Aeration for wastewater biological treatment: updating foreign terms and abbreviations

Summary

The study of domestic and foreign methods for aeration tanks evaluation and their design guidelines is presented. The analysis of modern approaches to the calculation of treatment facilities indicates that the calculated air flow rate is determined in accordance with the oxygen demand of the biological process for the oxidation of organic compounds, nitrification and denitrification. International terms and abbreviations have been adapted to Russian analogues taken in conjunction with the theory of oxygen mass transfer, as well as the international guidelines for the design of wastewater treatment facilities. The difference between the field (experimentally measured) and calculated (determined for the design) parameters OUR and AOR, SOTR and SOR is explained. Balance equality between OTR and AOR is an optimal and economical design solution. It is noted that the use of updated international terms and abbreviations in tender and competitive procedures (during design and delivery) will simplify their implementation and ensure mutual understanding between the parties. The need for regulation of the air supply to aeration tanks is justified by the balance of oxygen «consumption – transfer». In dynamic conditions for regulated systems OTR → OUR. With the automated maintenance of the set point for the concentration of dissolved oxygen this condition provides for the savings in energy consumption.

Key words

wastewater , biological treatment , nitrification , denitrification , aeration tank , aeration system , oxygen mass transport , terms , abbreviations , air flow rate control , OUR , AOR , OTR , SOTR , SOTE

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UDC 628.54

Sazonov D. V.

Influence of the pump type on the parameters of the pneumatic-hydraulic aeration system in flotation apparatus

Summary

Flotation has been one of the efficient water treatment technologies. Flotation treatment is based on small gas bubbles generated by different methods, pneumatic-hydraulic, in particular. A case is considered of air feeding before the pump and subsequent water-air mixture passing through the aerator, and air being broken to small bubbles. Possible operation in the presence of air determines the choice of self-priming pumps (centrifugal and vortex). Experiments were carried out on determining two of the most important aeration parameters: bubbling rate and average size of generated air bubbles that determine the efficiency of water flotation treatment. Based on the data obtained it is shown that in most cases centrifugal pumps have the advantages: considerable part of the air entering the pumps is dispersed at the outlet of the aerator to 30–100 μm bubbles; whereas in case a vortex pump is used air bubbles of more than 200 μm size are generated which is ineffective for water flotation. It is stated that for some wastewater types the use of vortex self-priming pumps can be more reasonable.

Key words

water treatment , centrifugal pump , aeration system , pneumatic-hydraulic flotation , aeration intensity , air bubble size

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UDC 628.356.3:336.7

Bazhenov V. I., Berezin S. E., Ustiuzhanin A. V.

Feasibility of air blower house construction on the basis of life cycle costs evaluation

Summary

The demand of the wastewater treatment facilities for the controlled air-blowing equipment with a significant energy saving potential has been growing. Therefore the design concepts based on this type of equipment are attracting the investor’s interest. The aim of the study is economic analysis of the technologically controlled and uncontrolled air supply options for aeration systems of aeration tanks under the conditions of a newly built pumping-air blower house with and without account of the project investment attractiveness. Conditionally prescribed irregularity of air supply to the pneumatic aeration systems has been taken as a reference condition. The research method is economic analysis of the life cycle costs (LCC) including and without including the mechanism of time-variable cost adjustment, i. e. bank interest and inflation. Three options of an air-blowing house design are presented: without process control (multistage); with controlled electric drive (multistage); with the rotating-blade mechanism control (single-stage). During the construction of air-blowing houses the option with the introduction of single-stage rotating blade turbo blowers with dual control is most attractive. This option provides for the lower LLC index compared to the option of using a controlled electric drive for 23.07% – in case
the cost estimates do not include inflation and discount; and for 21% – in case the cost estimates use the mechanism of time-variable cost adjustment (with account of inflation and discount).

Key words

aeration system , air-blowing house , air blower control , economic analysis , life cycle costs , project investment attractiveness

DOI 10.35776/VST.2022.06.01
UDC 628.35

Smirnov Aleksandr Vladimirovich, Babichev Aleksandr, Fediunin Viacheslav, Fediunin Viacheslav

Improving the environmental safety of the Urals: upgrading the Southern Wastewater Treatment Plant in Yekaterinburg

Summary

The Ural region has been traditionally considered the «backbone» of Russia with the center in Yekaterinburg. The environmental safety of the region is largely ensured by wastewater treatment at the Northern and Southern municipal wastewater treatment plants. The current upgrade of the Southern Wastewater Treatment Plant has become the biggest over the past 7 years: 345 million rubles have already been invested in the building, installation works and equipment. In 2022, the allocated finance will be another 120 million rubles. In the process of reconstruction and modernization of the Southern Wastewater Treatment Plant the mechanical sludge dewatering facilities were subject to upgrade resulting in the double reduction of the generated wastes. More than 70% of aeration tanks (8 of 11 sections) were reconstructed with a complete replacement of the aeration system, and secondary clarifiers were reconstructed with the replacement of sludge sucker (6 of 15 tanks). In general, the upgrade of the biological treatment facilities provided for increasing the environmental performance and improving the state of the ecosystem of the Iset River.

Key words

wastewater treatment , modernization , sludge disposal truck , aeration tank , secondary settling tank , aeration system

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UDC 628.334.2

Meshengisser Yu. M., Shchetinin A. I., Marchenko Yu. G., Zinchenko D. B.

Designing the aeration system of grit chambers

Summary

The procedure of designing the aeration system for grit chambers including energy relations and formulas for calculating the diameter and rate of air bubbles ascent is presented. The suggested relationships showed close agreement of calculated and experimental values of the transverse water circulation rate in the aerated grit chamber. On the basis of domestic and foreign recommendations on the given design procedure the bottom velocity of water circulating flow in typical aerated grit chambers was calculated. It was shown that the use of fine bubble aerators provides for 30–50% air saving.

Key words

air flow rate , grit chamber , aeration system , flow bottom velocity

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