The overview of the treatment methods for chromic wastewaters has been provided. The option for removing hexavalent chromic from wastewater for improving reagent treatment method has been presented. The electromembrane process of acid and base from sodium sulfate obtaining, secondary waste treatment of chromic wastewaters after reagent treatment method by electrodialyzer-synthesizer equipped with a three-chambered unit cell has been studied. The apparatus used both industrially produced bipolar membranes and its prototypes obtained by modified industrial membranes by chromium hydroxide. It has showed that the modified samples allow to obtain a higher yield of acid and alkali, as well as to reduce the energy consumption per unit of the target product. A principal process diagram of the chromic wastewaters purification from galvanic production by implementing electrodialysis at the stage of processing stage of sodium sulfate solution has been presented.

The possibilities of using activated sludge for cleaning the soil from a number of contaminants are considered. At the same time, it was noted that the use of activated sludge is the simplest way to use microbiological technologies for cleaning the soil from various contaminants, including oil products. The technological schemes for the production of a biological product are presented.

The results of an experimental study of the effect of additives of the original and chemical by modified hydrolysis lignin on the rheological characteristics of water-based clay polymer drilling fluids are presented. The content of lignin in solutions varied from 0 to 5 wt. %. It was established by the method of X-ray fluorescence analysis, that the concentrations of toxic elements in the studied components of drilling fluids are at the level of background values and the highest static exchange capacity is observed for lignin samples converted into the sodium form during the modification process. It is shown that the introduction of modified hydrolysis lignin additives into clay based drilling fluids has a significant diluting effect. Therefore, the use of modified hydrolysis lignins as components of drilling fluids is a promising way of utilizing large-tonnage waste from biochemical plants.

An overview of the ways of handling the waste of soda slurry pits, which correspond to the scheme "utilization – obtaining a useful product based on the recovered waste", is presented. As an indirect use of anthropogenic alkaline media with a high level of mineralization, the isolation of microorganisms-producers of industrially significant enzymes, which have unique properties: increased resistance to alkaline media and a high level of mineralization is considered. The results of our own studies of biodiversity of the current and old map of JSC "Bereznikovsky Soda Plant" by the method of metagenomic sequencing are presented, the Shannon and Simpson index, reflecting microbial diversity, uniformity and degree of dominance, are determined. Bacterial cultures with amylolytic, lipolytic, proteolytic and cellulolytic activities were isolated, and the predominance of lipolytic bacteria in soda sludge and technogenic surface formations of the coastal zone, proteolytics on the soil surface of the old slurry pit site and cellulosolytics at a depth of 10 cm was shown.

Methods of increasing the activity of mineral additives from technogenic raw materials: burnt mine rocks and fly ash are considered. The kinetics of hardening of binder compositions with the addition of fly ash has been studied. By the method of microscopic analysis, the state of the microstructure of binder compositions with burnt rock was investigated at different times of hardening. The mechanism of formation of the structure of binder compositions containing additives from technogenic raw materials is described.

The method of laboratory modeling was used to determine the rate constants, half-transformation periods, temperature coefficient, and free activation energy and activation enthalpy of the reaction of biochemical decomposition of sodium dodecyl sulfate in the water of the Petrozavodsk Bay of Lake Onega at different temperatures. The reaction rate constants increase from 0.064 ± 0.005 to 0.089 ± 0.006 day^-1 with an increase in temperature from 10 to 20 °C, and the half-life periods respectively decrease from 10.8 ± 0.8 to 7.8 ± 0.6 days. Kinetic and activation parameters make it possible to calculate the rate of decomposition of synthetic linear anionic surfactants in natural water under changes in environmental conditions.

The methods for implementing the Federal Law "On the Protection of Atmospheric Air" and the Decree of the Government of the Russian Federation of 13.03.2019 (No. 262 and No. 263) on equipping stationary sources with automatic means for measuring and transmitting information on pollutant emissions to the State Register have neen considered in this paper. An assessment of the options for the use of laser technologies and devices created on the basis of their use – lidars is presented. They can simultaneously determine several pollutants and microphysical parameters of aerosols (not only concentration, but also particles size and shape).

Study outcomes of 32 heavy metals and metalloids concentrations in road dust and its PM₁₀ fraction on Moscow roads with different traffic intensity have been presented. Priority pollutants of road dust and its PM₁₀ fraction in Moscow include Sb, Zn, W, Cd, Sn, Cu, Bi, Pb, Mo; PM₁₀ pollution is up to 6 times more intense than total dust. РМ₁₀ particles mostly accumulate Sb, Zn, W, and Cd in all administrative districts, but as for the Western and South-Western administrative districts those in addition are Sn and Bi, Sn and Cd for the Central district, Cd and Bi for the Southern district. PM₁₀ particles are especially dangerous in the courtyards of residential buildings where pollution reaches extremely high levels.

The results of studies on the gross content and fractional composition of heavy metals in loamy soils of agro-settlement landscapes, soils of floodplain landscapes of the Voronezh River, as well as sandy soils on sandy terraces of forest and parkland landscapes in the zones affected by Lipetsk metallurgical complexes. It has been established that the bulk of iron in the soils of urban landscapes is represented by sparingly soluble compounds (80–96 %). A significant amount of total cadmium (15–22 %) is connected to the fraction of easily replaced and unstable compounds which determines the element high migration activity. Areas of environmental risk with increased concentrations of heavy metals have been identified which include the flood area of the Voronezh floodplain (Zn, Pb) and the pine forest park landscapes on sandy soils in the affected zone by the Novolipetsk Metallurgical Plant (Zn, Pb, Cd).

Negative impact limits on the ecosystem of the Lake Baikal identified based on an algorithm developed by the authors for determining hazardous substances to this ecosystem have been studied. The current standards of maximum permissible impacts on the unique ecological system of the Lake Baikal have been studied, this analytical review and methods of their determination has allowed to identify the necessity of their improvement. As the result of wastewater composition and properties analysis, pollutants have been established which are represented by chemical substances and microorganisms, subject to be taken into account for ecological rationing. Based on the proposed algorithm, ration limits of hazardous substances in wastewater are determined for discharging into the Lake Baikal, limits of hazardous substances in wastewater run-off whitin water bodies of the central and buffer ecological zones of the Lake Baikal territory, the permissible substances mass discharged into the depressions of the Lake Baikal. As a result of the studies, recommendations were elaborated for regulating the negative impact on the water bodies of the Lake Baikal territory and for improving the ecological situation of the Lake Baikal.

The analysis of modern technological solutions in the field of CO₂ capture (absorption, adsorption, membrane and cryogenic separation, biological processes) is presented. Methods for eliminating the impact of sulfur and nitrogen-containing components during CO₂ capture by absorption are presented. Also it was determined that CO₂ – Enhanced Oil Recovery is a good pathway of CO₂ sequestration and main CO₂ injection technologies are described.

The results of a comprehensive agroecological assessment of the main watercourses of the Zuya river basin are presented. Studies were conducted in 2017–2020 and included: conducting a visual survey, measuring water consumption, assessing the qualitative characteristics of runoff, including phytotesting and determining its suitability for irrigation purposes. It was determined that the main pollutants of the watercourses were sulphates, phosphates, heavy metals. The assessment of salt composition of water resources has shown that they are mostly suitable for irrigation without restriction. However, according to the results of phytotesting, an inhibitory effect was recorded, which indicates a possible decrease in the yield of crops sensitive to water-contained pollutants. The water balance calculations showed the presence of a shortage of water resources in the Zuya river basin. The environmental situation on the surveyed water bodies was identified as unfavorable. The set of priority environmental measures includes: the creation of a permanent monitoring network, the arrangement of settlements with water disposal systems, the inventory of small water storage facilities and the implementation of the required repair and operational work on them, and the optimization of the number of water users.