Question: How do you plan to used scrap metal to clean water?

Harriet Aitken answered on 18 Jun 2014:

Hi 1606happyface,

There are a few different projects I’m working on all my systems center around one things – shaking things up! So there are actually quite a few different systems that are using scrap metal, the most popular one is made up of two buckets each with a layer of sand, metal and activated carbon (a type f charcoal with a very high surface area like a sponge). You pour water in the top and as it flows through the sand filters out big particles (including rust), the metal rusts where chemicals we don’t want in drinking water are adsorbed and removed and finally the activated carbon acts as a final filter for anything not trapped by the rust.

Now these are great because they are cheap, easy to use and very simple to put together. Unfortunately, they don’t always work so well! Quite often the water leaving the buckets isn’t actually clean as all the rust has been ‘used up’, it only has the ability to react with a certain amount of chemicals so it stops working. People often don’t even know as the water tastes and looks fine, but they are actually being slowly poisoned but won’t know until it’s too late.

My system is all about using metal to do the same job, but instead of doing things in a fixed bed (no movement, all material stays still) I am using a moving bed meaning my metal is always hitting together meaning all the old rust is moved into the water and new rust is always formed. We have tried a few different systems, one involving a shaking platform moving round and also used a pump to shoot a jet of water to move the iron. Both work pretty well but there are lots of things to think about in the design – would people be able to afford a pump? Would it be too difficult to operate? What if it breaks?

All of these things I still have to figure out! There are a few other ideas on the table so it’s still a work in progress…