SINGLE-SLUDGE SYSTEM OF ADVANCED LOW-OXYGEN WASTEWATER TREATMENT WITH NITROGEN COMPOUNDS REMOVAL

Abstract

Introduction. Low-oxygen methods of wastewater treatment have significant potential for further development and reduction of the overall energy costs at sewage treatment plants. When the aeration intensity at aeration stations decreases, the main task is to maintain the system in a stable state where it is necessary to oxidize organic pollutants and ammonia nitrogen. To solve it, it is required to implement a number of additional measures to control the operational parameters of the system simultaneously with a change in the oxygen regime. Methods. The paper addresses systems operating at low concentrations of dissolved oxygen with simultaneous nitrification and denitrification. The authors compared activated sludge performing well with a lack of oxygen with well-aerated nitrifying activated sludge. The study was carried out in a laboratory and at an experimental plant at existing treatment facilities. Results. During the experiment, the influence of increased sludge flow rates in circulation systems on the composition and characteristics of activated sludge at low concentrations of dissolved oxygen was confirmed. Maintenance of high speeds and relatively low specific loads for organic pollutants had a stabilizing effect, and thus reduced the risk of the filamentous swelling of activated sludge. Conclusion. The technology of simultaneous nitrification and denitrification implies the presence of nitrifying and denitrifying biomass in a sufficient amount, working under non-standard conditions. As a result of the study, operational parameters of the system were determined that made it possible to stabilize activated sludge and maintain it in a nitrifying state.