Abstract: The present invention relates to an improved design for a spiral wound membrane separation device. The improved module has one feed pipe separated into compartments which are connected axially to a porous spacer surrounded by a membrane envelope. A separate permeate pipe is immediately adjacent and generally in a parallel configuration to the fluid feed pipe and is in fluid communication with a different porous spacer sheet. When the porous feed membrane and pipe and spacer and permeate pipe are combined using appropriate complementary shaped spaced filling means, a spiral wound membrane separation device is obtained having two centrally located pipes. In one aspect, the membrane separation module further includes means for the addition of a countercurrent or cocurrent sweep fluid (gas) the permeate.