Devices and methods associated with these devices for significantly reducing or eliminating liquid (e.g., water) in a water or wastewater treatment unit above the underdrain from moving downwardly into the underdrain during an air only wash cycle of the treatment unit. The treatment unit can take many forms including but not limited to an upflow filter and a downflow filter. The treatment unit may include a filter bed having one or more layers of filter media supported by gravel above the underdrain. The treatment unit may also include an underdrain having a porous plate, slotted plate or slotted upper structure that obviates the need for gravel. Positive pressure is provided to the underdrain to overcome the downward force of the driving head in the treatment unit to significantly reduce or prevent liquid present in the treatment unit above the underdrain from moving downwardly into the underdrain.

Embodiments of the present invention relate generally to systems and methods for preventing mineral scale deposits in an aircraft water system, and more specifically, within devices and water transport systems, such as coffeemakers and other galley equipment, as well as the water lines themselves.

The invention provides an apparatus and method for purification of a fluid, the apparatus comprising: a vessel (1) for receiving, in operation, a filter bed (2) with granular filter material; a transport system (8) configured to, during operation, transport filter material from a cavity (5) underneath the filter bed (2) to a location (17) above the filter bed; a fluid inlet (14) for introducing fluid to be purified into the apparatus; a mixing section (3) adapted to, in operation, provide a mixture of fluid from the fluid inlet and granular filter material from the filter bed in a part of the vessel beneath the mixing section; and a plurality of gas lift injectors (4), wherein each gas lift injector (4) is configured to, in operation, transport the mixture of fluid from the fluid inlet (14) and granular filter material from the filter bed (2) to the cavity (5).

A fluid filtration system is disclosed herein. The filtration system includes a main tubular housing defining an interior chamber and having an outlet opening at a top end thereof and an inlet opening at a bottom thereof. A tubular inlet housing extends vertically into the interior chamber of the main housing through the inlet opening of the main housing. The tubular inlet housing has a hollow interior filled with shards of permanent magnets, a plurality of outlet portals located in the interior chamber proximate the bottom of the main housing, and an inlet opening at a bottom thereof. An inlet conduit is connected to the inlet opening of the tubular inlet housing. An adjustable fluid pump and can force the fluid from a supply of fluid to be filtered upwards through the inlet conduit at varying speeds. A permeable but compact horizontal layer of medium capable of trapping particulates is provided in the interior chamber of the main tubular housing adjacent the tubular inlet housing. The layer includes filtering particles that are attached to the magnets. Forces of magnetism produced by the shards of permanent magnets and gravity constrain the horizontal layer of filtering medium to maintain in place the layer of filtering particles. The adjustable fluid pump, an air pump connected to the inlet conduit, or electromagnets or vibrators mounted on an outer surface of the main housing can be used to disrupt the compactness of the layer of filtering particles to permit trapped particulates to be released and washed away from the layer of filtering particles.