Determination of modeled costs at sewage treatment plants in the case of different sequences of treatment

Introduction. The article considers the definition of the key components of operating costs at wastewater treatment plants with a capacity of 1 to 100 thousand cubic meters per day by modeling using specialized software. Materials and methods. In the study, two technological cleaning schemes were investigated — the conventional line-up with biological aeration reactor and secondary clarifier and the scheme of biological aeration reactor with submerged membrane bioreactor for sludge separation. The other structures for the two facilities were identical. Since it was important to obtain results that could be used at real facilities, the values of concentrations of major pollutants typical for urban wastewater before treatment, as well as technological parameters of operation, were used as initial data for calculations. Results. As the results of calculations, the values of concentrations of pollutants in wastewater after treatment using both technological schemes and the values of the required volumes for the arrangement of biological treatment facilities and the area occupied by them were obtained and analyzed. Operating costs were considered in terms of electricity costs for the operation of biological treatment facilities and treatment facilities in General, as well as the specific cost of electricity for treatment 1 m3 of wastewater. In addition, the cost of purchasing membrane modules was calculated, which can be classified as operational due their replacement frequency of approximately every 7–10 years. Conclusions. The results of the study showed that application of membrane technologies at the stage of secondary treatment could have a significant potential for the reconstruction of wastewater treatment plants in conditions of increased productivity and limited opportunities for expanding the area.