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

On Mon, 20 Apr 2009 08:22:29 -0700, wrote:



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".

Okay, I guess I took too far a stance in the opposite direction.
Agreed that many will get "caught" - it's as incorrect to say none
will as it is to say all will. However, the point of the flow rate is
to wash these away.

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.

Definition of lysed: The disintegration of a cell resulting from
destruction of its membrane by a chemical substance, especially an
antibody or enzyme

I honestly don't see how this would apply, unless it's a normal event
of decomposition? Is that it? I plead ignorance and welcome any info.

Implode/explode. Okay, I'll go with both are impossible because it's
fluid filled. This then negates any effect of high (or low) ambient
pressure in either event, so that argument is thrown out.

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.

Actually I would say it's a necessary idea. Wait, that reads
sarcastic. I don't mean it that way. I simply mean that I think it's
a necessary part of using an RO system.


Rather than play theory, here's the results of my real world
experience cruising and supplying water from RO:

Last go round I made on average 5 gallons of water per day for 2
years. That's a total of 3,650 gallons of drinking water with 36,500
gallons of reject water passing across the membrane and going
overboard. Very little of that total 40,150 gallons of water was
"clean sea water"; most of it came from bays, a bit from rivers. Some
very silty.

The setup included 2 prefilters - a 20 micron followed by a 5 micron.
The filters were inspected and cleaned frequently, and replaced as
necessary.

The routine, as above, was to reject the first few minutes, test, then
route to the tanks. The first good half gallon or so went into a
container, then this water was run through the system at shutdown.

A biocide treatment was done when the watermaker wasn't going to be
used within a couple days (The total time period was more than 2
years).

The membrane never got an acid and/or alkyline treatment. The reason
is product water flow was basically the same at the end as at the
beginning. I didn't have a flow meter then (I do now on the new boat),
but every two weeks I measured how long it took to fill the shutdown
container to a half gallon mark. It normally varied by a few minutes,
depending on temperture, etc. That one was a 1.5 GPH unit. I now have
a 3.4 GPH.

Now maybe I was lucky, or maybe it was the care and attention I took.
The manufacturer did not recommend the cleaning treatments unless
necessary.

A couple points. I now have a TDS meter, but the best "tester" is a
human. Smell, then taste.

Don't get a too big watermaker. Size it to run at least a couple hours
a day, and run it every day to top off the tank. Membrane fouling and
all that bad stuff happen when they're idle.

It bears repeating. If you don't run it every day, or at least every
two or three days, you will have problems. Do the biocide treatment
(pickle it!) if you're not going to run it for more than a few days.


Thousands (tens of thousands? hundreds of thousands?) of people drink
RO water every day. On boats, ships, islands, Israel, and now
California from processed sewerage water. I guess some get sick from
it. It would be interesting to see what percentage compared to those
that get sick from city water and bottled water.

Rick Morel

On Tue, 21 Apr 2009 07:59:35 -0500, Rick Morel
wrote:

Implode/explode. Okay, I'll go with both are impossible because it's
fluid filled. This then negates any effect of high (or low) ambient
pressure in either event, so that argument is thrown out.

If you put them in pure water the salts inside the cell will suck in
water. Osmosis. The cell membrane will become tighter, although I
don't know about actually exploding. Depends on the cell, I think.

Casady

Rick Morel wrote:
On Mon, 20 Apr 2009 08:22:29 -0700, wrote:


snip

snip

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.

Definition of lysed: The disintegration of a cell resulting from
destruction of its membrane by a chemical substance, especially an
antibody or enzyme

This is *one* definition. There are a number of others, and it is
commonly used for any action, mechanical/chemical/biochemical, that
ruptures the cell wall/membrane releasing the cell contents. It's from
the Greek "lysis" which just means a loosening, setting free, releasing,
or dissolution.


I honestly don't see how this would apply, unless it's a normal event
of decomposition? Is that it? I plead ignorance and welcome any info.

Yes, it is primarily through decomposition. As a biofilm forms on the
membrane (a layer of growing critters), the base, or underlying
organisms get farther and farther away from the source of nutrients (the
water flow) and they die. They then decompose, but instead of getting
flushed away by the water flow, their detritus gets trapped by the layer
of living and dying bugs above them. More food for the growing bugs.

Implode/explode. Okay, I'll go with both are impossible because it's
fluid filled. This then negates any effect of high (or low) ambient
pressure in either event, so that argument is thrown out.
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.

Actually I would say it's a necessary idea. Wait, that reads
sarcastic. I don't mean it that way. I simply mean that I think it's
a necessary part of using an RO system.

Depends on whether or not you want your first drink of the day
"fortified" or not ;-)



Rather than play theory, here's the results of my real world
experience cruising and supplying water from RO:

Well, it's not theory. It's 25+ years experience with qualifying high
purity water systems, all of which utilized RO as one part of the
purification process.


snip

Don't get a too big watermaker. Size it to run at least a couple hours
a day, and run it every day to top off the tank. Membrane fouling and
all that bad stuff happen when they're idle.

Happens whether they're idle or not, but your point is well taken. My
experience is with units in the 2000-3000gph range, typically running
24/7 with treated city water as feed. Still require routine cleaning,
and biocide treatment. Stagnant water is *always* a bad idea...


It bears repeating. If you don't run it every day, or at least every
two or three days, you will have problems. Do the biocide treatment
(pickle it!) if you're not going to run it for more than a few days.


Thousands (tens of thousands? hundreds of thousands?) of people drink
RO water every day. On boats, ships, islands, Israel, and now
California from processed sewerage water. I guess some get sick from
it. It would be interesting to see what percentage compared to those
that get sick from city water and bottled water.

I doubt you'll find *one* case of sickness from drinking water made from
a properly maintained RO system. But it does bear repeating that RO is
a very good incubator for water bugs if not maintained and operated
sensibly. Not that hard to do as you obviously have experienced.

Keith Hughes

wrote in news:49edff44$0$48228$815e3792
@news.qwest.net:

I doubt you'll find *one* case of sickness from drinking water made
from
a properly maintained RO system. But it does bear repeating that RO
is
a very good incubator for water bugs if not maintained and operated
sensibly. Not that hard to do as you obviously have experienced.

Keith Hughes



Yecch.....Reading all this I'm hugging my distiller for security and to
keep from throwing up lunch. My digital thermometer puts the hard
boiling sewage from the city water tap at 108C when she's in full
operation, here at sea level. There is no incubator to hide in. You
never forget your first steam/hand encounter when there's a tiny steam
leak. NOTHING survives, no matter how gross the calcium deposits that
DIDN'T become kidney stones I used to suffer becomes.

Let's all take my little water test my distiller passes without
exception....

Place an extra clean glass quart jar in your oven and heat it to 250F
for 15 minutes to ensure its biology doesn't survive. Let it cool,
completely, to room temperature. Fill it with your best shot RO water
and tightly cap it. Sit it on the dock in the hot summer sun for a
month.

Drink it to show me it's safe to drink.

After 6 months of South Carolina summer on my patio, distilled water is
as clean and biology-free as the day I filled that jar. City water
grows like a swamp! You can even see stuff MOVING! RO water wasn't
quite as bad as city water.....but none of the RO promoters would take
my offer and drink it all green and growing like that.....as I
confidently drank the distilled water that had been sitting in the sun
all summer....

What a shame all that waste heat that COULD be distilling seawater just
goes out the exhaust on a boat.....wasted.

--
-----
Larry
You can tell there's very intelligent life in the Universe
because none of them have ever tried to contact us.....

Gogarty wrote in news:20090421-210944.92.0
@Gogarty.news.bway.net:

You make a very good point. Are there not emergency stills that work on
sunlight?




Yes. Only trouble is they are evaporators, not stills. Biology grows
right up to around 180F so these solar evaps are easily contaminated, a
source of nasty bacteria because they are just right inside in temperature.

If you don't see it boil, it just isn't safe.



--
-----
Larry
You can tell there's very intelligent life in the Universe
because none of them have ever tried to contact us.....

Larry wrote:
Gogarty wrote in news:20090421-210944.92.0
@Gogarty.news.bway.net:

You make a very good point. Are there not emergency stills that work on
sunlight?




Yes. Only trouble is they are evaporators, not stills. Biology grows
right up to around 180F so these solar evaps are easily contaminated, a
source of nasty bacteria because they are just right inside in temperature.

If you don't see it boil, it just isn't safe.

Well, for most common pathogens, you are pretty much correct. However,
there are many spore forming thermophiles whose spores will just laugh
at you if you try to kill them with boiling water. Throw in 10 spores
of G. stearothermophilus in your boiling water. They'll still be happy
to grow up after boiling for 10 hours.

And you can throw in 10 B. subtilis/atrophaeus spores in your dry jar
and put in the oven at 250°F. They'll still be viable 600 hours later.
You'd need 10 minutes at 320°F. Dry heat sterilization is much less
effective than moist heat, for most all types of bugs, so jack up the
temp when you're trying to sterilize things in an oven.

Keith Hughes

wrote in
:

Larry wrote:
Gogarty wrote in news:20090421-210944.92.0
@Gogarty.news.bway.net:

You make a very good point. Are there not emergency stills that work
on sunlight?




Yes. Only trouble is they are evaporators, not stills. Biology
grows right up to around 180F so these solar evaps are easily
contaminated, a source of nasty bacteria because they are just right
inside in temperature.

If you don't see it boil, it just isn't safe.

Well, for most common pathogens, you are pretty much correct.
However, there are many spore forming thermophiles whose spores will
just laugh at you if you try to kill them with boiling water. Throw
in 10 spores of G. stearothermophilus in your boiling water. They'll
still be happy to grow up after boiling for 10 hours.

And you can throw in 10 B. subtilis/atrophaeus spores in your dry jar
and put in the oven at 250°F. They'll still be viable 600 hours later.
You'd need 10 minutes at 320°F. Dry heat sterilization is much less
effective than moist heat, for most all types of bugs, so jack up the
temp when you're trying to sterilize things in an oven.

Keith Hughes


My offer still stands to put sterile jars of your RO water and my
distiller water on the dock for the summer then we'll both drink what's
in it the last day of August.....

I'm sure DoD has some superbugs in their illegal arsenal of biological
warfare agents no distiller can kill.....But, when it comes to purifying
hose water from the sewage the city delivers as drinking
water....Distillers work much better than anything available, including
RO.



--
-----
Larry
You can tell there's very intelligent life in the Universe
because none of them have ever tried to contact us.....