Abstract. Non-linear mathematical models of biochemical wastewater treatment with activated sludge are developed. The proposed approach is based on the dynamic models by Monod, Haldane, and Canales, with environment temperature considered as the influencing external factor. The development of biocenosis takes place in a confined space of the reactor under certain technological limitations and assumptions. Dependence of the growth rate of microorganisms on the temperature of the environment is based on the empirical Van't Hoff equation. Results of model calculations are presented for four temperature regimes, change of regime is performed by gradual increase and subsequent decrease in temperature to the set values. The families of graphs of transient processes of substrate and active sludge concentrations under various temperature conditions are demonstrated. Optimal temperature conditions corresponding to the most favorable conditions for the development of biocenosis of activated sludge and providing the most effective purification are determined. The simulation results confirm the sensitivity of the system to temperature changes. The obtained results are recommended to account for in analysis of nitrification and denitrification models, which are characterized by higher dynamic orders, and in design of a control system to improve water quality and reduce the time spent on biological treatment.

Keywords: sewage disposal, activated sludge, models by Monod, Haldane, and Canales, external environment temperature

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