MEASUREMENT OF CHEMICAL OXYGEN DEMAND BY OZONE OXIDATION

摘要

PURPOSE:To measure a chemical oxygen demand quickly with a high reliability by measuring an oxygen consumption speed in the ozone oxidation of a sample water to determine the oxidation end time at which the oxidation rate attain the intended value from change in the speed with passage of time. CONSTITUTION:A sample water is sent to an O3 reaction tank 1 from a sample water feed/drain mechanism 7 while atmospheric air passing through a dehumidifier 3 is fed to an O3 generator 2 and O3 generated sent to the reaction tank 1. Immediately after the sending of O3, gas from the reation tank 1 is sent to an oxygen meter 6 passing through an O3 decomposition catalyst layer 5 from a dehumidifier 4 while a part of the air from the dehumidifier 3 is sent to the oxygen meter 6 to measure an O2 consumption speed Q due to a pollutant in the sample water based on the difference of the O2 concentration in the gas from the air and the layer 5 and the maximum speed Qm is entered into a hold circuit 8. When the coefficient beta (in the range of about 1 down to 0.3) predetermined from the speed Qm reaches the O2 consumption speed betaQm, a pulse signal is sent to a sample hold circuit 12 by a signal from a multiplier 9 to find an O2 consumption CODO3 up to the speed betaQm with integration circuit 11. This enables the online analysis of water quality within the measurable range of 1hr.