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A series of industrial experimental tests on the freeze treatment of colloidal sludge lignin precipitates was carried out under natural conditions. Changes in the physical and chemical properties of the precipitates were studied. It is established that three fractions are formed following the freeze treatment of colloidal sludge lignin precipitates, including demineralized water (up to 25 %), mineralized water (up to 15 %) and a restructured colloidal precipitate (up to 60 %). The total volume of the precipitate is shown to decrease to 40 %. Freezing precipitation of colloidal lignin slurry of "the Baikal Pulp and Paper Mill" leads to a decrease in toxicity from the third to the fifth class of danger. On the basis of frozen sediments, the lignin sludge of OJSC Baikal Pulp and Paper Mill with the addition of other waste from the Baikal region, a fertile soil was obtained that corresponds to GOST R 54651-2011 "Organic fertilizers on the basis of sewage sludge. Specifications".

The dynamics and efficiency of the use of frozen lignin-containing deposits of the pulp and paper industry and soils obtained on the basis thereof for the intensified reclamation succession of disturbed lands were analyzed. It was proved that over a four-year experimental period, an active process of self-overgrowing occurs with a change and an increase in the species diversity of phytocenoses with the stabilization of chemical and agrochemical composition of dumps of frozen lignin-containing sediments and soils as per the norme of GOST 54534-2011 “Resource saving. Sewage sludge. Requirements for disturbed lands for reclamation”.

The purpose of the present research is the inventory of the sources of accumulated contaminants at the former Vostsibelement industrial site located within the municipality of the town of Svirsk of the Irkutsk region (Russia) as well as the analysis of their impact on the environmental conditions. The conducted study included the calculation of the numerical assessment criterion of the overall impact of the accumulated environmental damage site on the state of environmental safety. On the basis of the results obtained, it was concluded that the industrial site of the former Vostsiblement factory is a source of accumulated harm, as well as an extremely environmentally hazardous site posing a potential threat to the entire upper territory of the Bratsk reservoir due to its location within the boundaries of the municipality of the town of Svirsk and the water protection zone of the Angara river. Based on the monitoring data, a geostatistical dispersion model of mobile lead in soil was constructed and anomalous contamination zones were identified. Three areas with an anomalously high content of mobile forms of lead (more than 6000 mg/kg) were identified in the soil on the territory of the industrial site of the former Vostsibelement battery factory. The content of mobile lead in the surface layer (0–20 cm) throughout the industrial site is not less than 100 mg/kg, which is 17 times higher than the maximum allowable concentration. The established excess of lead content in silverweed cinquefoil (Potentilla anserina) amounted to 10 background readings. A single point sample of bottom sediments of the Angara river at the entry of the industrial site, four meters from the water edge demonstrates an excess of the background content for lead, copper, zinc by 59, 12 and 4.7 times, respectively. The conducted research, analysis of the data obtained and review of the best available technologies allowed to introduce a concept for an environmentally friendly recuperative technology for the reclamation of the former Vostsibelement factory industrial site, which is very effective both from the technical and economic, and from the legal and social-ecological point of view. It also can be considered as an option to eliminate the accumulated harm of an extremely hazardous site.