I thought it would be useful to take a quick look at some of the actual RO membranes intended to be used at the WCRWP advanced water treatment plants and their modular configuration. I gathered most of this information (and the photograph) from a recent conference paper prepared by Troy Walker from Veolia Water Australia [1].

The WCRWP consists of three advanced water treatment plants treating effluents from six sewage treatment plants in Brisbane and Ipswich. Two of the advanced water treatment plants are located in the Brisbane area (Luggage Point and Gibson Island) and one just outside Ipswich at Bundamba.

The Bundamba plant is being built in two stages by the ‘Bundamba Alliance’ of Thiess and Black&Veatch. It will have an initial capacity of 20 million litres per day, which will then be delivered for use by Swanbank Power Station. This stage is due to be completed this month so we can probably expect an announcement fairly soon. The plant will then be expanded to deliver an additional 30 million litres per day available for Tarong Power Station by mid next year.

The Gibson Island advanced water treatment plant is being delivered by the ‘Gibson Island Alliance’ of Montgomery Watson Harza, Burns and Roe Worley, Balderstone Hornibrook and United Group Infrastructure. The Luggage Point plant is being delivered by the ‘Luggage Point Alliance’ of CH2MHill and Laing O’Rourke. These two plants will have a combined capacity of 116 million litres per day, which will be used to supplement the supplies of Wivenhoe Dam, -Brisbane’s main drinking water reservoir.

RO membranes are typically manufactured such that they are wrapped spirally around a porous tube. A further casing is then placed around the membrane to keep it in place and this unit is called a ‘membrane element’. This means that instead of membranes appearing as large flat sheets (which is what they are inside the element), they appear as a solid round tube. This tube is then placed inside a high-pressure vessel so that it can be pressurised to push water through it.

All three advanced water treatment plants will be using RO units with membranes known as ‘thin film composite polyamide membranes’. However, the membranes are expected to be sourced from different suppliers between the three plants. The different suppliers would have been selected based largely on commercial considerations of the various construction alliances, but also reflect variable feedwater characteristics such as nutrient and salt concentrations.

The vast majority of commercial RO membrane elements (for this type of application) are a standard 200 mm (8”) diameter and 1 m long. However, the Bundamba Alliance has designed that plant to use new generation 450 mm (18”) diameter, 1.5 m long membrane elements. These much larger membrane elements are manufactured by Koch Membrane Systems with the tradename ‘Megamagnum’. This element size is relatively new to the market and the Bundamba plant will be the largest installation of these membranes in the world.

Megamagnum RO membranes at Bundamba [1]

The larger membrane system results in a smaller number of membranes and pressure vessels on each RO unit itself, with 65 membranes used instead of what would be an equivalent of more than 450 smaller sized elements.

However, these membrane elements do present some additional challenges compared to standard 200 mm diameter elements. For one, they are much heavier (113 kg compared with 20 kg for new membranes), which has required the construction of a unique mechanical loading device.

While the membrane material itself is commonly used by many suppliers, the unique diameter of the element is only provided by Koch Membrane Systems. This carries an ongoing risk that if this membrane fails to meet treated water quality targets, or suffers from an unacceptable fouling rate, replacement membranes cannot be employed from an alternative supplier. One consideration under review is the possibility of installing smaller membranes into the 200 mm pressure vessels by means of a modified brine seal and sleeving.

The RO units at each plant will be arranged in a three-stage array. That means that the concentrated rejected stream from one membrane then moves on to a second, and then third, membrane where it is further concentrated each time. This arrangement is used to maximise the proportion of water that can be recovered as product water. The three plants are designed to achieve approximately 85% of feed volume as product water. The remaining 15% becomes the membrane ‘concentrate’, which will undergo further treatment prior to discharge to the Brisbane River and Moreton Bay.

Once recycled water starts being produced and delivered to Swanbank Power Station, I will –needless to say- be most interested to see some early performance data. Hopefully we will see some detailed data on contaminant rejection as well as achieved water recovery and energy consumption. When can we take a tour of the plant?

[1] Walker, T., Roux, A. and Owens, E. (2007) Western Corridor Recycled Water Project - The largest recycled water scheme in the southern hemisphere. In: Water Reuse and Recycling (Eds, Khan, S. J., Stuetz, R. M. and Anderson, J. M.) UNSW Publishing, Sydney, 498-511.

Saturday, August 11, 2007

Hard to swallow

An interesting article from The Australian this morning. A number of familiar names appearing and even brief cameo from yours truly, -if you make it that far. It’s good to see the draft water recycling guidelines generating some interest and receiving some analysis in the media.

As for ‘cockroach chip ice-cream’, could it really be so bad? I’m sure there must be a market for it out there somewhere…

Hard to swallow

Selina Mitchel
The Australian
August 11, 2007

Can drought-prone Australia afford to turn up its nose at recycled water any longer?

TO some, the idea of drinking recycled sewage is akin to eating cockroach-chip ice cream -- unthinkable, even if shown to be safe. Others in positions of power, such as Queensland's Premier Peter Beattie, are so desperate for a solution to dwindling dam supplies they are willing to risk community disgust and implement the option anyway, using treated effluent to eke out diminishing rainwater reserves.

All protagonists are keen for scientific evidence to back their arguments -- and now they feel they have their ammunition.

Australian health and science authorities have issued a draft of the world's first safety guidelines on recycling sewage for human consumption. Recycling has been taking place in some areas of the world for decades, but national guidelines have never been created in any of the countries doing so.

Details of the draft guidelines, released recently, are being seized on by both water experts and anti-recycling campaigners as fodder for their causes.

On the "pro" side, the draft guidelines state that it is possible to safely recycle sewage for drinking purposes, as long as strict treatment and management processes are followed.

But the guidelines set the bar so high that they are likely to stop small, parched towns from taking up the controversial option -- an assessment anti-recyclers seeing as a win.

The guidelines warn that the process of recycling waste water is highly complex and risky, and requires expensive technology and skills -- resources difficult to find among local government or small utilities. Anti-recycling campaigners say that the draft guidelines, as they stand, would have ruled out the failed Toowoomba waste water recycling plan and could scuttle proposals to augment supplies in Canberra and nearby Goulburn.

National Health and Medical Research Council (NHMRC) Water Quality Advisory Committee member David Cunliffe says the guidelines were not designed as a political tool, but to outline how to strip sewage water of contaminants such as viruses and chemicals so it is safe to drink.

"It can be done, but it is a challenge," Cunliffe said. "It is naive to think incidents won't occur, but controlled and timely responses will ensure incidents don't present a health risk."The expertise required will make it difficult for local governments and small utilities to do -- it is not an approach for a small town or utility and it will be a challenge even for the largest utilities or governments."

Brisbane will become the first Australian town or city to use recycled sewage for drinking by the end of next year, with recycled water to be pumped to the Wivenhoe Dam through the $1.7 billion western corridor pipeline, the biggest project of its kind in Australia. Despite voting against a recycled water proposal last year, Toowoomba will get recycled water from that pipeline.

The guidelines may be in draft form and open for public comment, but the Queensland, Goulburn and ACT authorities cannot wait until the final version is released: they need to know now how they could safely implement a scheme now. Each of these groups is relying heavily on the draft.

Along with a complicated 12-step system for the safe operation of water recycling facilities, the guidelines provide key principles for recycling. These include that the protection of public health is paramount and should never be compromised, any attempt to augment supplies must have community support, and utilities which take on the task must have the resources to properly meet the challenge and their staff must have appropriate skills and training.

While the draft fails to detail a specific set of technologies which must be used to treat the water, the principles do state that every system must use multiple barriers, such as membrane filtration, reverse osmosis and advanced oxidation, as none is perfect and each has strengths and weaknesses (see table).

Also, industrial waste water must be monitored and managed under separate programs. And each scheme must be subject to regulatory surveillance.

The guidelines all but rule out the direct augmentation of supplies -- where recycled water enters the drinking supply system without going through an intermediary receiving body of water, such as a river or reservoir. There is only one case of direct potable reuse in the world, and that scheme -- in Namibia -- was developed in the 1960s.

"The scope for assessing water quality and intervening before substandard water is supplied to consumers is limited," the draft says. Community acceptance of such schemes would be difficult and any successful implementation would be exceedingly expensive, it adds.

The draft guidelines -- developed by experts in public health, toxicology and drinking water management -- are based on the best available scientific evidence from around the world.

But the evidence on some health aspects of wastewater recycling -- such as the potential impact on allergy sufferers -- is still scant, the authors of the draft guidelines admit.

A group of government, science and legal experts met in Canberra earlier this month to discuss the draft, and similar public consultation workshops will take place in other capital cities over the next four weeks.

Queensland's chief health officer Jeannette Young and ANU infectious diseases expert Peter Collignon raise concerns about the lack of mention of potential effects on allergy sufferers in the draft.

"I am going to have every allergy group in the state asking if their child will be safe (drinking recycled water)," Young says.

Cunliffe says the issue of allergies will be considered before the final guidelines are released. "We know some pharmaceuticals have allergic outcomes for some people, but it is very difficult to assess. We will see if there is a way of dealing with it."

The authors of the guidelines do not doubt the technology. Their concerns centre on institutional capability and operator capacity -- the human element.

Technical director of the Water Services Association of Australia Peter Donlon says there are vast differences in the capabilities of water providers across the country, and most small operators are simply not equipped to recycle wastewater.

"If you are not big enough, don't bother," says Donlon. The WSAA is the representative of city water suppliers.

Donlon says there is already only very patchy implementation of guidelines for the treatment of drinking water from traditional sources, and that regulatory bodies need to ensure new (and old) guidelines are followed.

The capacity issue is not just one for local government, but for state government as well, Mark Batty from the WA Local Government Association says. He says the West Australian Government is currently investigating its capability to provide safe water to the public.

NHMRC Water Quality Advisory Committee chair Don Bursill likened novices running the recycling treatment process to a janitor flying a jumbo. "These are complex technologies. If people don't understand these things, they shouldn't be in the game.

Bursill says the main tenet of the draft guidelines is that domestic waste water can be recycled for drinking, but all other options must be ruled out first. "We do recognise that it has to be done sometimes," he says.

University of NSW water recycling expert Greg Leslie says many of the treatment and management systems and processes used in traditional drinking water supply systems could be used in recycled waste water systems just as effectively.

Collignon, who has raised concerns about the safety of a proposed recycling scheme for Canberra, welcomes the new guidelines. But he thinks they need to be improved, and should state recycling must only be considered as a last resort.

Toowoomba councillor and anti-recycling campaigner Snow Manners claims the NHMRC and other organisations that have endorsed the "flawed" guidelines are "flying blind", asserting there is not enough evidence to show recycling is safe.

Manners likens drinking recycled water to eating cockroach-chip ice-cream. "It is probably very nutritious and safe, but people don't like the idea of it," he says.

Karin Leder, from Monash University's Infectious Disease Epidemiology Unit, says she supports the guidelines. "We are not saying there is no risk -- we are saying there is acceptable risk."

Stuart Khan, program leader at the Centre for Water and Waste Technology, says more work is required on the guidelines. He says it will never be possible to check recycled water for every potential contamination, so it will be better to develop a list of surrogate chemicals which could indicate the overall quality of the treated water.

Over the next four weeks the draft guidelines will be taken to every capital city across the country for consultation. Overseas bodies have also grabbed the opportunity to assess the guidelines. So far, it seems they have only gone so far in clearing the public's mind over what is proving a very murky issue.

Saturday, August 04, 2007

DALY Dalliance

One of the Toowoomba-based anti-potable water recycling blogs posted an article this week titled ‘Recycled water - giving 1 person in 1000 the shits’. While I admire the creative title, the blog post revealed a need for more discussion and improved community understanding of microbial water risks.

Most people are not familiar with the concept of a ‘DALY’. This is understandable since it is reasonably complex and only quite recently introduced to international water safety guidelines. So let’s take a look at DALYs and their relevance to recycled water.

DALY is the acronym for a Disability-Adjusted Life Year. The use of DALYs is an important feature of the World Health Organisation (WHO) Guidelines for Drinking Water Quality. They are used to help us define a reference level of risk in order to define safe water.

Practically all drinking water supplies contain very very low concentrations of toxic chemicals. Among the most obvious are byproducts that are formed from chlorine disinfection. The chlorine reacts with natural organic matter (present in all natural waters) to form chlorinated chemicals such as chloroform and dichloroacetic acid. In high concentrations, these chemicals would be quite toxic. However, we understand from toxicology that low levels of exposure have very low risks of doing us harm. Accordingly, if we can somehow put a number on the level of risk that we –as a society- are prepared to tolerate, then this will help us to define acceptable concentrations of these chemicals in drinking water.

We have been associating numbers with acceptable risks of chemical exposure for many decades. For chemicals which are known or suspected to cause cancer, the acceptable lifetime exposure is defined in the WHO Guidelines for Drinking Water Quality as that which will result in one excess cancer case per 100,000 people. The Australian Drinking Water Guidelines are stricter and set limits based on one excess cancer case per million people.

However, applying numbers to microbial risks (pathogens) has always been a more challenging task. This is because infections with different microbial organisms (viruses, bacteria, protozoa, etc) can have vastly different health outcomes, which are difficult to compare. Some outcomes are nasty (eg diarrhoea) and some are really severe (eg typhoid). So the risk of acquiring one cannot be simply equated with all others. Furthermore, any one pathogen may have multiple diverse effects or variable effects on different people.

The idea of a DALY was developed in order to be able to objectively compare water-related hazards and the different health outcomes with which they are associated. The basic principle of a DALY is to weight each health effect for its severity from 0 (normal health) to 1 (death). This weight is multiplied by the duration of the effect, which is defined as the time in which the disease is apparent. When the outcome is ‘death’, the ‘duration’ is the remaining life expectancy. The product is then multiplied by the number of people affected by a particular outcome. It is then possible to sum the effects of all the possible outcomes due to a particular hazard.

Accordingly, the DALY is the sum of years of life lost by premature death and years of healthy life lost in states of less than full health (ie years lived with a disability, which are standardised by means of severity weightings).

The World Health Organisation has defined a tolerable level of risk of 1 millionth of a DALY (one microDALY) per person-year. This is equivalent to the loss of one DALY per million people per year. This could be interpreted as one person in a million losing one year of life, or it could be interpreted as a larger number of people suffering less severe impacts. For a pathogen causing watery diarrhoea (but rarely causing death), this reference level of risk has been determined to be equivalent to around 1 in 1000 annual risk of diarrhoea to an individual, -or about 1 in 10 risk of contracting diarrhoea over a lifetime.

Of course, the outcomes of these risks would not actually be observable. For example, the normal reported rate of diarrhoeal illness in Australia is about 0.8-0.9 cases per person per year. In other words, the average Australian gets (and reports) diarrhoea just slightly less often than once per year.

Now that this ‘benchmark’ risk level has been defined, concentrations of specific hazards, which are consistent with this benchmark can be determined. Based on an understanding of source water quality (and variability), this information can inform us about the minimum level of treatment that is required to make the water safe for consumers.

DALYs are used in the Australian Guidelines for Water Recycling in a manner that is entirely consistent with the WHO Guidelines for Drinking Water Quality. Most of the discussion of how they are used is included in Phase 1 of the Guidelines (recycling for non-potable uses). However, they apply equally to the draft Phase 2 Guidelines (recycling for drinking water). DALYs are also expected to be included in the next revision of the Australian Drinking Water Guidelines.

While the guideline risk benchmarks are the same for recycled water as for drinking water, this doesn’t mean that the actual risks are the same. Indeed, a well managed comprehensive advanced water recycling scheme can be expected to achieve much better water quality for most hazards, compared with simply meeting the drinking water guideline.