Introduction. Scientific support for measures aimed at providing centralized water supply to rural settlements has been entrusted to the Department of Agricultural Water Supply of UkrNIIGiM (now the Institute of Water Problems and Land Reclamation of NAAS) since 1991. The main task of this department of the institute was to develop scientific and technical solutions for reliable supply of all consumers in rural areas with water in the required quantity, of the proper quality and with the necessary free pressure while minimizing capital and operating costs, rational and economic use of water resources and environmental protection from pollution by the wastewaters. Suggested scientific approaches: - decentralization of the withdraw processes, purification, supply and distribution of water with the splitting into drinking and technological water; - reliable supply of high quality drinking water and technological water with low cost; - creation of closed water supply systems at agricultural enterprises with minimal consumption of fresh water and use of treated wastewater for technical needs or irrigation of agricultural crops, and sludge - for soils fertilizing; - development of new water treatment technologies based on the reproduction of intensified factors of the biogeochemical cycle of water in the course of its natural self-purification in order to reduce the cost of the water treatment process and increase the barrier capacity of existing structures. - reliable protection of territories against flooding by filtrated waters from reservoirs using these waters for agricultural water supply and irrigation; - optimization of the interoperability of all interacting structures with systems to minimize the per unit energy consumption for water transportation. Prospects. One of the main fundamental theoretical questions that need further development is new approaches to filtering theory. Since the time of D.M. Mintz this research direction have been stagnated. This is especially felt in domestic developments, despite the fact that there has been a significant breakthrough in the creation of filter materials (mainly in the case of filter materials that are lighter than water, which were not used at the time of D.M. Mintz). A breakthrough in the development of measuring apparatus has also taken place, and it now allows measuring the electrokinetic and dimensional characteristics of colloids in water source and filter loading grains, which makes it possible to consider the filtration process and especially the adsorption of colloids on the surface of filter loading grains from a different angle. Conclusions. The results of scientific researches carried out in the laboratory of agricultural water supply for 28 years of its existence, and were implemented at the existing local and group agricultural water supply systems. Materials of scientific researchers are published in 4 monographs and more than 100 articles and conference materials in domestic and foreign scientific journals. The proposed solutions are patented in 46 patents for inventions. Using the research of the laboratory staff, 3 doctoral dissertations (V.P. Khoruzhyi, V.G. Novokhatnii, and D.V. Charnyi) and 14 PhD theses were defended.

Relevance of research.To increase the efficiency and reliability of the territory protection against flooding with the infiltration water of the Kakhovsky Reservoir, it is proposed to replace the low-performance ground water cutoff with an airlift water intake system for the protection of the Kamensky Pod’s area with a groundwater cutoff with a siphon intake system from wells. That will enable to increasesignificantly the efficiency and reliability of the ground water cutoff and greatly reduce the specific costs of water pumping. The reliability of the ground water cutoff with a siphon intake system is achieved by ensuring the reliable sealing of the entire siphon collecting conduit. In case of a slightest damage, there is a loss of sealing of the pipes and the water stops flowing into a drain well. The purpose of the research. To determine the best parameters of ground water cutoff with a siphon intake system from the well, in particular: - the optimal number of wells, the distance between them; - estimated depths of each wells connected to the siphon collecting conduit; - estimated water flows from each well and the decrease in the static water table in them taking into account the hydro-geological interaction between them during their collaboration; - optimal pipe diameters on each section of the siphon collecting conduit to ensure the reliability of its operation. The research methods. The research involves the use of analytical and mathematical methods, in particular: calculations, iterations, forecasting. The research results. New approaches enabling to find an optimal variant of uniform water drawdown in the aquifer along the whole length of the siphon water conduit by reducing the depths of the intake wells towards the intake well. To optimize the ground water cutoff with the siphon intake system from the wells, it is proposed to drill drain wells of different depths and place them at different distances from each other along the entire length of the collecting conduit, determining the required depth of the well depending on its diameters and vacuum value. The conducted studies as in the case of calculating the Kamyanka-Dniprovskaground water cutoff showed that the minimum depth of drainage wells depends on the diameter of the well and the vacuum value in it, and the most efficient option of all possible ones is the option when there are drain wells with different depths and they are located at different distances from each other that provides a minimum specific cost for the construction of wells and siphon collecting water conduit.

The article analyzes the ways to improve the water supply system at agro-industrial enterprises. It is stated that the Institute of Water Problems and Land Reclamation of NAAS proposed to improve closed water supply systems at these enterprises to spend water and energy rationally and economically by developing highly efficient wastewater treatment technology to reuse wastewater and its sediments for technological needs. During the work, the main tasks to be solved were the analysis of the reasons of unsatisfactory operation of traditional wastewater treatment plants and their current quality indicators and improvement of the rational technological scheme of closed water supply at the agro-industrial enterprises. Scientific and practical results were obtained by analyzing the operation of wastewater treatment plants of industrial enterprises dealing with agricultural products processing, their quality indicators and known methods of improving technological schemes of biological wastewater treatment. It was specified that traditional technology of biological wastewater treatment do not ensure the proper treatment quality, as the quality of wastewater from enterprises has significantly deteriorated due to the inflow of harmful impurities (xenobiotics, heavy metal ions, etc.) and high concentrations of organic matter, the content of which amount to: suspended solids> 1000 mg/dm3, COC> 10000 mgO2/dm3, BOC5> 6000 mgO2/dm3, BOCcomplete> 2000 mgO2/dm3, nitrogen and phosphorus ≤50 mg/dm3, which prevents the effective operation of aeration tanks. The practicability of improving the "bioconveyor" technology by downward filtration through fibrous loading in bioreactors and upward filtration through floating filter loading in contact and clarifying filters to increase the efficiency of wastewater treatment was scientifically substantiated. It was proved that this method provides high efficiency of biological wastewater treatment by reducing the amount of sediment and the absence of reverse activated sludge, and thus reducing capital and operating costs. Natural mechanisms of household sewage treatment with reuse of water and sediments when cultivating agricultural crops are used as much as possible are used in the specified system of water supply at agro-industrial enterprises. The optimal design and technological parameters of these structures are determined using the recommendations developed on the basis of our experimental research. The proposed technology of closed water supply at agro-industrial enterprises provides for the separation of water supplied to consumers into technical and drinking one, as well as supplements of sewage treatment plants with bioreactors and contact-clarifying filters. Such systems ensure a minimum intake of water from natural water sources having its preliminary treatment directly in water reservoir, maximum use of treated wastewater and protection of the environment against wastewater pollution.

Analysis of the state of water resources in Ukraine provides an opportunity to improve the ecological situation on the basis of hydrographic and water management zoning using the latest methodological approaches and technologies for constructing the water balance of the basin areas. The aim of the research is to establish patterns of change in the quality indicators of the country's water resources in the largest basin of the Dnipro River. The study was carried out on the basis of an assessment of indicators for monitoring changes in the quantitative and qualitative indicators of water resources in the Dnipro basin in 2016-2021.A decrease in the Dnipro runoff was recorded: the average long-term natural runoff at the mouth is 53.3 km3, and the actual runoff is about 11 km3 (20%) less than the natural runoff. A decrease in the quantitative indicators of water intake from the Dnipro basin in 7365 million m3, a decrease in the quantity (up to 547.1 million m3) and a deterioration in the quality of return water and the general state of water resources in the basin from the northwest to the southeast. The measurements’ results of the indicators of the waters’ qualitative state in the reservoirs and the main watercourses of the basin at the locations of the monitoring points indicate that the norms are exceeded by a multiplicity of more than 5 times, including in terms of BOD and COD, which reflect the intensity of pollution of water bodies with easily oxidizing and difficult oxidizing organic compounds. The screening of pollutants revealed the content of pesticides, drugs, antidepressants, heavy metals-carcinogens in the Dnipro water, which makes it possible to investigate the problems with water resources, taking into account the specifics of the river basin. Such an assessment shows that climate change and industrial enterprises, as notable anthropogenic component, are significant factors affecting water resources. This indicates the importance of the direction of the policy of state regulation on water monitoring, the introduction of an irrigation and drainage strategy, the construction of centralized water supply and sanitation systems and strict control over the indicators of wastewater discharge.

Relevance of research Ukraine has an urgent problem of supplying adequate quality drinking water, especially in rural areas. Only 30% Ukrainian rural areas are equipped with water supplying systems. The main sources of water supply in local agricultural water pipelines are groundwater. However, groundwater in Ukraine is often characterized with a rather high iron content, which is sometimes ten times higher than the current regulatory requirements Cn = 0.2 mg / dm3. The purpose and objectives of the study For groundwater treatment we propose to use biological methods with the placement of treatment facilities in the body of the water tower (WT), which can significantly reduce capital and operating costs. When the downward movement of aerated source groundwater through the bioreactor (BR) a transition of divalent iron into a ferric iron form occurs with the help of iron bacteria, immobilized on fibrous media, and when the ascending movement of water through floating polystyrene foam media of the contact clarification filter (CCF), it is clarified from colloidal particles of iron hydroxide due to their compressed sedimentation in the subfilter space of the CCF. Research methods. The results of laboratory research on iron reduction when water deferrization for a certain period of time are given, the technological solution for the optimization of constructive and technological parameters of WT and CCF in the absence of repeated "charging" of the filter is offered.  When a contact-clarifying filter is flushed it is recommended to leave a part of the Gmin residue, which will serve as a catalyst during the next water deferrization cycle. Prospects for research, directions for further work. We proposed a new automated water deferrization plant equipped with an elevated water tank. The advantage of it is to provide a high efficiency of biological water-based iron removal with complete automation of water filtration and filter flushing, while reducing the cost of its construction and operation.