Balancing Price, Durability and Weight with Backpacking Supplies
So I've been struggling with how to balance the backpacking budget, durability and weight....Read more
I was pointing you to evidence in the form of the PET UV transmission spectrum. The spectrum shows that PET strongly absorbs light below 300nm, with some PET variants having an even higher UV cutoff. SODIS requires UV light shorter than 300nm. That means SODIS will be ineffective using PET containers.
Instead you need a container that will not filter out (absorb) the wavelengths necessary for pyrimidine dimer formation.
no association with milk implied.
Now that I have a few minutes… Although I appreciate your interest (and attempt to engage on my level), your argument, quite frankly, falls short. Setting aside, for just a moment, the fact that SODIS (Solar Water Disinfection) has been around since at least the mid-eighties (I believe), and that the CDC, the NCBI, the WHO and other international organizations are all very well aware of the use of PET (polyethylene terephthalate) plastic bottles for SODIS use, and of course the BILLIONS of people all over the world who have benefited from precisely that, “Mooniac” has an opposing opinion, shall we?
Firstly, while you are very emphatic about “… no association with milk implied…”, you’re also very nonspecific, but presuming you’re talking about the figure at the top of the page you cited (at https://tinyurl.com/rg8zwwp), I can only guess you didn’t actually READ the very article you cited starting with the title, which is, “Protective Influence of Several Packaging Materials on Light Oxidation of Milk”, 2005, from the Journal of DAIRY Science (which you would have easily found if only you had clicked the “view publication” button. HELPFUL HINT: You may want research that is on point to support your arguments!
Alternatively, you may want to re-start your research with a ‘quick’ look at an article called “Solar Disinfection of Viruses in Polyethylene Terephthalate Bottles”, 2015, from a journal called Applied and Environmental Microbiology (at https://aem.asm.org/content/82/1/279#sec-2), which I found with just a quick check. An even MORE on point article called “A Pilot Study of Solar Water Disinfection in the Wilderness Setting”, 2014, from a journal called Wilderness & Environmental Medicine (at https://www.wemjournal.org/article/S1080-6032(14)00076-3/pdf) may also be of interest, if your interest is sincere.
On the other hand, you may simply want to read (or RE-read) my earlier post on SODIS in which I wrote, “Pathogenic microorganisms are vulnerable to two effects of sunlight: radiation in the spectrum of UV-A light (wavelength 320-400nm) and heat (increased water temperature). A synergy of these two effects occurs, as their combined effect is much greater than the sum of the single effects. This means the mortality of the microorganisms increases when they are exposed to both temperature and UV-A light at the same time.”
You apparently disagreed stating, “… PET strongly absorbs light below 300nm…”, clearly this is a NON-issue since, as I stated, UV-A has a wavelength of 320-400nm! (not that you mentioned which TYPE of UV light you were referring to, perhaps UV-B?) I will say this, the ability of SODIS to kill viruses is less certain than bacteria, but that’s nothing new if you read my initial post since I made it clear viruses are harder to kill than bacteria. On the other hand, HERE, in North America (specifically the U.S. as in other first-world countries), we don’t really have viral issues with our water. In fact, and to restate, our backcountry “wild water” is actually fairly clean! Sure, there is the POSSIBILITY of giardia or crypto’, but except for relatively few people, they present essentially non-issues making SODIS a very valid and viable solution as an emergency water treatment option, particularly in emergency/survival situations. Questions?
I’m watching this show called Alone where 10 people are dropped into the wilderness and I’m watching this man walk the course of the river talking about I need water! I’m like what do you mean you have a whole river. He said he’s not worried about making a fire, he needs to find water while walking next to a river. WTF. So i had to look around and see if I am tripping. Can’t you just boil it I thought to my self? So yeah thanks for the great article.
Ah yes, on The History Channel, I know it (and they know ME... or at least they know my trail name / online handle). I almost always know who has a chance and who doesn't (near the beginning), andwho will tap-out next.
I don't know what his issue was, do you have the production number? (season and episode).
LOL. Well it was season 1. I don’t know production number or anything. As I continued to watch I realized maybe it was because he was on the ocean and it was salt water. But even still they had pots and tarp and it pretty much rained 85% of the time.
AH, yes, I predicted Allen Kay would win before the first episode was over! The rest were fakes, frauds and pretenders!
I seem to recall one guy who poured brackish water through spagna moss, thinking THAT would make it potable. DORK!!
Another (young-is) guy who was trying to collect rain water with his tarp in the hole of a log.
Any of those ring a bell? And yes, part of the game is they can bring a limited amount of gear.
I have "Alone" recorded (of course), but I don't feel like going through it to find your reference. Instead, I'll just do a few posts for you, one on seawater and one on sphagnum moss.
And yes, he could have caught rainwater with the tarp and kept it in his pot. If he had a tube, he may have been able to make a water still.
Really? No discussion of Steripens and UV light purification? This must be a surprise to NYC that only uses UV for water purification
LOL, okay. I did cover solarization/SODIS, but okay.
They may have come up with a better version of the Steripen, but I recall seeing reviews that complained it tended to fall apart. Also, it uses batteries, so there's THAT issue. But otherwise, it works. However, as with solarizing/SODIS, the water MUST have low turbidity! (cloudiness). If there are any particulates, they really SHOULD be screened/filtered out. Otherwise the UV light can't do its job.
Most cities that use chlorine to treat their water have, or are, switching to chlorine dioxide. However, most bacteria only take about 10 seconds to kill with UV light, provided the light source is within about 6 inches. NY has the LARGEST UV (Ultraviolet Germicidal Irradiation to be exact) treatment system, San Francisco also has a massive UV system, so it could be a model for other cities/countries in the future. But as I said, UV works best IF the water is clear.
Along with UV treatment, "ozonaton" (treating with ozone gas) is another option that has received a lot of research. You can buy ozone generators, but I remember seeing a D.I.Y. approach.