An improved cartridge, typically in cylindrical or panel form that can be used in a dry or wet/dry vacuum cleaner. The cartridge is cleanable using a stream of service water, or by rapping on a solid object, or by using a compressed gas stream, but can provide exceptional filtering properties even for submicron particulate in the household or industrial environment. The cartridge has a combination of nanofiber filtration layer on a substrate. The nanofiber and substrate are engineered to obtain a maximum efficiency at reasonable pressure drop and permeability. The improved cartridge constitutes at least a substrate material and at least a layer including a non-woven, fine fiber separation layer.