AUTOMATIC MONITORING OF DENITRIFICATION RATES AND CAPACITIES IN ACTIVATED-SLUDGE PROCESSES USING FLUORESCENCE OR REDOX POTENTIAL

A novel method is described to automatically estimate several key para meters affecting denitrification in activated sludge processes: the ni trate concentration, the denitrification capacity, and the maximum (su bstrate unlimited) and actual denitrification rates. From these, the c oncentration of active denitrifying microorganisms and the quality of available organic substrate pool can be estimated. Additionally, a mod ification of the method allows the determination of the efficacy of va rious carbon substrates to enhance dentrification, and this can be use d to determine optimal dosing rates of an external carbon source. The method is based on measurements of either fluorescence or redox potent ial (ORP) in an isolated mini-reactor, the Biological Activity Meter ( BAM), situated in the anoxic zone of the wastewater treatment plant. A dvantages of the method are that it is in situ operating at the same t emperature as in the measured anoxic zone, requires no pumps or pipes for mixed liquor sampling, consumes little or no reagents, and uses me asurement signals which are instantaneous and low maintenance, one of which provides a direct measure of biological activity. (C) 1998 Publi shed by Elsevier Science Ltd. AII rights reserved.