Mark Borgerson wrote in
:

Shipboard evaporators also have other problems: the resulting water
needs pH adjustment and and treatment to kill bacteria, since the
water is often distilled at only 60 deg. C.


RO sounds great and I know you love yours....but, alas, there's a long
trail of problems related to RO its supporters, and especially
manufacturers and dealers, don't like to talk about.

Too many people forget about the bacteria piled up against the membrane at
high pressure. When that bacteria breaks under pressure, its toxins DO
pass through the membrane making your RO love boat cruise much more
interesting, but lots less fun, than you'd planned.

If you put "reverse osmosis toxins" into Google, the first 9 pages of
findings are all ads for RO systems, or "reports", disguised RO ads from
someone hawking RO products. Like reading a boat magazine, there's never a
discouraging word. If there are bad reports not from the industry, they
have them well buried in bull**** Google finds.

It's very hard to get unspoiled information from neutral sources.....

--
================================================== ==========
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?

In article ,
says...
Mark Borgerson wrote in
:

Shipboard evaporators also have other problems: the resulting water
needs pH adjustment and and treatment to kill bacteria, since the
water is often distilled at only 60 deg. C.


RO sounds great and I know you love yours....but, alas, there's a long
trail of problems related to RO its supporters, and especially
manufacturers and dealers, don't like to talk about.

I don't have a boat large enough to need an RO filter---in fact
I don't have a boat at all since I donated my Windrose 18 to the
sea scouts.

I've used RO filters to generate ultra-pure water for the testing
of optical oceanographic instruments. However, we were more concerned
with particulates than with a few ppm of dissolved salts. (Scattering
makes PPB of solid particles detectable, but dissolved minerals don't
really show up). I also maintain a GE home RO system that generates
about 18l per day that is in my wife's greenhouse. It runs off the
pressure from our well. A few ppm of salts and bacterial residue
aren't much of a problem there.

Too many people forget about the bacteria piled up against the membrane at
high pressure. When that bacteria breaks under pressure, its toxins DO
pass through the membrane making your RO love boat cruise much more
interesting, but lots less fun, than you'd planned.

We had to clean our RO filters with a pretty strong peroxide solution
a few times per month to flush the junk off the filters. I suspect
that filters for seawater may need cleaning even more often, as the
lab was starting with tap water passed through a 1-micron filter.

Why do you assume that the materials passing through the filter
are toxins? Perhaps they're nutritional carbohydrates? Such
assumptions and wording seem to show a bias against RO filters
in your response. In any case, you probably get a good dose of
the same 'toxins' in your city drinking water after the chlorination
has killed the bacteria.

If you put "reverse osmosis toxins" into Google, the first 9 pages of
findings are all ads for RO systems, or "reports", disguised RO ads from
someone hawking RO products. Like reading a boat magazine, there's never a
discouraging word. If there are bad reports not from the industry, they
have them well buried in bull**** Google finds.

It's very hard to get unspoiled information from neutral sources.....

You need to be a bit smarter in your searches,then. I Googled

"RO filter bacterial accumulation"

and found this in the first link:

http://www.sciencedirect.com/science...B6TFX-42KDG2J-
N&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view =c&_acct=C000050221
&_version=1&_urlVersion=0&_userid=10&md5
=b78fb8fa60f8aef434d57d032c5d96df

"No doubt that biofouling is one of the most serious problems associated
with the RO membrane systems which has not yet been effectively solved."



OTOH, if you get your ship's water from flash distillation, you have
to worry about contamination from volatile organics. For this reason,
many ships don't start producing water until they get 12 miles offshore.

http://www.docstoc.com/docs/2372744/...oard-Drinking-
Water-Chemical-Contaminants


Mark Borgerson

Mark Borgerson wrote in
g:

Why do you assume that the materials passing through the filter
are toxins? Perhaps they're nutritional carbohydrates? Such
assumptions and wording seem to show a bias against RO filters
in your response. In any case, you probably get a good dose of
the same 'toxins' in your city drinking water after the chlorination
has killed the bacteria.


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.

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.

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.

We're still talking about FILTRATION. Anything small in molecular size
passes through because the holes have to be big enough for water to pass
through in large quantities. There are a lot of such molecules. Water
is a fairly large molecule because of its oxygen atom's atomic number.
I just don't think it's the holy grail the sales brochures profess it to
be. Dissent against the RO community is treated the same way as someone
who wonders how 6,000,000 bodies in Nazi concentration camps fit in such
a tiny space...to be attacked at all costs!



--
================================================== ==========
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?

In article ,
says...
Mark Borgerson wrote in
g:

Why do you assume that the materials passing through the filter
are toxins? Perhaps they're nutritional carbohydrates? Such
assumptions and wording seem to show a bias against RO filters
in your response. In any case, you probably get a good dose of
the same 'toxins' in your city drinking water after the chlorination
has killed the bacteria.


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.

Must be different from our greenhouse RO filter system, then. It
runs off the 40 to 65PSI from our well pump and tank.

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.

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.

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.

We're still talking about FILTRATION. Anything small in molecular size
passes through because the holes have to be big enough for water to pass
through in large quantities. There are a lot of such molecules. Water
is a fairly large molecule because of its oxygen atom's atomic number.
I just don't think it's the holy grail the sales brochures profess it to
be. Dissent against the RO community is treated the same way as someone
who wonders how 6,000,000 bodies in Nazi concentration camps fit in such
a tiny space...to be attacked at all costs!


OK. I invoke Godwin's Law.


Mark Borgerson

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.



--
================================================== ==========
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?

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

Larry, I usually agree with your posts, but I have to respectfully
disagree with these about RO water. I've been "making" and drinking RO
water for several years with no problems nor any ill effects.

I have no affliation with any RO watermaker company other than as a
customer.

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.

Incorrect. The reason high pressure is used is because the salt
concentration of seawater results in an osmotic pressure of about 800
psi. Brackish water generally ranges between 200 and 400 psi.

Home RO systems (and brackish water systems) use different membranes
and lower presures - 30 - 65 psi for home, freshwater systems. Same
for large commercial _freshwater_ plants; sal****er ones use the
higher pressure with seawater membranes.

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. I guess it could happen if feed water flow were
insufficient. Generally a system is set up for 10% recovery. That is
feedwater flow is 10 times freshwater output. 60 GPH feed to get out 6
GPH of potable water. So 90% of the feed water is rushing through the
system, in one end and out the other. This flow rate, along with the
design of the housing and membrane result in optimum "washing" of the
membrane surface.

I think you may be under the impression that the "other end" is closed
off and all the water is forced though the membrane. Not so.

Shutting down with seawater in the system, then not running it for too
long, will result in bacterial growth and eventual "plugging" of the
membrane. The result is reduced product water flow with no "pieces" of
bacteria included.


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

The nearest thing to your scenerio occurs right at startup and lasts
at most 5 minutes. There will be a certain amount of "smelly stuff" in
the water, mostly hydrogen sulfide. That "rotten egg" smell. Running
enough product water, about a gallon, through the system just before
shutting down minimizes this.

This is because seawater (or river water) contains organic material:
plankton, seaweeds and flotsam of all types. After a watermaker has
been turned off, this material soon begins to decompose, both in the
prefilters and the membrane housings. As it does, it breaks down into
a number of chemicals composed of smaller molecules. Some of these
molecules are small enough to pass through the watermaker membrane
along with the product water.

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

Rick Morel
S/V Valkyrie
http://www.morelr.com/valkyrie