Ole-Hjalmar Kristensen wrote:
This discussion has set me thinking about what is the final products
of the LectraSan. If it does electrolysis of sodium chloride...

It does not. The Lectra/San creates hypochlorous acid by charging the
ions in salt water with electrical current. It's a very unstable
solution...it's hypochlorous acid as long as current is being
applied...but when the stimulus (electrical current) is removed it
reverts to salt water, leaving no free chlorines in the discharge.

Does anyone know if this potential problem
has been investigated?

Extensively...your concerns are unfounded.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1

Strange. By their own words, they definitely do elctrolysis of sodium
chloride (snipped from raritan web site):


The process starts with salt water in the treatment tank. NaCl --
Na+ + Cl- Sodium Chloride is a strong electrolyte so it exists in
water as sodium and chloride ions.

H2O -- H+ + OH- Through hydrolysis, water breaks into hydrogen ions
and hydroxyl ions.

The electrode pack is energized during the treatment cycle and
electricity passes through the conductive salt water. Hypochlorous
acid, a powerful bactericide and oxidizing agent, is produced on the
surface of the plates.

At the Anode: 2Cl- + OH- + H+ -- HCl + HOCl + 2e- Hydrochloric acid
and hypochlorous acid are produced, liberating two electrons.

At the Cathode: 2e- + 2 H+ + 2Na+ + 2OH- -- 2 NaOH + H2 The two
electrons, hydrogen ions, sodium ions and hydroxyl ions combine to
produce sodium hydroxide and some hydrogen.

The Net Reaction is: 2Cl- + 3OH- + 3H+ + 2Na+ -- HCl + HOCl + 2NaOH +
H2 With constant mixing from both motors, the products are mixed
together for continued reactions.

NaOCl + H2O -- NaOH + HOCl Hypochlorous acid (HOCl) is formed when
sodium hypochlorite reacts with water.

HOCl + XXXX -- HCl + XXXXOx Hypochlorous acid reacts with soil, dirt,
and bacteria giving up its oxygen; leaving hydrochloric acid.

HCl + NaOH -- H2O + NaCl The hydrochloric acid reacts with the sodium
hydroxide to form salt and water.

The usual explanation of reactions in a sodium chloride cell is this,
and I wonder how they make the reactions above happen instead of the
ones below.

Sodium hypochlorite/chlorate manufacturing process:

Electrochemical and chemical reactions occurring in cells
[1] 2Cl- == Cl2 + 2e- (anodic reaction)
[7] 2H2O + 2e- == 2OH- + H2 (cathodic reaction)
[8] Cl2 + 2OH- == OCl- + Cl- + H2O (hypochlorite formation)
[9] 3OCl- == ClO3- + 2Cl- (chlorate formation)
[12] NaCl + H2O == NaOCl + H2 (overall hypochlorite reaction)
[13] NaCl + 3H2O == NaClO3 + 3H2 (overall chlorate reaction)
[14] 3Cl2 + 6NaOH == NaClO3 + 5NaCl + 3H2O (chemical chlorate
formation)

--
C++: The power, elegance and simplicity of a hand grenade.

Ole-Hjalmar Kristensen wrote:
Strange. By their own words, they definitely do elctrolysis of sodium
chloride (snipped from raritan web site):

My knowledge of chemistry is definitely that of a layman...Yes, sea
water IS a sodium chloride solution...but I don't think I was too far
off when I said the L/S creates hypochlorous acid by charging the ions
in salt water with electrical current:

"NaOCl + H2O -- NaOH + HOCl Hypochlorous acid (HOCl) is formed when
sodium hypochlorite reacts with water."

But what I THINK you're missing is...the Lectra/San is not a "cell" to
which current is continuously applied and from which treated waste is
discharged while that's happening. The L/S is only a two-chambered
container of salt water and waste to which current is applied for only 2
minutes after each toilet flush...during which time waste is NOT
discharged--it only discharges when new incoming waste from the toilet
into the first chamber displaces an equal amount of treated waste from
the second chamber...by which time the solution has reverted to sea
water again as described in the last step of the process: "HCl + NaOH
-- H2O + NaCl The hydrochloric acid reacts with the sodium hydroxide to
form salt and water" (again). And a bit you neglected to include: "The
hydrogen formed at the cathode bubbles off into the atmosphere. The
water and salt by-products are eventually discharged into the receiving
waters."

So as I understand it, other than the amount of voltage, what happens in
a Lectra/San--and its impact on the environment--is really no different
from what happens in the immediate surrounding waters when a lightning
strike hits the ocean...both are very temporary.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1

Here is another view on the system (from a competitor, it seems :-)

http://216.239.59.104/search?q=cache...chlorine&hl=nl

"PH" == Peggie Hall writes:

PH Ole-Hjalmar Kristensen wrote:
This discussion has set me thinking about what is the final products
of the LectraSan. If it does electrolysis of sodium chloride...

PH It does not. The Lectra/San creates hypochlorous acid by charging the
PH ions in salt water with electrical current. It's a very unstable
PH solution...it's hypochlorous acid as long as current is being
PH applied...but when the stimulus (electrical current) is removed it
PH reverts to salt water, leaving no free chlorines in the discharge.


Does anyone know if this potential problem
has been investigated?

PH Extensively...your concerns are unfounded.

PH --
PH Peggie
PH ----------
PH Peggie Hall
PH Specializing in marine sanitation since 1987
PH Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems
PH and Other Sources of Aggravation and Odor"

PH http://www.seaworthy.com/store/custo...0&cat=6&page=1


--
C++: The power, elegance and simplicity of a hand grenade.

Ole-Hjalmar Kristensen wrote:
Here is another view on the system (from a competitor, it seems :-)

http://216.239.59.104/search?q=cache...chlorine&hl=nl

A former competitor whose Type I MSD--the SeaLand SanX, which requires
the use of a formaldehyde based chemical, and barely treats to legal
standards was finally discontinued a couple of years ago. It's not just
the Lectra/San he lobbies against...it's the use of ANY treatment
device. Because the SeaLand device is the most environmentally
UNfriendly any Type I treatment device could be, he became a committed
advocate of universal "no discharge" in an effort defeat pending new
legislation that would have reduced the allowable bacteria count in the
discharge from treatment devices from it's current level of 1,000/100 ml
to 10/100 ml (which the SeaLand device could not come close to meeting,
but the Lectra/San does) and allowed the discharge of treated waste from
devices that met the new standard in all coastal waters including those
designated "no discharge." McKiernan was determined to defeat it rather
than risk losing sales of holding tanks to competitors' treatment devices.

I suggest you also read this:

http://www.raritaneng.com/pdf_files/...20Response.pdf

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1