FLUORESCENCE MONITORING OF AN ALTERNATING ACTIVATED-SLUDGE PROCESS

The fluoresence of a nitrification/denitrification tank in an activated sludge nutrient removal process was monitored over a two month period. The process employs an alternating mode of operation which subjects the sludge to a periodically changing environment (aerobic, anoxic and anaerobic) at the point in the process where the fluoresence is measured. The fluoresence signal decreased slowly during aerated periods and increased slowly during anoxic (denitrifying) periods. An abrupt rise in the fluoresence signal was found to occur upon the transition from anoxic to anaerobic conditions. The minimum fluoresence signal occurring during each operation cycle appeared to define a baseline whose general upward and downward movements correlated well with peak oxygen uptake rate,