So next time I go to the US I should bring a LifeStraw?
This is an actual question: How much do these filters help against the type of contamination that's in US drinking water?
This is an actual question: How much do these filters help against the type of contamination that's in US drinking water?
>The chemicals were used in products like Teflon and Scotchguard and in firefighting foam. Some are used in a variety of other products and industrial processes, and their replacements also pose risks.
All of these chemicals are in common use throughout the developed world. This isn't just a case of evil corporations dumping industrial waste into impoverished children's drinking water, though corporate environmental pollution does play a role. They come from everyday use and wear of common products, and they are incredibly expensive to filter even by centralized plants once they've made it into the water supply through e.g. dish washing, clothes washing, and street runoff. And the issue is that they accumulate over years or possibly decades.
LifeStraw even states
>Chemicals, salt water, heavy metals and viruses will not be removed.
http://help.lifestraw.com/en/articles/2507813-does-the-lifes...
Sawyer states
>Taste
>The Sawyer filter removes taste that comes from bacteria, dirt, and green matter.
>Chemicals
>The Sawyer filter does NOT remove iron, sulfur, other chemicals, or simple compounds. Taste can be masked by using flavor additives like Gatorade or crystal light (filter needs to be cleaned immediately after using them).
>Heavy Metals
>The Sawyer filters are not made with charcoal. While other portable filters have charcoal, they lack in amount of media and adequate dwell time. Therefore, they only remove small amounts of heavy metals, pesticides, etc. (when used in real life applications). Try using better sources of water, if possible.
What about fractional distillation?
That would work but I imagine it's going to have some amount of inefficiency depending on the contaminant, you'd have to do several passes to get to really low trace levels I imagine as you're going to keep some contamination simply by what collects on the walls of the vessel and runs back down.
With some contaminants I imagine you could introduce more chemicals to get a reaction that would make the filtration easier. I imagine some could also be changed sufficiently by heating the sample to a point where you get a chemical change in the contaminant, although, I'm guessing this would be the most 'expensive' method unless energy wasn't an issue (fusion).
Wash the packed column and boiling vessel with the heads and then discard them. Discard the tails. Repeat the process with the mains.
Your twice-distilled mains are now pure water, discounting contamination from inferior distillation apparatus.
Get some food-grade calcium chloride (E509, de-icing salt), magnesium sulfate (Epsom salt), sodium bicarbonate (baking soda), and potassium chloride (NoSalt brand table salt substitute) and add some (known) minerals back into the result for your drinking water, because pure distilled water has a very poor taste profile.
The only types of chemical that cannot be easily removed by this distillation process are those that form azeotropes with water, such as ethanol, and those chemicals are unlikely to be present in quantities significant enough to be a problem.
Plus remineralization isn't as effective as you would think. Most of the minerals removed by RO can't be easily reintroduced as they aren't readily dissolved.
I've been eating plant based whole food lately and at 1903 kcals yesterday I managed (per Cronometer):
- 646.4mg of calcium
- 636.1mg of magnesium
- 785.1mg of sodium
Which are the 3 big ones in common tap water. Even if you factor in a 25% error margin, through my diet I'm getting way more than I would drinking random tap water.
>Reverse Osmosis Systems will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.
https://www.cdc.gov/healthywater/drinking/home-water-treatme...
Seems about as close as you can get to completely clean water.
Hilariously inefficient use of energy, but I think the only contaminants you are likely to encounter would be... nitrous oxide (N2O)?
As I understand it electrolysis of water converts chloride salts (table salt) to chlorine gas (poisonous), fluoride salts (rarer) to fluoride gas (really poisonous), etc.
So to promote electrolysis, add KOH or NaOH (lye) instead of NaCl (table salt). Or don't add anything, and let your charge carriers be H3O+ and HCO3- from dissolved CO2.
The chlorine will come off first, and if you have a reducible anode, it will attack that first. If you have a graphite anode, you will get Cl2, which will oxidize pure hydrogen just fine. You'll get HCl in the combustion, which isn't dangerous when diluted (it's the same acid that's produced in your stomach).
Fluorine gas is not produced from aqueous fluoride salts because the oxygen is always oxidized first.
The half-reactions:
2 H2O + 2 e- --> H2 + 2 [OH-] (-0.83 V)
2 H2O --> O2 + 4 [H+] + 4 e- (-1.23 V)
2 [Cl-] --> Cl2 + 2 e- (-1.36 V)
2 [F-] --> F2 + 2 e- (-2.87 V)
2 F2 (g) + 2 H2O (l) --> 4 HF (aq) + O2 (g)
By the redox half-reactions, it looks like oxygen should be produced before chlorine, but there is also something called "overpotential" at the electrode. On a graphite electrode, the activation overpotentials for H2, O2, and Cl2 are -0.62V, +0.95V, and +0.12V, respectively. There is also a "bubble overpotential" of the tiny bubbles that form on the electrode. That pushes the preference towards chlorine gas. Tiny oxygen bubbles will form, but the energy required to grow them large enough to detach from the electrode and rise to the surface exceeds that required to form and grow a chlorine bubble.
Though as you stated it still doesn't solve root cause.
https://www.seychelle.com/water-filters
> The Radiological filter removes the four basic zones of contamination: aesthetic (chlorine, taste and odor), chemicals (from industry and agriculture), dissolved solids (heavy metals such as lead, mercury, chromium 6) and up to 99.99% of radiological contaminants such as gross beta, radon 222, alpha radium 226, plutonium, uranium, cesium 134 and 137. Removes up to 90% of fluoride. (Not to be used with salt water.)
> The RAD/ADV filter removes up to 99.99% of chlorine, chemicals (VOC’s), heavy metals, radiological contaminants and up to 90% of fluoride. It removes up to 99.9999% of bacteria and viruses, as well as 99.9% of giardia and cryptosporidium. The RAD/ADV filter can be used for emergency preparedness, disaster relief, and radiological contamination. Just like the Advanced filter the RAD/ADV filter is ideal for traveling around the world and used with water of unknown quality. (Not to be used with salt water.)
So there's a chance that these might be able to remove other chemicals and perhaps microplastics.
The Berkey filter also seems to remove quite a few contaminants:
https://www.berkeyfilters.com/pages/filtration-specification...
I wonder if there will be a boom in the water filter industry after more mainstream articles come out about the problem and the government eventually starts recommending them openly.