Mathematical simulation of wastewater treatment processes in aeration tanks

Summary

A new version of the mathematical model of wastewater treatment processes in aeration tanks with biological nitrogen removal and biological-chemical phosphorus removal has been developed based on the mutual complementation of the VODGEO/SamGTU and ASM2d methods. The «inverse problem» of technological calculation of aeration tanks has been solved mathematically, i. e. by determining the pollution concentrations in effluent with available data on the qualitative and quantitative composition of the raw wastewater for the specified values of process and design parameters of the facilities. An algorithm for providing quantitative process recommendations has been developed. Following the conducted research, the Potential software was developed designed for the primary acquisition, technological calculations and providing recommendations to the personnel of the treatment facilities. The implementation of the software will reduce the operating costs by optimizing the process flow pattern of the biological wastewater treatment facilities in the shortest possible time.

The study was carried out within the framework of Agreement No. 4951GS1/85526 with the Federal State Budgetary Institution «Foundation for Assistance to Small Innovative Enterprises in Science and Technology».

Key words

wastewater , biological treatment , kinetic constants , mathematic modelling , NII VODGEO/SamGTU methodology , calculation of aeration tanks , ASM2d model , formulas of enzymatic kinetics

Principal risks in designing wastewater treatment facilities. Calculation of aeration tanks (part 1) (for the discussion)

Summary

A detailed calculation of the values of the aerobic age of activated sludge is presented to ensure the required quality of the effluent, both in terms of ammonium nitrogen and nitrite nitrogen, with examples. Similar indicators have been calculated, for the most part, by the Danilovich–Epov empirical method, and on the basis of the calculations it is shown why the Danilovich–Epov method gives underestimated values of the sludge aerobic age. It is shown that calculations of the aeration tank volumes in our country have always (since 1974) been based on the formulas of enzymatic kinetics and, hence, have been theoretical (mathematical) models. Most process engineers in our country have always calculated and still are calculating biological wastewater treatment facilities using the formulas of enzymatic kinetics; therewith, this approach is always the next step compared to empirical models.

Key words

nitrification , sludge age , removal of nitrogen and phosphorus from wastewater , calculation of aeration tanks , ASM model

Results of the mathematical simulation of wastewater treatment processes in aeration tanks at the Samara Municipal Wastewater Treatment Facilities during the upgrade and commissioning

Summary

The results of mathematical simulation of the operation of the existing biological wastewater treatment facilities using POTENTIAL software that was used for 10 months to optimize the operation of aeration tanks during the upgrade and commissioning are presented. The data on the quantitative and qualitative composition of wastewater supplied to the aeration tanks adopted in the project are compared with the actual data for the period 2023–2024. Calculation of the actual values of the growth and aerobic age of the activated sludge using the formulas included into the POTENTIAL software showed that the sustained required quality of the effluent in relation to ammonium and nitrites was observed with an aerobic age of activated sludge of 24.1–27 days and a wastewater temperature of 19.1–24.8°C, provided the concentration of N–NH₄ was less than 1 mg/l, and N–NO2 was less than 0.1 mg/l. As a result of calibration and verification of the mathematical model embedded in POTENTIAL software, the values of kinetic constants and coefficients were selected for a separate process line «aeration tank No. 7 – secondary settling tank No. 5» resulting in predicting the operation of the aeration tanks with a high degree of accuracy (deviations between the calculated and actual data were less than 8%).

Key words

wastewater , kinetic constants , mathematic modelling , NII VODGEO/SamGTU methodology , calculation of aeration tanks , ASM2d model , formulas of enzymatic kinetics , biological removal of nitrogen and phosphorus from wastewater