Quantitative assessments of a number of potentially harmful factors inherent in localised plasma-electrolyte treatment (PET) were performed. The negative impact of the electrolytes used and the operation of the PET equipment on the environment and service personnel is shown to be negligible.

It is noted that at obtaining 1 kg of oxidised graphite by dichromate technology, 180.21 thousand litres of waste water containing 1394.11 kg of sulphate ions and 224.11 kg of total chromium are generated. The technology of graphite oxidation is proposed, which consists in the fact that at the stage of oxidising mixture dilution waste water with pH = 0÷1 (very acidic) from the previous graphite oxidation process, containing the highest concentrations of sulphate ions and total chromium, was used. To produce 1 tonne of oxidised graphite using this technology, 176.7 thousand litres of waste water containing 1349.15 kg of sulphate ions and 223.06 kg of total chromium were discharged to the sludge fields. It was found that the composition of waste water (in terms of sulphate ions and total chromium) remains practically constant when its volume is reduced by 6.5 thousand litres. It is concluded that graphite oxidation using waste water reduces the ecological load on the environment.

The calculation model of the liquid chlorine evaporator for the drinking water disinfection system (chlorinator) was developed, based on the solution of the system of criterion equations of convective heat and mass exchange and heat transfer, describing two stages of the evaporator working process – evaporation of liquid chlorine and superheating of the obtained vapors. It is noted that the existing normative methods of calculation of chlorinator evaporators are outdated and do not fully take into account the heat and mass exchange processes occurring in them. A good match was found when comparing the calculated parameters of the evaporator with those of the prototype. It is concluded that the developed methodology can be used in calculation and design of chlorinators of different capacity.

The results of the study of stability of activated sludge agents to periodically increasing influence of sulfide-ion concentration are presented, the toxic effect of which on flocculus-forming microorganisms causes the effect of biocenosis swelling and, as a consequence, failures in the operation modes of treatment facilities, accompanied by the removal of toxic and nutrients into the hydrographic network. The structure of the community under conditions of sulfur-containing wastewater was studied and succession of dominant agents of activated sludge — predators and protozoa — was established. It was noted that the sanitary functions of activated sludge were preserved in all experiments, which indicates the adaptation of the biocenosis to new ecological conditions.

Six biopreparations containing microalgae of the genus Chlorella and Spirulina were investigated for their possible use in utilization of carbon dioxide from industrial emissions. The adaptive abilities of microalgae to nutrient media, intensification of growth and development of the most viable culture of microalgae at increasing concentration of carbon dioxide, its resistance to the gas formed as a result of tests of power plant containing methane and the potential of this culture of microalgae in reducing the level of CO₂ in model flue gases were evaluated. It was confirmed that the biopreparation “SPIRULINAFOOD” (Chlorella sp.) has high viability and provides growth of microalgae cultures in conditions of increased content of CO₂ and methane, showing the efficiency of CO₂ removal from model flue gases comparable with the efficiency of natural consortium of microalgae – up to 15 %.

The conditions for measuring the concentrations of the antibiotics tylosin and ciprofloxacin by absorption spectra against the background of natural organic substances in soil and aquatic ecosystems have been determined. The use of pectrophotometry in combination with ecotoxicity measurement in sensitive biotest systems is proposed to be used for standardization and establishment of safe doses of antibiotics for biota in soils, manure and wastewater.

An automated system for ensuring environmental safety at the end of operation of municipal solid waste disposal facilities (MSW) is considered, which includes a subsystem for monitoring and control, as well as a subsystem for assessing environmental risks in waste disposal areas at the post-operational stage. Solutions have been developed to check the state of atmospheric air at the MSW landfill, allowing both monitoring at the "early" stages after the decommissioning of these MSW landfills and long-term monitoring.

Classification of in-situ methods of remediation of deep soil contamination with oil products is presented. The optimal calculation scheme for designing a bioventilation system was developed, which boils down to determining the radius of the aerobic influence of the injection well, taking into account the porosity of the soil, the oil pollution rate and the flow rate of the supplied air. The technology of the injection well arrangement for bioventilation was considered. The methods of intensification of bioventilation was proposed: for the territories deeply polluted simultaneously with oil products and heavy metals – preliminary treatment with solutions of humic-mineral complexes; in conditions of low oildestructive potential of native microorganisms – introduction of activated forms of biopreparations; in case of pollution at a depth of more than 20 m – equipping injection wells with turbodeflectors (in the non-vegetation period) to activate degassing of volatile organic compounds.

It presents the results of determining the individual composition of natural gas from the Urengoyskoye field by chromatographic methods, based on which the calculation of the highest and lowest calorific value, Wobbe number, gas density, hydrogen sulfide and mercaptan content at various times of the year for the period from 2022 to 2024 was performed. It is shown that during summer period the values jf the heat of combustion of natural gas, the Wobbe number and density of the gas decrease.

The assessment of the state of the Arctic urbanized territory environment is given on the basis of the data of changes in the content of metals (Na, Ca, K, Al, Sc, Fe, Mn, Cd, Cr, Cr, Zn, Sr, Cu, Ni, Ba, Pb, Co, V) in soils and plants (bark of Siberian larch Larix sibirica, Ledum decumbens, lichen Cladonia stellaris). The example of Novy Urengoy city shows the role of various types of anthropogenic impact in the pollution of urban environment, which is located in the zone of impact of urban infrastructure facilities, road and rail transport, municipal waste landfills, linear oil and gas transportation facilities. Associations of chemical elements in soils reflecting the predominant impact of motor transport (Cd-Pb-Zn-Cu-Ni) and residential development (Ca-Mn-Co-Sr) were established. Soil toxicity probability index (MERMQ), Nemerov index and total pollution index Zc were calculated, which showed low toxicity of most of the studied soils. The average toxicity of soils near major highways and toxic waste disposal site was noted. Calculations of integral indicators of pollution: LTP (Landscape Total Pollution) and BIP (Bioindication Integral Parameter) on the basis of Harrington's desirability function, which indicate a low level of pollution of the study area, were performed.

The carcinogenic risk of aerogenic nature to the health of the population of Rostov-on-Don for the period from 2008 to 2023 was assessed. The actual concentrations of carcinogenic substances contained in the surface air are analyzed, taking into account the values of parameter P, on the basis of which three districts with alarming levels of atmospheric air pollution are identified within the city. It was shown that the individual and total carcinogenic health risk of an aerogenic nature of an alarming level in all three regions was due to the presence of a combination of carcinogenic substances: formaldehyde, chromium, nickel, lead, benz(a)pyrene. The important role of weather and climatic conditions of the city, building density, traffic congestion, lack of landscaping in the formation of an alarming level of air pollution was noted. Measures are proposed to reduce the dangerous level of pollution of the city's atmosphere.