| 摘要 |
<p>1418203 Treating sewage ATLAS AS 24 April 1973 [28 Aug 1972] 19352/73 Heading B1D [Also in Division Cl] An apparatus for the treatment of domestic and industrial sewage in order to reduce its biological oxygen demand, in which apparatus the sewage is separated by mechanical separating means into a solid phase and a liquid phase and the liquid phase is treated with a chemical precipitant, is characterised in that the mechanical separating means is an inclined strainer (2), the upper edge (3) of which is adjacent a raw sewage inlet and from the lower edge (5) of which a passage (4) to a sump tank (30) leads, the area below the strainer being part of a mixing tank (16) comprising a mixer (8) and dosage means (10) for the chemical precipitant, the lower part of the mixing tank being connected to an inclined, sedimentation tank (19) having an outlet (24) for purified water with pumping means (21) and a connection (28) from the lower part to the sump tank. The strainer is preferably a curved strainer and the mixing tank may be divided into 2 compartments connected through a small opening (15) near the bottom, the first compartment, placed below the strainer, containing the dosage means for the chemical precipitant and the mixer, and the second compartment (16) being connected with the sedimentation tank. An overflow (17) may be provided in the wall (14) between the 2 compartments to deal with peak loadings. In the embodiment shown, which has parallel flow in the sedimentation tank, the second compartment is connected with the sedimentation tank by a channel 18 and the sedimentation tank has inclined baffle plates (27) to improve sedimentation. Air is excluded from the tank by means of an air trap at the top of the tank connected to the pumping means (21). Water under pressure may be supplied by the pumping means (21) to the bottom of the tank (19) at (31) and to the connection (28) at (32) in order to adjust the viscosity of the precipitated matter for easy transfer. In a second embodiment, Figure 2, (not shown), countercurrent flow in the sedimentation tank is obtained by having the tank connected directly to the second compartment (16) and having the top of the tank connected to the pumping means (21).</p> |
