Liquid purification or separation – With gas-liquid surface contact means – With separator
Patent
1993-05-14
1995-02-07
Wyse, Thomas
Liquid purification or separation
With gas-liquid surface contact means
With separator
210194, 210219, C02F 308
Patent
active
053873351
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to improvements in a sewage disposal apparatus employing a buoyant filter system, particularly large buoyant filter media having a diameter of several to ten centimeters or so, which apparatus is suitably employed for purifying a large capacity of water, for example for purifying river water.
BACKGROUND ART
The sewage disposal apparatus employing large filter media has a filter bed formed by an assembly of a multiplicity of buoyant filter media in a septic tank, with aerobic or anaerobic bacteria which are effective for sewage treatment being allowed to proliferate on this filter bed, and sewage is designed to be purified gradually as it is allowed to flow slowly downstream in the septic tank in contact with the filter media in the filter bed.
However, in the prior art sewage disposal apparatus employing large filter media, the filter bed is fixed, so that sludge clogging occurs in each medium or between the media to reduce purifying capacity of the apparatus after a predetermined amount of treatment. In order to eliminate such reduction in the purifying capacity, the filter media in the apparatus must entirely be replaced with new ones or cleaned and the apparatus must be overhauled periodically, leading to great operation cost elevation.
There are other conventional methods which prevent such clogging by employing filter media hard to be clogged or by pretreating sewage to reduce the sludge concentration thereof, followed by treatment of the diluted sewage for final sewage disposal treatment.
However, the conventional method employing pretreatment of sewage requires considerably troublesome work for the pretreatment itself, and all what it can do is to delay clogging. Thus, it is impossible to thoroughly obviate clogging itself, and eventually, the filter media must be replaced with new ones or cleaned periodically, which requires troublesome, heavy work.
Meanwhile, a buoyant, spherical filter medium hard to agglomerate itself with others is disclosed, for example, in Japanese Patent No. 1343032 (Japanese Patent Publication (Kokoku) No. 61-2440). Such contrivance may impart a high level of clogging inhibitory capacity to the medium itself, but it is not sufficient to completely eliminate clogging.
The present invention has been made in view of such problems in the prior art, and it is therefore an object of the invention to provide a sewage disposal apparatus, in which a gentle flow of the filter bed is provided by a circulatory movement of the filter media, while the sewage under purification treatment flowing through the filter bed is adapted not to be affected, or the flakes of sludge coming off from the filter media are prevented from diffusing into the treated water as the filter media are moved, and further the filter media are cleaned by utilizing this circulatory movement thereof whereby to prevent effectively the clogging of the filter medium as well as to constantly enable efficient sewage disposal treatment.
DISCLOSURE OF THE INVENTION
The objects of the invention can be attained by a circulating filter type sewage disposal apparatus having a septic tank containing many buoyant filter media to form a filter bed consisting of an assembly of these filter media, in which sewage is purified by the action of bacteria proliferating on the filter bed as the sewage is allowed to flow downstream in contact with the filter bed in the septic tank, said apparatus comprising:
a filter moving means for returning the filter media to the upstream extremity from the downstream extremity of the septic tank; and
a first current forming means for generating a vortex current and a second current forming means for generating a straight jet stream current, at the upstream extremity of the septic tank;
wherein the filter media separated from the filter bed at the downstream extremity of the septic tank are brought back to the upstream extremity of the septic tank by the filter moving means, while the filter media brought back to the upstream extremity are returned
REFERENCES:
patent: 2071591 (1937-02-01), Tholin
patent: 4055490 (1977-10-01), Hasegawa et al.
patent: 4500429 (1985-02-01), Reimann et al.
patent: 4863606 (1989-09-01), Ryall
patent: 5030353 (1991-07-01), Stuth
patent: 5198105 (1993-03-01), Kauling et al.
Iwai Isamu
Nirasawa Chikatsu
Bednarek Michael D.
Wyse Thomas
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