Could a wastewater recycling system like this one
soon be working in your backyard?
Image courtesy of Perpetual Water

In the world’s driest inhabited continent it may seem incredible that much of our most important resource is washed down the drain. But the next generation of water recycling technologies could change all that.

“When you have bothered to pipe good quality water to a house, it makes no sense to use it once, then pump it out again and dispose of it,” says Professor Richard Pashley of Murdoch University.

Professor Pashley, a world-leading chemist and head of the new federally-funded Centre of Excellence in Desalination to be based in Perth, believes scientific advances in wastewater recycling will soon clean grey water – from your washing machine, bath, shower and sinks – faster and better, using relatively little energy.

And when you consider that the average family of four wastes 100,000 litres of water a year, which could be recycled to water the garden and to flush toilets, greywater technologies are crucial to Australia’s future needs.

Andrew Pearce of industry body the Australian Grey Water Institute has even claimed that if 156,000 city households installed a recycling system there would be no need for another desalination plant.

Murdoch’s program chair in environmental engineering Dr Martin Anda says that within a decade water-saving technologies will be standard in every home in WA.

“Rainwater harvesters, internal tanks, integrated greywater systems, powered by photovoltaics, will be in every home,” he says.

“Demand is already out there, and the industry will have to ‘upskill’ tradespeople. I know tradespeople who are already on to this. Some of them have even travelled to the Eastern States to learn how to install the new technologies.”

Under the state government’s Five Star Plus initiative, new houses in WA will be required to incorporate energy and water efficiency measures.

In its second stage, the legislation will require plumbing to toilets to allow for an alternative water supply; drainage to allow easy recycling of greywater; and an alternative water supply (such as rainwater tanks) for flushing toilets.

Dr Anda says government should lead the way by building public housing that is “sophisticated in terms of its sustainability”.

At the Water Innovations Conference in Perth on May 29 he will present the early results of a Premier’s Water Foundation research project on three greywater recycling trials.

“Everyone will soon prefer to have a house that has a high energy and water rating,” he says. “Market forces will determine that houses which don’t have these efficiencies will depreciate or not appreciate as quickly as those they have.”

Environmental technologist John Poon of engineering company CH2M Hill, which has been responsible for water reclamation projects throughout the world, points out that the water industry is already adapting recycling technology from nanotechnology, micro-fabrication, biotechnology and semiconductor physics.

Microbiologist Tony Taylor of the Australian Nuclear Science and Technology Organisation has developed a nano-particulate membrane (NMB) bioreactor that turns waste water into water that is apparently clean enough to drink.

The NMB is a series of the gills made from a special membrane that lets toxins diffuse across them where they are devoured by films of biomass.

Because it breathes air, the system is self-perpetuating, requiring very little energy to run, and it has been commercialised as Australian Membrane Technologies.

Professor Pashley, a member of the Premier’s Science and Innovation Council, has helped to develop a patented “physio-chemical process” that is the first in the world to clean grey water without relying on membranes, reverse osmosis or biomass (waste-eating bacteria).

“Membranes get filthy so quickly and in reverse osmosis you have to pre-filter the water over and over,” he says.

“What stabilises the dirt that comes off your body is you add soap and that forms the particles in water. In the case of cleaning the greywater that comes from you washing machine, you can use the surfactants to your advantage.

“In a physio-chemical process, when you know the chemicals the waste water contains, you can tailor the processes so that the reclamation is very, very fast. This method can clean water in about two minutes.”

He says his second generation recycling system can clean household grey water to Class A plus – or drinkable – standards.