Abstract: The present inventive concept relates to devices and methods for pressure filtration utilizing spiral wound membranes, in which the volume between the filter membrane and the filter housing is partially or essentially completely filled with an impermeable material. The resulting device permits rapid filtration rates with improved pressure resistance and reduced contamination and microbial growth within the filtration device.

Abstract: Systems and methods are described for flushing one or more filters using a pressurized permeate stream. The permeate stream can be pressurized within a front flush unit, which can also receive a feed water stream. Energy needed to increase the pressure of the permeate stream to a pressure sufficient to cause flushing of the filters can be generated through work exchange with the pressurized feed water stream.

Abstract: A backflush fluid line is configured to provide a backflush fluid, under a pressure, to a filtration membrane of an encapsulated filtration vessel. A control subsystem can be used to assist in determining when the vessel should be backflushed, and a plurality of valves can cooperate to switch between a filtration mode and a backflushing mode. In preferred embodiments the backflush fluid line can be configured to provide at least some of the backflush fluid to the vessel via the permeate port, and debris fluid exits the vessel via the feed fluid inlet port. Three-way valves are preferably used to control the fluid flows.

Abstract: The inventive subject matter provides apparatus, systems and methods in which a feed fluid entering a filtration system is mixed with a portion of a reject fluid. The re-introduced reject fluid is preferably pressurized using a positive displacement pump, and more preferably using a work exchange pump having a translatable piston. The re-introduced reject fluid is preferably pressurized to within 10 psi, or more preferably to within 5 psi, of the uncombined feed fluid. The filtration system can have one or more filters.

Abstract: A sand filter apparatus (10) for treating water includes a filter retention vessel (16) having an outlet (18) from which filtrate can be supplied. An inlet arrangement (48) is in fluid communication with the filter retention vessel and is connectable to a supply of waste water. A filter is interposed between the inlet arrangement and the outlet. The filter includes two layers of aggregate (12, 36) and a layer of sand (26) interposed between the two layers of aggregate. The sand is at least one of, or a mixture of, granite-based sand and substantially pure silica based sand.