SEWAGE TREATMENT METHOD AND SYSTEM

摘要

PROBLEM TO BE SOLVED: To effectively and stably eliminate phosphorus with a little amount of coagulant while keeping high activity of biological treatment.

SOLUTION: This sewage treatment system is provided with: an aerobic tank 24 aerating organic sewage 20 containing phosphorus in the presence of activated sludge; a sedimentation basin 26 separating effluent of the aerobic tank 24 into a primary treated water 32 and the sludge; a sludge drawing pump 40 drawing out a prescribed amount of sludge-mixed water in the aerobic tank 24 so as to obtain a prescribed concentration of the sludge in the aerobic tank 24; a mixing tank 48 for mixing at least a part of the primary treated water 32 discharged from the basin 26 with the sludge-mixed water drawn by the pump 40 and added with the coagulant thereto; and a settler 56 for separating aggregate formed in the mixing tank 48.

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