GB949439A - Treatment of aqueous sludges - Google Patents

Abstract

949,439. Cyclic treatment of sludge. EQUIPEMENTS TECHNIQUES INDUSTRIELS. Aug. 22, 1962, No. 32307/62. Heading B1D. Aqueous sludge introduced at 7 to a primary tank 2, Figs. 3 and 1, is screened at 1, and the resulting sludge with only large solids removed passes out at 10 to a "discriminator" 3 (see also Fig. 4), whence liquid with colloidal solids still in suspension is withdrawn at 11 and liquid with settled solids is withdrawn at 12. Material from line 11 passes directly by line 15 to a biological precipitation device 5, whilst material from line 12 passes to a separating device 4 (preferably a centrifuge), the solids from which are disposed of at 14, and the filtrate from which passes at line 13 to line 15. The mixture from device 5 passes along line 16 to a decantation tank 6 whence pure supernatant liquid is withdrawn at 17 and settled sludge is withdrawn at 18, the major portion of the latter being recycled at 20 to the upstream side of the biological precipitation device 5 and the minor portion being recycled at 19 to the primary tank 2, Fig. 1. Water may be added at 8 to the primary tank 2, Fig. 3, and supernatant from the final decantation tank 6 may be added at 17 via a further tank 32, Fig. 3. The "discriminator" 3, Fig. 1, is shown in detail (with a draining pipe 28 added) in Fig. 4, though the pipe immediately above the axial inlet 26 may be omitted.