Abstract: Fluid separation membrane module assembly with a vessel (7) having a tubular shape with a tubular surface and two opposite end apertures and one or more fluid separation membrane modules (12) positioned along a centerline of the vessel (7). Each fluid separation membrane module (12) comprises membrane elements configured for separating a feed flow into a residual flow and a permeate flow. Adjacent ones of the one or more fluid separation membrane modules (12) are fluidly connected together. The fluid separation membrane module assembly further comprises a feed and permeate connection assembly (6) closing off one of the two opposite end apertures of the vessel (7). The feed and permeate connection assembly (6) has a feed connector (5) and a permeate connector (3). The feed connector (5) and the permeate connector (3) are positioned off-center in the feed and permeate connection assembly (6).