Not to our taste: Would you drink recylced drinking water?
Recycling sewage into a potable source of drinking water could be the answer to Western Australia's rapidly diminishing water supplies, but only if the people are willing. Dominic Pearce takes a look at both the technical and social sides of water recycling facilities.
Would you drink recycled water?
It’s the question that both the state government and media have been putting to Western Australian citizens in recent months. WA has just finished one of its driest winters in recent years, and we are running out of water, it would seem.
“From a scientists point of view, it’s cleaner than what comes out of a reservoir,” says Dr. Jason Antenucci, Deputy director for the Centre of Water Research at the University of Western Australia.
Dam reservoirs are down to almost 30 percent of maximum capacity across the nation, stream flow into Perth’s water catchments have declined by 64% in the past thirty years, and in August the State Government applied for Federal drought relief funds to aid farmers suffering from the lack of rainfall this winter.
With our water supplies said to be diminishing, drinking treated sewage may at first seem like a desperate move.
Initial public response to the idea of drinking recycled effluent, commonly referred to as the ‘yuk’ factor, is negative. That much was evident when the Queensland city of Toowoomba overwhelmingly rejected city council plans to add recycled effluent to its drinking water supplies.
Unsurprisingly, most people are a little sceptical of drinking recycled sewage.
However, drinking treated water is by no means harmful or disgusting. It is in fact a very safe and effective means of conserving water.
“It’s more a question of when is the public ready for it rather than when is the technology available to do it,” says Dr. Antenucci.
Dr. Antenucci’s department handles research and development work for water utilities both nationally and internationally.
Water-recycling plants are by no means new technology; America has used water-recycling facilities for more than 20 years and mixing recycled sewage with drinking water reserves is becoming a growing trend all over the world.
Dr. Antenucci believes that negative response to water recycling stems from a lack of understanding how the process actually works.
The Process of Recycling Sewage
The international standard for recycling sewage into potable water is a three-stage process that combines physical, biological and chemical means.
The first stage, generally known as primary treatment, removes large physical debris, grit and sediment. Biosolids removed from the water during this process are used for compost material and conditioning soil.
The second stage of treatment, commonly referred to as ‘Bug Farming’, uses biological processes to remove remaining contaminants. Populations of bacterial microorganisms breakdown organic material within the water, consuming it like food.
The third stage of the process, known as advanced treatment, prepares the water for reintroduction into fresh water supplies. Sand filters and disinfectants are used to remove any remaining bio-organisms and chlorine from the water, before releasing it back into water reservoirs as ‘effluent’.
Solid material left over from the purification process, known as biosolids, are generally used for agricultural purposes, compost heaps and fertilizers.
For most plants, such as Perth’s Kwinana Water Reclamation Plant, treated water is released into fresh water reservoirs after the advanced treatment stage. The Kwinana Plant however, only produces water for industrial and agricultural use.
For water to be purified to a stage where humans can consume it safely, the purification process requires a further step. One such plant willing to go that extra mile is Singapore’s aptly named ‘NEWater’ facility.
NEWater
The NEWater treatment plants, first constructed in 2002, are an example of not only how practical water recycling technology can be, but how proper education on the process itself can help promote public acceptance of treated sewage.
Hui Ling Lim, media officer for Singapore’s Public Utilities Board, explains the depth of education given to the public on water recycling.
“Prior to the launch of NEWater in 2002, briefings were held for various groups such as the community leaders, business communities and other government agencies.”
“As part of a more sustained public education programme, the NEWater Visitor Centre was also set up. Apart from tourists, schools in Singapore have also been arranging their students to visit the NEWater Visitor Centre to understand the NEWater process,” explains Ms. Lim.
The plants are as much a tourist attraction as they are water treatment facilities, having received more than 350,000 visitors to the NEWater Visitor Centre since their opening. In addition, more than five million bottles of treated water have been given away to the public at National Day celebrations and various other community events.
Another important factor to NEWater’s success as a potable water source lies in the final stage of treatment. Whereas our method sees treated water sent back into ground water sources, treated water in Singapore is first mixed in with reservoirs of fresh water, then taken back out and treated again.
The process, known as Reverse Osmosis, sees the water passed through a semi-permeable membrane to remove microscopic bacteria and debris. The water is then purified with ultraviolet disinfection, making it far more pure drinking water.
Recycled water is but one of four methods in place for sustaining Singapores water needs. Known as the Four National Taps, water is drawn from not only recycled water, but imported water from Malaysia, local catchment, and desalination plants.
Embracing new technologies to sustain water demands, such as Singapore has with recycled water, is what precisely what Dr. Antenucci thinks Western Australia could benefit from.
The People Shall Decide
“I think the recycling form is important,” says Dr. Antenucci. “You’ve already spent the money to get the water into the system, it’s already in the metropolitan area and ending up at the waste water treatment plants, so there is good opportunity there.”
Another important misconception about treated sewage water is that it does not make up a large percentage of fresh water supplies. Treated water in Singapore makes up only 1% of daily drinking water supplies, which would be similar to the amount used here in W.A.
“I believe it would be on a similar scale,” says Dr. Antenucci, “[Singapore’s] population is a little bit bigger than ours, but we’re probably heavier water users per head.”
At this stage, no official legislation has been passed to introduce recycled sewage to W.A’s fresh water supplies.
Should the state government ever follow in Toowoomba’s footsteps however, Dr. Antenucci suggests the decision will lie very much in the hands of the people.
“It’s well recognized in the industry that the problem with water recycling is not anything to do with technology, it’s everything to do with public perception.”
