| 摘要 |
PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus capable of suppressing clogging of a membrane used for MBR treatment while suppressing an increase in the amount of sludge.SOLUTION: A wastewater treatment apparatus 1 comprises: a first biological treatment tank 12; a membrane separation biological treatment unit that includes a second biological treatment tank 14 biologically treating first treated water treated in the first biological treatment tank 12, and a membrane separation module 16 separating second treated water, treated in the second biological treatment tank 14, into sludge and third treated water by a separation membrane; and a sludge drawing device (22, 24) that draws the sludge in the second biological treatment tank 14. The sludge drawing device (22, 24) draws the sludge in the second biological treatment tank 14 so that the second biological treatment tank 14 is operated in a soluble-BOD sludge load range of not less than 0.05 kg-BOD/kg-MLSS/d and less than 0.10 kg-BOD/kg-MLSS/d, and then discharges the sludge to the outside of the membrane separation biological treatment unit without returning the sludge to the first biological treatment tank 12.SELECTED DRAWING: Figure 1 |
