On this picture you can see 3 aeration pumps (white containers with black cover), they supply the storage tank and MBR tank with air. Additional there is permeate pump visible (cylindrical part). It provides a vacuum and the greywater is sucked through the membrane with 38 nm nominal pore size. (you can find notes, if you move the mouse over the picture) Photo by Katharina Löw, May 2011