PURPOSE: To increase COD removing ratio and to reduce treating cost, by providing a means for adding an electrolyte and a means for controlling the quantity of the electrolyte to be added so that electric current to be applied to an electrostatically treating device has a predetermined value or above.
CONSTITUTION: Waste liquor in a reservoir 1 is fed through pipes 10, 11 to a cartridge filter or a filter 2 packed with a conventional filter medium by means of a pump P1 to remote an SS component. The waste liquor from which the SS component is removed is introduced into an electrostatically treating device 3 wherein its inner tube is negatively electrified and its outer tube is positively electrified by DC to treat electrostatically the liquor. The waste liquor is treated by passing it through a space between the outer tube 22 and the inner tube 23 of the electrostatically treating device. When the electrical conductivity of the waste liquor to be treated is low, an electrostatically treating effect in the electrostatically treating device 3 is low, and hence, the electrostatically treating effect can be improved by increasing the electrical conductivity of the waste liquor by adding an appropriate electrolyte soln. according to the type of the waste liquor.
YOSHIMURA FUMITAKA
INOUE NOBORU
KURITA WATER IND LTD
ZEOTETSUKU ERU AARU SHII KK