A module arrangement (5) according to an embodiment of the invention consists of a plurality of membrane modules (6) arranged in a two dimensional array (7) and extending between upper and lower block-type manifolds (8) and (9), respectively. The array of modules is further divided into sub-groups of modules (10) separated from each other by space (11) extending transversely across the membrane array (7). An integrated support frame (12) is positioned in the space (11) between the sub-groups (10) and is fixed to the upper and lower manifold blocks (8) and (9) to form an integrated support structure within the module array (7).