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140 million liters of water down the drain

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Kremmen:

--- Quote from: EEVblog on April 22, 2014, 03:47:07 am ---This is a typical analysis of a Sydney water supply (source only, pipes not included)
https://www.sydneywater.com.au/web/groups/publicwebcontent/documents/document/zgrf/mdq0/~edisp/dd_044731.pdf
and for a total wank:
http://tapsydney.com.au/
and for the full info:
http://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/eh52_aust_drinking_water_guidelines_update_131216.pdf
Page 189 has chlorine.
They even pump ferric chloride into the system (the stuff you use for PCB etching)
Page 1161

--- End quote ---
Quote from the Helsinki Waterworks website: (note they mention ferrous sulphate which to me sounds more plausible as feric chloride would likely eat into the metallic piping...
"Drinking water production at the
Pitkäkoski and Vanhakaupunki plants
The raw water from Lake Päijänne is treated at the water treatment plants in Pitkäkoski and Vanhakaupunki in order to obtain clean domestic water. The water treatment processes of the two water treatment plants are the same.
First, the humus contained in the raw water is precipitated with ferrous sulphate, and the resulting precipitate is stirred and mixed in order to improve clarification. After this, the precipitate is separated from the water in settling tanks and sand filters.
Any microbes in the water are killed with ozone, which also improves the odour and taste of the water. Then, carbon dioxide is added to the water. This increases the alkalinity of the water, thus reducing corrosion.

The remaining organic matter is removed by means of activated carbon filtration, after which the water is disinfected with UV light. Finally, bound chlorine, i.e., chloramine, is added to the water in order to limit microbial growth in the distribution network. The pH of the water is adjusted with lime water, and the alkalinity is regulated with carbon dioxide."

Recent water quality analysis - sorry,  in Finnish but anyone with a any chemistry knowledge will easily identify elements from their periodic table lettercodes. http://www.hsy.fi/vesi/juomavesi/vedenlaatu/Sivut/vedenlaatutaulukko.aspx

IanB:
Ferric chloride is not added in any concentrations that would corrode piping. Also just enough is added to cause the precipitation reaction and it gets removed with the precipitate, so it doesn't stay in the water after it's added. Ferric chloride works a little more efficiently as a clarifying agent than ferrous sulphate but they both perform essentially the same function.

I'm confused about carbon dioxide "increasing the alkalinity" of the water. Is this a mis-translation? Carbon dioxide is an acid gas and will decrease alkalinity/increase acidity. I think perhaps they increase the pH with lime water and decrease the pH with CO2. That would give them control in both directions and would fit the chemistry better.

Artlav:
Why is it called drinking water, btw?
Isn't it the water that would come out of the faucets?

Or are there separate faucets for drinking in Portland?

Kremmen:

--- Quote from: IanB on April 22, 2014, 08:54:10 am ---Ferric chloride is not added in any concentrations that would corrode piping. Also just enough is added to cause the precipitation reaction and it gets removed with the precipitate, so it doesn't stay in the water after it's added. Ferric chloride works a little more efficiently as a clarifying agent than ferrous sulphate but they both perform essentially the same function.

I'm confused about carbon dioxide "increasing the alkalinity" of the water. Is this a mis-translation? Carbon dioxide is an acid gas and will decrease alkalinity/increase acidity. I think perhaps they increase the pH with lime water and decrease the pH with CO2. That would give them control in both directions and would fit the chemistry better.

--- End quote ---
Fair enough, just my gut feling - it is true that it would be quite a soup if FeCl was aded in PCB etching concentrations :)

As to carbon dioxide - no mistranslation, the same wording can be found on the original Finnish page. In fact the case is not that simple. Some dissolved CO2 in water turns partly into carbonic acid H2CO3 and from there it dissociates at least partially into ionic forms HCO3- (the bicarbonate ion) and CO32- (carbonate ion) the proportions depending on the original pH of the water. The bicarbonate ion at least is an amphoteric compound that can act either as an acid or a base, depending on the acidity of the original solution. So i think they knew what they were writing. At the same time there is a diagram of the process here: http://www.hsy.fi/vesi/Documents/Juomavesi_ja_veden_laatu/Vedenpuhdistusprosessi_HSY.pdf describing how they add CO2 ("Hiilidioksidi") and lime water ("Kalkkivesi") as the last stages of the treatment, in that order.

electrolux:

--- Quote from: NiHaoMike on April 20, 2014, 11:28:32 pm ---Give it to the farmers. They'll appreciate all the water with a trace of "fertilizer" added...

--- End quote ---
Yeah, fertilizer Plus drowning cows

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