The production of agricultural products, especially livestock and aquaculture products containing high amounts of protein, has a significant impact on the environment. However, humankind cannot forego the production of such products, since a balanced diet is necessary to maintain a healthy lifestyle. In Russia, where climatic features of most regions are unfavorable for agricultural activities, industrial aquaculture has a negative impact on the environment. In order to achieve the Sustainable Development Goals and develop a cyclic bioeconomy, it is necessary to improve fish keeping technologies in RAS or open ponds using probiotic-enriched Biofloc systems designed to purify water from biogenic nitrogen. When studying the synergistic effect of the interaction of various components of floc-forming systems, the most efficient formation of flocs by individual bacterial strains was revealed. The quality of floc protein allows using activated sludge with Bacillus probiotics to obtain floc biomass, which comprehensively reduces the costs of animal feeding, due to the processing of waste products into fodder raw materials. Also, improvement of the technology will reduce energy costs for water treatment, which will contribute to the achievement of sustainable development goals.

The purpose of this article is to evaluate the categorical concept of entropy in the structure of natural and technical systems related to the use of water resources, the quantitative and qualitative indicators of which are formed within the spatial limits of river basin geosystems. Using fundamental basic concepts as a universal measure of the forms of motion of matter – energy, time, system, system approach and important concepts – irreversibility, ecological state, environmental safety, as well as fundamental laws of thermodynamics – conservation and changes in the zones of influence of the “Object of Activity” in the form of a complex of hydraulic structures and associated buildings as part of natural-technical system “Natural Environment–Object of Activity–Population” (NTS “NE-OA-P”) on the use of water resources in economic and other activities, to give a detailed understanding of Entropy.