Abstract
Biological activity of sludge systems at microscale level is extensively used for effective wastewater treatment. The creation of nature-like artificial ecosystems with a large species diversity is a key point for biocenosis adjusting ability in the municipal wastewater treatment structures. The aim of the study presented is to model at the laboratory scale and to study a stability of active sludge mixed biocenosis physiological state during its aging. The measurements performed using the flow model of aeration tank-mixer with built-in sump.