Abstract: A filter has a channel layer film defining a channel, a boundary layer mounted to at least a portion of the channel layer film and forming a non-adhesive boundary for the channel, and filter media disposed in fluid communication with the channel. The boundary layer typically includes a non-porous or semipermeable film. The filter is configured and arranged to provide for flow of at least a portion of a fluid along the channel and into the filter media. This filter can be used in a device as a filter over a vent in a housing of the device.

Abstract: An apparatus and method are provided for mixing gas and liquid. An impeller is rotatably mounted inside a draft tube having a constricted section. Rotation of the impeller draws liquid down through the constricted portion of the draft tube. A gas delivery system introduces gas under the surface of the liquid downstream from the constricted portion of the draft tube to entrain the gas in the liquid by a venturi effect. The impeller creates a turbulent gas-liquid mixing zone and also projects liquid radially into the gas as it enters the draft tube. The gas-liquid venturi mixer is particularly suitable for treating industrial and municipal waste water, as well as various other liquids. Gases such as air, oxygen, hydrogen, and the like are efficiently dissolved in such liquids during operation of the gas-liquid venturi mixer.