Simulation of biological wastewater treatment systems
with simultaneous nitri-denitrification using ASM3P-2SND
(for discussion)

Summary

The issues of mathematical simulation of biological wastewater treatment systems with activated sludge based on empirical equations are considered. It is noted that the available approaches to simulation technique have shortcomings that complicate describing biological processes with activated sludge at the facilities with simultaneous nitri-denitrification. An improved mathematical model ASM3P-2SND for municipal wastewater treatment with activated sludge is proposed. This model takes into account in addition the transformations of phosphorus compounds during the activities of autotrophs and heterotrophs, describes the mutual transformations of oxidized forms of nitrogen – nitrates and nitrites; besides, it can also be adapted to consider the diffusion limitations of substrate and oxygen penetration into activated sludge flocs in bioreactors with simultaneous nitri-denitrification. The convergence test, adjustment and calibration of the proposed model were performed at the operating facilities with simultaneous nitri-denitrification, as well as in pilot conditions of wastewater treatment in airlift bioreactors. It was found that the proposed ASM3P-2SND model of activated sludge adequately describes the processes of biological treatment with simultaneous nitri-denitrification and is capable of accounting for the diffusion limitations of oxygen and dissolved substrate penetration into activated sludge flocs. The dependence of the diffusion limitation coefficients proposed for the adaptation of the model on the size of activated sludge flocs was qualitatively established.

Key words

biological treatment , simultaneous nitri-denitrification , activated sludge , simulation modeling , ASM3P-2SND model