Water treatment, flocculation, and Alum

[Lynn LeFey]

I have watched a lot of videos on emergency/BOB/Get home Bag/survival type stuff. I have seen and read a lot about water purification, and seen some fairly novel ways to purify water. But, strangely, I have heard almost nothing on 'flocculation', and absolutely nothing about alum.

So...

Flocculation is the process of adding a chemical to water that causes small particulate matter that is normally suspended in the water, causing torridity, to clump, or floc, and settle out of the water.

I got these little packets of 'Chlor-floc' at one point for very space efficient water purification, and the 'floc' part got me to reading up on all this. Chlor-floc, I believe, uses a kind of clay particle, but I was wondering if there was something cheap, and readily commercially available that could do it. And there is. Alum.

The stuff in the baking isle, just labeled 'alum'. I THINK it's usually used as a secondary leavening ingredient in baking, but is also a flocculent. And, wow, it does not take much. I tried something like 20 grains the size of sand grains in a 12 oz glass, and it drastically cut torbidity. even stranger, when I then filtered the water through a double layer of cotton cloth, the cloth of the treated water caught more of the remaining particles than untreated water. A container cost me about $3 for 1.9oz (53g).

I know that my preference, and probably everyone's, would be a good filter like a sawyer squeeze or a pump filter like a katadyne, but for mini kits (like an altoids tin), or home use in long-term situations, or some such, I thought this was an interesting find.

Oh, here's a video on flocculation...

[Fortytwo]

Alum is also used as a blood coagulant and is available to treat razor mishaps. I wouldn't count on it for anything great but for small nicks it might come in handy.

[Lynn LeFey]

I wanted to look up if they're the same chemical, because there's an entire group of related chemicals called 'alum'. They're both Potassium Alum.

And apparently works as a deodorant, so... there's that...

[AimlessWanderer]

Interesting, but according to the clip, the result of the process still needs skimming and purifying to be potable. Personally, if I have water that contains stuff I don't want to drink, I'm disinclined to add more stuff I don't want to drink - even if they do cause each other to sink. Surely a decent filtration system is a better way forward - even if it's just a sock filled with layered grass, sand and charcoal. Alternatively, use the ground itself by digging a "gipsy well" at a suitable location. Subtraction rather than addition makes more sense to me - unless of course it's the addition of heat to boiling point  The only way I could see it being of any significant advantage (other than in mass processing plants) is if there is a flocculent that effects desalination, as brackish water isn't compatible with the filtration systems

My two methods are a filtration water bottle, and one of the filtration straws (from the same manufacturer) as a back-up. So far I have escaped any nasty illnesses.

Oh.... and it's great to see you around again Lynn

[Don Pablo]

This alum sounds like the SAK of chemicals. 

I  this!

[Smashie]

Alum is a good choice but I'd also include Potassium permanganate as it's got a few more uses 

[Lynn LeFey]

Hey 50, sadly, no, it doesn't affect salinity. At least, not that I know of.

Removing salt from water is still one of those holy grail technologies. So far, evaporation/condensation is the best that I know of. There ARE methods involving screens and absurdly high pressures. but that won't fit in a bug out bag.

I'm of the opinion that, long term, removing as much particulate from the water before filtering would improve the life of you filter. That's untested right now, though.

And, oh... hey... potasium permanginate... cool... Looked it up... yeah, lots of good uses.

[Gerhard Gerber]

To be clear, my only experience is 5 days putting every drop I drank through a Sawyer filter, while the rest of the group used "Chlorine" water purification tablets.

You can add powder cool drink mix to overcome the taste, but at some point when it gets hot enough you'll just want plain water.

The Sawyer doesn't remove all bad tastes but it comes close.

The filtering process was an absolute hassle, but that will be the option I go for every time.

For a BOB I would pack a Sawyer and Aqua Salveo drops.

[Mike Kennedy]

I have a degree in Water Quality so this brings back many memories. There are many types of flocculants for many purposes. The military uses a product called Chlor-Floc that both settles particles and chlorinates the water. The big advantage to settling out colloids is you don't have to drink them. trying to purify water with regular water purification tablets on turbid water can be haphazard because bacteria can actually be within particles. Boiling water may kill all the bacteria but you are still ingesting all the particles. Using a flocculant then treating the skimmed off water will provide a safer and better-tasting water than treatment alone. Any filtering device will tend to work better with water that has had a flocculant added to it as the particles all become bigger. Also if you just filter the skimmed water the work your filtering system is much less and less likely to clog and become useless. pet stores sell a type of flocculant that you add to the tank to clear water. The smaller particles clump together and the coarser filter will then remove the turbidity.

[Steinar]

Removing salt from water is still one of those holy grail technologies. So far, evaporation/condensation is the best that I know of. There ARE methods involving screens and absurdly high pressures. but that won't fit in a bug out bag.

Reverse osmosis pumps have become pretty small. E.g. https://www.katadyn.com/en/de/149-8013418-katadyn-survivor-06 weighs in at 1.13 kg. Expensive, not light-weight as such, but if that's what you need, that's what you need. 

[Lynn LeFey]

1) HOLY SHIIIiii.... that's frickin' cool.
2) HOLY SHIIiiii... that's FRICKIN' EXPENSIVE!!! 

Wow. Awesome. Out of my price range, but awesome to know they exist. Thanks for that.

EDIT to add: Wow... that is one LOW flow rate. .8 liters per HOUR. Still, very good for emergency use like lifeboats.

[Steinar]

Ray Mears featured the technology in one of his shows and noted you on a life raft should do the pumping at night if in a warm climate, simply because of the hard work involved, as implied by the flow rate.