| 摘要 |
1,261,964. Treating sewage. NEPTUNE MICROFLOC Inc. 31 Jan., 1969 [5 Feb., 1968], No. 5425/69. Heading B1D. [Also in Division C1] A sewage treatment plant includes a sewagereceiving and aeration chamber 22, means, e.g. a weir 50, for transfer of solid-depleted effluent from the aeration chamber to a filter chamber 24, and a chamber 28 to receive the filtrate, means, e.g. pipes 58, 60, pump 21 and valve 71, being provided to pass back filtrate from chamber 28 to the filter chamber to effect cleansing of a filter 52. The plant comprises an outer steel container 10 into which the raw sewage is passed via inlet 30 and a bar screen or comminutor 32. An air compressor 34 may supply air to diffusers 38 or mechanical surface aeration devices may be used. A bank of tubes 44 settle out suspended solids from effluent passing to the filter chamber 24 and allow them to slide back into the aeration chamber 22. The filter 52 comprises a bed of three or more materials of different specific gravities and is supported on a perforated plate 54. Filtrate is passed through pipes 58, 60 by a pump 62 into chamber 28, chlorine being injected at 64. Treated filtrate is discharged through an over-flow pipe 66. The flow rate of effluent through filter bed 52 is controlled by a float valve 72 in series with pump 62, the float valve being operated by means, e.g. a float 74, which senses the level of effluent above filter 52. When the level of effluent reaches a predetermined maximum in filter chamber 24, the float 74 operates a switch 77 which shuts off pump 62. An overflow outlet 78 is provided for discharge of excess effluent. Filtrate is passed back by pipes 58, 60 to a point below filter 52 by means of pump 21 and valve 71. Surface cleansing of filter 52 is effected by diverting some of the backwashed filtrate from pipe 60 to a surface wash system 29 via a pipe 27. Material dislodged from filter 52 flows into a sludge storage chamber 26 through line 23 and a valve 79 closes weir 50 to prevent entry of backwashed filtrate to the aeration chamber 22. Liquid displaced from the sludge storage chamber 26 is transferred to the aeration chamber 22 through a baffled decant pipe 25. Return of filtrate to the filter. chamber 24 may be initiated at set intervals or automatically by pressure sensors 81, 82 or a filtrate turbidity meter 84. A float 80 in chamber 28 operates a switch 76 to shut off pump 21 when the level of liquid in chamber 28 falls to a minimum. Scum &c floating above tubes 44 may be transferred to aeration tank 22 through pipes 51, 55 and air lift pump 53. An air lift pump 90 pumps excess sludge from aeration chamber 22 into sludge storage chamber 26 via pipe 92. |
