SOW – SAVE OUR WATER – 6 EASY WAYS

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6 ways to SOW — Save Our Water

child drinking from water fountain image www.h2o-water.com

As water consumers, we’re constantly tap dancing around the truth: there’s only so much water out there. Water on Earth is a closed system. For practical purposes, it can neither be created nor ex-sponged (sic). It seems obvious that cleaning up the water we use for re-use and re-distribution, and re-use and reticulation and re-use and recharging of aquifers, rivers and wetlands is the path for the present and ever increasingly the way of the future.

In Australia, the Millennium Drought (2002 to 2007-9) focused government, community and industry attention on drought-proofing. Several states prepared to suck up the sea. Desalination plants became the new coastal development. In Queensland in 2005, Toowoomba, with its dam-held water supply at 20%, thought its thirsting residents might be prepared to drink wastewater—let’s call it sewage—that had been completely restored to potable standards. Whatever they called it, it didn’t go down well and the proposed treatment scheme was voted out by referendum.

And yet around the same time that Toowoomba was trying to live down the runaway reverse-PR train that had dubbed it Poowoomba, the Australian Government issued a complete rewrite of its water-recycling guidelines, officially recognising the part that reuse must play in the country’s economy and wellbeing. “The guidelines now work on a risk-management approach, principally considering human health, though also strongly covering the environment,” says Simon Toze, research director of the Liveable, Sustainable and Resilient Cities Program at CSIRO’s Land and Water Flagship. “They look at ways to minimise the risk way below what might be considered acceptable.”

If we said membranes, porous roads and cocktails are shaping up as a more full-bodied approach to Australia’s water challenges, there might justifiably be dancing in the streets. Translate that as a wide range of solutions based on innovation, engineering and resilience through diversity (a cocktail of water-treatment strategies!), and there’s still cause for enthusiasm.

You can’t get under it, you’ve got to go through it

WATER TREATMENT PLANT GIF IMAGE www.h2o-water.com

ZeeWeed ultrafiltration membrane technology turns sewage into water for reuse. 

Membrane technology isn’t new. It’s a key water-filtration solution. GE’s ZeeWeed membrane technology, has been around since the early 1990s and has undergone constant innovation and development since: it takes less energy to run, is resistant to clogging, is easy to use and reports on its own maintenance needs. Importantly, “The cost of our membranes is basically 20 times cheaper today than it was 20 years ago,” says Chris Harpham, commercial manager of Equipment Solutions, GE Water, Australia & New Zealand. So what might once have been an elite water-processing tactic, suitable only for high return-on-investment situations, has been far more generally applied as a solution at thousands of sites around the world.

Membrane processes are important in water recycling,” says Harpham, “because they provide a definitive barrier against pathogens, so you know that if operated correctly and tested and checked and verified, they perform to a very high standard.”

In Australia and New Zealand, ZeeWeed-based plants have been installed in some 70 varied situations. Queensland councils on the Great Barrier Reef-facing coast have so far installed four ZeeWeed plants: the first was commissioned for Townsville’s Cleveland Bay in 2007, two in Cairns are now in their sixth year of operation and the latest at Sarina near Mackay was switched on last year. The aim in each case has been to reduce discharge of nutrients into the ocean, in line with more stringent regulations for cities in the reef area. In Cleveland Bay alone, the discharge of nitrogen has been reduced from 138 tonnes a year to 30 tonnes; and phosphorous discharge has come down from 43 tonnes to eight tonnes.

zeeweed water treatment system image www.h2o-water.com

ZeeWeed uses seaweed-inspired membranes punctured with thousands of tiny holes 400 times smaller than the diameter of a human hair. 

Nanotechnology is at the heart of ZeeWeed’s waving, weed-like, hollow-fibre membranes. The membranes are dotted with holes just 40 nanometers wide; when water is drawn through them, they filter not only sediments and solids but unwanted nutrients, and pathogens such as bacteria. Capable of processing large volumes of water with only a relatively small plant footprint, ZeeWeed based bioreactors have been retrofitted to existing plants, such as New Zealand’s Rotorua waste-water treatment facility. ZeeWeed helped control algal bloom (caused by excessive nutrient discharge) on Lake Rotorua, meeting stricter environmental regulations without the requirement for extra, costly infrastructure.

“Membrane processes like ZeeWeed also provide a very clean water downstream, so that subsequent processes, such as ultraviolet disinfection, ozonation and chlorination can work more effectively,” says Harpham.

Please recharge your glasses

One way of getting around the “yuk factor”, as Simon Toze calls our resistance to bringing recycled sewage into our potable water supply, is to use treated water to recharge the environment, and to save drinking water for other uses. Until recently, Sydney’s Warragamba Dam, one of the city’s main sources of drinking water, was also required to release some 18 gigalitres of water per year into the Nepean/Hawkesbury River system to maintain environmental flows. A treatment plant using ZeeWeed Ultrafiltration and GE reverse osmosis technology is now processing effluent from three sewage-treatment plants—at St Marys, Penrith and Quakers Hill. The resulting clean water safely recharges the rivers while the dam retains its drinking-water supply.

Our urban existence will continue to put more and more pressure on drinking-water systems … in some places we won’t have enough drinking water to maintain our environment, and for our growing urban centres.

“In Western Australia, they have the Gnangara Mounds Aquifer Replenishment Project,” says Toze. “They’re taking their wastewater, treating it to potable standards and beyond, and injecting it back into the aquifer. Firstly, it’s to repressurise the aquifer because levels have been falling—Perth’s climate has been dry for quite some time. Then that water will come back into the drinking-water bores in between 30 to 50 years.”

By then Australians should be well and truly over their squeamishness. Pressure to introduce recycled wastewater into the drinking supply more directly will be high because, says Tozer, it’s the most cost-effective way to recycle. “People look at the set-up costs for bringing wastewater back to potable standards, which are a lot more expensive than treating it to lesser standards for agriculture and so on, but when you do a long-term lifecycle analysis, you get the most use from your water by putting it through the drinking-water system.”

Never mind that Australian cities are going to run out of drinking water. “Our urban existence will continue to put more and more pressure on drinking-water systems, to the extent that in some places we won’t have enough drinking water to maintain our environment, and for our growing urban centres. We need to be bolder and treat our wastewater for return to the drinking water system,” says Toze.

Urbane water management

The capture, redirection and recycling of urban runoff is the next big thing in city water management, says Toze. “In Adelaide, they’re doing quite a bit of work on capturing urban storm water, which is not necessarily clean, doing some treatment through wetlands, and taking it back through managed aquifer recharge. The project has shown that it is capable of producing water for a wide range of uses: agriculture, industry, irrigation of parks and,  with a bit of tweaking, potentially putting it back into the drinking-water system.”

Toze has been investigating many options for reducing the flow of urban wastewater; not just capturing it, but reducing hard surfaces in cities and redirecting runoff through vegetated swales and porous roads, planting more trees along roadside verges that accept some of the water that normally rushes past in the gutters; and creating more green riparian zones (the areas that connect land to water systems), which would filter some of the grunge, oil, chemicals and pathogens that gather on city surfaces and are currently swept into urban streams and out to sea during heavy rains.

The demands of a growth industry

If drinking water is the holy grail, agriculture is the environment’s thirstiest customer.

The 2012-2013 Australian Water Account, the most recent available, showed that agriculture consumed 65% of water extracted from the environment, the largest percentage, followed by water, sewerage and drainage services at 12%, households at 9%, and mining and manufacturing at 3% each.

In Australia and New Zealand, farming has frequently been the cause of water fouling due to excess nutrients washing into rural watercourses. Levels of agricultural fertilisation are now able to be more closely regulated, but in New Zealand, where rich pastures allow far greater density of grazing, particularly in the dairy industry, the runoff of manure into waterways is an unwelcome by-product. When Auckland needed to meet increased water demands in 2002, Watercare, the regional body charged with responsibility for water, identified the Waikato River as a reliable source, but there were concerns that the river was prone to dairy-farm runoff. GE Water and Process Technologies supplied ZeeWeed membrane technology as a part of the solution that also included granulated activated carbon filtration and chlorination. Drinking-quality water from the plant is stored and distributed from a local reservoir.

What’s mine is yours

From pump to paddock: GE technology is taking recycling to a whole new level, turning water that was once ‘unusable’ into an asset to Australia’s agriculture industry.

Although mining shows a seemingly small percentage of national water use, it frequently occurs in areas where the water resource is small and has competing users, or where it’s precious to farmers. In South East Queensland, Queensland Gas Company (QGC) sought a locally friendly solution to handling saline wastewater generated during coal-seam gas extraction. It decided to install treatment plants that would process the water to a level suitable for farm use and dam recharge. The first plant opened at Kenya, near the town of Chinchilla in October 2014 and the second, at Woleebee Creek near Wandoan, will begin operations this year.

GE supplied the integrated-process solution of advanced-membrane and thermal-water treatment technologies for both plants, each of which has the capacity to treat 100 million litres a day. Some farmers in the Chinchilla region reported large increases in productivity of the land, as a result of the increased water availability for farming, while others are still deeply concerned by their loss of local on-property water to the CSG process.

Diversity, the divining factor

Toze, who has 20 years of experience in researching water solutions, believes that all forms of water treatment are valid in securing Australia’s future supply, and primarily that the country should aim to recycle as much water as possible before drawing from the environment.

“When there’s a glut of water, as happened from 2011 onwards, there’s a tendency to say, ‘Oh, we’ve got so much water, we don’t need the desalination plants’, for example, and we switch them off. Which is why we’ve got some governments saying they were a waste of money, a white elephant. Well in a climate as variable as ours, we will go back into long periods of drought again. So desalination is one resilience measure.

“The reality is that resilience costs money,” he adds, and that we need to invest in a number of approaches to water security. “It’s the idea of security through diversity.”

You will never taste the cocktail effect of water drawn from sewage, desalination, stormwater treatment and enhanced natural filtration, but swallow it and you’ll be able to keep hydrating, and swimming in clean waters, farming and fishing … forever.

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Henry Sapiecha

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