DOI 10.35776/VST.2022.03.05
UDC 628.355
Kevbrina M. V., Gavrilov Dmitrii, Belov N. A., Agarev Anton
The effect of the operation of secondary settling tanks on the efficiency of biological removal of nitrogen through the example of Kuryanovskie wastewater treatment facilities
Summary
«Mosvodokanal» JSC conducted an industrial-scale experiment with the secondary settling tanks of the new section of the Kuryanovskie wastewater treatment facilities in Moscow in order to determine the effect of the operation of settling tanks on the efficiency of biological removal of nitrites. With an increase in the level of sludge stand in the secondary settling tanks, conditions arise in the sludge layer at the bottom of the settler for the anaerobic processes that cause the lysis of activated sludge cells. Under these conditions, a sufficient amount of organic matter is generated in the sludge layer, both residual, occluded on sludge flocks, and formed during the lysis of part of the cells, so that in the presence of nitrates, the process of incomplete denitrification starts with the formation of nitrites. The occurrence of anaerobic processes in the bottom sludge layer in the secondary settling tanks is also affected by the oxygen concentration in the mixed liquor entering the secondary settling tanks. The process parameters of the operation of the facilities that prevent a decrease in the quality of effluent are determined: regulating the operation of secondary settling tanks depending on the load and residence time of the sludge dry matter that prevents the sludge from long staying in the bottom layer, as well as maintaining a high oxygen concentration at the end part of the aeration tanks.
Key words
wastewater , biological treatment , sludge disposal truck , secondary settling tank , activated sludge , nitrite nitrogen
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UDC 628.356.5
Kevbrina M. V., KOZLOV M. N., Dorofeev A. G.
Secondary settlers: comparison of the calculation methods in designing and analysis of the parameters of efficient operation of the facilities
Summary
The results of the comparison of methods of calculating secondary settlers through the example of a model wastewater treatment plant (domestic method according to SNiP 2.04.03-85, German method according to Germany Standard ATV-DVWK-A131E, American method based on mass flow theory) are presented. It is shown that the surface area of settlers calculated according to Standard ATV has higher values compared to the calculations according to SNiP 2.04.03-85 and American method. The values of the surface area of settling tanks calculated according to SNiP 2.04.03-85 and American method are very close. At the same time the SNiP method is much simpler and requires much less initial parameters than the American method. For the domestic practice of operating secondary settlers it is proposed to introduce a new parameter – «dry matter loading on the settler surface» taken from the mass flow theory. This indicator indicates how much dry matter of the mixed liquor from aeration tanks enters per unit surface of secondary settlers per hour and corresponds to the incoming mass flow. By varying the dry matter loading on the surface of secondary settlers it is possible to provide for the standard suspended solids concentration in effluent. Through the example of the operating 54 m diameter settlers the dependence of the clarification efficiency on this parameter is shown.
Key words
wastewater , biological treatment , sludge index , secondary settling tank , activated sludge , calculation method
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UDC 628.356.57.001.5
SHVETSOV V. N., MOROZOVA K. M., Smirnova I. I., Semenov Mikhail, Lezhnev M. L., Ryzhakov G. G., Gubaydullin T. M.
The Use of Bioblocks at Wastewater Treatment Facilities
Summary
Results of the laboratory study of an aeration tank operation for the purpose of technological comparison of two new modified bioblocks, BBZ-45P-14 and BBZ-65P-10, having the similar surface structure but different geometric parameters are presented. It is shown that these bioblocks can be used successfully in aeration tanks for immobilization of microorganisms of activated sludge. The tests of loading material samples have been carried out at biomass density in bioblocks of 0,3–0,36 kg/kg, at equivalent concentration of sludge in the system – 2,3 g/l. The bioblock BBZ-65P-10 is used preferably in aeration tanks, BBZ-45P-14 – in aeration tanks with low load on activated sludge, blocks of aftertreatment for additional clarification of water treated biologically and in biofilters for build-up of biological film. The comparison of results of tests on rate of activated sludge adhesion obtained with new types of bioblocks and BBZ-65 tested earlier makes it possible to conclude that the adhesion process goes off more intensively on rougher surfaces of modified models of bioblocks.
Key words
wastewater , biological treatment , biofilter , bioblock , aeration tank , secondary settling tank , adhesion , activated sludge
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DOI 10.35776/MNP.2020.07.07
UDC 628.356.5
Kevbrina M. V., Novikov S. N.
Method of analyzing the operation of secondary settlers with the purpose of the optimization (for the discussion)
Summary
According to the results of laboratory tests on determining the sedimentation rate of sludge mixture particles in aeration tanks of wastewater treatment facilities, the curves of the gravitational mass flow, calculated in two ways, were plotted. Through the example of sludge mixture in the experimental aeration tank at the Lyuberetskie wastewater treatment facilities in Moscow, a method for analyzing the operation of secondary settlers State Point Analysis, based on the theory of mass flows, is presented. This method provides for estimating the operation of secondary settlers with the purpose of making an operational decision to optimize their operation. «Dry matter load on the surface of secondary settlers» indicator is proposed to be introduced into the practice of operating secondary settlers as another tool for the control of their operation. This parameter shows the amount of dry matter of the sludge mixture in the aeration tanks that is supplied per unit surface of the secondary settlers per hour, and corresponds to the incoming mass flow. The dependence of the concentration of suspended solids in the effluent on the dry matter load and sludge index is given. By changing the dry matter load on the surface of the secondary settlers the standard quality of effluent in terms of suspended solids can be ensured.
Key words
wastewater , biological treatment , sludge index , aeration tank , secondary settling tank , activated sludge
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UDC 628.33
Kevbrina M. V., Bogomolov M. V., Streltsov S. A., Belov N. A., Kolbasov G. A.
Optimization of the mode of sludge removal from secondary settling tanks
Summary
In the process of upgrading the Moscow Novokur’ianovskie wastewater treatment facilities the scraper mechanism for activated sludge collection in 54 m diameter secondary settling tanks was replaced by SO-54 sludge sucker. Since it was the first experience of using sludge suckers at the Kur’ianovskie wastewater treatment facilities it was decided to carry out experimental tests of the operation of the secondary settling tanks equipped with sludge suckers as well as to develop and approbate the method of efficient activated sludge collection and removal from the bottom of the settling tanks. The operation of SO-54 sludge sucker in different modes was analyzed. It was shown that the design of the settling tank provided for the operation control by switching off and on the suction pipes of the upper level of the sludge suckers, i. e. eliminating the use of complicated instruments. Regulating the operation of the suction pipes of the upper level of the sludge suckers with a time switch provides for maintaining the optimal height of the activated sludge layer. Switching off the suction pipes of the upper level of the sludge suckers results in the increased concentration of recycle sludge. As a result of changing SO-54 sludge pump operation the dosage of recycle sludge was increased from 4.6 to 7.1 g/l eliminating the effluent quality in relation to suspended solids. This allowed reducing the recycle sludge volume subject to pumping to the aeration tanks, and reducing the number of operating pumps, and power saving.
Key words
treatment facilities , sludge disposal truck , secondary settling tank , activated sludge , power saving
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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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DOI 10.35776/VST.2022.02.05
UDC 628.32:22.765
Semin M. M., Tokarev Nikolai, Iavtushenko Marina, Lobanov Fedor, Chukalina Tat’iana, Plekhanov A. V.
Use of a chemical regulator at the wastewater treatment facilities operated by MUE Vodokanal of Podolsk
Summary
Possible use of natural minerals based on calcium carbonate (monocalcite) to correct pH (carbonate-bicarbonate equilibrium) in order to improve the treatment effect of activated sludge bacteria in the aeration tank and the sedimentation properties of activated sludge in the secondary settling tank is considered. The sedimentation properties of activated sludge are corrected because of the interaction between functional oxygen-bearing substrata of activated sludge flocculation bacteria and calcium ions. As a result, firm, rapidly settling flocs are formed and, consequently, the value of the sludge index decreases compared to the technological line and settling line operating in the regular mode. It is recommended to use a chemical regulator to normalize the operation of the aeration tank in winter (possible bioflotation), spring and autumn periods at high hydraulic loads.
Key words
calcium carbonate , sludge index , aeration tank , secondary settling tank , activated sludge , bioflotation
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