How do you deal with a problem like arsenic in drinking water, especially in developing nations where people can't afford the complex purification facilities needed to clean the water to potable levels? It turns out there's a much simpler way. It involves using chopped up hunks of plastic from soda bottles, and coating them with an easily-produced nutrient.
There's a protein called cysteine which is found in a wide variety of foods, as well as hair and feathers. It has the rather useful property of acting like a magnet around arsenic, sucking it out of liquid. And it sticks easily to plastic.
A group of researchers has published a new proposal that suggests collecting plastic bottles locally in the affected nations, chopping them into chunks, then coating them with cysteine. Then, all you have to do to make the water drinkable is stir the plastic into the water, and then discard it. The arsenic binds to the cysteine, and is removed from the water.
The major advantage of this method is that it doesn't require large and expensive filtration units, and doesn't require any major training to use. That said, you do need to isolate the cysteine, which requires at least a little hardware. If wikipedia is to be believed it can be gathered from the hydrolysis of human hair or duck feathers — dissolving them in hydrochloric acid, then separating out the compounds. Not something you can do with a home chemistry set, but certainly easier than building large filtration devices.
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