Question on the biocide additive for the Katadyn PUR Survivor 06 and 35 Reverse Osmosis Manual Desalinator Pumps:

Is the biocide to kill organisms in the freshly pumped water or is it to protect the unit itself?

If it is to kill organisms in the freshly desalinated water, what is the biocide?

Could one use the biocide for other non-desalinating systems or even manually?

If unable to use the biocide, can you run the desalinated water through a conventional filtration with or with out a silver or iodine system to achieve the same results as the biocide?

Pete

Pete,

I know that Katadyn has been good about answering my questions about a couple of their hiker model filters via email. You might try their marine products email address:
marine@katadyn.com

They might be able to give you more details. Hope it helps.

The biocide is strictly for storage purposes in these Katadyn/PUR devices. It is flushed during the intial pumping, as per the attached instructions.

Thanks.

If that is the case, does the water produced still have potential microbial pathogens?

Pete

The unit is a reverse osmosis unit. Like the unit under someone's sink or purifying water for the ice machine or water dispenser at the store, it pretty much gets rid of just about anything bigger than a water molecule. It makes for a lousy water filter due to the high effort for the water it produces. Worth the effort in a life raft; totally unsuitable for conventional water purification.

How much more energy is required to operate the pump as compared to conventional systems?

Would it then be fair to say, cost aside and/or energy input requirements, the Katadyn PUR Survivor 06 and 35 Reverse Osmosis Manual Desalinator Pumps theoretically would be the gold standard or the best universal system to have even if not around a marine environment on a regular basis?

Pete

LOTS more! The 06 takes considerable effort, relatively little leverage on the commercial model, at the rate of 40 strokes per minute, to produce a bit over a liter per hour. Do the math, that equals 2400 strokes to desalinate about a quart of water. Believe me when I say this is not easy or much fun. It's better than dying of dehydration, but do it for long and you will lose plenty of weight. If you aren't in particularly good shape and are by yourself, you will run out of steam in less than an hour. Anything much less than 40 strokes/minute doesn't work and anytime you stop, you have to flush the system again. The 35 is much better, but also much bigger and more expensive, weighing in at 7 lbs. Still have to keep that stroke up, but the longer pump arm makes it a little bit easier. It produces water at the rate of about 1.5 gallons per hour. If energy input isn't part of the equation, theoretically yes, but you also have to ensure the water is pretty clean to begin with, as in tap water clean, because the membrane will clog very quickly otherwise. They make electrically operated versions and many other companies also make electrically operated marine RO desalinators. They aren't found in other environments because there's lots more economical and efficient ways to purify dirty or contaminated water via conventional filters and/or chemical treatments. There are no other compact or efficient ways to desalinate water.

Thanks.

Pete

At the risk of sounding glib (while reviving an old thread). Does that include "Cryptosporidium"? I am going to venture a guess that it does, but I know virii are extremely small when compared to bacteria.

They're also pretty huge when compared to a water molecule.

Cryptosporidium (Cryptosporidium parvum), are not viruses, but a parasitic protozoan and are much larger then bacteria. Here is a good web site for more information. Pete

http://vm.cfsan.fda.gov/~mow/chap24.html

Yeah... and there's anecdotal evidence that oocysts will settle out in still water - apparently they are denser than water. So maybe one could greatly reduce the number of oocysts ingested in emergency situations simply by letting water sit for a few hours and then carefully decanting off the upper region of water?

You wouldn't happen to have some lying around the lab that you could confirm my theory with, would you, Pete? Giardia or Crypto or both?

As we've discussed previously, it requires a certain quantity of ingested oocysts to cause problems - a few / several won't bother most folks at all. And some folks seem to be unaffected by fairly large numbers - huge variability in folks vulnerability...

The problem is protozoans cannot be cultured as they are obligate intracellular parasites. We do receive mice that are infected with Giardia and/or Entomebia and/or other protozoans and we are able visualize their non-cystic state with a phase-contrast microscope from intestinal/cecal contents. However, we do not stain for the cysts, nor do we collect them for any additional studies.

It would be logical to believe the cysts would eventually sink to the bottom, as it is likely their density is greater than water. However, it might not take much movement to re-suspend them. I would not rely totally upon that method.

Pete

We have an electrically operated RO system in our RV. We are able to provide power with our solar array as well as run all of our other needed electrical stuff. The process is slow, but it provides for our needs.

The system is one of the under sink models purchased from Sams Club. The brine is fed back into the supply tank. This method has worked for years and we have the membrane checked abour once a year. Had to replace the membrane once after several years because of damage done to it during handling. It was still functioning well.

RO is nice in the southwestern US as there are many dissolved salts in the water. Now I hate to drink anything else.

For an interesting article on living with Giardia, see
http://www.getlostmagazine.com/mcbee/2004/0404giardia/giardia.html

And several of the sites I have visited on Giardia & Crypto indicate that trouble can be caused by as little as one cyst. You can be treated multiple times, and still might have the cysts lying dormant, waiting for a nice, stressful period in your life to flare up again.

YUCK!

Sue

Sue,

Sounds like fun... but seriously, the "one cyst" is kind of like the golden BB that brings down an aircraft - it can happen, but... plenty of evidence that a measurable portion of the population is highly resistent and the "average" person (if there is such an animal) has to ingest some larger number - 30? 50? - whatever - before getting sick. Or maybe it's "don't drink the water in Months with an "R" " or...

Good thing we're variable like that or one bug would wipe out the species next week... wait, was was that about only 2 varieties of wheat grown now...

I don't worry about it, in any event.

Tom