Science for beginners . of merely running the sewage over the bedand allowing it to soak into the bed, the sewage is under some8 or 10 feet of head , the sewage in the dosing tank is8 or 10 ft. above the level of the sprinkler, and is allowed topass through sprinklers which throws the sewage into theair in a fine spray just as a garden sprinkler throws a fine 448 WATER SUPPLY AND SEWAGE DISPOSAL spray of water upon the lawn. This fine spray of sewageabsorbs oxygen from the air until it is saturated. 527. The Activated Sludge Process.—The activatedsludge process is a method of sewage dispos
Science for beginners . of merely running the sewage over the bedand allowing it to soak into the bed, the sewage is under some8 or 10 feet of head , the sewage in the dosing tank is8 or 10 ft. above the level of the sprinkler, and is allowed topass through sprinklers which throws the sewage into theair in a fine spray just as a garden sprinkler throws a fine 448 WATER SUPPLY AND SEWAGE DISPOSAL spray of water upon the lawn. This fine spray of sewageabsorbs oxygen from the air until it is saturated. 527. The Activated Sludge Process.—The activatedsludge process is a method of sewage disposal which is justcoming into use if necessary. It is a still more rapid processof changing the organic matter in sewage to mineral matterthrough the action of aerobic bacteria. In the activated sludge process much less land is requiredfor the plant. The original cost of the plant is less than itis when the Imhoff tank and either a contact filter or asprinkling filter is used. It costs more to operate the plant, ^—u .Fresh Sewage u aP SIudgel-pcLPump I -t^~ Aeration Tank ^?s Porous Plates in Bottom Aeration Tank I Effluent flows over top of the Fig. 274.—Diagram of an Activated Sludge Tank. Upper portion iscornering view in perspective; lower portion is the top plan. The activated sludge process is easily understood. Theequipment consists of a concrete tank, often a hundred feetor more in length and perhaps 10 or 12 feet wide and about 8or 10 feet deep. In the bottom of this long tank porous platesare placed above a passage through which air is pumped. DISPOSAL OF SEWAGE 449 Fresh sewage, however,The name of this process,from the fact that about Fresh Sewage 1 - Jf Sludge Pump Sludge, from Settling Tank Fig. 274A.—View of the leftend of the activated sludgetank. The air passes up through the porous plates in very numerousand small bubbles which rise through the sewage. The sew-age, as it passes along through the tank appears to be boilingviolently, on account of
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscience, bookyear1921
