Comparison of the results of calculating aeration tanks according to the method of Danilovich–Epov and ASM2d model (part 1)

Summary

The analysis of the method proposed by D. A. Danilovich and A. N. Epov for calculating aeration tanks that implement nitrogen and phosphorus removal technologies is carried out. A comparison of the results of calculations by this method and ASM2d method is given. It is shown that, in contrast to the ASM2d method that refers to theoretical models and describes the processes of biological wastewater treatment using the formulas of enzyme kinetics, the method under consideration is, in essence, an empirical calculation that contains constants that are invariable and, for the most part, not having the physical meaning. Since empirical models make a connection between the parameters obtained on the basis of the experimental data of a particular object under strictly limited conditions, these models can only be applied if all the parameters of another object exactly match the data of the object the proposed model was compiled for. Accordingly, using any empiric models, including the method under consideration, at the facilities that were not the objects for the compilation of these empiric models, leads to the risk of obtaining incorrect calculation results. Based on the performed calculations, the risks and constraints of using the method proposed by Danilovich and Epov for the calculation of biological treatment facilities are shown. In the first part of the paper, a design analysis was carried out to determine the values of the aerobic age of activated sludge that were the basic values for calculating the volume of aerobic zones of aeration tanks.

Key words

wastewater , biological treatment , nitrification , denitrification , activated sludge , kinetic constants , theoretical and empirical mathematical models , comparative calculation of the biological treatment facilities , ASM2d

DOI 10.35776/VST.2022.11.03
UDC 628.35

Kharkina O. V.

Comparison of the results of calculating aeration tanks according to the method of Danilovich–Epov and ASM2d model
(рart 2)

Summary

The analysis of the method for calculating aeration tanks proposed by D. A. Danilovich and A. N. Epov, based on the German ATV method, is continued. Due to certain limitations of the empirical ATV methodology developed on the basis of the data on the wastewater the authors were able to study, the ATV methodology cannot be applied anywhere except the treatment facilities where those studies were carried out. The Methodology has been compared with ASM2d model (a matrix of enzyme kinetics equations describing the growth rates of microorganisms and the rates of the corresponding biochemical processes), as well as with the NII VODGEO/SamGTU method that is a completely theoretical model, and the calculation formulas being enzyme kinetics equations. Calculations of aeration tanks according to the formulas of enzyme kinetics were laid down in SNiP «Sewerage. External Networks and Structures» in 1974; whereas in SNiP 1984, the calculation was given in the form of a proven methodology for biological treatment facilities for the oxidation of organic compounds. The empirical approach proposed in the Methodology opens not only a technological question about the scope of its application, but also the question of its expediency in general. The use of empirical approaches, to which the Methodology belongs, formally connects the inherent parameters in the form of invariable coefficients and empirical dependencies obtained experimentally in a narrow range of parameters and conditions of a particular object bringing the risks of significant errors. It is shown that the Methodology for municipal wastewater provides for underestimated volumes of aeration tanks by tens of percent compared with the results of calculations using the theoretical methods ASM2d and VODGEO/SamGTU developed by V. N. Shvetsov, S. V. Stepanov, K. M. Morozova that describe wastewater treatment processes using enzyme kinetics formulas. Herewith, it is shown that ASM2d and the VODGEO/SamGTU methodology give a high convergence of the results within differences of less than 10% which allows to speak about the robustness of the ASM2d model and the VODGEO/SamGTU methodology, and the limitations of the Method that can be used only for rough estimates.

Key words

wastewater , biological treatment , nitrification , denitrification , activated sludge , kinetic constants , theoretical and empirical mathematical models , ASM2d , NII VODGEO/SamGTU methodology , enzyme kinetics equations , comparative calculation

DOI 10.35776/VST.2021.05.02
UDC 628.35

SHVETSOV V. N., Kharkina O. V., Stepanov S. V.

Comparison of the calculation results for aeration tanks using the NII VODGEO/SamGTU and ASM2d models

Summary

Проведено сравнение результатов расчета аэротенков, реализующих процессы аэробного окисления органических соединений, нитрификации, денитрификации и удаления фосфора (химического и биологического) по двум различным математическим моделям (методикам): ВОДГЕО/СамГТУ (Самарского государственного технического уни-
The paper presents a comparison of the results of calculating aeration tanks where the processes of aerobic oxidation of organic compounds, nitrification, denitrification and phosphorus removal (chemical and biological) according to two different mathematical models (methods): VODGEO/SamGTU (Samara State Technical University) and ASM2d have been implemented. These models are theoretical and describe the processes of biological wastewater treatment using enzymatic kinetics formulas. Calculations for the same input and output data showed a high reproducibility in terms of the volumes of the process zones of aeration tanks. For the quality of effluent meeting the MPCs for fishery water bodies (option 1), the discrepancy is –0.3 and 3.3%, respectively, for the anoxid and aerobic zones. With indicators for effluent discharge into a water body of category B (option 2) for large-scale to extremely large-scale facilities, the difference in the results of calculating the volumes was 13.8 and 15.4%, respectively. While making calculations with account of the effluent quality reaching the process indicators for discharge into a water body of category G (option 3) for large-scale to extremely large-scale facilities, the discrepancy in the values of the volumes of aerobic zones was 48% owing to the expediency of ensuring stable nitrification at high loads. Therefore, option 3 according to the VODGEO/SamGTU method was actually performed for a lower sludge load and more enhanced nitrification than according to the ASM2d method (1 instead of 2 mgN–NH₄/l). It is shown that the mathematical models underlying both methods, based on the fundamental equations of the enzymatic reaction, a very high reproducibility and consistency of the calculation results give grounds to assert that both of these models are, to the greatest extent known, acceptable for calculating biological treatment facilities with the removal of nitrogen and phosphorus.

Key words

biological treatment , nitrification , denitrification , activated sludge , kinetic constants , industrial and municipal wastewater , VODGEO/SamGTU and ASM2d process calculation methods , theoretical and empirical mathematical models , comparative calculation of the biological treatment facilities

DOI 10.35776/VST.2022.09.04
UDC 628.35

Kevbrina M. V., Dorofeev A. G., Agarev Anton

Comparison of the results of calculating aeration tanks according to different methods (for discussion)

Summary

The calculation results are compared according to the method described in the book by D. A. Danilovich and A. N. Epov «Calculation and technological design of processes and facilities for the removal of nitrogen and phosphorus from municipal wastewater», and the method given in the book «Wastewater technology. Processing and recovery of resources» (fifth edition, Metcalf & Addy), in a model unit, for which earlier in the article by V. N. Shvetsov, S. V. Stepanov and O. V. Khar’kina «Comparison of the calculation results for aeration tanks using the NII VODGEO/SamGTU and ASM2d models» calculations had been made according to the method of NII VODGEO/SamGTU and following the model developed by ASM2d. It is shown that calculations based on the equations of enzymatic kinetics and microbial growth (NII VODGEO/SamGTU, ASM2d and Metcalf & Addy) give similar results in terms of the volume of aeration tanks with the «tabular» method based on the German standard ATV-DVWK-A131E and revised taking into account the growth kinetics of nitrifying microorganisms. The difference in approaches gives different results as for the age of activated sludge; however, the final results of the volumes of aeration tanks and zones in them have discrepancies that do not exceed 15–20%. Simulation of the operation of aeration tanks in BioWin-3 program, designed on ASDM model that is essentially close to the ASM group of activated sludge models, with zone volumes calculated using different methods, showed a similar calculated quality of effluent. This confirms the possibility of any of the considered methods to adequately calculate the volumes of aeration tanks. The choice of the calculation method for each specific case depends on the availability and ease of use of the methodology, as well as on the personal preferences of the designer.

Key words

nitrification , denitrification , aeration tank , wastewater biological treatment , anaerobic zone , theoretical and empirical mathematical models , comparative calculation of the biological treatment facilities , technological calculation methods , anoxic zone