To provide a waste liquid treatment method and a device therefor where, in floatation separation treatment, the phenomenon that suspended solids are largely exhausted into treated water exhausted from a floatation separation tank because of their insufficiency in floating-up is prevented, and the waste liquid treatment method satisfying environmental standards can be performed, and to increase the efficiency of their floatation separation by performing the floatation separation treatment under the conditions in accordance with a waste liquid load.
In the waste liquid treatment method, a waste liquid containing metal substance such as an industrial waste liquid is mixed with a resin having a reduced apparent specific gravity in a mixing tank 1, thereafter, pH regulation is performed in a pH regulation tank 2, so as to insolubilize the metal substance in the mixed waste liquid, subsequently, pressurized water is poured therein, and the insolubilized substance is subjected to floatation separation in a floatation separation tank 3. At this time, in the floatation separation tank 3, the floating-up of the insolubilized substance is assisted by a resin with a reduced specific gravity present in the waste liquid, and the floatation separation can be efficiently performed. Further, suspended solids in the waste liquid after the pressure floating treatment are measured with a suspension gauge 5, and, in accordance with the measured result, in the case the quantity of the suspended solids is large, the apparent specific gravity of the sludge is reduced, e.g., by increasing the quantity of the pressurized water, thus the floatation separation performance thereof is raised.
Fujitsuna Hideyoshi
Osamu Suzawa