More recycling info - desalination conspiracy?!?!? long...
A funny thing happened recently... on May 3rd my letter to the editor of The Advertiser (Adelaide local daily paper) was published. The gist of my letter, which was severely edited by The Advertiser, was that water recycling is cheaper than making new water by desalination. In my letter I quoted an ABC FM radio interview by Margaret Throsby of Associate Professor Greg Leslie, who stated that Singapore industry actually prefers using recycled water because of its purity.
A day or two later someone else's letter to the editor was published, this one being much more pro-desalination and almost anti-recycling in its tone. The author claimed that the desalination process does not increase salinity as 'the process takes tonnes of salt out of the seawater and puts exactly the same salt back in. There is no change in the salinity at all.' Oops, if you've done elementary chemistry you know that if you reduce the amount of water in a container and don't reduce the suspended materials by the same amount then the concentration level increases. If you are using salt water, for example, what is left behind becomes saltier. The writer was just a leetle misleading in his statement.
And then a few days later I happened to hear a brief news item on a popular Adelaide FM radio station and it mentioned something about Singapore's use of recycled water and how it needs separate piping systems or something like that, which was intended to make listeners doubt the wisdom of using recycled water!
What struck me as interesting was that there had been no other Adelaide news about Singapore's use of recycled water that I was aware of, beyond what I had written in my letter to the editor.
Could there be big money to be made in selling a desalination plant to the South Australian government? One wonders...
FURTHER RESEARCH RESULTS...
A check of the Sydney Water website about the proposed desalination plant there says that the water returned to the sea would be about twice as salty as the normal sea water. And the temperature of the returned water would be about 2 degrees warmer than the normal sea water.
Probably not a train smash - the returned saltier water does dilute into the normal seawater. But it would have an effect on the local environment before it dilutes. Maybe like finding those 'warm spots' when you are swimming? But this one doesn't go away. Not nice if you happen to be a sponge or barnacle living where the warm brine is discharged.
South Australia already has a desalination plant operating on Kangaroo Island at Pennshaw. It cost $4m in 1999 to build, and it creates about 300,000 litres of fresh water daily. From 100 litres of water processed it makes 30 litres of fresh water.
Half of all the freshwater that Adelaide uses daily ends-up as waste water in the sewers. Industrial waste water is added to this.
According to SA Water, all of our waste water is treated to secondary level before it is either dumped back into the sea or used for crop irrigation. I don't know how much is dumped back into the sea compared with how much is used by agriculture.
The problem is this dumping the treated waste water back into the sea. We are already treating it to a secondary level to be able to return it to the sea without polluting the ocean, or to use it as irrigation water for crops in the Bolivar area north of Adelaide. What would it cost to further treat it so more waste water could be reused?
What do the golf courses in Adelaide use to keep the courses irrigated - bore water, fresh water, recycled water? I'll check further.
There is a wealth of information on the web about Singapore's recycled water projects. 'NEWater' is their branded recycled water. It is quite a success.
So it seems to me that the argument comes down to two related points - we 'waste' probably close to half the freshwater that we use daily in Adelaide by dumping it into the sewers; and as Associate Professor Leslie says, we need to get past the 'use once' mentality. Water is recyclable - SA Water says that waste water is 99.9% water, with 0.1% being generally dissolved or suspended material. It isn't difficult to rid the 99.9% water of the 0.1% waste products.
Western Australia has built a desalination plant at Kwinana, powered by a wind farm at Emu Downs. The plant is supposed to supply 17% of Perth's water supply when fully on line, or 130 megalitres per day. This plant cost $387 million.
It's commendable that the power for the Perth water plant is from a wind farm. We recently changed our electricity supplier so that we use 'green' energy like from solar, wind or hydro. What this actually means, as you can't guarantee that power from any of these green sources is actually working when you need it (you can't store electricity - it has to be made on demand) is that the energy retailer we use buys a kilowatt of electricity from a green producer for each kilowatt that we use. So despite wanting to, our current energy infrastructure still relies on fossil fueled power generation.
I wonder also what the carbon impact is in building a wind farm - surely the manufacturing processes use a lot of energy (probably fossil fuel generated for the most part). What's the 'total' life carbon impact of building a wind farm and a desalination plant?
Melbourne Water warns that building a desalination plant would have a significant impact on household water bills. Perth's Water Corporation info about the desalination plant says that if the total capital and operating cost of the plant was passed-on to consumers it would cost them about $44 per year.
Locating a desalination plant for Melbourne is another issue - apparently Port Phillip Bay, which is a huge body of water constricted by a relatively narrow opening, is too shallow to adequately disperse the brine discharge from a desalination plant, without causing environmental problems. Others think that issue can be overcome.
Interestingly, the technology used in a modern desalination plant is very similar to that used in a modern water recycling plant - reverse osmosis filtering.
Yesterday Adelaide used 197 megalitres of freshwater for the 24 hour period to 8:00 am. The daily average for May for Adelaide freshwater use is 385 megalitres. Pumping half of either of those amounts out to sea as treated waste water is, frankly, 'wasteful!'
I'm not against building a desalination plant - but why build it to make more water and then dump the waste water from it? Say we build a desalination plant like the one in Western Australia, 'creating' 130 megalitres per day. What then, pump half of what we currently use plus half of the newly desalinated water out to sea as treated waste? That's dumb!
References:
Sydney Water: http://www.sydneywater.com.au/EnsuringTheFuture/Desalination/index.cfm
SA Water: http://www.sawater.com.au/SAWater/Education/OurWastewaterSystems/
Perth desalination: http://www.news.com.au/heraldsun/story/0,21985,20791840-5005961,00.html
Melbourne Water: http://www.theage.com.au/news/national/push-for-huge-desalination-plant/2007/04/06/1175366479355.html
Singapore's NEWater: http://www.pub.gov.sg/NEWater_files/index.html
A day or two later someone else's letter to the editor was published, this one being much more pro-desalination and almost anti-recycling in its tone. The author claimed that the desalination process does not increase salinity as 'the process takes tonnes of salt out of the seawater and puts exactly the same salt back in. There is no change in the salinity at all.' Oops, if you've done elementary chemistry you know that if you reduce the amount of water in a container and don't reduce the suspended materials by the same amount then the concentration level increases. If you are using salt water, for example, what is left behind becomes saltier. The writer was just a leetle misleading in his statement.
And then a few days later I happened to hear a brief news item on a popular Adelaide FM radio station and it mentioned something about Singapore's use of recycled water and how it needs separate piping systems or something like that, which was intended to make listeners doubt the wisdom of using recycled water!
What struck me as interesting was that there had been no other Adelaide news about Singapore's use of recycled water that I was aware of, beyond what I had written in my letter to the editor.
Could there be big money to be made in selling a desalination plant to the South Australian government? One wonders...
FURTHER RESEARCH RESULTS...
A check of the Sydney Water website about the proposed desalination plant there says that the water returned to the sea would be about twice as salty as the normal sea water. And the temperature of the returned water would be about 2 degrees warmer than the normal sea water.
Probably not a train smash - the returned saltier water does dilute into the normal seawater. But it would have an effect on the local environment before it dilutes. Maybe like finding those 'warm spots' when you are swimming? But this one doesn't go away. Not nice if you happen to be a sponge or barnacle living where the warm brine is discharged.
South Australia already has a desalination plant operating on Kangaroo Island at Pennshaw. It cost $4m in 1999 to build, and it creates about 300,000 litres of fresh water daily. From 100 litres of water processed it makes 30 litres of fresh water.
Half of all the freshwater that Adelaide uses daily ends-up as waste water in the sewers. Industrial waste water is added to this.
According to SA Water, all of our waste water is treated to secondary level before it is either dumped back into the sea or used for crop irrigation. I don't know how much is dumped back into the sea compared with how much is used by agriculture.
The problem is this dumping the treated waste water back into the sea. We are already treating it to a secondary level to be able to return it to the sea without polluting the ocean, or to use it as irrigation water for crops in the Bolivar area north of Adelaide. What would it cost to further treat it so more waste water could be reused?
What do the golf courses in Adelaide use to keep the courses irrigated - bore water, fresh water, recycled water? I'll check further.
There is a wealth of information on the web about Singapore's recycled water projects. 'NEWater' is their branded recycled water. It is quite a success.
So it seems to me that the argument comes down to two related points - we 'waste' probably close to half the freshwater that we use daily in Adelaide by dumping it into the sewers; and as Associate Professor Leslie says, we need to get past the 'use once' mentality. Water is recyclable - SA Water says that waste water is 99.9% water, with 0.1% being generally dissolved or suspended material. It isn't difficult to rid the 99.9% water of the 0.1% waste products.
Western Australia has built a desalination plant at Kwinana, powered by a wind farm at Emu Downs. The plant is supposed to supply 17% of Perth's water supply when fully on line, or 130 megalitres per day. This plant cost $387 million.
It's commendable that the power for the Perth water plant is from a wind farm. We recently changed our electricity supplier so that we use 'green' energy like from solar, wind or hydro. What this actually means, as you can't guarantee that power from any of these green sources is actually working when you need it (you can't store electricity - it has to be made on demand) is that the energy retailer we use buys a kilowatt of electricity from a green producer for each kilowatt that we use. So despite wanting to, our current energy infrastructure still relies on fossil fueled power generation.
I wonder also what the carbon impact is in building a wind farm - surely the manufacturing processes use a lot of energy (probably fossil fuel generated for the most part). What's the 'total' life carbon impact of building a wind farm and a desalination plant?
Melbourne Water warns that building a desalination plant would have a significant impact on household water bills. Perth's Water Corporation info about the desalination plant says that if the total capital and operating cost of the plant was passed-on to consumers it would cost them about $44 per year.
Locating a desalination plant for Melbourne is another issue - apparently Port Phillip Bay, which is a huge body of water constricted by a relatively narrow opening, is too shallow to adequately disperse the brine discharge from a desalination plant, without causing environmental problems. Others think that issue can be overcome.
Interestingly, the technology used in a modern desalination plant is very similar to that used in a modern water recycling plant - reverse osmosis filtering.
Yesterday Adelaide used 197 megalitres of freshwater for the 24 hour period to 8:00 am. The daily average for May for Adelaide freshwater use is 385 megalitres. Pumping half of either of those amounts out to sea as treated waste water is, frankly, 'wasteful!'
I'm not against building a desalination plant - but why build it to make more water and then dump the waste water from it? Say we build a desalination plant like the one in Western Australia, 'creating' 130 megalitres per day. What then, pump half of what we currently use plus half of the newly desalinated water out to sea as treated waste? That's dumb!
References:
Sydney Water: http://www.sydneywater.com.au/EnsuringTheFuture/Desalination/index.cfm
SA Water: http://www.sawater.com.au/SAWater/Education/OurWastewaterSystems/
Perth desalination: http://www.news.com.au/heraldsun/story/0,21985,20791840-5005961,00.html
Melbourne Water: http://www.theage.com.au/news/national/push-for-huge-desalination-plant/2007/04/06/1175366479355.html
Singapore's NEWater: http://www.pub.gov.sg/NEWater_files/index.html
posted by Rick's Rambles at 7:32 PM
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