Modelling of Nutrient Removal Processes in an Intermittently Aerated Bioreactor

J. Derco, M. Králik and A. Kovács

Abstract
The general IAWPRC kinetics extended by volatilisation and the influence of wastewater composition on oxygen transport rate was used for description of lab-scale experiments simulating a Carrousel industrial reactor. Number of model equations and parameters were reduced by introduction of “switching functions”, which express proportions of the reactor volume with different biochemical conditions. Majority of values of model parameters estimated for an industrial wastewater were close to those published in literature for municipal wastewater, except the hydrolysis rate constant of slowly biodegradable COD which was found significantly lower: 0.12 comparing to 3 g (g cell COD)–1. The lower value was estimated due to the exploitation of a more precise model involving evaporation of volatile compounds. A strong inhibition effect of cadmium (II) salts was reflected by more than tenfold decrease in maximum growth rates of autotrophs and the rate constant of ammonia removal.

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Keywords
Biokinetic parameter values, cadmium effect on biological processes, experimental and mathematical modelling, industrial wastewater treatment, intermittently aerated completely mixed activated sludge reactor, simultaneous nitrification and denitrification processes, volatilisation process