| 摘要 |
Sewage treatment plant comprises a concentric arrangement of ring-shaped reservoirs (8-12) forming interlinked anaerobic, contact, anoxic and oxic reactors. A sewage treatment plant comprises a number of concentric reservoirs surrounded by (preferably circular) concentric walls (2-7). A first reservoir is an anaerobic reactor where the sewage is mixed with anoxic sludge, a second reservoir is a contact reactor where the sludge/water mixture from the first reservoir is mixed with returned sludge, and a third reservoir is an anoxic reactor where the sludge/water mixture is mixed with nitrate-rich sludge. A first transport device supplies sewage to the first reactor, an optional second transport device removes phosphate-rich water from the first reactor, a third transport device transfers the sludge/water mixture from the first reactor to the second reactor, a fourth transport device transfers the sludge/water mixture from the second reactor to the third reactor, and a fifth transport device transfers anoxic sludge from the third reactor to the first reactor. A fourth reservoir present within the periphery wall (2) is used as an oxic or aerobic reactor where nitrogen compounds present in the sludge/water mixture from the third reactor are converted into nitrate by aeration. A sixth transport device substantially incorporated into the peripheral wall of the plant transfers the sludge/water mixture from the third reactor to the fourth reactor. An Independent claim is also included for: (1) a second sewage treatment for non-pre-treated effluent, where gases liberated in at least one of the treatment steps are used to contact the liquid mixtures in at least one of these steps; (2) a third sewage treatment plant for non-pre-treated effluent, where gases liberated in at least one of the treatment steps are introduced into the sludge/water mixture so that they become absorbed by the flocked sludge, preferably in at least one aerobic or oxic step; (3) a fourth sewage treatment plant with a main channel (preferably an anaerobic reactor) having an inlet for sewage and two outlets for separated light and heavy components, device for separating the flowing sewage into these components, and an auxiliary channel separated from the main channel by a periphery wall and containing an inlet for the second (lighter) component; (4) a method for treating sewage in the fourth plant, to form sludge and water fractions; (5) a fifth multi-reservoir sewage treatment plant with a concentric arrangement, as in the first plant, where each ring-shaped reservoir is provided with an aeration device and at least one damming device operated independently from the aeration device; and (6) a sixth multi-reservoir sewage treatment plant with a concentric arrangement, where at least one of the ring-shaped reservoirs has its inlet upstream from the outlet.
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