homesewage

Hi everybody, I'm a new person there and I have a couple of questions about individual wastewater treatment plant. First one is about the most effective technology to remove sewage, please give me your individual solution for this problem. Secondly I would like to know cost of investition from project to execution. It must be compatibile with the law .
I need this to my school project, so please treat it seriously.
Please give me also the advantages and disadvantages of you proposal.
Thanks a lot for your answers :)