In the present study, literature information on the functioning of the biofloc technology (BFT) system, its components, the state of the organism of hydrobionts, and water quality is analyzed. It is shown that this technology allows reducing financial costs for water treatment by 30%, increasing the efficiency of protein assimilation in the feed composition by two times, and creating a high-protein substrate, which can be further used as a component of feed for aquaculture. The BFT contains a large number of microorganisms, including photoautotrophic microorganisms (algae), chemoautotrophic microorganisms (nitrifying bacteria), and heterotrophic microorganisms (fungi, infusoria, protozoa, and zooplankton). This technology contributes to the improvement in water quality, aquaculture productivity, and hydrobionts. Despite the higher initial costs, BFT can yield higher economic profits. In this paper, the authors summarize data from many recent studies devoted to BFT. Based on the analysis of a number of studies, it can be concluded that this technology has a high potential for scaling up in industrial aquaculture.

Volumetric hydraulic drive systems are quite widespread in many industrial sectors. To determine the degree of reliability of hydraulic machines, it is necessary to conduct resource tests. The main requirement for such tests is the compliance of the load level with the operating mode of the hydraulic machine. Analysis of existing methods of creating such a load showed a significant drawback of bench tests—the lack of useful work. Therefore, a number of authors suggest the use of stands with a regenerative drive system. One peculiarity of the work of such stands is the possibility of returning part of the spent energy back to the test system. However, such systems are insufficiently studied and have significant drawbacks. The purpose of this work is to increase the efficiency of the regenerative drive system of the test bench of volumetric hydraulic machines of rotational action by improving the theory and methodology of its calculation and design. This article describes the principle of operation of the circuit of the regenerative drive of the test bench of rotary hydraulic machines. A model of the elastic-dissipative state of the sections of the elements of the hydro-mechanical drive system of the stand is also proposed, which allows for the calculation of the structural and energy parameters of the regenerative hydro-mechanical system. The main structural and functional parameters affecting the operational performance of the system as a whole are also identified. A “test efficiency coefficient” is proposed, which allows for evaluation of the energy efficiency of the test process.

Aquaponics is an integrated method of aquatic animal and plant cultivation in a closed recycling system where the wastewater from aquatic animals is purified by microbes, which transform pollutants into nutrients for plants at the end of the chain. This technology allows to the efficiency of the area to be increased by a combination of cultivated plants and aquatic animals. Aquaponics produces environmentally friendly products by reducing fertilizer use and wastewater volume, increasing the extent of reuse by up to >90%. A promising way to increase efficiency in aquaponics is to use bacterial preparations (probiotics). This will allow control of the development of pathogens in the growing system, improving water quality and the growth rate of aquatic organisms. This paper overviews the experience of using probiotic preparations in aquaponic systems. It is shown that probiotics are able to increase the survival rate of aquatic organisms, improve the hydrochemical regime in recirculating aquaculture systems, and mitigate the risk of pathogenic contamination. There are a number of problems in aquaponics that prevent it from becoming more widespread and achieving maximum productivity, including problems with optimal pH and temperature, problems with nutrient and oxygen depletion, as well as diseases caused by phytopathogens and fish pathogens. The probiotics used do not take into account the biological needs of all components of the aquaponic system. The development of probiotic preparations from soil bacteria of the genus Bacillus will allow us to create a new class of probiotics specifically for aquaponics. Such preparations will work in a wide pH range, which will allow us to achieve maximum productivity for all components of aquaponics: animals, plants and bacteria.

Introduction. At the stage of designing technical devices and performing appropriate strength calculations of metal structures, sufficiently large reserves of strength are taken, which, theoretically, exclude any failures of parts. In fact, the machines work with frequent failures. Of interest are undiagnosed failures that lead to a critical decrease in safety, especially at hazardous production facilities. It is assumed that the previously applied approaches of selective determination of the maximum (minimum) reliability value, based on point estimates of the distribution parameters of the two-parameter Weibull law, lead to an overestimation of the calculated indicators of the probability of failure-free operation, i.e. underestimation of risk. Therefore, the work objective is to consider an approach to assessing the risk of operating production facilities in a situation of accidental occurrence of dangerous and undiagnosed failures in systems.Materials and Methods. Methods for technical devices safety assessment based on probability theory were used in the work, and the probability of machine failure was determined based on the well-known method of reliability theory. This method consists in calculating and constructing distribution functions of random variables (load-bearing capacity and loading) that influence the occurrence of failure. The level of increase in the reliability index was determined, leading to frequent unpredictable failures of technical devices (machines) and a decrease in the safety of their operation.Results. The signs of inconsistency of strength calculations based on overestimated safety margins, which in theory exclude failures of parts and machines in general, are identified and substantiated. A new approach to risk assessment of operating production facilities in a situation of accidental occurrence of dangerous and undiagnosed failures by safety systems has been developed and implemented. An algorithm for determining the three parameters of Weibull's law for a population based on sample data has been developed. The resource distribution densities of the boom of the single-bucket excavator EK-14 are constructed. The recommendations are given to increase the probability of failure-free operation to 0.9989.Discussion and Conclusion. The results of the conducted research allow us to substantiate a new approach to risk assessment of operating production facilities in the event of dangerous and undiagnosed failures of basic parts by safety systems, leading to negative consequences.

Introduction. Under designing, a large safety margin of components and units is included at the calculation stage, which does not exclude premature failures that occur at random. The consequences of such failures are not only economic losses, but also threats to the safety of people and the environment. In modern literature, the topic of assessing the reliability of machines, considered as complex probabilistic systems that take into account not only the dynamic parameters under operation, but also the processes of manufacturing the components of the system, is not sufficiently covered. Therefore, to provide for the targeted management of the reliability of machines as complex technical systems, it is required to apply the principles of cybernetics. The research objective is to study the method of monitoring the reliability of technical systems by identifying the entropy of the causes of their failures.Materials and Methods. The materials for the study were statistical data on machine part failures obtained through long-term observation of the working condition of basic parts of lifting-and-shifting machines, as well as road and construction machines. The paper used mathematical statistics and probability theory — a parametric method for assessing reliability with a simplified approach, which assumes the deterministic behavior of the machine as a system with a predetermined functioning that does not depend on external circumstances. The value of the safety margin is taken at a level greater than one.Results. The degree of impact of the uncertainty of the reference values of the operating process, design features, manufacturing technique of machine parts and the malfunctions that occur in them, on the final probability of failure-free operation and reliability of machines is determined.Discussion and Conclusion. The analysis of the theory of verification calculations of machines confirmed the compliance of the obtained results with regulatory requirements. The conducted studies have proven that machines are deterministic systems, whose behavior is specified in advance by the calculation. Therefore, it can be argued that the developed method of monitoring the reliability of technical systems, based on identifying the entropy of the causes of failures, will allow establishing a quantitative and qualitative relationship between the design, material, size, manufacturing technique of machine parts, and failures that occur in them.

The use of antibiotics in aquaculture is associated with significant environmental risks, including ecosystem disruption and the accumulation of antibiotics in reservoirs and soil cover, as well as the spread of antibiotic-resistant strains, which encourages the search for sustainable alternatives, such as probiotics. This review summarizes the research results on the use of probiotics in aquaculture systems. Special attention is paid to the action mechanisms and diverse effects on the health of aquatic animals, water quality and, most importantly, on the properties of soil in ponds. The research results show that certain strains of probiotics, in particular Bacillus spp., effectively decompose organic substances in sediments, reduce toxic metabolites’ concentration (ammonia, nitrites, hydrogen sulfide), stabilize soil structure, improve aeration and regulate sediments’ pH level and microbial diversity. However, the efficacy in field conditions can vary. Probiotics represent a science-based strategy to reduce dependence on antibiotics, increase system resilience by improving soil and water conditions, and increase productivity. In order to achieve maximum results, it is necessary to optimize the application methods, whilst taking into account local environmental factors.