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UDC 628.35

SHVETSOV V. N., MOROZOVA K. M., Stepanov S. V.

Designing facilities for municipal and industrial wastewater biological treatment in aeration tanks with nutrients removal

Summary

Biological treatment facilities are the basic facilities for the purification of domestic, municipal and industrial wastewater of most of the industries (chemical, petrochemical, oil refining, food, textile, consumer goods, coke-chemical industries, agriculture etc.). However until now there has been no scientifically-grounded method of designing wastewater biological treatment facilities with nitrogen and phosphorus removal in the Russian Federation. Many years of extensive research carried out by NII VODGEO and «Water Supply and Wastewater Disposal» chair of the Samara State Technical University at the laboratory and pilot plants, at the operating facilities with processing data bulks provided for developing an adequate method of designing aeration tanks with nutrients removal. The presented method is a supplement of the method of process design of biological treatment facilities stated in SNiP 2.04.03-85 with regard to designing aeration tanks with nitri-denitrification and biological phosphorus removal; and provides for the calculations of upgrade and new construction of the facilities for biological treatment of municipal, domestic and industrial wastewater. Behind the process design is the concept of the process description with enzyme kinetics equations. The method includes the following stages: substantiation of the relevant basic data on the flow rates and qualitative composition of wastewater; determination of the process flow scheme and burden balance calculation of all the critical pollution components; determination of the kinetic constants and coefficients of enzyme kinetics equations of the transformation of each basic pollution component (BOD, nitrogen compounds, phosphorus etc.) and activated sludge growth by the statistical analysis of the operation data and chemico-analytical analysis of wastewater samples of the operating treatment facilities, by experimental data or on the basis of the available analogies; calculation of the volume of all the elements of the facilities with determination of the limitative component and treatment level in relation to other pollutants; final correction of the vo­lumes and parameters of all the process zones with account of the requirements to the level of treatment in relation to all the dictating pollution components. An example of the calculation is set. It is noted that the computation algorithm and formulas included into the method provide for designing any complicated process flow schemes with nitrogen and phosphorus removal applied both to municipal and industrial wastewater. The method provides for calculating not only the rate of removing BOD and nitrogen compounds but also other certain pollution components (oil products, detergents, fats etc.) offering additional opportunities of the wastewater biological treatment method. The method is especially useful in designing industrial wastewater biological treatment facilities because most of the foreign methods are mainly focused on the purification of domestic and municipal wastewater to the concentrations adopted in those countries. The method is developed on the principle of essential sufficiency; however is contains 70 design parameters and 28 formulas and equations. Accordingly the calculations are performed in Microsoft Office Excel which makes it possible for users even with middle software skills. Herewith it is possible to perform calculations straight for several options interactively and/or upgrade the treatment facilities in the process of their operation.

key words

biological treatment , nitrification , denitrification , nitrogen , phosphorous , activated sludge , kinetic constants , process design method , industrial and municipal wastewater

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UDC 628.35:661.5

SHVETSOV V. N., MOROZOVA K. M.

Procedure of designing wastewater biological treatment facilities
with nutrients removal

Summary

The procedure of designing wastewater biological treatment facilities with nitrification-denitrification is presented. Biological treatment facilities shall be designed on the basis of experimentally determined kinetic constants, nitrification and denitrification process factors, and for every limiting value depending on the requirements to the quality of treatment. Kinetic constants and factors required for designing municipal wastewater treatment facilities are given. Design algorithm is set out including the following stages: substantiation of the initial data on flow rates and qualitative wastewater composition according to the required level of reliability (more than 85–90% probability); selection of the process flow scheme – number of steps and(or) stages, operation procedure and lay out; determination of kinetic constants of equations of enzyme kinetics of every basic pollution component transformation from experimental data or from the available data base; preliminary calculation of excess activated sludge volume and adjustment of nitrogen and phosphorus mass balance; determination of limiting pollution component that needs maximum time to be oxidized; calculation of the facility capacity by limiting component with determination of the treatment level for other pollution components. The results of the long-term experimental studies of nitrification-denitrification processes with different types of municipal and industrial wastewater provide for supplementing the method of aeration tank design specified in SNiP 2.04.03-85 with formulae and data for design and optimization of aeration tank operation with nitrogen and phosphorus removal.

Key words

wastewater , biological treatment , nitrification , activated sludge , kinetic constants , denitrification

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UDC 628.35:661.5/.63.001.2

SHVETSOV V. N., MOROZOVA K. M., Domnin K. V., Arkhipova Elena

Designing nitrification-denitrification retrofit at the biological treatment facilities

Summary

The results of studies carried out at the Khabarovsk wastewater treatment facilities are presented. The developed process flow sheet of wastewater biological treatment included nitrification-denitrification processes to eliminate nitrogen compounds according to the set standards. The process flow sheet provided for retrofitting dephosphatation zone to ensure maximum level of phosphorus removal at the biological treatment stage in order to reduce chemical consumption at the subsequent treatment stages. The process design of the biological treatment facilities was carried out.

Key words

treatment facilities , wastewater , nitrification , dephosphatization , activated sludge , denitrification

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UDC 628.35

Mishukov B. G., Murashev S. V.

Calculation of low-capacity plants with membrane filtration  for biological wastewater treatment

Summary

The calculation of standard series of plants for biological treatment of wastewater is set. The plants include a fermentation settling tank and a membrane bioreactor. The method has been approbated for calculating the plants with a capacity less than 500 m³/day. It was determined that increasing the activated sludge dosage from 3 to 5 g/l provided for 1.5 reduction of the size of the treatment facilities; at that increasing the activated sludge dosage more than 3-fold (more than 8 g/l was inexpedient. The size of the plants for 3 and 5 g/l activated sludge dosages with account of 25% volume increase (with correction for reliability) is given. The use of the suggested process flow scheme provides for increasing the efficiency of wastewater treatment. The effluent quality parameters approach the maximum permissible sanitary-hygienic regulations for the discharge into fishery water bodies. At that the use of chemicals for nutrients removal is not foreseen. The use of membrane filtration provides for equalizing and enhancing biological processes by means of possible increase of activated sludge concentration, and also for reducing the size of the plant, increasing the efficiency of wastewater treatment by means of enhanced removal of suspended solids.

Key words

wastewater , biological treatment , nitrification , denitrification , membrane filtration , dephosphorization

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UDC 628.35

Dubovik Ol’ga, Markevich R. M., Antonov K. V.

Improvement of biological removal of nitrogen and phosphorus compounds from wastewater under the conditions of cascade denitrification

Summary

In view of ever toughening requirements to wastewater treatment the optimization and intensification of wastewater treatment facilities operation become priority areas. The flow process scheme of wastewater biological treatment at the Minsk Wastewater Treatment Plant is represented by traditional aeration tanks and aeration tanks with organized cascade denitrification scheme. The main component of this scheme is the lack of inner recycle and possibility of dispersed inflow of clarified wastewater over the aeration tank zones. This provides for the presence of easily oxidizable organic substances in every anoxic zone. In view of building-up of pollutants in incoming wastewater and toughening the requirements to their removal the intensification of the biological stage has been an important aspect of the treatment facilities operation. The research objective was the scheme of cascade denitrification at the operating treatment facilities for the optimization of which different options of clarified wastewater distribution over the aeration tank zones were used. Wastewater entering the cascade denitrification is characterized by insufficient quantity of organic substances because a significant amount of industrial wastes. To increase the amount of organic substances it was decided to take out of service the primary settling tank and to reduce the frequency of sludge removal. The chosen optimal distribution of clarified wastewater over the aeration tank zones and increase of organic loading the efficiency of phosphate removal increased from 60 to 70%; and that of nitrogen removal – from 61 to 67%.

Key words

wastewater , biological treatment , nitrification , activated sludge , nutrients removal , cascade denitrification

DOI 10/35776/MNP.2019.09.08
UDC 628.353:661.5

Iantsen O. V.

Advanced solutions for the reconstruction of small-scale wastewater treatment facilities: design and calculation

Summary

The advanced solutions proposed for the reconstruction of small wastewater treatment facilities that contain biofilters are considered. The peakpoint of designing and constructing biofilters occurred in the 1960–1970s. At present biological filters are often used for wastewater treatment. It is proposed to use them again as the basic treatment facilities. These structures, as a rule, are structurally reinforced concrete tanks; so it is advisable to develop new process flow schemes taking into account the use of existing structures. Three process flow schemes with different combinations of nitrification and denitrification zones are considered. Graphic results of sanitary and technical analyses of a number of indicators are presented on the basis of which sufficient purification efficiency is shown that allows discharging effluents into fishery water bodies. A method for calculating biofilters for specific media materials is proposed. It is concluded that the height of the structure depends not only on the required level of purification, the parameters of the incoming water but also on the type and size of the media material. The proposed process flow schemes will provide for the wider use of biofilters both in the reconstruction of existing and in the design of new treatment facilities.

Key words

reconstruction , wastewater , nitrification , biofilter , ammonia nitrogen , denitrification , biofilm , enhanced wastewater treatment , small-scale wastewater treatment facilities

DOI 10.35776/VST.2021.07.03
УДК 628.35

Kharkina O. V., Iskalieva Karina, Malich Ekaterina

Comparison of aeration tank calculations using ASM2d and ATV models

Summary

A comparison is made of the results of calculating aeration tanks by ATV model (Standard ATV-DVWK-A131 E «Dimension of Single-Stage Activated Sludge Plants 2000»), that is a stochastic «table» model, and by ASM2d model, that is referred to as theoretical and describes, unlike ATV, biological wastewater treatment processes using enzymatic kinetics formulas. Calculations are performed for the same input data. The calculation results show essentially limited use of ATV model; this model, as originally given in the description of this model by the designers, provides for calculating aeration tanks only for a single value of the effluent quality in terms of ammonia nitrogen as 1 mg/l and does not provide for calculating aeration tanks in terms of nitrites. Moreover, the comparison of ATV and ASM2d show that achieving the specified quality of effluent in terms of ammonia nitrogen as 1 mg/l is possible only at specific values of the kinetic constants determined by the authors in this article; whereas, any change in at least one kinetic parameter of the wastewater results in an increase in the required aerobic age of activated sludge and, as a consequence, in the calculated volume of the aerobic zone by tens of percent, which proves the risk of not achieving the required effluent quality while using ATV model even for ammonium nitrogen concentration of 1 mg/l. Taking into account the fact that ATV Method does not provide for calculating aeration tanks for the effluent quality in terms of nitrites, the results of our calculation show that the aerobic age of activated sludge of 4.05 days for a temperature of 17 ºС proposed in ATV will make it possible to achieve the effluent quality in terms of nitrite nitrogen, 0.35–0.52 mg/l N–NO2, proving the unavailability of ATV, if the requirements to the effluent quality in terms of nitrites are specified. The authors, on the basis of the calculations, make conclusions about the risk of failure to achieve the effluent quality in terms of ammonia nitrogen as well as 1 mg/l while using ATV, because ATV is a stochastic model, that is, all dependencies presented in this method have been determined for the specific operating conditions. Moreover, as specified in the ATV description, this method, even in limited conditions, is applicable strictly for urban wastewater. The calculations show that if there are requirements for the effluent quality in terms of nitrites, regardless of the required concentration value of nitrites, the ATV method is absolutely not suitable, while ASM2d, taking into account the fact that it is based on the formulas of enzymatic kinetics, provides for calculating aeration tanks for any required effluent quality in terms of both ammonium nitrogen and nitrite nitrogen and is applicable for any type of wastewater.

Key words

biological treatment , nitrification , activated sludge , kinetic constants , industrial and municipal wastewater , comparative calculation of the biological treatment facilities , ATV and ASM2d process calculation methods , aerobic age of activated sludge , theoretical and stochastic models

DOI 10.35776/VST.2022.05.03
UDC 628.35

Kharkina O. V.

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

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UDC 628.35:661.635

Ambrosova G. T., Funk A. A., Ivanova Sargylana Dmitrievna, Ganzorig Shonkhor

Comparative evaluation of the methods of phosphorus removal from wastewater

Summary

The evaluation of the methods of eliminating phosphorus, a most important nutrient that is a limiting element in water body eutrophication, from wastewater is presented. Biological, physical, chemical and combined methods are considered that differ from each other in the method of implementation, construction and operating expenditures. The biological method is based on phosphorus removal through its utilization in biomass synthesis in the biological system. Physical and chemical methods suppose mandatory application of chemicals used for free phosphate-ion binding to low soluble ortho-phosphate. Combined methods suppose dephosphorization at the biological treatment stage with subsequent inclusion of phosphate-ions into crystals at the physical and chemical treatment stage. The examples of practical implementation of the methods are presented; process flow schemes are considered; the process parameters of the treatment facilities are pointed out where the process of phosphorus removal is taking place; the data on the process efficiency is provided; the advantages and drawbacks of the applied methods are reported. The experience of adjustment works is described together with the results of experimental selection of chemicals for phosphorus binding and determination of the optimal point of their addition carried out by the authors in the laboratory, during pilot and full-scale studies.

Key words

filter , nitrification , bioreactor , reagent , aeration tank , denitrification , nutrient , wastewater , crystal , dephosphorization , effluent polishing , sludge growth

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UDC 628.35:661.5

Lominoga O. A., Agapov D. V., Bol'shakov N. Yu.

The technology of biological wastewater treatment with nitrification-denitrification at the Zelenogorsk wastewater treatment facilities

Summary

The results of introducing the technology of biological wastewater treatment with the use of nitrification-denitrification processes in the «aeration tank-secondary settling tank» system at the Zelenogorsk wastewater treatment facilities are presented. It is shown that the use of nitrification-denitrification enhance significantly the efficiency of nitrogen removal. The findings allow recommending the suggested technical solution for the introduction at other municipal wastewater treatment facilities.

Key words

aeration , nitrification , nitri-denitrification , aeration tank , ammonia nitrogen , denitrification , organic substances , nitrate nitrogen , total nitrogen

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UDC 628.35:661.5

Danilovich Dmitrii, Smirnov Aleksandr Vladimirovich

The technology of step-feed nitri-denitrification in municipal wastewater treatment: the analysis of options and case record

Summary

The experience of MY PROJECT JSC in designing biological treatment facilities (aeration tanks) at the municipal treatment facilities of the Russian Federation with the use of step-feed nitri-denitrification is considered. Over the past 10 years more than 20 treatment facilities have been upgraded and built with the introduction of a step-feed scheme; the author of the article made a personal commitment in commissioning of more than 10 biological treatment facilities for municipal and industrial wastewater processing. In order to observe the data confidentiality, no data is provided on the chemical analysis of the operation of structures; however, with the help of mathematical modeling, the specific features of the implementation of step-feed denitrification are shown. The key process engineering aspects of the implementation of the schemes of a step-feed process with a different number of stages (two and three), cases of the need to use or reject nitrate recycling, as well as using, where applicable, an additional substrate (methanol) with particularly stringent requirements to the nitrogen concentration at the effluent discharge are considered. Traditionally, it is believed that the scheme of step-feed denitrification is designed for nitrogen removal; however, additional positive modifications of step-feed denitrification have been also considered that provide for arranging biological removal of phosphorus. The design of an anaerobic zone upstream the first denitrification cascade (D1), the use of step-feed denitrification in the implementation of the process scheme of the University of Johannesburg (JHB), as well as the arrangement of step-feed of return sludge are considered.

Key words

biological treatment , nitrification , denitrification , aeration tank , biological phosphorus removal , step-feed technology

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UDC 628.35:661.5

Gogina Elena, Gul’shin I. A.

Nitrogen removal in a circulation oxidation ditch model
under the conditions of lowered concentration of organics in wastewater

Summary

The summarized results of the third stage of an integrated study of energy efficient processes of wastewater treatment in circulation oxidation ditches are presented. The experiment was carried out in a laboratory model of a circulation oxidation ditch with horizontal directional flow of mixed liquor. The impact of low concentration of dissolved oxygen in the bioreactor volume (at 0.5 mg/l level) and low concentration of organic pollutants in the incoming model wastewater on the treatment efficiency and biomass stabi­lity was studied. The highest efficiency of total nitrogen removal was reached at the specific organics load on activated sludge (BOD) R = 0.07 g/(g∙day), average dissolved oxygen concentration 0.5 mg/l and 7.5 hours aeration time. At that the concentration of ammonium nitrogen in the effluent was about 0.6 mg/l; the concentration of nitrate nitrogen was 9.6 mg/l. The operation of the bioreactor at lowered dissolved oxygen concentrations resulted in partial biomass bulking. The sedimentation properties of activated sludge changed; however stayed at satisfactory level.

Key words

wastewater , nitrification , energy efficiency , activated sludge , denitrification , circulation oxidation ditch , biological removal of nitrogen

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UDC 628.35 (211)

Kounakhovich A. A.

Domestic wastewater advanced treatment unit for the use in the settlements of the northern climatic region

Summary

The experts from «Engineering Equipment Trading House» developed and mastered manufacturing of the treatment facilities for domestic wastewater and industrial wastes close by composition to domestic wastewater for the camps in the northern construction climatic region. Tver-C units for advanced treatment of domestic wastewater provide for the comprehensive solution to ensure efficient operation of the treatment facilities in rigorous climate northern areas.

Key words

disinfection , suspended substances , aeration , nitrification , wastewater treatment , phosphates , nitrites , nitrates , chlorides , microflora , denitrifier