Environmental Issues of Desalination

In the article, in order to solve various design problems of the hydraulic engineering and reclamation class, taking into account the conditions of functional operation of soft floating structures as water intake structures, the main aspects of the development of protective devices for irrigation water are formulated. As a result of the conducted research, based on the experience of designing water intake structures with water treatment systems, a specialized algorithm for solving problems of creating constructive and technological developments for reclamation water intakes in the water management complex was developed. The obtained results of the design and inventive tasks for a soft surfaced structure used as a water intake structure make it possible to select the estimated irrigation water costs (Q, m?/s) in the required quality and quantity and ensure the environmental safety of the reclamation system. In order to solve the tasks of ensuring the environmental safety of the reclamation system, the entire complex of structural structures, protective devices and technological equipment included in the water management complex was divided into three interconnected structural and technological schemes as part of a specialized type of natural-technical system “Water object – Water intake structures – Meliorative system”. Soft surfaced biopositive structures of a water intake structure as part of a reclamation system have been developed, in which the main protective agent is the first proposed by the author for the purification of irrigation water – a ruff filtrating load, which is an environmentally safe means of protecting the reclamation system from mechanical and biological contamination. An economic and mathematical model of a specialized type of natural-technical system “Water object – Water intake structures – Meliorative system”is presented, which represents the final stage of ensuring environmental safety of reclamation water intake, which is the main factor in increasing soil fertility and, accordingly, economic efficiency in the whole agricultural complex.

Introduction. Efficient and reliable operation of water intake structures within reclamation systems in Southern Russia and the North Caucasus is a challenging issue. In this article, we address the operational reliability of reclamation water intakes in the foothill areas of small rivers. Many water intake structures built on small rivers are in poor operating condition and, therefore, need improvement and complete reconstruction. Methods. We performed analytical and field studies on the head structures of foothill reclamation systems. Based on the results, we identified the reasons for the low efficiency and reliability of old water intake structures. Since it is impossible to improve these water intake structures, new types and designs of high-performance water intakes are required. Therefore, we propose some original types of underground horizontal and underflow water intakes and determine corresponding technical parameters and performance criteria. Results. Due to low efficiency as well as high energy and material consumption of existing water intake structures, it is required to significantly reduce the cost of supplied irrigation water by introducing new types of high-performance water intake structures. Based on the studies of alluvial regimes of rivers and retention basins as well as hydraulic regimes of head water intake structures, we prepared design and process solutions that help control sediment effectively, increase the water intake coefficient, and regulate water supply to irrigation canals. The design features of new water intakes have a beneficial effect on river flows and the quality of irrigation water. Conclusion. The study results confirm the high performance and manufacturability of the proposed horizontal and underflow water intakes protected by patents for inventions. This year, our designs have been included in the state grant program for the development of standard hydraulic structures within reclamation systems.

Conceptual foundations development of nature-like technical systems based on system analysis and synthesis of man-made component interaction processes within natural-technical systems class “Water object - Water intake structures - Reclamation system”. Conceptual bases of methodology for creation and development of natural-technical systems class “Water object - water intake structures - reclamation system” on water resources use in reclamation system branches were developed, using system approach as a way to describe relationship, interaction and relationship processes between natural, anthropogenic components and reclamation system. The results of the study were tested at the design stage, construction of the Nevinnomyssky irrigation canal located within the basin geosystem of the Upper Kuban in the territory of the Karachay-Cherkessia Republic of the North Caucasus.KeywordsBasin geosystemReclamation systemsWater intakesNatural water object“object of activity”Ecological acceptabilityRelevanceReflection of objective realitySystem integrityCognitionSkill“Nature-like” technical systems (NTS)

Purpose: to develop a water intake structure for land reclamation purpose under the conditions of water withdrawal from mountainous natural water sources. Materials and methods. The paper is based on the theoretical analysis of the river hydrological and geological characteristics, which made it possible to calculate the minimum flow required for the stable operation of water intake structure and guaranteed water withdrawal during the growing seasons. The design parameters of the water intake structure were developed using the method of expert assessment with non-parametric statistics by comparing several dependent variables. Having determined the required qualities for a water intake structure, the design of a reclamation facility adapted for the conditions of the mountain and foothill zones of the North Caucasus was developed. Results. To achieve this goal, a static method for analyzing water intake structures was adapted, and statements with a factorial rating scale for expert assessment were developed. Kendall's concordance coefficient was 0.726, the data were consistent, the significance level P was less than 0.05, the differences between the factors were significant. The layer-by-layer latticed type of water intake structure has maximum efficiency. The design of a bottom-type water intake structure has been developed on the basis of the river hydrological regime and the method of water supply to the system. This type of structure demonstrates high efficiency in conditions of difficult terrain and unstable water source regimes during the growing seasons, ensuring stable water intake with minimal impact on the ecosystem. Conclusions. The proposed design of a water intake structure can be adapted to different types of water resources and their fluctuations, which makes it acceptable for mountainous areas with variable water levels in natural water sources. Minimal impact on the ecosystem is ensured by a high degree of water purification without significant changes in river channels.

Finite element seismic safety assessment of water intake structures

Purpose: development of justification for the feasibility and possibility of application and structure schemes of filtering water intakes for water intake from canals, its preliminary purification and supply to drip irrigation systems. Materials and Methods. During development of justification, general and specific scientific methods of analysis and synthesis of information on the advantages and disadvantages of filtering water intakes were used, and during the development of their designs, technologies of research design were used. Results and Discussion. It has been found that filtering water intakes can simultaneously perform the functions of water intake, trash barriers, fish protection and purification facilities. Structural flexibility and simplicity of performance, environmental friendliness, multifunctionality and high technical and economic indicators are the basic characteristics that made it possible to substantiate the feasibility of their application as water intake and treatment facilities for drip irrigation systems. As a result of the research, at the level of inventions, structural schemes of water intake structures with inlets equipped with filter panels with bottom and slope locations were developed. The water intakes provide for the arrangement of catchment and water storage containers, ensuring the water collection seeped through the filter panels and its subsequent drainage into the water conducting stream. The water intake structures provide for the possibility of selective water intake from the least polluted horizons of the water flow. The problematic issues of the use of filtering water intakes are noted in terms of the need to create a developed water intake front and periodic flushing or replacement of filtering panels. Conclusions. The feasibility of using water intake purification facilities, providing water intake from water sources and its preliminary treatment for the needs of drip irrigation systems, has been substantiated, as well as filtering water intakes designs recommended for the arrangement and use in drip irrigation systems are proposed.

More than 80% of the annual water consumption in Uzbekistan comes from large transboundary rivers such as the Amu Darya and Syr Darya. The rest of the water is formed on the territory of the Republic. Almost all year round, the turbidity of the Amu Darya and Zaravshan rivers is 3÷5 g/l, reaching 15÷18 g/l during flood periods.in most cases, water from the rivers is taken into irrigation channels using damless water intake structures. In order to prevent the ingress of bottom sediments from rivers into channels, thresholds have been constructed at water intake structures, the height of which is set constructively. As a result, bottom sediments pass through thresholds and move along the bottom of channels, reducing their cross-sections, as well as filling the chambers of pumping stations and pressure basins of hydroelectric power plants with sediments. After getting into the flow parts of pipelines and hydraulic machines (pumps and hydraulic turbines), they lead to abrasive wear, as well as other negative consequences. A lot of work has been done to prevent sediment from entering through water intake structures, but so far none of these proposals has provided an effective solution. In the laboratory of the Tashkent Institute of irrigation and agricultural mechanization engineers, a series of experiments were conducted on a glass hydraulic tray to determine the height of bottom sediments, taking into account their heterogeneity. Based on experiments, the dependence on determining the height of the ridge is derived. Based on the obtained dependence, a method for determining the height of the threshold of a damless water intake structure is proposed. This technique was experimentally tested on a laboratory tray. Specifying the threshold height will lead to optimization of capital costs for the construction of the threshold of the water intake structure, as well as reduction of operating costs for cleaning channels from sediment and repair work of hydraulic machines from hydroabrasive wear.

The article analyses the case of cavitation in centrifugal pumps of the 1st lift pumping station (PS-1) of the water supply system of one of the cities of Ukraine, supplied with water from a reservoir on the Dnipro River. In the classical scheme of a water supply system from a surface source, the operating mode of water treatment facilities should be uniform throughout the day, considering the water treatment’s physical and chemical processes. According to this, the operating mode of PS-1, which supplies ‘raw’ water to the water treatment plant, is considered uniform throughout the day. However, one caveat is that fast filters are washed with drinking water from clean water reservoirs. Its replenishment occurs due to the accelerated operation of the water treatment plant, and, at this time, PS-1 should increase the water supply to the water treatment plant. However, if the influx of water from the water intake structures is fixed, it occurs when the centrifugal pumps PS-1, operating under the bay, begin to capture some air. A two-phase flow of water forms in the pumps, which breaks away from the impeller blades, and cavitation occurs, destroying this impeller. It was necessary to establish the cause of cavitation and develop measures to eliminate it during the further operation of pumps at PS-1. The reasons for cavitation may be the following: failure of the operating point according to the Q–H characteristic at both low and high water flow rates; water flow breaks away from the blades with the formation of cavities and two-phase flow; violation of the requirement of the permissible cavitation reserve – the minimum pressure at the pump inlet if the pump is installed above the water level in the tank; violation of the requirement that there must always be more water at the pump inlet than at the outlet when installing the pump under the bay. The main reason for pump cavitation at PS-1 is the discrepancy between the water inflow from the water intake structures and the water supply regime to the water treatment facilities. The influx of water to PS-1 from the water intake structures is fixed, and the water use at the water treatment plant is uneven, as it depends on the technological process of water purification. The need to coordinate the modes of water supply into the suction pipeline of the pump and the mode of water supply to the pressure pipeline becomes urgent. In this case, there will be no cavitation. Keywords: water supply system, operating mode of facilities, 1st lift pumping station, cavitation.

Both brackish water desalination and seawater desalination processes are well established and in common use around the globe to create new water supply sources. The farther the location of the source water from the ocean or seashore, the lower the salinity (TDS) of the water and the lower the osmotic pressure that needs to be overcome when desalinated water is produced. This is one of the major reasons that brackish desalination is often considered less costly than seawater desalination. A number of project considerations, however, indicate that seawater desalination can be beneficial and more cost-effective than brackish water desalination. To make a fair comparison, we need to properly compare all major aspects of both types of projects to define the best and most appropriate desalination technology. While brackish water has less feed water TDS, it is more challenging to dispose of the produced concentrate. Also, although brackish water desalination needs less energy to overcome osmotic pressure, it usually requires more energy to draw the water from the well than it takes to pump seawater from the open ocean intake. Another factor is that the temperature of the brackish well water may be lower than the temperature of ocean water, giving seawater desalination an advantage in energy demand. In comparing brackish to seawater desalination, these major aspects should be evaluated: (1) Locations of seawater and brackish water plants, relative to the major consumers of the desalinated water, (2) Transportation (pumping and disposal) costs of the feed water and produced water, (3) Potential colocation of a seawater plant with a large industrial user (e.g., power plant) of the seawater for cooling or other purposes, (4) Produced quality of brackish water and seawater desalination in terms of major minerals and emerging contaminants, (5) Sustainability of the water source: capacity and depth of the brackish water wells, as well as the type of soil. (6) Technical and economic aspects of produced concentrate disposal, (7) Permitting process costs for brackish and seawater desalination, and (8) The economics of both brackish and seawater desalination treatment processes: capital costs, operational and maintenance (O&M) costs, lifetime water cost, and total water cost (TWC). This paper discusses the major evaluation criteria and considerations involved in properly comparing the economic and technical aspects of brackish and seawater desalination to determine the more favorable desalination technology for a given desalination project.

In paper, researches of riverbed and hydraulic processes at the water intake from mountain rivers are observed. Classification of designs of the mountain water intake structures, based on continuity signs is offered. Perfecting of base designs of water intake structures of a mountain-foothill zone and means of their hydraulic automation is carried out. The technological, theoretical and experimental substantiation of parameters of basic elements of these designs with a glance of hydromorphometric characteristics of the mountain rivers is given. Complex hydraulic researches of kinematic characteristics and carrying ability of a two-phase stream on water intake structures are executed. Bases of a technique of engineering calculation of the offered designs of water intake structures and the recommendation of their designing and maintenance in various hydrological regimes are developed.

Desalination and the environment

Desalination and the environment

Prediction of recirculation flow rate for icing prevention in water intake supply systems of nuclear power plants

The integration of desalination plants and mineral production

The article presents the results of system analysis of the problems in irrigated agriculture and irrigation restoration in Ukraine. The results of classification of water and land use conditions within the irrigation systems are given in this paper. The methodological approaches to the development of integrated plans for consolidation of water and land resources have been elaborated. Based on the surveys and questionnaires in the studied regions, 5 groups of land fragmentation problems were identified, which are outlined in this study and illustrated on some examples with using maps. The following types of conditions of water use were distinguished: lease of land plots by one large farm or agroholding within the area of one or more water distribution channels of large irrigation systems; the using of lands of intra-farm irrigation systems, which typically belong to the territories of individual village councils and are served by several water intake structures, and a large number of medium and small tenants; the using by several tenants of an area serviced by one water intake structure or one pumping station; fragmentation of land use and land ownership conditions within a single field; the presence of land plots with different leases terms within the individual fields, used by one agricultural enterprise. According to the types of land use conditions, three options for integrated land consolidation plans for irrigation systems were proposed. In order to develop integrated land consolidation plans and to restore irrigation, a complex analysis of land use maps and maps of the projected irrigation area will be needed. Therfore, it is necessary to establish a dialogue with stakeholders, namely with all farms, farmers and individual landowners on drawing up the most economically and environmentally optimal land consolidation plan within irrigation restoration areas. When drawing up such a plan, it is necessary to carry out an expert evaluation of the different scenarios of irrigation restoration, taking into account the composition of crops, probable techniques and methods of irrigation. Once the consolidation plan has been agreed, it is important to have a permanent land users association in place to attract and invest in irrigation restoration and to operate the irrigation infrastructure after the restoration. The issues of creating Water User's associations (WUA) in the irrigation areas was considered; the role of associations and land consolidation in restoring the on-farm irrigation network was determined. The list of functions of Water User’s associations has been provided, the main one of which is the exploitation of on-farm irrigation systems and water distribution between water users.