Mark Borgerson wrote in
g:

You still haven't shown why you think the bacterial fragments
are 'toxins'. Toxins are generally considered to be special-purpose
chemicals released by an organism for a specific purpose.

Toxin:
"A poisonous substance, especially a protein, that is produced by living
cells or organisms and is capable of causing disease when introduced
into the body tissues but is often also capable of inducing neutralizing
antibodies or antitoxins"

This definition doesn't seem to include fragments of dead bacteria.


First, this isn't court so I don't have to "show" you anything. People get
sick drinking it, so it's a toxin. People get sick on cruise ships
drinking it, too.



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================================================== ==========
Larry

I've decided to worship Thor. My god has a hammer and isn't
afraid to use it. Your god is a pacifist who got nailed to a
tree.

Any questions?

On Mon, 20 Apr 2009 04:16:01 +0000, Larry wrote:

AS it was explained to me, these boat RO systems, to be small, use very
high pressure on the membrane, as opposed to large commercial systems
like a public utility would use in a purification plant at low pressure.

Higher pressure is needed to desalinate sea water, much higher. It
depends on the quantity of disolved salts, not membrane size.

Rick Morel wrote:

This high pressure traps the bacteria against the membrane, where I
suppose it's like his little head is stuck in a hole his body can't fit
through, a crude cartoon-of-the-mind's-eye.

Never heard of that.

Happens all the time. Biofilms are the bane of RO systems and need to
be addressed through proper membrane care (cleaning, sanitizing,
replacing, etc.). RO membranes provide a perfect substrate for bugs,
and the constant flow provides a fresh source of nutrients. Take care
of the system, however, and it need not be a problem.

snip

Now trapped in a high pressure environment, at some point, the bacteria
explodes, releasing its internal load of really small toxins onto the
surface of the membrane where it can, because of its tiny size crude
molecules pass through the membrane with the H2O, contaminating the
outlet water. The key, I'm told, is the high pressure, which rips many
biologicals apart into tiny pieces. I don't see why this is not a
possible scenario and a source of possible sickness for the drinkers.

Doesn't happen. The bacteria normally is not "trapped". The little
bugger is spun around and bounced around, then spit out of the reject
line.

That's *one* possibility of course, but with millions of opportunities,
over time, many of the little buggers do get "caught".

BTW, the poor little creature would implode, not explode.

Well, considering its fluid filled, how would it implode? It will be
lysed in either event.

snip

Again, all this is flushed out after a few minutes. It's simply a
matter of rejecting the first few minutes of product water.

Dumping the first few minutes of product is always a good idea.

Keith Hughes

Mark Borgerson wrote:

snip
You still haven't shown why you think the bacterial fragments
are 'toxins'. Toxins are generally considered to be special-purpose
chemicals released by an organism for a specific purpose.

Toxin:
"A poisonous substance, especially a protein, that is produced by living
cells or organisms and is capable of causing disease when introduced
into the body tissues but is often also capable of inducing neutralizing
antibodies or antitoxins"

You're talking about "exotoxins". Larry is talking about endotoxins
(I'm assuming).


This definition doesn't seem to include fragments of dead bacteria.

Endotoxins are typically lipopolysaccharide components of the cell
membranes of gram negative bacteria (like pseudomonads which like to
live in water). When the cells are lysed, the endotoxins are released.
However, and a big however it is, endotoxins are generally in the
range of 10 kda to 100000 kda or more, and the RO membranes are more in
the 1 kda range relative to retention.

We're talking *drinking* water here. The FDA allows the manufacture of
Water for Injection to be manufactured with dual pass RO (i.e. safe for
injecting into your veins). Problems do arise, however, when the
pressure is jacked up to deal with poorly maintained plugged membranes,
and you get seam or joint cracks, o-ring leaks, etc. that allow water to
bypass the membranes.

Like any other critical system, RO needs to be maintained properly to
work properly.

Keith Hughes

In article ,
says...


Mark Borgerson wrote:

snip
You still haven't shown why you think the bacterial fragments
are 'toxins'. Toxins are generally considered to be special-purpose
chemicals released by an organism for a specific purpose.

Toxin:
"A poisonous substance, especially a protein, that is produced by living
cells or organisms and is capable of causing disease when introduced
into the body tissues but is often also capable of inducing neutralizing
antibodies or antitoxins"

You're talking about "exotoxins". Larry is talking about endotoxins
(I'm assuming).


This definition doesn't seem to include fragments of dead bacteria.

Endotoxins are typically lipopolysaccharide components of the cell
membranes of gram negative bacteria (like pseudomonads which like to
live in water). When the cells are lysed, the endotoxins are released.
However, and a big however it is, endotoxins are generally in the
range of 10 kda to 100000 kda or more, and the RO membranes are more in
the 1 kda range relative to retention.

Thanks for the explanations. It's been decades since my last biology
course. I'm not familiar with the kda term, so I'll have to look it up.

We're talking *drinking* water here. The FDA allows the manufacture of
Water for Injection to be manufactured with dual pass RO (i.e. safe for
injecting into your veins). Problems do arise, however, when the
pressure is jacked up to deal with poorly maintained plugged membranes,
and you get seam or joint cracks, o-ring leaks, etc. that allow water to
bypass the membranes.

Like any other critical system, RO needs to be maintained properly to
work properly.


Mark Borgerson

The heck with this battery water stuff. Go Lithium-ion!
http://www.genasun.com/genasunbattery.shtml
Only 5 grand a pop!
Gordon

Mark Borgerson wrote:
In article ,
says...


Thanks for the explanations. It's been decades since my last biology
course. I'm not familiar with the kda term,

Its kilo-dalton. One dalton is the mass of one Hydrogen atom. When you
start talking about very minute masses - as in tangential flow (TFF) and
diafiltration systems (like RO as an example)- daltons are a common
unit, especially in the biotech world where TFF is commonly used for
protein purification/extraction for example.

Keith Hughes

In article ,
says...


Mark Borgerson wrote:
In article ,
says...


Thanks for the explanations. It's been decades since my last biology
course. I'm not familiar with the kda term,

Its kilo-dalton. One dalton is the mass of one Hydrogen atom. When you
start talking about very minute masses - as in tangential flow (TFF) and
diafiltration systems (like RO as an example)- daltons are a common
unit, especially in the biotech world where TFF is commonly used for
protein purification/extraction for example.

Must be more of a biochemical thing. In chemical oceanography, we
generally used either AMUs or micro-moles.


Mark Borgerson

Mark Borgerson wrote:
In article ,
says...

Mark Borgerson wrote:
In article ,
says...
Thanks for the explanations. It's been decades since my last biology
course. I'm not familiar with the kda term,
Its kilo-dalton. One dalton is the mass of one Hydrogen atom. When you
start talking about very minute masses - as in tangential flow (TFF) and
diafiltration systems (like RO as an example)- daltons are a common
unit, especially in the biotech world where TFF is commonly used for
protein purification/extraction for example.

Must be more of a biochemical thing. In chemical oceanography, we
generally used either AMUs or micro-moles.


1 Dalton = 1 AMU. Since there are historically a couple different
definitions for AMU (physical and chemical), a Unified Atomic Mass Unit
was identified, and that equals 1 Dalton. Neither is an official SI
unit, but both are recognized by SI. In biochemistry (esp. proteins)
the dalton is the unit that's used, and since UF/DF is really geared to
the biochem industry, that's what they use as well.

What good are units if you can't use them to confuse everyone? :-)

Keith Hughes

wrote in :

What good are units if you can't use them to confuse everyone? :-)

Keith Hughes



"If we knew what we were doing, we couldn't call it research!"
Albert Einstein





--
================================================== ==========
Larry

I've decided to worship Thor. My god has a hammer and isn't
afraid to use it. Your god is a pacifist who got nailed to a
tree.

Any questions?