| 摘要 |
PURPOSE: To efficiently treat an oxidizable substance by guiding an aq. electrode soln. from an anode chamber to a cathode chamber when the oxidizable substance in waste water is subjected to oxidation treatment and injecting oxygen into the cathode chamber to keep the concn. of nitric acid in the cathode chamber constant. CONSTITUTION: The waste water in a waste water tank 17 passes through a second washing column 28, the anode soln. circulating tank 22 of a silver recovery device and the anode soln. circulating tank 15 of a nitric acid recovery device to reach the anode soln. circulating tank 4 of an oxidative decomposition device. An anode soln. is guided to an anode chamber 1 by circulating piping 41 to be returned to the anode soln. circulating tank 4. Monovalent silver ions in the anode soln. guided to the anode chamber 1 are converted to divalent silver ions. The greater part of the oxidizable substance contained in the waste water supplied to the anode soln. circulating tank 4 is oxidized and decomposed in the anode chamber 1 and the remainder thereof is oxidized and decomposed in the anode soln. circulating tank 4. Nitric acid in a cathode soln. is reduced to nitrous acid in a cathode chamber 2. Oxygen is supplied to the cathode chamber 2 through piping 47 in order to regenerate nitrous acid formed in the cathode chamber to nitric acid. |
