A membrane filter apparatus for splitting a feed into filtrate and retentate is provided. The apparatus comprises a body chamber, a feed inlet disposed on the body chamber, a retentate outlet located in the body chamber, a feed distribution tube connected to the feed inlet, and a filter assembly having a filter. The feed distribution tube has a length sufficient to cause the feed to enter the body chamber at a feed distance from the filter assembly of no greater than 50% of a total length of the body chamber. The feed flows across the filter in a direction parallel to a surface of the filter assembly. The filtrate passes through the filter assembly and the retentate flows through the body chamber in a direction antiparallel to the feed flow through the feed distribution tube and out through the retentate outlet.