The article discusses the impact of nutrients from sewage on the state of the sewage receiver. Bioremediation was carried out through the use of effective microorganisms. The potential recovery of valuable mineral and organic substances in the form of fertilizers was also examined. The Słoneczko Reservoir is a bathing area and serves many people in the summertime as a place of water recreation. Water quality deteriorated intensively from 2006 as a result of illegal wastewater discharge and the impact of fecal pollution from bathers. The high concentration of nutrients in the water was the cause of the eutrophication process and blooms of cyanobacteria, which pose a threat to human health in the bathing area. The bathing area was also closed many times by sanitary services as a result of exceeding the number of Escherichia coli and Enterococcus faecalis in the water. At the bottom of the reservoir, there was a layer of sediments with a thickness of 30–70 cm. Thus, the processes of anaerobic decomposition generated odor, causing nuisance in the reservoir area. Water transparency varied from 30 to 50 cm, due to the accumulation of suspensions and biomass of planktonic algae. The reservoir was subjected to microbiological bioremediation in 2017 and 2018 to polluted water treatment and to reduce the organic content of bottom sediments. Already after the first application of biopreparations putrefactive odors and the eutrophication process disappeared at the end of the 2017 summer season. Bioremediation reduced the value of E. coli and E. feacalis to the acceptable level. After the second application in 2018, the organic fraction of the bottom sediments was reduced to a very low level and the water transparency reached the bottom (maximum depth was 2.2 m) throughout the entire bathing area. The effect of the water remediation was maintained until 2019, and the surface water quality remained at a very good level. An important aspect in this case is also the exploitation of bottom sediments, because they are rich in nutrients and organic matter, and therefore it may have some potential as a fertilizer. The recovery of nutrients can be used in plant or pot production. However, they contain compounds that degrade quickly, causing unpleasant odors and threatening the environment. Thus, they should be managed and handled in an environmentally friendly and sustainable way.

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For most underground hydraulic structures it is possible to determine only approximately by static calculations the necessary dimensions and safety factors; therefore, experimental investigations usually are carried out to substantiate the design. Along with field investigations model studies are widely used, the virtues of which lie in the possibility of controliing the loads, separately studying different factors, and repeating the experiments. The most common methods of model investigations of underground hydraulic structures at present are the polarization optical method of determining stresses (photoelastic method) and method of equivalent materials.Model investigations of underground structures at the OrgenergOstroi Institute showed that the best results can be obtained with the combined use of the methods of photoelasticity and equivalent materials. It is expedient to use the photoelastic method to investigate a structure in the elastic state in order to obtain relations between stresses and loads and other factors under conditions corresponding to the design scheme. When testing models of equivalent materials it is possible to control and correct the obtained results with maximum approximation to full-scale conditions and by loading the model to failure. Of particular interest are the studies presently underway at the Orgenergostroi Institute to develop test stands on which elastic models of tunnel linings are placed in a medium of equivalent materials simulating rock. Such modeling permits investigating the joint behavior of an underground structure and the rocklenclosing it under conditions close to natural.The methods and effectiveness of model investigations of underground structures of hydroelectric power stations carried out in recent years at the Orgenergostroi Institute can be illustrated by the following examples. Selection of Design and Investigation of the Mutual Influence of Pressure Tunnels of Hydroelectric PowerStations. The investigation by the photoelastic method was carried out to obtain comparative data on the stress state of round and horseshoe linings for a 15 m tunnel with a head of 10 gauge arm at a thickness of the reinforced concrete of I m in rocks with a modulus of elasticity of 150.000 kg/cm z. Another problem of the investigation was to check the correcmess of the designated size of the unexcavated block between parallel pressure tunnels (Fig. 1). As a result of the experiments it was concluded that it was expedient to adopt in this case a circular tunnel (Fig. 2) and it appeared possible to reduce the size of the block from that designed.Investigation of Problems of Selecting the Cross-Sectional Shape of Pressure Tunnels. Comparative experiments by the photoelastic method were carried out on models of round and horseshoe linings under different loads and a variable ratio of the moduli elasticity of the lining and rock. The area of application of horseshoe linings in pressure tunnels as a function of elastic characteristics of the lining and rock, thickness of the lining, dimen...

Aim of the study: The study aims were to evaluate the aeration process and MBBR bioreactors operation in the bioremediation process of polluted water reservoirs. Material and methods: The authors presented a review of water reservoir revitalization methods used in industry practice. Fine and microbubble aeration systems are subject to detailed characteristics. There is described the role of innovative mobile platform systems with MBBR bioreactors in the revitalization of water reservoirs in the article. Results and conclusions: Based on the presented scientific information, it has been indicated that the use of effective microaeration and fine bubble aeration systems has a very positive effect on the improvement of the efficiency of revitalization processes. The authors assessed that the indicated methods can only support the main biological method used in the bioremediation of degraded water bodies. The main methods of biological bioremediation was biotechnological methods based on microbiological biopreparations and the formation of eco-barriers (ecotones). A diagram of a prototype rehabilitation platform for water reservoirs is also presented.

Aim of the study: The work aims to assess the possibility of the application of selected types of biological beds to support the revitalization processes of strongly degraded water reservoirs. Material and methods: The authors reviewed the literature on biological methods used in the treatment processes of various types of wastewater. Certain types of beds have been selected that show tolerance to temperature changes and significant changes in organic pollutant loads. The self-purification potential of water and the role of natural methods in the revitalization of water reservoirs were characterized. The characteristics of biological methods based on MBBR moving and fixed beds are presented. Results and conclusions: The possibility of application of selected types of MBBR moving and fixed beds in supporting the treatment of highly contaminated surface waters were assessed. Biotechnological methods based on liquid and solid biopreparations normally used in water revitalization were discussed. It has been shown that when biotechnological methods are not able to operate efficiently, it is very beneficial to start additional biological processes to improve the efficiency of the revitalization process.

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