Pure Earth http://www.pure-earth.com/ sells what look like very efficient
high intensity one pass sanitizers. I have only looked at the specs, they
look good. Of course, specs and reality may be different.

"Keith Hughes" wrote in message
...


Frank wrote:

Don't see why they would not work in lake water, with a pre
filter/strainer
of some kind to remove junk, and an ultraviolet sterilizer after the
unit to
get rid of bacteria. Salt water would probably be too much.
Frank

If you're relying on UV to sanitize the water, you'd better plan on a
recirculation system that runs continuously - not really desireable in
boating application. UV is a very poor sanitizer, especially in a
one-pass installation.

Keith Hughes

"frank" wrote in :

Pure Earth http://www.pure-earth.com/ sells what look like very efficient
high intensity one pass sanitizers. I have only looked at the specs, they
look good. Of course, specs and reality may be different.



Easy to test....

Pump holding tank water into the RO's inlet. Put a glass under the outlet.
Have the sales wienie drink it. Wait 2 hours for the results before
getting out your checkbook....(c;

FYI, Ashley River water distills quite nicely (brackish with treated
sewage), but makes a tougher cleanup of the boiler after a few gallons. I
can't tell any difference in the taste even though the total dissolved
solids goes up to 12-15 ppm, which is nothing.... The residue looks like
pluff mud and salt crystals.

--
Larry

This jerk called my cellphone and was nasty.
Continental Warranty -- MCG Enterprises -- Mepco-
24955 Pacific Coast HWY Suite C303
Malibu California 90265
888-244-0925
Fax: 310-456-8844
Email:
Read about them he
http://www.ripoffreport.com/view.asp...3&view=printer

Having spent a fair amount of time trying to validate such systems in
pharmaceutical water plants, I'm highly dubious. It can be done, at
small flow rates and long exposures, but it is *sanitization* not
sterilization. Bacteria are fairly adept at repairing UV induced damage.
And UV doesn't kill the bacteria, typically, just makes them unable to
reproduce.

And, as Larry pointed out, you still have issues with endotoxins that
can permeate the membranes. Maintenance is always critical with RO
systems, as the pressure increases as you form a biofilm on the
membranes, making leaks more common (o-rings, membrane
cracks/perforations, etc.). Once you get that leak, then you have tons
of critters cruising through, enough to make you sick even if they can't
reproduce.

IMO, relying on RO to take care of water that has too high a bioburden
to drink otherwise is asking for trouble.

Keith Hughes

frank wrote:

Pure Earth http://www.pure-earth.com/ sells what look like very efficient
high intensity one pass sanitizers. I have only looked at the specs, they
look good. Of course, specs and reality may be different.

"Keith Hughes" wrote in message
...

Keith Hughes wrote in
news
Having spent a fair amount of time trying to validate such systems in
pharmaceutical water plants, I'm highly dubious. It can be done, at
small flow rates and long exposures, but it is *sanitization* not
sterilization. Bacteria are fairly adept at repairing UV induced damage.
And UV doesn't kill the bacteria, typically, just makes them unable to
reproduce.


Keith, I noticed these small RO systems put in boats use quite a bit more
pressure than the commercial units, say for a muni water system. Wouldn't
that make them break down the dead bacterium much faster, releasing their
toxins into the water supply?

--
Larry

This jerk called my cellphone and was nasty.
Continental Warranty -- MCG Enterprises -- Mepco-
24955 Pacific Coast HWY Suite C303
Malibu California 90265
888-244-0925
Fax: 310-456-8844
Email:
Read about them he
http://www.ripoffreport.com/view.asp...3&view=printer

Larry,


Keith, I noticed these small RO systems put in boats use quite a bit more
pressure than the commercial units, say for a muni water system. Wouldn't
that make them break down the dead bacterium much faster, releasing their
toxins into the water supply?

I doubt it. The water bugs that create the biofilm are pretty tolerant
of pressure, they just balance internal and exterior pressure. Hardy
little beasts. I would certainly expect a higher level of membrane
compaction, shortening the life, and a much greater propensity for
o-ring and membrane failure. The additional pressure will, of course,
help move any cellular debris through any holes, including the membrane
'pores'. Most of the commercial systems I've dealt with operate closer
to 600-650 psig, and they still have leakage problems.

Keith

Keith Hughes wrote in
:

to 600-650 psig, and they still have leakage problems.


I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....


--
Larry

This jerk called my cellphone and was nasty.
Continental Warranty -- MCG Enterprises -- Mepco-
24955 Pacific Coast HWY Suite C303
Malibu California 90265
888-244-0925
Fax: 310-456-8844
Email:
Read about them he
http://www.ripoffreport.com/view.asp...3&view=printer

On Sun, 10 Jul 2005 20:47:35 -0400,
Larry wrote:
Keith Hughes wrote in
:

to 600-650 psig, and they still have leakage problems.


I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....



How much power does it take to make a gallon of fresh water from
seawater with your distillers?

--
Jim Richardson http://www.eskimo.com/~warlock
Silence is one of the most effective forms of communication.

On Sun, 10 Jul 2005 18:32:24 -0700, Jim Richardson
wrote:

On Sun, 10 Jul 2005 20:47:35 -0400,
Larry wrote:
Keith Hughes wrote in
:

to 600-650 psig, and they still have leakage problems.


I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....
I love my distillers....



How much power does it take to make a gallon of fresh water from
seawater with your distillers?


Hmmm...let's pencil in the numbers on back of an envelope.

A (US) gallon of water is 8 lb that's 8/2.2 kg = 3.636kg = 3636 gm

From 20 degC, it takes 80 cal to get to BP then 540 cal/gm to get to
steam. Totals....3636 X (80 + 540) = 2.254 Mcal = 9.5 MJ

So if you could be happy with one gal/hr, it would take
9.5 MJ.hr or 9.5MJ / 60X 60 = 2.63 kilowatts.

But some or all those heating watts could maybe get returned to the
feedwater from the distilled water, and that's the trick to cutting
the power consumption of a still. Or how about a low vacuum process,
so the water feed boils at low temp?

Brian Whatcott Altus, OK

Jim Richardson wrote in news:8qu8q2-
:

How much power does it take to make a gallon of fresh water from
seawater with your distillers?


25c at 8c/kWH from South Carolina Electric and Gouge.

What I can't figure out is why marine engine builders can't build a good
distiller right into the engine heads. The coolant in there is BOILING,
already! In yachts with dry stacks, a simple heat exchanger right in the
exhaust stack would provide an amazing amount of distilled seawater in
motor yachts, just like an evaporator does on a steamship. It isn't rocket
science, like RO is. You need a seawater pump, already mounted on the
engine that's pumping cooling water into it at some pressure, a float-
regulated tank to maintain the seawater in the heat exchanger tubes perking
away in the exhaust stack, and a seawater condenser using the same seawater
pump on the engine to cool the steam back into distilled water. Feed that
through a carbon pile filter to take out distillables like benzenes and
what comes out is the freshest water in the world...no toxins, no
chemicals, no bacteria leaking through tiny holes in million-dollar
membranes. It would run 24/7 in a motor yacht until you ran out of tankage
to store it. A backflush timer would dump the salt and residues every few
hours overboard or you would have an overflow at some level to constantly
lose some of the huge energy in the stack dumping it over continuously
cleaning it. It's just salt and bugs and seaweed crap left over. Make it
out of stainless tubes so it doesn't corrode with a zinc in it, if
necessary.

Distillers are FAR less complex than RO science projects....really simple
devices. The boat would probably be overrun with fresh water in a yacht
with twin dry-stack diesel beasts burning up 20 gallons an hour, most
energy going right up that stack.

Larry

This jerk called my cellphone and was nasty.
Continental Warranty -- MCG Enterprises -- Mepco-
24955 Pacific Coast HWY Suite C303
Malibu California 90265
888-244-0925
Fax: 310-456-8844
Email:
Read about them he
http://www.ripoffreport.com/view.asp...3&view=printer

I am not sure either of you guys has any idea what goes on inside a R/O
pressure vessel. First of all the normal pressure range for a seawater
system is between 750 and 850PSI. Seawater R/O membranes are made from
completely different materials and construction from municipal and most
other industrial purification membranes. They can withstand pressures
almost twice that high. Unless they are damaged by chlorine they don't
leak. The only O-ring that might potentially leak brine into the product is
at the output end of the product tube. Any leakage there would immediately
raise the salt level above the drinkable level. The other two O-rings seal
the pressure vessel itself and when they start to leak with 800PSI behind
them the result is more than a little bit noticeable.

Now as to squashed bacteria. The process of reverse osmosis is not simply
squeezing water through super small holes. The salt is rejected by the
electrical charge of the salt ions. The charged ions are pushed away from
the membrane surface. In the process bacterial is pushed away with the
ions. The seawater flow across the membrane surface is 7 times that of the
product flowing through it. Bacteria being several million times larger
than the salt ions are swept away so they never get a chance to collect on
the membrane in normal operation. If you leave the membrane idle for
several days however the bacteria can settle on the membrane and start
reproducing and THAT can cause clogging. What causes scaling is the
accumulation of molecules of minerals with very low charge. A flush with a
mild acid every couple of hundred operating hours will take care of that.

Normally R/O desalinated water is 100% free of bacteria but if you are
drawing from a harbor or other polluted water with a high virus count
statistically some viruses can get through the membrane and that is what UV
post treatment is for.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com