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During 2009–2011, 50 points of the Daube River Basin were surveyed. In 23 of them, seven species of Unionidae were recorded: U. pictorum, U. tumidus, U. crassus sensu lato, A. anatina, A. cygnea, P. сomplanatа and S. woodiana, which is an invasive species. Th e index of occurrence of freshwater mussels in general was 100 % in the Lower Danube River (5 study areas), 42 % in Tisa River (31 study areas), 33.3 % in Seret River (3 study areas), 36 % in Prut River (11 study areas). Th e index of occurrence of species was rather low: 24 % of A. anatina, 22 % of U. tumidus, 22 % of U. crassus, 16 % of U. pictorum, 14 % of P. complanata, 14 % of S. woodiana, and 2 % of A. cygnea. U. crassus was not found in the Lower Danube river, while A. cygnea was found only there outside the main watercourse. Th e invasive species S. woodiana occurred in the Lower Danube River and in the sub-basin of Tisa River (with 83 % and 20 % frequency, respectively. Th e mean values of population densities ranged from 1.00 (A. cygnea) to 6.14 ind./m2 (S. woodiana), and the mean biomass varied from 1.14 (P. сomplanatа) to 797.54 g/m2 (S. woodiana).

The production of aquaculture products in closed water supply plants is becoming more widespread, and the volume of cultivation with such systems of freshwater fish is increasing. The use of closed water supply plants is the most promising global trend. When growing in closed water supply facilities, all parameters of the technological process are supported by automated devices, and the influence of natural factors on the process of the process is minimal. However, such systems require complex technological support, which needs constant improvement. When working in closed water supply plants, a precipitate is formed that needs to be recycled. It is expedient to utilize these sediments using methods that allow to receive additional heat and electricity for the needs of closed water supply plants in the production of aquaculture. On the basis of generalization and analysis of literary sources, it was found that the average value of the coefficient of conversion of mixed fodder during fattening of pigs is from 2.8 to 3.2 kg of feed per kg of weight gain. The average value of the coefficient of conversion of mixed fodder during fattening cattle is from 6.3 to 7.2 kg of feed per kg of weight gain. When growing broilers, the feed conversion rate is from 1.6 to 2 kg per kg of weight gain. The average value of the coefficient of conversion of mixed fodder during the cultivation of trout was 1.6 kg of feed per kg of weight gain, and at feeding sows – 1.2 kg of feed per kg of weight gain. The results of the development of block diagrams for the installation of closed water supply for the production of aquaculture with the provision of partial energy autonomy due to heat and electricity generated during the cogeneration of biogas generated during methane digestion of organic constituents of the sediment formed during the operation of the closed water supply system are presented.

Water, as one of the main media of human existence on earth, is the basis of the functioning of most societies. This article discusses various activities related to water resource management and analyzes the evaluation of selected quality parameters of tap water in Poland and Ukraine. The aim of the manuscript was to compare opinions on tap water quality and habits of its use in Poland and Ukraine, taking into account different seasons of the year as periods of use of supplied water. The hypothesis of the study was that tap water parameters are evaluated differently in Poland and Ukraine at different times of water supply. Due to the complexity of research aspects, a mixed-methods research procedure was used, in which a literature review was combined with a survey and statistical analysis. For the purpose of the survey, the authors’ questionnaire “Survey of customers’ opinions on selected parameters of tap water supplied in Poland and Ukraine” was created. The results of the research confirmed the hypothesis and allowed for the development a model for the evaluation of parameters of tap water supplied on the territory of Poland and Ukraine and to get to know the expectations of customers of these countries. The presented model provides practical indications that can be used to optimize water supply and meet customers’ expectations, including improvement of water quality parameters.

Wastewater from food production enterprises could have significant concentrations of total iron that must be decreased. Aquatic macrophytes, for example ?Lemna genera?, have a high potential for iron ions removal, but kinetics and treatment parameters should be qualified. The aim of the work is to increase in the efficiency of removal of iron ions from wastewater in the process of biological wastewater treatment using ?Lemna minor? and to determine rational parameters of the treatment (biomass, process duration, hydraulic load). The kinetics of the removal of iron ions from the water was studied in the batch mode of a biological reactor operation under various biomass quantities. Verification of the obtained rational parameters of the process was carried out under continuous mode conditions. The results obtained from the kinetics of the batch mode the bioreactor operation process indicate an increase in the degree of removal of ferrous ions from wastewater from 61.0% to 91.7% with an increase in the plant biomass concentration from 8 mg/L to 25 mg/L during the wastewater treatment process of 24 hours. The rational parameters of removal of iron ions from wastewater in the batch mode of the bioreactor operation are determined: biomass of duckweed is 25 mg/L; the treatment process duration is 8 hours; the hydraulic load is 0,126 L/(h?L). The purification effect was 89.8%.

The correlation between the development of a regional economy and the degree of infrastructural development of a country or its territory is a common practice. Considering this, the paper is aimed at studying the impact of water infrastructure on the economic security of regional socio-economic systems in order to develop a water security system for them. A variety of threats against key waterworks can seriously undermine the national economy and water security of regions and cities. Thus, the study analyzes the process of transformation of water infrastructure in the context of ensuring the economic security of regional socio-economic systems. It offers the definition of such categories as “water infrastructure” and “water security of a regional socio-economic system” to formulate a relevant economic policy in Ukraine based on world experience. The study proves the need to attribute water infrastructure to the critical infrastructure sectors of Ukraine and its regions, based on the best world practices in managing water resources and protecting the water infrastructure itself from technogenic, physical, and cyber-physical threats. According to the study results, conceptual bases for ensuring the economic security of regional socio-economic systems are developed, which differ in view of the water security system of the regional socio-economic system, giving priority to the engineering and technical infrastructure of a region.

Energy strategies of most developed countries include the sustainable development of all types of renewable energy, including energy generation from biomass. Co-digestion of sewage sludge and plant biomass has a number of synergetic effects leading to increasing of the digestion rate and output of biogas. The range of potentially effective co-digestion of sewage sludge with plant raw materials is considered on the example of the full-scale estimation study for Lviv WWTP, Ukraine. Substitution of the 25% of dry organic matter of sewage sludge by the same amount of plant raw matter can increase total output of the methane at the biogas station about on 5.8%.

The need to develop effective technology for the treatment of liquid effluent of dye-intensive industries such as textile, rubber, paint, and printing is synonymous with the need to save the life-threatening risks posed by these carcinogenic and mutagenic pollutants on human and aquatic lives. Isotherms of adsorption of crystal violet (CV) on activated carbon (AC) synthesized from rice husk are presented herewith to elucidate the mechanism of the adsorption process of crystal violet dye contaminated water on rice husk activated carbon. AC was synthesized from rice husk via a phosphoric acid activating agent at low temperatures. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D-R) isotherm studies were employed. The mean square values for Langmuir, Freundlich, Temkin and D-R models were 0.98, 0.91, 0.94, and 0.63, respectively. Analysis of the isotherms of the adsorption of crystal violet sorbate on the synthesized rice husk sorbent suggested that the adsorption process proceeded via a homogeneous monolayer mechanism. Langmuir isotherm gave the best fit of the adsorption process. Langmuir isotherm constant was –1.40 l/mg, and the equilibrium adsorption capacity was 13.53 mg/g.

Riverine systems act as converging pathways for discarded litter within drainage basins, becoming key elements in gauging the transfer of mismanaged waste into the ocean. However, riverine litter data are scarce and biased towards microplastics, generally lacking information about larger items. Based on the first ever database of riverine floating macrolitter across Europe, we have estimated that between 307 and 925 million litter items are released annually from Europe into the ocean. The plastic fraction represented 82% of the observed litter, mainly fragments and single-use items (that is, bottles, packaging and bags). Our modelled estimates show that a major portion of the total litter loading is routed through small-sized drainage basins (<100 km2), indicating the relevance of small rivers, streams and coastal run-off. Moreover, the major contribution of high-income countries to the macrolitter inputs suggests that reducing ocean pollution cannot be achieved only by improving waste management, but also requires changing consumption habits and behaviour to curb waste generation at source. The inability of countries with well-developed recovery systems to control the leakage of waste into the environment further supports the need to regulate the production and use of plastic on a global scale. We acknowledge the additional members (coordinators and observers) of RiLON, listed in Supplementary Data 5, for their support in the field data collection and feedback during the data quality control. D.G.-F. was supported by the JRC institutional exploratory project RIMMEL (272346), PLASTREND (BBVA Foundation) and the European Union (H2020-MSCA-IF-2018 846843 - LitRivus). J.V. and C.M.-C. were supported by the MIDaS project (Spanish Ministry of Science, Innovation and Universities, CTM2016-77106-R, AEI/FEDER/UE). Peer reviewed