GB412871A - Sludge digestion apparatus for treating sewage sludge - Google Patents

Abstract

412,871. Treating sewage. MILLS & CO. (ENGINEERS), Ltd., Moss Iron Works, Heywood, Lancashire.-(Assignees of Pruss, M. ; 30, Moltkestrasse, Essen, Germany.) Jan. 17, 1934, No. 1651. Convention date, Feb. 27, 1933. Addition to 412,115. [Class 111.] A sludge digestion tank comprises a floating cover consisting of two or more concentric floating rings b, c, instead of one ring as described in the parent Specification, and with gas covers provided between the rings over the sludge surface. The tank is formed with an outer wall a and a central well f and the bottom has one or more V-shaped channels or grooves. The gases are deflected upwards by ledges k and by screens g covering the gaps between the rings and the walls. The ledges k limit downward movement of the rings. Sludge is introduced by a pipe p and rotary joint r to distributing conduits s. One or two agitators comprising a deflector cone l, pipe i and propeller motor k are suspended from the gas cover. The rings may be rotated horizontally as by a chain or cord and a winder n. Rollers on the cover engage the outside wall of the well f. Heavy chains or flexible scrapers may be dragged round the bottom of the tank to stir the heavy sludge. The sludge is drawn off by pipes u to a well v and thence to a well x and outlet y. Supernatant water is drawn off into the well f and sludge removed therefrom to the well v. After clarification, the supernatant water is drawn off by a floating pipe i<1> to the well v and thence to well x and an outlet. Heating pipes n<1> may be supported from the cover. In one form, Fig. 3 (not shown) three floating rings are provided with four annular channels in the bottom and a sludge draw-off pipe is provided for each channel. The lower ends of the pipes may be elastic or resilient so that they bend when the rings and covers are lowered.