Abstract
De composition of organic substances, nitrification and denitrification occur consecutively in a completely mixing type reactor of activated sludge process.
These phenomena were demonstrated by modelling the reaction of microorganisms from the point of view of the chemical thermodynamics. The standard oxidation reduction potentials (ORP) for decompositions of the organic substances are minus at pH 7.0. The ORP for nitrification was 430 mV and that for denitrification was 747 mV at pH 7.0. Then, the organic substances may be sufficiently decomposed under the foregoing ORP level for nitrification. And if the potential of the system is maintained between these two values, both nitrification and denitrification may be occured simultaneously. Thus, the ORP is an important index for the simultaneously proceeding of nitrification and denitrification in a completely mixing type reactor.
