GB578383A - Improvements in or relating to water treating apparatus and methods - Google Patents

Abstract

578,383. Purifying water. INFILCO, Inc. Jan. 19, 1944, No. 1054. Convention date, Jan. 7, 1943. [Class 46] In a process for the softening or clarification of water in which raw water and reagent react in the presence of a large body of slurry arising from previous treatment a non-turbulent horizontal flow of slurry is caused to occur at the interface between the clarified water and the top of the body of slurry ; the finer solids are thus washed away from the interface for further aggregation, and the clarification of the water is thus facilitated. As shown in Fig. 2, a treatment tank has a sloping partition 13, whereby a separation zone 16 and an agitation space 14 are formed, the latter - containing a paddle agitator 19 by which the slurry is kept in suspension. Centrally of the tank is a conduit cylinder 42 closed at the top and having radially-extending conduit arms 40 with jet apertures 41, whereby slurry drawn from the lower portion of the separation zone and through the agitation space by an impeller 44 on a quill shaft 45 within the cylinder is forced through the apertures to give a non-turbulent horizontal flow at the level of the interface between the clarified water and the top of the body of slurry. The impeller should give a flow of about twice the through-flow so that the return circulation flow is about equal to the through-flow. The clarified water passes by a weir 27 to a launder 28 and service line 29. Baffle plates 33 are provided to prevent rotational motion in the circulating slurry. Raw water and reagent are supplied by pipes 25, 26 respectively. Sludge is drawn off at pipe 31. In the arrangement shown in Fig. 4 tne agitation space 61 is formed within an upright conical partition member 57, agitator bars 67 being provided additional to the paddle agitator 68, and the non-turbulent horizontal flow at the interface between the clarified water and the top of the slurry is effected by the suction action of a pump 78 which draws liquid through the apertures 76 in the radial conduit arms 75 to deliver it to the top of the agitation space 61 for circulation therethrough to the bottom of the separation zone 62 where it enters by the opening 70 provided with vertical baffles 71. In the arrangement shown in Fig. 6 the non-turbulent flow at the interface between the clarified water and the top of the slurry arises by the circulation flow passing through a continuous slot 135 provided in the partition member 123 the impeller 137 being located adjacent the bottom of the separation zone and arranged for downward flow. The raw water may be introduced into the lower part of the separation zone by a tangential inlet pipe 141 over a horizontal baffle 142.