Water is too precious to use just once. Fighting drought for over a decade now, Melbourne residents know this well and have upped the ante when it comes to reusing their water.
Local Golf Course being watered with treated wastewater SOURCE:City West Water
Since 2003, central and western suburbs of Melbourne, Australia have turned to wastewater for a fair share of their water needs. That year, City West Water (CWW), one of three retail water companies providing metropolitan Melbourne with water and wastewater services, ended a 3-year development process to enhance wastewater treatment and supplied its first customer with recycled water.
Since then, CWW has implemented several water reuse schemes, varying from a single customer demanding large volumes of recycled water, i.e. a golf course, to supplying domestic properties through a reused water reticulation network. CWW’s recycled water falls under the Class A category, which means it is treated to a standard very close to drinking water. Its current uses include toilet flushing, watering vegetable and other gardens, irrigating public open spaces, and general outdoor uses such as car washing or construction.
“CWW put a lot of effort into planning,” says Matthew Giesemann, CWW’s General Manager for Engineering, “and maintained a steady stream of communication and consultation with our customers so they readily accepted recycled water,” he added.
With Melbourne entering its 11th year of drought and its storage levels at under 27% capacity, CWW’s water reuse schemes effectively deflect demand on the city’s starving water catchments.
Australia isn’t called the driest inhabited continent for nothing. Some say that if its annual run-off was spread evenly over the continent, the water depth would be a mere three centimeters. Drought is therefore constant.
Some droughts, however, have more devastating impacts than others, and the current one ranks among the top in terms of economic and agriculture losses, e.g. number of sheep fell to 77 million, the lowest level recorded since 1920, and rice production plummeted by 89%.
To combat this situation, various local governments are taking extra steps to drought-proof their localities. Melbourne is no exception.
Home to approximately 3.9 million people and located in the south-eastern part of Australia within the state of Victoria, Melbourne is the second most populous city in the country. Despite its water shortage, the city has consistently ranked among the world’s most livable cities since 2002.
Together with the rest of Victoria, Melbourne is implementing measures designed to preserve and augment scarce water resources. These include permanent water saving rules—such as no hosing of paved areas or putting trigger nozzles on hoses—and additional water restrictions imposed in March 2007. Under these restrictions, residents can be fined up to A$454 or have their water supplies reduced to trickles if they’re caught using drinking water for washing vehicles and paved areas, watering lawns at any time, or for watering gardens outside of nominated water days and times.
“We have dedicated crews roaming the streets in clearly marked vehicles keeping an eye out for water cheats,” warns CWW Managing Director Anne Barker.
T155, a campaign to reduce personal water consumption to 155 liters per day using water saving techniques, was also introduced in November 2008. Many embraced this campaign so wholeheartedly that average per capita consumption by May 2009 was down to 139 liters, way ahead of target and a vast improvement from the 422 liters per capita consumption in the 1990s or the 180-liter rate in 2008.
Melbourne is also constructing a large desalination plant, scheduled to be operational in 2012, which will supply 150 megaliters of water daily, roughly a third of Melbourne’s water supply.
Despite the enthusiastic community response and the reduced water consumption, much more is needed. So CWW figured out a way to reuse water from the over 900 million liters of sewage generated each day.
Tank of recycled water ready for supplying nearby properties SOURCE:City West Water
Ninety percent of Melbourne’s wastewater is treated at two large treatment plants and discharged as treated effluent into Bass Strait and Port Philip bay. The rest are treated at local treatment plants run by the retail water companies like CWW. Converting wastewater to Class A recycled water involves sophisticated sludge treatment processes, ultraviolet disinfection, and chlorination. Further treatment could be undertaken as needed.
In 2000, CWW began designing schemes to bring recycled water to some of its roughly 276,000 residential and 31,300 industrial and commercial customers. Each scheme takes into account feasibility, affordability, time to implement, and ability to manage.
“We also run a risk analysis for each project at the planning stage so risks can be avoided or designed out,” explains Matthew.
Today, the purple hoses and signs indicating the use of recycled water can be seen in some of CWW’s coverage area—from chemical plants to school yards, golf courses to stockyards. Among CWW’s schemes are supplying recycled water to
MacKillop College to irrigate its sporting fields, gardens, and recreation areas, saving 20 million liters of drinking water a year
Werribee Technology Precincts with water for irrigation, washing down animal enclosures, and pump cooling
Other customers via a standpipe at the Western Treatment Plant, where they can collect the water themselves or buy it from licensed water carters.
CWW also began supplying new residences after it trained and certified Melbourne plumbers to ensure that they can properly install the purple coded pipes for recycled water.
None of these schemes, however, involved using wastewater as drinking water so Melbourne hasn’t seen highly charged scenes like that in Toowoomba, Queensland where residents vehemently voted against such a project. Instead, Melbourne residents took to recycled water like duck to water. Of course, it helps that recycled water, which isn’t covered by the water restrictions, is cheaper than drinking water—A$0.85 per 1000 liters as compared to A$1.02-A$1.77 per 1000 liters as per 2008-2009 prices.
In 2002, the government committed to using 20% of Melbourne’s wastewater by 2010. “We reached this target 2 years ahead of schedule. In 2007/08, we recycled 23.2% of our wastewater,” said Tim Holding, Victoria’s Water Minister. Today, Melbourne uses roughly 30% of its treated wastewater.
Still, it’s not all smooth sailing for Melbourne’s water recycling.
Even if Melbourne already uses more recycled water than any Australian city, it still pumps most of its wastewater out to sea. Many see this as a waste of resource. In June 2009, after an 18-month investigation, a parliamentary committee recommended 100% use of Melbourne’s treated water. If implemented, this would mean massive and expensive upgrades.
Cost is also a big consideration. As Matthew explains, “The main problem is that sewerage is a gravity system and treatment plants are always located at the lowest level. Hence, any redistribution of treated wastewater requires new pipeline systems, often in already developed areas, and a lot of pumping.”
There is also the environmental catch 22 of recycled water—improving the standards of treatment means using higher amounts of energy, opening doors to greater climate risks. Australian treatment plants experienced a four-fold increase in energy consumption as they upped sewage filtration standards and this trend is expected to continue as recycled water finds greater use.
At the end of the day, though, there is no argument that recycling water remains an effective way of reducing the demand for scarce potable water.
CWW is pursuing other reuse projects as it monitors the progress and ensures the quality of its current schemes. Among its future undertakings would be supplying 2.5 billion liters of recycled water per year to industry and golf courses in the Altona area, supplying the Sunshine Golf Course with recycled water from sewer mining, and catering to more industrial and residential areas.
A valuable lesson it learned along the way is that while reuse schemes can be introduced at any time, sustaining them will require the cooperation of health and environmental regulators, the water utility, and the community. It will also require competency in wastewater treatment, laboratory testing, risk management, and disinfection.
“Reusing water is both viable and affordable but you have to make public health your first priority and ensure that processes are in place to ensure the quality of recycled water is maintained,” stresses Matthew.
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