On the discussion on the comparison of methods for calculating aeration tanks with the removal of nitrogen and phosphorus (for the discussion)

Summary

The arguments of the authors of the book «Calculation and process engineering of processes and facilities for the removal of nitrogen and phosphorus from municipal wastewater» are given in response to the critical article by O. V. Khar’kina in the «VST» journal on the method proposed for calculating aeration tanks. Based on the literature review, it is shown that the calculation of aeration tanks in terms of the sludge age is not empirical, however based on the kinetic laws; and, herewith, in the field of application recommended by the authors, the use of a smaller number of empirical coefficients is required eliminating their choice. Explanations are given why accounting for the concentration of dissolved oxygen and calculation for the nitrite nitrogen concentrations less than 0.05 mg/l should not be included in the calculation procedure. Explanations are given for the dependence of kinetic coefficients on the concentrations in the effluent because of the change in the species composition of nitrifiers according to the theory of competitive exclusion of species. Information is provided on the successful comparison of the methods proposed by the authors with the simulation in the GPS-X program and on the operation of a new block of the Liubertsy Wastewater Treatment Facilities (Moscow), calculated according to the method. The operation of the block testifies to the complete sufficiency of the volume of the aerobic zone of the aeration tanks.

Key words

wastewater , biological treatment , nitrification , simulation , sludge age , kinetic coefficients

On the criticism of the NII VODGEO method of designing
biological wastewater treatment facilities with nutrients removal

Summary

The analysis of the critical notes published in the article by Ph. D. (Engineering) D. A. Danilovich and Engineer A. N. Epov «Comparative analysis of the methods of designing biological wastewater treatment facilities with nitrogen removal» in which the opponents make the following statements: the NII VODGEO method is «manual» and simplified, cannot be considered as mathematical model; the specific nitrification rate parameter cannot be used in calculations; the effect of temperature and other factors are not taken into account; «simplified» equations of enzyme kinetics cannot be used for nitrification-denitrification processes because of the inadmissible distortions under the impact of factors that these equations do not take into account; sludge age is determined by the effluent quality regardless of the pollutant concentration in the incoming wastewater; in sludge growth calculations sludge age shall be used; the residual concentration of a substance (in effluent) does not depend on its initial concentration; aeration tank calculations shall be based on sludge age is presented. Based on the detailed analysis of the comments and statements of the opponents their inconsistency and lack of proof is shown. It is proved that not a single substantial fact damaging the NII VODGEO method has been mentioned in the article, and the conclusions made by the authors are unfounded and unsubstantiated. The conclusion is made that the availability of a reliable and approved national calculation method will provide for restricting the unsubstantiated use of inadequate, untested calculation methods; eliminating unjustified construction and upgrade overpricing, uncontrolled engaging of untested foreign inventions in the projects; reducing the level of corruption in this field; implementing correctly the developed best available technologies in domestic practice. It is noted that up to now the calculation method included in SNiP 2.04.03-85 has been the only opportunity for the experts to design and control the facilities for municipal and industrial wastewater biological treatment. Consequently, improving and updating a universal, scientifically grounded and field-proven domestic method of designing the facilities for municipal and industrial wastewater biological treatment with regard to the nutrients removal has been a crucial and pending task. The attention is called to the need of urgent restoration of the expert competency, the revival of the Russian scholarly traditions on the basis of the immense scientific and practical capacity established by our predecessors.

Key words

wastewater , biological treatment , nitrification , denitrification , nutrients removal , sludge age , facilities design

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