how do you make a organic sewage system?

Question

I onced visted the earth centre in north england. they had a system of microbes and plants that filtered sewage till it was clean water that could be returned to the nearby river. Can anyone tell me exactly how it works, where i can buy one or/and how i can make one

Answer 1

Do a search for Rock/reed filter, Plant rock filter or "Constructed Wetland"

Here are the design standards for one state:

http://www.msdh.state.ms.us/msdhsite/_static/resources/59.pdf

Answer 2

Most sewage treatment plants use the same theory for 95% of the pollutant removal or even 100% in some cases. Conventional sewage plants are very organic. The only thing special about these "constructed wetlands" plants are that they use the reedbeds for that last 5%, where some regular sewage plants may have to use a chemical like alum (which is very natural) for the final polishing due to the strict limits imposed by the government. Sometimes ozone has to be added to kill of the last of the bacteria. The problem with constructed wetlands is that they can only be used on small scale projects, because they take up so much space. For example, New York City would need to convert all of Connecticut to be able to do it (maybe just half, but you get the idea). They are not practical on a large scale.