GB782357A - Improvements in or relating to scraping and scumming apparatus for sedimentation tanks - Google Patents

Abstract

782,357. Treatment of sewage &c. AMES CROSTA MILLS & CO., Ltd. March 15, 1955 [March 17, 1954], No. 7708/54. Class 111. In scraping and scumming apparatus for sedimentation tanks of the kind in which a floor scraper and a scum-sweep are carried by levers pivoted beneath a carriage which spans the tank and is adapted for self-propulsion longitudinally thereof, the apparatus in one direction urging sludge and scum into receivers and being raised clear of the floor and liquid surface in the other direction, the floor scraper is mounted upon the lower arms of submerged rocking levers together with one or more buoyancy chambers, one or more additional chambers being carried by the upper arms of the levers and ballasting liquid being transferable between the upper and lower chambers to depress or raise the scrapers. Longitudinal rails 14 sup. port a transverse wheeled carriage 12 on which is mounted an electric driving motor adapted, through limit switches to traverse the carriage over the length of the tank 5. Four spaced triangular frames 28 depend from the carriage to support the tubular frames 32 of rubberedged scrapers 35 which are pivoted to the frame 28 at 30. At top and bottom, the scraper frames carry buoyancy tanks 34, 33 interconnected by the tubes of the frame and connected through compressed-air lines 44, 43 to a control valve and compressor mounted on the carriage 12. One tank is filled with liquid to depress its end of the pivoted frame 32, the compressed air being directed by the control valve to transfer the liquid from the tank 33 to the tank 34 or vice versa, a neutral position of the valve locking the liquid in the filled tank. Normally the frame 50 of a scum-sweep 49 rests in its operative position on a bracket 52 on the depending frame 28 : the frame is pivoted at 51 and partly counterbalanced by a bracing 53 connected by a slack chain 54 to the top buoyancy tank 34 so that movement of the scrapers to their inoperative position lifts the sweeps to their like position. The sedimentaiton tank 5 has a collecting pit 9 at its inlet end and a floor sloping downwards thereto.