| 摘要 |
796,438. Treating sewage and waste effluents. NEDERLANDSE ORGANISATIE VOOR TOEGEPASTNATUURWETENSCHAPPELIJK ONDERZOEK TEN BEHOEVE VAN DE VOLKSGEZONDHEID. Feb. 3, 1956 [Feb. 7, 1955], No. 3492/56. Class 111. Sewage or the like is supplied at 3 through a sieve 4 to a ring-shaped reservoir 1, Fig. 1, and circulated in the direction of the arrow, and at the same time aerated, by a rotating brush 2. Purified effluent is discharged to open surface water 5. When sewage is supplied discontinuously, openings 11 in a dam wall 6, Fig. 2, are provided, allowing so much water to pass through continuously that no water is discharged over the upper edge of the dam on introducing a fresh charge of sewage into the circuit. The rotating brush 2 may be stopped during such introduction to prevent the discharge of unpurified sewage. An automatic switch device may be provided which periodically stops the rotating brush so that sludge is deposited, subsequently effects discharge of a certain quantity of purified effluent, and then effects supply of an equal quantity of sewage. The last two steps may be modified in that the switch device effects the supply of sewage, by which an equal quantity of purified effluent is discharged. The sludge has a mineral content of at least 30 per cent. Preferably the oxygen content (free and as nitrate) of the mixture in the apparatus is maintained at not less than 3 mg per litre, the sludge (both supplied and formed) is substantially decomposed in a detention time of at least 40 hours, and the BOD (5) reduction is from 90 to 95 per cent. The surface dimensions of the apparatus are such that at least three inhabitant-equivalents of sewage are treated per square metre per day and the capacity is not less than one-and-a-half times the daily supply of sewage. |
