GB773124A - Combined anaerobic treatment and clarification unit - Google Patents

Abstract

773,124. Digestion apparatus; gravityseparation apparatus. DORR-OLIVER, Inc. Sept. 15, 1955, No. 26415/55. Class 111. Sewage or industrial waste is introduced e.g. at 15 to an anaerobic digestion compartment 20 and displaces therefrom a quantity of relatively solids-free liquid through a pipe 21 to the feedwell 23 of a superimposed clarifying compartment 24, whence clarified effluent emerges at 27 and sludge is scraped back into the digestion compartment through a boot 45 and past a rotating closure plate 46. Some gas formed in the digestion compartment collects under the partition wall 12, thus forming a thermal seal, the remainder thereafter collecting in a gas chamber 53. Gas is prevented from rising into the clarifying compartment by overlapping of the upturned edge of plate 46 and the lower edge of boot 45, and upward liquid flow at this location is prevented by the downward flow of solids. Scum in the digestion compartment is broken up by inter-engagement of rotating blades 39 with fixed blades 40. Sludge in the bottom of the digestion compartment is circulated mainly towards a well 19 by scrapers 32, whence it is withdrawn at 35. Influent may alternatively be introduced to the well 19 by pipe 17 instead of at 15, in which case sludge is withdrawn at 33. Mixing of the influent with the digestion compartment contents is assisted by the rotation of scraper arms 30, blades 32 and supporting truss 31. The effluent may pass to a sand filter (not shown), which, as a result of the above process, has no tendency to clogging or ponding, even when the influent contains grease, soap and detergent solids.