The method serves for operating an air fractionization installation for obtaining oxygen on board an aircraft, with at least two molecular sieve chambers. The method includes, optionally, identification of problematic filamentous bacteria and matching virulent bacteriophage, use of bacteriophage from phage libraries and concentration of filamentous bacteria and bacteriophage from the wastewater to be treated. The second body includes a key pad and is slidably coupled to the first body. The securement member captures the first member within the second member and permits relative movement between the first and second members in a direction along a longitudinal axis of the first and second members, and restricts motion between the first and second members in a direction transverse to the longitudinal axis.