抄録
Microelectrode was used to investigate oxygen consumption mechanism in activated sludge. Oxygen fluxes and distributions of oxygen consumption activity were determined from the microprofiles. The spatial distributions of oxygen and nitrate consumption activity were heterogeneous. Under conditions in which oxygen concentration in the bulk liquid was less than 120μM, oxygen consumption activity was high in the outer zone and anoxic zone developed in the center part of the activated sludge. Oxygen consumption activity of the activated sludge was comparable to that of the domestic wastewater biofilm. Distribution of nitrate consumption activity showed that denitrification occurred in the anoxic zone of the activated sludge. Oxygen consumption activity increased as oxygen concentration in the bulk liquid increased, which resulted in increase in oxygen fluxes of the activated sludge. In contrast, when oxygen concentration in the bulk liquid was more than 120μM, oxygen fluxes were unchanged due to limitation of microbial density. Oxygen fluxes at more than 120μM of oxygen in the bulk liquid were lower than those at about 120μM of oxygen.
