To reduce the impact of alumina sludge storage on the environment, engineering solutions have been developed to intercept drainage waters and localize the discharge area of the groundwater horizon in the area adjacent to the sludge storage by pumping contaminated water into the circulating system of the alumina combine. It has been established that the proposed drainage water interception system provides an additional volume of recycled process water up to 28.8 thousand m³ per year due to the implementation of the function of an active hydrogeological barrier. It is concluded that drilling wells in the discharge zones of aquifers allows to obtain an environmental effect due to the organized extraction of groundwater from the sludge storage, reducing the risk of uncontrolled release of alkaline waters, preventing pollution of the water body and destruction of surface ecosystems.

Compositions of ash-and-slag mixtures were developed, and experimental pavement structures were constructed. Based on the results obtained, the possibility of using ash-and-slag waste for the construction of base layers of pavements with low traffic loads, as well as for the working layer of the roadbed under continental and polar climatic conditions, was established

In order to process titanomagnetite concentrate (Khibiny massif), optimal technological regimes were selected: temperature 80 °C, СH₂SO₄ concentration 50%, solid-to-liquid ratio 1:3, stirring intensity 400 min-1, duration 180 min. Iron sulfate was obtained from productive solutions, from which a coagulant for the removal of suspended solids was prepared. It was established that the efficiency of suspended solids removal using the coagulant reached 97.3%. A technological scheme for concentrate processing with the production of iron sulfate crystals was proposed.

Environmental aspects of the formation of technogenic formations from solid wastes of various dispersity in mountain forest ecosystems were considered. The processes of natural restorative successions of phytocenoses on the surface of technogenic formations composed of solid mining wastes with different dispersity in the mountain forest zone were investigated. Regularities and stages of qualitative and quantitative development of secondary phytocenoses preceding the process of self-restoration of the edificator synusia of initial phytocenoses are established as a necessary condition for transition to sustainable development of the natural-technogenic system in the post-operational period. The ecological expediency of accounting for the direction of restorative succession dynamics both in selecting the general structure of the solid waste storage system and in determining the parameters of individual technogenic formations is substantiated. It is shown that such transformation of methodological approaches is one of the necessary conditions for transition to sustainable development of the natural-technogenic system of subsoil use.

A technology of stepwise reclamation of ash dump No. 2 of the Reftinskaya GRES power station was developed. The possibility of purification of the ash substrate from heavy metals using a phytoremediating plant, such as willow, is considered. An assessment of the effectiveness of the selected plant for primary reclamation of contaminated ecotopes is provided. The results of studies of the chemical composition of ash from the operating ash dump No. 2 of the Reftinskaya GRES power station in terms of heavy metal content are presented, as well as the results of phytoextraction of heavy metals such as copper, cobalt, chromium, and zinc. A conclusion is drawn about the positive experience of using such plants for the initial stage of ash dump reclamation with preparation of the ash substrate for further reclamation.

Adaptation of the modified struvite precipitation process to wastewater treatment technology of complex composition was carried out. It is noted that this technology eliminates the drawback of the traditional method associated with the need to use an excess of Mg²⁺, NH⁴⁺ or PO₄^3- ions. It is concluded that the use of the modified technology made it possible to increase the degree of wastewater purification from NH⁴⁺ and PO₄^3- to 95% and higher without using their excess, and to ensure a yield of high-quality precipitate up to 98–99%.

The issues of prioritization of objects of accumulated environmental damage are considered using criteria for identifying sites where accumulated environmental damage requires priority remediation. An approach for ranking sites by priority for remediation is proposed. An analysis of the distribution of objects of accumulated environmental damage according to the developed ranks and prioritization criteria was carried out. It has been established that the main parameters influencing the classification of the objects of accumulated damage as objects of ranks 1 and 3: the location/non-location of the site within the boundaries of a populated area with city status; the population size residing in the territories that are negatively affected by the facility of the negative impact of the facility; the risk category of the harmful impact of the objects on the life and health of citizens; the location/non-location of the objects in special zones.

An analytical review of studies devoted to physicochemical processes occurring during the interaction of high-calcium ashes with Portland cement was carried out. The main phases formed as a result of hydraulic and pozzolanic reactions of basic ashes are considered. Positive and negative aspects of using basic ashes in concrete production are highlighted. It is shown that key factors controlling properties include the chemical and phase composition of ash, its dosage, and the use of activation methods (mechanical, chemical, biological). It is concluded that alkaline activation and bioactivation by microorganisms are effective for accelerating pozzolanic reactions and improving the final strength and durability of concrete.

The distribution of mass concentrations and their elemental composition by a set of chemical elements in selected territorial-production clusters of Primorsky Krai was assessed. New data was obtained on the proportion of dust from unorganised emissions formed during the storage and transshipment of bulk materials within the total composition of suspended particulates in the port city. The contribution of motor vehicles to the formation of PM10 particles was also identified. A link was established between high concentrations of copper (Cu) and chromium (Cr) and the distribution of mobile emission sources. The negative impact of the seaport on the chemical composition of suspended particles, as evidenced by high concentrations of heavy metals (V, Ni, Fe, Mn, As, Cd, Ti and Zn), was recorded.

A comparative analysis of the carbon footprint of two types of asphalt concrete mixtures – conventional hot mix and rubber crumb modified, obtained from recycled automobile tires – is presented. It is shown that the use of rubber crumb ensured a reduction in total greenhouse gas emissions by 1.46 kg CO₂-eq./t of finished mixture (approximately 2.5 %), mainly due to partial replacement of the most carbon-intensive component – bitumen. It was established that more than 83 % of the carbon footprint is formed at the stages of raw material extraction and transportation, which indicates the dependence of the environmental efficiency of the product on the choice of suppliers and logistics. It is concluded that the technology of asphalt concrete modification with rubber crumb not only complies with the principles of the circular economy, ensuring waste utilization, but also demonstrates a positive environmental effect within the boundaries of the considered system.

An analysis of long-term environmental monitoring results during the liquidation of a hydraulic structure – sludge storage facility in the Northwestern Federal District – was carried out. Specific features of sludge storage liquidation using the inert material “Arbolit-M”, specially developed for hydraulic structure liquidation and representing a non-metallic construction product based on organic plant fillers, are described. A reduction in environmental risks and cost optimization when using “Arbolit-M” is noted. Chemical and toxicological indicators of soils, groundwater and atmospheric air, as well as compliance with safety standards, are analyzed. It is revealed that pollutant levels remain close to background values, confirming the effectiveness of the selected reclamation methods.