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How is stagnant storage thermal storage water preserved? - Page 3

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Posted by SJC on November 29, 2005, 10:29 pm
 



do think that bacteria will grow in Propylene Glycol?

Me

After further reading I came across a comment that if propylene glycol is put
into
a pond, it will cause an algae bloom. So this may be a consideration also.


Posted by Steve Shantz on November 30, 2005, 2:11 am
 
You would be suprised where bacteria can grow... acidic hot springs at
212 degrees, in ultrapurified water... almost anywhere.  High pH in
antifreeze may help but don't count on it.   The ethylene glycol is a
good food source, especially if diluted down.

This whole antifreeze idea seems like a questionable solution
considering that one would have to buy several thousand gallons of the
stuff.  And the specific heat isn't as good as water.  Diluting it will
almost certainly make it more likely to grow.  (Honey is antimicrobial,
but dilute it in water and bacteria will love it!)

These same problems exist with industrial evaporative coolers.  Try a
Google search for evaporative cooler biocide.  Lots of good info.

See http://www.engr.psu.edu/ae/iec/abe/topics/legionnaires.asp

Here, they make a case that water above 122 F will slowly kill
legionnaires, and above 140 F it is 'fast death'.  I think I was taught
in my microbiology course that water over 65 C (149 F) is not good at
supporting the growth of anything except a few exotic thermophiles.

So my idea is this... If you can get your water tank above 140 and keep
it there for any appreciable time, microbial growth is killed off.
Hotter is better.  Winter time when temperatures fall to a range that
supports growth... no bacteria to grow any more... they have all been
killed off.

Steve


Posted by SJC on November 30, 2005, 4:25 am
 
You would be suprised where bacteria can grow... acidic hot springs at
212 degrees, in ultrapurified water... almost anywhere.  High pH in
antifreeze may help but don't count on it.   The ethylene glycol is a
good food source, especially if diluted down.

This whole antifreeze idea seems like a questionable solution
considering that one would have to buy several thousand gallons of the
stuff.  And the specific heat isn't as good as water.  Diluting it will
almost certainly make it more likely to grow.  (Honey is antimicrobial,
but dilute it in water and bacteria will love it!)

These same problems exist with industrial evaporative coolers.  Try a
Google search for evaporative cooler biocide.  Lots of good info.

See http://www.engr.psu.edu/ae/iec/abe/topics/legionnaires.asp

Here, they make a case that water above 122 F will slowly kill
legionnaires, and above 140 F it is 'fast death'.  I think I was taught
in my microbiology course that water over 65 C (149 F) is not good at
supporting the growth of anything except a few exotic thermophiles.

So my idea is this... If you can get your water tank above 140 and keep
it there for any appreciable time, microbial growth is killed off.
Hotter is better.  Winter time when temperatures fall to a range that
supports growth... no bacteria to grow any more... they have all been
killed off.

Steve

  Pretty much my thought as well. The thread started with a large volume
of water at cooler temperatures. I imediately thought of smaller water
volumes at higher temperatures and your problem probably does not
exist. The propylene glycol was just the standard recommendation to
keep solar thermal from freezing, but I don't believe they were thinking
in terms of 10,000 gallons!


Posted by nicksanspam on November 30, 2005, 10:06 am
 Why do we need to "preserve" water? Bacteria need food, and nutrients
disappear fast in warm water with oxygen... 5 parts per billion of
copper ion can kill algae if needed, eg a teaspoon of copper sulfate
"root destroyer" in a huge tank.

Nick


Posted by Solar Flare on November 30, 2005, 10:37 pm
 Copper sulfate is a preservative used for PT wood
products. This is called "preservative"


food, and nutrients

per billion of

copper sulfate


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