Question: Tell me about the tiny membranes? What are they they made out of? What size particles do they filter?

Emily Hayward answered on 16 Jun 2014:

Hi Kirstie2000. The tiny membranes I am using are made of a material called aluminium oxde. It is white in colour and can occur naturaly or be made in the lab. It is a material which is cheap to make, very available (not rare) and has excellect properties as its strong and can be effectively used as a filter. They are great as you can change the size of the holes in the material allowing different things to be filtered. I am currently using ones which are 0.8 um – this means the holes in the filter are sluightly smaller than bacteria are, so bacteria or anything bigger can not pass through them. You can also get them much bigger or much smaller – the smaller ones only allow water molecules or anything smaller to pass through, however this requires a lot of energy to push the water through as the holes are so small that its a tight fit!