FLUORESCENCE MONITORING OF AN ALTERNATING ACTIVATED-SLUDGE PROCESS

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