Sewage purification installations; Sea water desalination plants; Water filtration and purification units and replacement cartridges and filters therefor; Filter cartridges for industrial dust collection systems for use in pulse-jet cleaning; Water treatment equipment, namely, water filtration units and reverse osmosis units; Water purification, sedimentation and filtration apparatus for clarification, thickening and filtration of water, waste water and industrial water; Filters for fluids, n...