Watch this coagulant make dirty water drinkable

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Also known as “flocculation”, it’s used in every water treatment plant to shorten the time (and thus mega-litres of storage) needed in the plant to clarify the raw water. (Filter beds clog up fast if you don’t let the worst of the dirt settle out for a few hours first, and flocculants like alum get ten hours of settling to happen in two hours.) Alum is no longer popular, however, as they’ve been coming up with amazing new things like “polyacramides” that us BSc engineers with our two chemistry courses have to trust the real chemists on.

Presumably, that research has turned up this remarkably powerful flocking agent, though I suspect it’s cost will limit it to emergency uses like this.

And that’s the real question here: how much per litre? How much per day of family use, for people who lack clean water to start with because they make only a buck a day?

You can also do pretty well with five layers of canvas (and a lot of patience) plus a teaspoon of chlorine bleach (at five per penny) per gallon.


Pretty neat, but I hope discarded coagulant isn’t going to be a future problem itself…


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Pretty much the same thing that fining agents do to beer or wine - like bentonite clay, or isinglass (made from fish!). But those take a LOT longer to do their work and settle out.


Yep. The military uses flocculants too to provide clean drinking water in the field. Note that the resulting “clean” water still needs to be filtered or sterilized in order to remove parasitic cysts and, in developing countries, bacteria and viruses. You can still get sick drinking clear “clean” water, as anybody who’s ever gotten giardia from a clear mountain stream can attest. But getting rid of the sediments means your filter lasts a lot longer between backflushes (where you backflush with clean water to clear out the stuff filtered out by your filter).


This video – or at least GIFs derived therefrom – seems to be having a huge resurgence as of late, but I notice it dates to May 2017. I thought it was a lot older than that, though.

I found this article that dates to 2012.

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I suspect not. It’s non-toxic and biodegradable - its primary ingredient is a product of bacterial fermentation. If you’re familiar with the fermented soy product “natto,” this is the sticky part, apparently.


As the city water engineer I used to work with said, “it’s not the stuff you can see that’ll kill ya, it’s the stuff you can’t.”


This method uses sunlight. Hmm, I think I’d leave that as a resort just before drink my own pee time. (And limes are hard to come by in the Canadian wilderness.) Use bentonite clay if you’ve got it.


Yeah, I have real doubts about this. I don’t understand the mechanism by which water that was already sitting in the sun teeming with parasites can suddenly be disinfected by. . . a few more hours of sun. That means it’s Wikipedia time, I guess.

Flocculation has two added benefits.

  1. It makes chemical treatments like chlorine dioxide more effective. Each particle of dirt provides numerous hiding places for bacteria, cysts, and viruses. By sinking them so that they’re not being consumed, the overall treatment becomes more effective.

  2. People are more likely to drink clear water than turbid. So flocculation translates to better hydration.

Looks like kombucha. I see a marketing opportunity.


If it’s loaded with T. Gondii, it’s a win-win!


Entrepreneur Juice™




While this coagulant is neat i have concerns. Unless this is simple/cheap to make locally or on the go the people that need this the most are just not going to have access to it. I don’t see this being super useful. The video also says that the water that’s at the top is clean and drinkable, which is just not true or hard to believe at face value with no proof. It’s cleaner sure but depending on what was in the soil it could have bacteria, heavy metals, chemicals, etc.

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