Abstract: A method of treating a hollow fiber membrane microfiltration filter having an influent side and an effluent side to improve performance of the filter is disclosed. The method entails sealing imperfections in surfaces of the filter by flushing the filter with a liquid aqueous suspension of particulates. Filter cartridge devices also are disclosed. The devices may include a bactericidal chamber. A radial flow filter may be included in the devices. The filter cartridges may include a drain tube positioned within the filter for removing of effluent generated by the filter. A plurality of filter cartridges may be-positioned-on the drain tube.