Filter device, and method of assembly

A filter device comprising:

• a common inlet manifold;
• a common outlet manifold;
• and
• at least two membrane filter units which are configured to be elongated, each of the at least two membrane filter units comprising:
• an inlet opening for a fluid flow to be processed,
• a first outlet opening for at least a retentate portion of the fluid flow, and
• a second outlet opening for at least a remaining portion of the fluid flow,
• wherein,
• each inlet opening of each of the at least two membrane filter units is fluidly connected to the common inlet manifold, and
• each first outlet opening of each of the at least two membrane filter units is fluidly connected to the common outlet manifold,
• wherein,
• at least one of the at least two membrane filter units is arranged at a first position along a longitudinal axis, at least another one of the at least two membrane filter units is arranged at a second position along the longitudinal axis, the two membrane filter units being staggered with respect to each other and not being axially aligned with respect to each other, and
• the at least one of the at least two membrane filter units is fluidly connected to the common inlet manifold and to the common outlet manifold via a first set of conduits, and the at least another one of the at least two membrane filter unit is fluidly connected to the common inlet manifold and to the common outlet manifold via a second set of conduits.