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UDC 628.171

Ivankova T. V.

The current state of water supply in the Republic of Crimea
and possible additional water sources

Summary

The state of water availability of the Crimea peninsula in the period 2014–2017 is considered; the water consumption of the population is analyzed. The main problems with the supply of high-quality drinking water to the population are associated with the unsustainable use of water resources, poor water quality in rivers, surface water bodies, discharge of raw or insufficiently treated wastewater, wasteful flow and significant water losses in the water supply system. In 2017, the total water abstraction in the Republic of Crimea amounted to 301.33 million m³: from surface sources – 177.67 million m³, underground – 123.66 million m³. Water supply of cities and rural settlements is provided from surface (water reservoirs) and underground (artesian wells, groundwater intake structures) sources. The consumption of fresh water was 267.67 million m³, the losses during transportation – 12.3 million m³ (4.7%). The most unfavorable regions in terms of sanitary and chemical indicators of drinking water are: the cities of Krasnokopsk, Armiansk, Evpatoria, Dzhankoy, as well as Krasnoperekopsky, Pervomaisky, Leninsky and Saki districts. Methods of supplying fresh water used in arid countries (Israel and UAE) are considered. For the water supply of the Crimean peninsula a set of measures is proposed: step-by-step reconstruction of the water management complex; upgrade and additional construction of local drinking water treatment facilities; replacement of outdated water distribution networks; reconstruction of the existing water reservoirs and the construction of additional bulk reservoirs, storage ponds on the local flow; the introduction of water-saving technologies in industry, utilities and agriculture; the use of drip irrigation systems in agriculture; the use of brackish underground sources; desalination of sea water; promotion of water conservation.

Key words

ground water , water supply system , desalination , water availability , water scarcity , water reservoirs

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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 628.16.066.7

Boldyrev Vladimir Vasil'evich

Analytical model of sedimentation process based on the equation of continuity of settling polydisperse suspension flow (to be discussed)

Summary

In the well-known studies on the precipitation of polydisperse suspension the latter is identified with suspended (fluidized) bed. However all currently used mathematical models of natural and wastewater sedimentation processes do not take this circumstance into account and sometimes contradict it. Models of the processes of sedimentation in the strict sense have not yet been developed; instead separate methods are used with the help of which the process of sedimentation implemented in laboratory cylinders is carried out in industrial clarifiers. In this simulation the value of the main parameter of the sedimentation process (hydraulic size or sedimentation rate) always decreases with time. In the proposed model the flow of settling suspension is presented as fluidized bed. Moreover this flow has the properties of integrity and continuity of the values of its physical characteristics; whereas the flow rate in this case remains constant. In the process of the model design it was suggested that the concentration of suspended solids in the flow remained average by volume of the clarifier. Taking into account the continuity equation the sedimentation rate is proposed to be understood as the sedimentation rate of polydisperse suspension in the selected flow section that corresponds to the mass flow of suspension through the given section. Based on the above prerequisites a balance differential equation has been compiled that describes the process of sedimentation in a batch clarifier including laboratory cylinders. The solution of the differential equation provides for the formulas for calculating the clarification efficiency both for batch and flow-through clarifiers with time. In order to check the adequacy of the mathematical model the results of calculating the clarification efficiency using the obtained formulas were compared with the results of experiments carried out by other authors and with the typical project solutions. From the analysis of graphs it was concluded that the values of the clarification efficiency calculated theoretically have good convergence with the experimental data given in typical projects.

Key words

clarification , batch clarifier , flow-through clarifier , precipitation of polydisperse suspension , concentration of nonsettleable solids , clarification efficiency , analytical model , equation of continuity , balance differential equation

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UDC 628.212.2/.316

Prodous O. A., Mikhailov A. V.

The experience of using peat filtration for surface runoff treatment

Summary

The 20-year experience of using peat filtration technology for surface runoff treatment has been described. The advantages of the technology are given; the simplicity of operation in a large range of surface wastewater amount is noted. The choice of treatment techno­logy and filtering materials is a rather complicated task, since it requires achieving effective purification at minimum cost and without using extra electricity. The natural origin of peat, its availability, good filtering properties, ease of disposal and low cost determine the prefe­rence of its use in surface runoff treatment technologies. In the period 1994–2018 a group of companies developed a system for passive mechanical treatment of surface runoff using peat filtering materials. At the facilities of the North-West Federal District of the Russian Federation more than 900 systems for the purification of surface runoff of various amounts were introduced including more than 300 on the R-21 Kola highway and large Pulkovo-3 facilities with a capacity of 700 m³/h in St. Petersburg. The absence of the need to use electricity even in minimal amounts has provided for the efficiency of such technologies. The widespread introduction of peat filtration can be attributed to the best available technologies.

Key words

surface runoff , efficiency of treatment , peat filtration , filtering material

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UDC 628.24:620.197:620.193.8

Primin Oleg, Ten A. E., Gromov Grigorii

Protection of sewers from corrosion

Summary

Accidents on sewers accompanied by the destruction of building structures have been a most serious problem not only for the water industry but also for the entire city. In the world the damage from the deterioration of reinforced concrete sewer tunnels and in-line structures due to corrosion is estimated at billions of euros per year. A way out of the current situation with corrosion in sewers can be timely and prompt repair and rehabilitation using protective coatings applied by trenchless methods. One of the methods of sewer rehabilitation is lining the internal walls of the sewers with plate composite materials (blocks) or continuous protective coatings where polymer concrete can be used. Polymer concrete comprises a thermosetting organic binder (usually epoxy resin) and a large amount of dispersed filler (talc, aerosil, crushed quartz, basalt, granite chips, etc.). The special composition of filler materials and advanced production technologies ensures the high qualities of polymer concrete. An assessment of the technical and economic indicators of the reconstruction of existing sewers and canals using polymer concrete blocks is given. Through a realistic example it is shown that the most effective option of the reconstruction of a sewer canal while ensuring environmental safety is lining with polymer concrete blocks (segments).

Key words

reconstruction , sewerage , collector , corrosion , repair and rehabilitation operations , lining , polymer concrete

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UDC 628.14:004.415.53

JUDIN M. Iu., Hyamyalyainen M. M., Smirnova S. V., Rusanova E. V.

On the rules for developing electronic models of water supply
and wastewater disposal systems

Summary

The development of electronic models of water supply and wastewater disposal systems is mandatory for large communities. However the methodological documents defining the construction and further use of electronic models are not available. In this connection situations often arise when the models are developed formally and are not suitable for use in water supply and wastewater utilities. To improve the efficiency of the use of electronic models it was proposed to develop methodological recommendations that determine the necessity to take into account domestic experience and international practice. The development of rules summarizes the experience of designing and operating electronic models of water supply systems, water supply and wastewater disposal schemes as well as design experience based on multiple-version hydraulic calculations. According to the «Rules for the development and approval of water supply and wastewater disposal schemes» approved by Decree of the Government of the Russian Federation of September 5, 2013 No. 782, the electronic model of water supply and (or) wastewater disposal systems is thought of as an information system that includes databases, software and hardware. This system is designed to store, monitor and update the information on the technical and economic condition of centralized hot water supply, cold water supply and (or) wastewater disposal systems, the implementation of the operational control mechanism in the specified centralized systems, and provide for hydraulic calculations. In the process of designing models a variety of software is used.

Key words

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UDC

KOZLOV M. N.

Birth of the Moscow engineering and technology school
of wastewater treatment (part 2)

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UDC 697.92

Agafonova V. V.

Indoor air quality assessment in office buildings

Summary

The assessment of indoor air quality in an office building is given. The analysis of the results of reviewing Russian and foreign authors on this topic showed that at CO₂ concentration of 600–800 ppm and higher the well-being of people worsens, which leads to impaired productivity and increased fatigue. Prolonged exposure to carbon dioxide in humans can lead to chronic diseases. The results of an experimental study of the change in carbon dioxide concentration in an office of a public building with an area of ​​30 m² with continuing presence of five people are presented. The CO₂ concentration was measured using MT 8057 portable carbon dioxide detector during 24 hours. According to the measurement results a graph of CO2 concentration is plotted against the time. It was concluded that the air quality was not satisfactory during certain periods of the working day (from 10:40 to 13:30 and from 14:45 to 19:00 the CO₂ concentration exceeded 1000 ppm) which indicates problems with the ventilation system and excessive sealing of the room (because of plastic windows). The necessity of taking measures to improve the efficiency of inflow exhaust ventilation has been substantiated.

Key words

carbon dioxide , ventilation , personalized air terminal device , air quality , air exchange , public buildings , sick building syndrome,