Batch test procedures as tools for calibration of the activated sludge model - a pilot scale demonstration

Abstract

Various mathematical models have been developed to facilitate the design and operation of biological nutrient removal plants. Proper calibration of such models can be a difficult task due to the large number of variable process coefficients. The paper describes a strategy for model calibration based on batch characterizations of wastewater and activated sludge biomass and demonstrates its applicability through modelling of the process dynamics in a highly dynamic activated sludge pilot plant. A comprehensive experimental programme was undertaken comprising batch characterizations of readily degradable and easily hydrolysable COD in influent wastewater, maximum and endogenous process rates for functional microorganism groups in the activated sludge, and half-saturation process constants to describe the impact of oxygen on nitrification and denitrification. An on-line measurement of ammonia and nitrate and nitrite using a Flow Injection Analysis System was conducted for two consecutive days to study the process dynamics in a BioDenitro pilot plant for two parallel activated sludge process tanks. It was possible to closely mimic the dynamics of the nitrogen removal processes in the two tanks based on the model calibration strategy using wastewater and biomass characteristics determined in batch experiments.