Can you please criticize my 3D drawings of a biogas plant?

Question

This is a masonary worked chinese model biogas plant. this is the top view.
http://www.imageno.com/112n68kvqhatpic.html

This is the front view-
http://www.imageno.com/rodj3fr5m803pic.html

This is a bottom view-
http://www.imageno.com/cqs5w3ce3verpic.html

This is the CAD model-
http://www.imageno.com/pj0ka974g5fgpic.html