Making every drop countWould you drink a glass of treated effluent? That question has become part of a heated national debate about water recycling, as people try to find solutions to the lack of water supplies brought about by climate change and a growing population.
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Recycling across Australia Wastewater has been recycled and used in Australian towns and cities for decades, but usually for watering recreational facilities such as parks and golf courses. However, a recent proposal for one drought-stricken Australian community to recycle sewage and use it to top up drinking supplies has left a lot of people with a bad taste in their mouths. In a referendum, residents of the city of Toowoomba in south-east Queensland rejected a scheme to recycle sewage to top up drinking supplies. The issue divided the small community and roused passions, but it also highlights a major issue facing all Australians. A drying climate due to global warming and a growing population has created the need to find and adopt innovative, sustainable methods to slake our thirst for water. Overcoming the ‘yuk factor’ Researchers and water authorities in Australia say there’s no scientific or health reason that recycled wastewater can’t be safely used as part of drinking water supplies if treated properly. But there can be a formidable psychological reason. It’s called the ‘yuk factor’ – based on the thinking that the water in the glass in your hand might have started off in someone’s toilet bowl. But should we be worried? Overseas, it’s not unusual for treated wastewater to be part of drinking supplies. The city of London is located downstream from numerous wastewater recycling plants that discharge into the Thames river. Which is why there’s a common saying that when you drink a glass of water in London, the water has already passed through several pairs of kidneys. And recycled wastewater is successfully used to top up drinking water supplies in Namibia, the United States and Singapore (Box 1: Turning recycled sewage into a tourist attraction). Many informal ‘taste and tell’ surveys reveal that most people can’t tell the difference between tap water, bottled water and recycled water. So why the fuss? Well, that’s what some residents of Toowoomba, in south-east Queensland, and Goulburn, in New South Wales, are thinking. A tale of two cities Both Toowoomba and Goulburn were planning to introduce schemes to recycle sewage into drinking water supplies to help their communities overcome chronic water shortages due to drought and long-term, below-average rainfalls. Toowoomba would have been the first city in Australia to use recycled sewage for drinking water, with its proposal for a new $68 million wastewater treatment plant to top up potable water supplies at Cooby Dam. The Goulburn proposal – which is still being considered – involves building a new wastewater plant as part of a $32 million project to recycle effluent and return it to the Sooley Dam catchment. But recycling effluent for drinking is an emotive issue. In Toowoomba, a group of concerned citizens collected some 10,000 signatures for a petition opposing the project. That’s despite advocates of the proposal saying their recycled wastewater will be so pure it could be used for hospital purposes such as kidney dialysis. Backers of both proposals also point out recycling is part of much wider water saving strategies that are feasible, sustainable, and necessary – and that they can help drought-proof their communities for decades to come. How to make wastewater drinkable There are a number of ways in which to purify water – including sewage water, groundwater or seawater – to obtain drinking water. Methods include distillation, freezing, reverse osmosis, electrodialysis or ion exchange. Each method has advantages and disadvantages, and the method chosen depends on the scale, location, source of water, cost and available energy sources.
Treating wastewater to make it suitable to add to drinking supplies often involves the reverse osmosis process, along with other purification treatments. In Toowoomba, for example, the wastewater would have been treated using ultrafiltration, reverse osmosis, ultraviolet disinfection and oxidation processes to destroy microorganisms. During reverse osmosis, water is forced under pressure through very fine membranes which allow water molecules to pass through, but not salts and other matter. The technology is already used around the world to provide water for industrial purposes and drinking water on ships, and there are plans to use it on spaceships (Box 2: Making water for astronauts from sweat, breath – and urine). Using a process called ‘indirect potable reuse’, the recycled wastewater would then top up existing drinking water supplies to be stored at the nearby dam and then undergo conventional water treatments. It would then become part of residents’ daily drinking supplies. But there are two common concerns with such water purification projects. Firstly, they require considerable amounts of energy. Secondly, there are environmental concerns about what to do with the concentrated salty waste water that is made during the process. The big picture Residents of Toowoomba have voted against their wastewater scheme, but the issue is now being looked at on a much wider scale. The publicity involving the Toowoomba poll has helped put the spotlight on other Australia-wide initiatives to quench our growing thirst for water. Australia is the driest inhabited continent and climate change resulting in below average rainfall and extensive droughts have prompted the search for new, innovative and sustainable water supplies, and ways to curb demand. Growing demand from agriculture, industry and a growing population, have exacerbated the problem. According to national State of Environment reports, industry and householders are using increasing amounts of water. As a result, there is a push for new sustainable water supplies taking place at all levels of government in every State. And it’s easy to see why. Much of the sewage treated at Australian wastewater treatment plants is fed directly into the sea or rivers – in effect, it goes down the drain. But water recycling is now set to play a much greater part in the water management cycle. Many states are committed to increasing water recycling targets in years to come. Although there are differing views, researchers and health authorities say it’s possible to recycle water to the relevant standard for whatever use the water is required, be it irrigation, horticulture, agriculture, household use – or drinking water. What’s important, they say, is defining what standards are required for particular uses, and then implementing relevant risk management, quality assurance, and monitoring programs to provide safe drinking water, or alternative uses that spare potable water. And then there’s one other vital issue to consider, which you can sum up with the adage: ‘You can lead a horse to water, but you can’t make it drink’. Overcoming the yuk factor might turn out to be the most crucial part of the whole process. Boxes 1. Turning recycled sewage into a tourist attraction 2. Making water for astronauts from sweat, breath – and urine Related Nova topic:
Box 1: Turning recycled sewage into a tourist attractionRecycling sewage for drinking purposes is done in Singapore, the United States and Africa – so why not here in Australia? In Singapore, the NEWater facility recycles sewage to top up drinking water supplies using microfiltration, reverse osmosis and ultraviolet treatment. The NEWater facility provides about one per cent of Singapore’s total daily water consumption using indirect potable reuse by adding it to the country’s reservoirs. According to authorities, the NEWater recycled water consistently exceeds World Health Organisation guidelines for water. The NEWater facility is even being marketed as a tourist and education attraction with the NEWater Visitor Centre holding several tours daily. The tours involve multimedia presentations and interactive computer displays to guide visitors through the water recycling processes. In the United States, the output from a major sewage treatment plant in Centreville, Virginia, ends up in the Occoquan Reservoir which provides drinking water for the Fairfax County Water Authority. In 2001, a year-long study by researchers with the University of Southern Florida compared water samples from eight sites at the wastewater treatment plant and compared their microbiological quality with water in the reservoir. The study found that in all cases, the treated wastewater was of a better quality than the water in the reservoir. Related site
Box 2: Making water for astronauts from sweat, breath – and urineIf you’re an astronaut, chances are you’re already familiar with water recycling – and maybe even having to drink recycled urine. NASA is currently developing several initiatives to recycle water more efficiently on the International Space Station, as well as preparation for future trips to the moon and Mars. Aboard the International Space Station, crewmembers are allocated two litres of water daily. Most of it is delivered – at great expense – via NASA's Space Shuttle or the Progress supply ships sent up by the Russian space program. But part also comes from recycling wastewater, condensate in the air, and urine aboard the Space Station. Researches are developing a new technology to recover water from astronauts’ sweat, breath vapour and urine. The system includes a urine processor assembly to recover water from urine. This water is then purified to a potable standard by a Water Processor Assembly, which is expected to produce 132 litres of potable water daily – sufficient for a seven-person crew. The technology is also expected to be of use here on Earth, where it could be used by humanitarian groups in countries where fresh water is unavailable, or in the wake of disasters such as the 2004 Indian Ocean tsunami. Water recycling is also playing a part in preparations for a possible trip to Mars around the year 2030, with experiments currently underway in Antarctica. The French-Italian crew from the European Space Agency is spending a year at Concordia station in Antarctica to research two projects related to a possible Mars trip. The projects look at what’s involved in psychologically adapting to a new environment and developing a group identity, as well as research looking at how microbes spread and evolve in an isolated environment. To preserve the pristine Antarctic environment, all greywater from the showers, dishwashing and laundry is recycled, and all waste material removed from the continent. Related sites
Activities
Additional information on coliform nomenclatureThe terms coliforms, thermotolerant coliforms and E.coli are sometimes used in literature more or less interchangeably. Microbiologists and public health authorities make distinctions between them as follows:
Significance of these differences It follows, therefore, that fermentation tests in bile-lactose media on water samples that are carried out at 35° to 37°C will indicate the presence of bacteria belonging to the broad coliform group; these may or may not be of faecal origin. Positive fermentation tests conducted at 44°C (thermotolerant coliforms) indicate the presence of coliforms that may be of faecal origin. Water testing laboratories usually test for coliforms and thermotolerant coliforms.
Further readingATSE Focus June 2007 What is missing in national water reforms? Provides discussions on recycled water and water management challenges in Australia.
May 2004 Water recycling in Australia Provides a thorough technical analysis of water recycling in Australia and overseas.
Australasian Science January-February 2007, page 9 Water recycling gains support Reports on a recent survey into attitudes towards water recycling.
November–December 2004, pages 33-34 Desalination: a solution to water woes? (by Simon Grose) Looks at desalination of sea water as a source of water, focusing on Perth.
August 2004, page 8 The rain in WA fall mainly beyond the plain Suggests that the decline in rainfall in south-west Western Australia is due to a combination of land clearing and global warming.
July 2004, pages 38-42 Water recycling options for a thirsty country (by John Radcliff) Describes the potential for recycling wastewater, stormwater and rainwater to supply water for agriculture, industrial and domestic purposes.
Cosmos 28 June 2007 Going with the flow (by Craig Scutt) Explores the water recycling process in detail.
Ecos Ecos, No. 139, 2007, page 6 Grey water recycling without buckets Reports on the development of a domestic grey water recycling unit.
No. 132, 2006, page 6 A global win for the Gold Coast's Pimpama Coomera water plan Reports that the Gold Coast City Council won the Global Grand Prize at the recent World Water Congress in Beijing for its Pimpama Coomera water plan.
No. 131, 2006, page 7 Miserly water recycler installed in Melbourne Describes a laundry water recycling system.
No. 131, 2006, pages 16-17 Making a natural impact An interview with Dean Cameron, who developed an award-winning waste treatment system.
No. 129, 2006, pages 14-17 Building a water resources observation network (by Clare Peddie) Reports on the use of technology by the Water Resources Observation Network to monitor the use of water resources.
No. 127, 2005, page 5 Global winner, Biolytix, is taking on effluent society Describes the prize-winning Australian sewage and greywater recycling unit, Biolytix.
No. 124, 2005, pages 23-26 Making water – hold the salt (by Steve Davidson) Discusses the pros and cons of some desalination options in Australia.
No. 122, 2004, pages 8-10 The Aquadam (by Wendy Pyper) Describes the Aquadam Project to capture and store rainwater, stormwater and desalinated seawater in a flexible, floating dam out at sea.
Issues July 2003 Contains a number of articles about water including the following:
New Scientist 17 March 2007 A wee drink for thirsty astronauts (by Hazel Muir) Reports on NASA’s answer to its water shortages on the International Space Station.
26 August 2006, page 14 Catch every drop to fight world hunger (by Andy Coghlan) A report suggests that a third of the world's population is affected by economic or physical scarcity of water.
8 April 2006, page 32-37 The quantum elixir (by Robert Mathews) Looks at the physical properties of water and their affect on biological molecules.
3 December 2005, pages 47-48 To your good health (by Bryant Furlow) Suggests that reduced immunity to water borne pathogens may result from drinking water that is highly purified.
27 May 2004 Israel lays claim to Palestine's water (by Fred Pearce) Looks at the political side of water allocations.
7 June 2003, pages 30-34 Replumbing the planet (by Fred Pearce) Looks at large scale projects to redirect water towards major population centres.
29 March 2003, pages 8-9 Safe water remains a mirage (by Fred Pearce) Comments on the lack of an action plan from the World Water Forum meeting in Kyoto.
11 April 2002 Ski resort recycles sewage into snow (by Marina Murphy) Describes the use of treated sewage to make artificial snow in Australia.
Newsline Issue 28, winter 2003, pages 5-7 Running water Looks at research addressing the management of water supplies and wastewater networks.
Issue 28, winter 2003, pages 8-9 The treatment Looks at techniques used to remove by-products of disinfection.
Issue 28, winter 2003, pages 10-11 Catching the bug Looks at new methods to detect Cryptosporidium in water supplies.
Scientific American 10 May 2006 Microbes convert wastewater into useable electricity (by David Biello) Describes microbial fuel cells that produce electricity.
The Source March 2006 Drastic action Describes the water recycling plants used by Toowoomba and Goulburn
December 2005 Powerful driver Describes a new national water efficiency rating scheme and labeling scheme for household appliances and commercial carwashes.
Useful sitesA thirst for recycled water (South Australian Policy Online)
A national survey carried out by Flinders University researchers has found a high level of acceptance towards the use of treated wastewater in non potable applications.
Cooperative Research Centre for Water Quality and Treatment, Australia
Water made clear (National Health and Medical Research Council, Australia)
Provides an overview of the supply of drinking water. Includes possible sources of water contamination, storage, treatment options and sampling for analysis of water quality.
What is water quality? (New South Wales Environment Protection Authority, Australia)
Discusses aspects of water quality used for drinking, irrigation and maintaining aquatic ecosystems.
Wastewater (Queensland Government’s Environmental Protection Agency, Australia)
Lists some questions and answers about wastewater.
Commonwealth Scientific Industrial Research Organisation, Australia
Dry and getting drier (Melbourne University Up Close Podcast, Australia) Transcript of an interview with Professor Langford and Professor Millis. Discusses the need for radical changes in water management in Australia. The audio is also available for download.
About Water Futures (Water Futures – Toowoomba, Australia)
Provides information on the Water Futures project, recycled water and other water options considered for the town’s drinking water supply.
Introduction to desalination technologies in Australia (Australian Government Department of Agriculture, Forestry and Fisheries)
Summarises desalination methods and their potential use in Australia.
How does reverse osmosis work? (How Stuff Works, USA)
Summarises the process of reverse osmosis.
Desalination of brackish water with wind-powered reverse osmosis (Water Resources Research Center, University of Hawaii, USA) Looks at the use of wind power to supply fresh water.
Australian Broadcasting Corporation
Glossarycatchment. The area from which a river, stream, lake or other body of water receives its water.disinfection. Physical or chemical treatment to destroy harmful microorganisms. The disinfecting properties of sunlight are due to ultraviolet light. global warming. An increase in the average temperature of the Earth's surface. Global warming is one of the consequences of the enhanced greenhouse effect and will cause worldwide changes to climate patterns. groundwater. Water that is found beneath the surface of the ground, usually in porous rock known as an aquifer. The top of this groundwater is called the water table. For more information see Interacting sub-systems of the Earth that together produce a unique biome – What is groundwater? (University of New South Wales Groundwater Centre, Australia). membranes. A thin sheet of material that is permeable to substances in solution. microfiltration. A membrane filtration process which removes contaminants from a liquid by passage through a microporous membrane. The pore size of a typical microfiltration membrane ranges from 0.1 to 10 micrometres. Microfiltration can remove many pathogens from water including Giardia, Cryptosporidium and large bacteria. osmosis. The movement of water between two solutions, separated by a membrane that permits the free passage of water but prevents or slows down the passage of dissolved substances. The water moves more rapidly from the less concentrated solution to the solution of a higher concentration than in the opposite direction. Reverse osmosis is the movement of a solvent in the opposite direction from osmosis. Pressure – usually 5 MPa - 20 MPa – is applied on the high concentration side of the membrane, forcing the solvent through a membrane to a solution of lower concentration. Pure solvent is obtained on the other side. The membranes used for reverse osmosis do not have pores: rather, separation takes place in a polymer layer of microscopic thickness. For more information see How reverse osmosis works (How Stuff Works, USA). potable. Water that is fit for drinking purposes. sewage. Liquid and solid waste carried in sewers. ultrafiltration. Is a type of membrane filtration in which hydrostatic pressure forces a liquid against a semipermeable membrane allowing only the passage of small molecules. Ultrafiltration only differs from reverse osmosis and microfiltration in the size of the molecules it retains. ultraviolet.The term for electromagnetic radiation that has a wavelength just beyond the violet end of the visible spectrum. Ultraviolet disinfection can be used to kill microorganisms in water. For more information see FAQs about ultraviolet water disinfection (Triangular Wave Technologies, USA). External sites are not endorsed by the Australian Academy of Science. Posted August 2006. The Australian Foundation for Science is also a supporter of Nova. This topic is sponsored by the Australian Research Council Linkage Learned Academies Special Project Grant.
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