Concentric cylinder settlement device for water treatment - with right-and left-handed helical spirals in between

摘要

Settlement device, with a round cross-section, is intended for water-treatment plants; it comprises built-up baffle-plate elements through which the water passes before being purified. These elements consists of at least two cylindrical concentric tubes with helical blades arranged between them. The blades make an angle of about 60 degrees with the horizontal; they are delimited in the radial direction by another cylinder, so as to form five separate circulation paths. These paths are swept by slow ascending currents of water charged with solid particles; these descend on the surfaces of the blades by gravity which surmounts the ascensional forces and allows the particles to slide towards the base along the helical surfaces to a collector. The water from which the solids have at least been partially eliminated leave by the top of the device, possibly to undergo a complementary treatment. The helical surfaces, which are only illustrated between two internal cylinders, are alternately right- and left-handed. The cylindrical shape allows the whole of the area of the device to be used as a settling area as compared with existing rectangular tanks; more efficient operation is thus attained. The device can be made from plastic materials e.g. polyethylene or from metals e.g. steel.