A membrane filtration process includes pretreating an influent solution to remove suspended solids, to produce a pretreated solution. Each antenna assembly includes two subreflectors with a plastic matching element. Hierarchies of requirements andor offerings may also be expressed and matched such that a more specific case of a requirement or offering may be matched against a more general case of the same requirement or offering. Therefore, even when the rotation of the valve body is small because the water flow in the secondary side is small in a conventional actuated valve type water flow detection device, it is possible to increase an opening angle of the valve body. The processing method includes the steps of exhausting the atmosphere replacing chamber while introducing first gas below predetermined humidity to the atmosphere replacing chamber, and vacuum-pumping the atmosphere replacing chamber after said exhausting step, by reducing an amount of the first gas to be introduced into the atmosphere replacing chamber. A different embodiment uses interlocking barbs.