BIOLOGICAL TREATMENT METHOD AND BIOLOGICAL TREATMENT DEVICE

摘要

By efficiently carrying out neutralization during the biological treatment of organic wastewater discharged during the manufacturing stage of electronic devices, the present invention uses a smaller amount of neutralizer than conventional biological treatments, in which neutralizers are used excessively, and reduces the amount of inorganic flocculant used in a subsequent flocculation stage and the saline load of reverse osmosis (RO) membrane separation and ion exchange treatment. When organic wastewater discharged during the manufacturing of electronic devices is successively passed through and biologically treated in 2 or more biological treatment tanks including at least 2 aerobic biological treatment tanks, which include a final stage aerobic biological treatment tank, neutralizers are added to the biological treatment tank(s) other than the final stage biological treatment tank such that the M-alkalinity of the liquid in the final stage biological treatment tank is maintained at or below 50 mg/L as CaCO3.