The article highlights the origin and development of forestry, forest science and forest education in Imperial Russia, as well as the main milestones in the development of the St. Petersburg State Forest Technical University named after S.M. Kirov (hereinafter – University) in different periods of history. The contribution of teachers and students of the University to the defense of the country during the First World War is described in detail. Using the example of the post-revolutionary history of the University, it is shown how a compromise was found between the Soviet government and the scientific elite in 1917–1922. The transformation of a single-faculty institute into a multidisciplinary Forestry Academy made it possible to strengthen its leading position in the era of "industrialization". The Leningrad blockade period became a special page in the history of the University. Considerable attention in the article is paid to the scientific achievements of scientists and the preservation of the continuity of scientific schools. The article also describes the modern structure of the University and the planned directions of development.

Data on the structure and phytomass of vegetation on the fires of 13-15 years ago are presented. The objects of the study are located in different forest areas of the forest fund of the Republic of Karelia. On the site of the former lichen pine forest, young trees with a predominance of pine and birch are formed at the research objects. Admixture of other species – spruce, aspen and gray alder is represented by single individuals. Differentiation in height and age of all forest-forming species is clearly expressed. The range of height variation is 0.1-5 m, the age variation is from 3 to 17 years. The undergrowth is represented by a small number of species with a total number of 350 copies/ha. The composition of the undergrowth as a percentage is 65 Rowan, 25 Willow, 5 Shadberry, 3 Juniper, 2 Honeysuckle. After a forest fire, a living ground cover was formed at the research sites, including more than 21 species. In the composition of the grass-shrubby tier, heather, cowberry, tussock-grass, reed grass and in the composition of the moss-lichen tier – in one case, green mosses, – a protective coating of 60%, in the other – polytrichum juniper, a protective coating of more than 31%. The total phytomass of living ground cover in the experimental plots was 2156 and 2623 kg/ha. The data obtained can be used in the design of forestry measures on fires of various ages. Data on phytomass of scientific and practical importance are the basis for compiling tables of plant yields by species. The purpose of the study is to establish the species composition and structure of all components of phytocenoses formed on burning, and to determine the phytomass of living ground cover by species.

Soils, which are out of agricultural use, have a high potential for the formation of productive coniferous forest plantations. It is necessary to validate which stands will be more effective not only in terms of timber volume, but also in terms of quality  increasing its density. In this regard, we conducted a study of the influence of the stand composition in mature stands with the predominance of pine and spruce on the indicators of their wood density. The question was considered under different conditions of local growth  on old-fallow lands and on forest soils. A series of sites with different participation of the main forest-forming species was identified, where taxation data and wood samples were collected. Then, after conducting an analysis of the basic wood density, the resulting volume of data was processed by means of mathematical statistics. Transition from sample wood density to trunk wood density was carried out using conversion equations. The analysis showed that on forest soils, the variability of coniferous wood density by stages of stand thickness is less than on old-fallow soils, which is due to the smaller length of the diameter classes range representation of both spruce and pine in these plantations. The indicators of wood density in stands on forest soils in the spruce part of the stand is generally lower than in the pine part on all study sites, regardless of the share of participation of the species. For stands on former old-fallow land, the opposite trend is generally observed. Analysis of variance showed that for the spruce part of the stands on post-agrogenic lands, the share of its participation in the composition significantly affects the wood density, and for the pine there was no statistically significant difference between the experimental sites. Thus, on post-agrogenic lands, pine, regardless of stand composition, forms a more homogeneous wood density than the spruce part, but smaller in value than on forest soils. For stands of pine and spruce growing on forest soils, analysis of variance showed a significant dependence of wood density on stand composition for both pine and spruce. On old-fallow lands, more favorable growing conditions neutralize the influence of the spruce forest element on the pine part of the stand, but lead to the formation of wood with lower density compared to stands on forest soils.

The aim of the study is the comparative assessment of Norway spruce plus trees based on the analysis of rank dynamics of their seed progeny in progeny tests for subsequent allocation of plus trees to the elite category. Progeny tests of the European spruce established in 1976 on the area of 4.2 ha in Quarter 161 of the Gostilitsy subdivision of Lomonosovsky Forestry of the Leningrad Region are discussed. The diameters of the trees and heights of the plants at the age of 24, 36, and 46 have been measured. The dynamics of changes in the ranks of plus tree families during the age periods under study have been analyzed. Families that dominated in the growth rate at an earlier age turned out to be among the best at the age of 46. In the vast majority, such families do not go beyond the top third of the rank distribution list of the diameter average values during the whole growth period. By the age of final assessment, the slow-growing families included those the growth rate values of which in the preceding age periods were no higher than the population average. It is noted that in terms of rank position, the group of families with average growth rates is the most variable part of the stand under study. Based on the measurements, recommendations are given for the allocation of part of the plus tree families growing at the plot into the elite category, which will allow in the near future elite production of European spruce seeds in the Russian Federation.

The article touches upon the overgrowth of developed sand quarries in the conditions of the Western sibirian north taiga plain forest region. On the basis of the trial plots? Quantitative and qualitative indicators of undergrowth formed in the depleted sand quarries were established. It has been established that the process of natural overgrowing stretches for a long period. Even 35–40 years after the cessation of sand mining, the amount of undergrowth on most the trial plots is not enough to transfer the quarry to the lands covered with forest vegetation. The reasons for slow overgrowth of a quarry in woody vegetation is overblowing of the sand by the wind the low fertility of the sandy substrate and the lack of seeds. To accelerate the overgrowth process it is recommended to cover the surface of the worked-out quarry with a layer of plat sand mixture of 15–20 sm, as well as to fix the sand by sowing and grass planting. With a distance to reliable of more than 100 m, it is advisable to carry out a ball range of reclamation works including the surface covering with a layer of plat sand mixture as well as creating forest plantations of pine. A combination of natural and artificial reforestation well minimize the cost of land reclamation and will accelerate the involvement of disturbed lands in forestry turnover.

The article discusses the complexity of the configuration of the boundaries of open public green spaces (OPGS) of St. Petersburg, which is considered as the most important parameter of the territory along with its area. The complexity of the configuration is assessed in order to improve the preparation of tasks for the design of public green spaces. As initial data, information about the OPGS was taken from the regional geoinformation system of St. Petersburg, then the data were processed in the QGIS program. The article clearly shows exactly how the configuration affects the design solution and the planning structure, and what significance it has for landscape design. The complexity of the configuration is estimated by comparing the length of the boundaries of the OPGS with the perimeter of the reference figures – a circle and a rectangle with an aspect ratio according to the rule of the "golden section". It is shown that the choice of a reference figure does not significantly affect the assessment of complexity. For the calculated configuration complexity coefficient, Jenks natural breaks optimization and clustering based on minimizing the sums of intra-group variances of neighboring clusters (MSIV) were used. It is shown that the use of the MSIV algorithm is preferable. For each of the selected classes of configuration complexity (simple, advanced, complex, very complex), visual illustrations and descriptions of the essential features of the figures belonging to the classes are given. In the conclusion of the article it is shown that the proposed complexity classes make it possible to divide all OPGS into ordered groups, that the complexity of the configuration is often caused by formal reasons. The results of the study led to the conclusion that simple configurations (Class 1) and very complex configurations (Class 4) require noticeable differences in the use of design techniques and, as can be assumed, the conditions for the maintenance of objects.

The history of the study of growth and productivity of stands is characterized by the constant development of new models that improve and complement the previous ones. The purpose of the study is to develop empirical models of the dynamics of the basal areas and stocks of pine plantations of different initial density based on the materials of long-term observations on permanent sample plots. The object of the study was pine cultures on permanent trial plots of the Forest Experimental Station of the Russian State Agrarian University – Moscow Timiryazev Agricultural Academy. To modeling the dynamics of the basal areas and stocks, an additive model was used based on the Weibull probability density function, the parameters of which are expressed linearly from the initial density. The dynamics of stand indicators in each forest stand is individual, and it is influenced by many internal and external factors. Due to the heterogeneity of the action in space and time of environmental factors in the dynamics of stand indicators, deviations from monotonous curves appear, which indicate the presence of self-regulation mechanisms in populations of woody plants with the passage of forest stands through several stages from a stable to an unstable state. The tables of the course of growth do not reflect the dynamics of stand indicators of actual forest stands and cannot be used for its forecasting. It is impossible to present in tabular form the whole variety of trajectories of stand dynamics that are possible in nature. The tables of the course of growth of normal stands contain information on the limiting values of the basal areas and stocks, but plantings cannot be in such an unstable state in nature for a long time. The life cycle of a forest stand is a wave-like process of the dynamics of stand indicators, due to different intensity of the impact of both internal (manifestation of self-regulation in tree communities and feedback loops) and external factors. To model the nonmonotonic dynamics of forest stand indicators, it is possible to use models obtained by summing several simple growth functions or nonmonotonic ones with one maximum point.

The article is devoted to a little-studied period in the history of the lands belonging to Pargolovskaya manor, located in the northern environs of St. Petersburg, on the route of the ancient Vyborg road. The early history of the famous manor is considered in the context of a general history of reclamation of the North-East coast of the Gulf of Finland in the first half of the 18th century which was closely connected with construction of the «Sestroretsk factories» and giving them vast forest lands for permanent use in accordance with the Tsar Peter the Great decrees of 1719 and 1720. The article presents the results of archival, bibliographic, historical and landscape research carried out with a considerable amount of primary sources, most of which have been researched for the first time. Among the new data is the list of owners of the Pargolovskaya manor in the 18th century, which was opened by R.K. Areskin and L.L. Blumentrost, the Tsar Peter the Great's personal physicians, and the documented date of transfer of the land estate to the Shuvalov family, which is a subject of much discussion among historians and local historians of St. Petersburg. Particular attention is paid to previously unpublished plans of the Pargolovsky estate of 1747 («Mordvinov's Plan») and 1799–1804 («A reduced plan of Disputable and Uncontested parts» of the factory forests). The revealed plans are analysed and compared to the well-known plan of the Pargolovskaya manor of Count A.P. Shuvalov («Okunev's Plan») of 1770. The paper resulted in an attempt to trace the regularity of changes in territorial and spatial organization of the Pargolovsky estate, which throughout the 18th century underwent transformation from modest «economic» estate of the Tsar's personal physicians, two-thirds of which were forests assigned to the «Sestroretsk factories», to one of the most respectable noblemen's estates near St. Petersburg.

The indicators of the development of the European spruce bark beetle in the outbreak foci of the Roshchinsky forestry have deteriorated significantly. The average energy of reproduction in 2022 was 1.5 (in 2021 for different generations – 6.0 and 4.7). The same indicators were typical for the spruce forests covered by the outbreak in 2022 with the expansion of the area of the outbreaks. The population density has increased. The bark beetle stock decreased to 400 thousand individuals/ha in the 2021 outbreaks and to 1300 thousand/ha in the 2022 outbreaks high and possibly higher. Some model trees died as a result of exclusively additional feeding of the European spruce bark beetle, which passed through the entire area of the bark from the base to 5 m in height and, possibly, higher. The colonization and successful development of the second generation are marked on the model trees. In some cases, the development of the second generation occurred simultaneously with the third sister generation, while in others only the development of the second generation was observed. The development indicators of different generations did not differ significantly. The 2022 growing season was significantly colder than the previous year. Nevertheless, the second generation, as well as in 2021, has been quite successfully formed. Populations of the European spruce bark beetle steadily switched to a development combining monovoltine and bivoltine variants. Previously, such a phenomenon in this geographical area was not observed. The transition to the bivoltine model of development of the typographic bark beetle in the Leningrad region corresponds to the same process taking place in the Scandinavian population of the European spruce bark beetle. The appearance of bivoltinity increases the likelihood of large-scale outbreaks of reproduction of this pest. Despite some expansion of the area of foci, it can be assumed that the outbreak will end in 2023. However, continuation or recurrence of the outbreak after a short period of time is likely with an increase in temperature in the first half of the growing season, the formation of windblows, and the intense impact of anthropogenic factors.

Studying of complex relations between forests and game animals is actual and necessary to save forest biodiversity. Concerns forestry management in the relation of game species is necessary to define and proof the concept of the term by law. Plans of increasing (staying at a certain level, decreasing) of number of game animals should be based and provided with conformed forestry actions. The regional system of forestry actions is a complex of mutually conditioned actions, united by the main forest use and hunting enterprises aims, concerning silvicultural characters of wood species, forest groups, natural and economical conditions of forestry areas or districts, based on a specific technical level and guaranteed forest reproduction and sustainable forestry in case of their realization. Forestry management of game animals is a system of forestry actions aimed at population’s management of game species. A strong example of forestry management of game animals can be a situation with young pine trees, damaged by moose. According to the present number of moose such damages can be seen everywhere. It isn’t possible to plan increasing of ungulates (the moose, red deer etc.) without planning to increase feeding grounds for them. Otherwise, this increasing of ungulates damages forests. It will be necessary to increase areas of the cultures of young pine stands to increase the moose number. The author offers to name these cultures as «fodder young pine stands».

A dynamic model of the "operator-feller-buncher machine-object of labor-tree" has been developed. The mathematical description is in the form of the Lagrange equation of the second kind. The system of equations is solved for the elastic deformation of the operator's seat back by the Runge-Kutta method, using the MathCAD programming environment. Approbation of the model was carried out on the example of commercially available feller-bunchers machines LP-19A.

About 120 thousand hectares of forest are cut down in our country every year, so it is necessary to carry out artificial reforestation. The level of mechanization of sowing and planting forests is low – 22%, and in order to increase it, it is necessary to develop new and improve existing forest planting machines. The development of structures and mathematical apparatus should be carried out using domestic software. To determine the parameters of the forest planting apparatus, it is necessary to determine the movements of its links. In this work, domestic software was used. A three-dimensional model of parts and assembly of a forest planter was modeled in CAD KOMPAS-3D. A simulation model with geometric parameters obtained from a three-dimensional model was made in the SimInTech dynamic simulation environment. A simulation experiment was carried out in SimInTech, the trajectories of the studied points of the gripping mechanism were determined, taking into account the furrow profile, feed rate and geometrical parameters of the structure. The simulation model also includes a requirement for the quality of the machine, namely, maintaining a zero gripping speed relative to the ground when planting seedlings in the soil. The developed simulation model can be integrated into the control device to adjust the disk rotation speed when the machine feed speed changes, as well as to match the speeds with the seedling feed mechanism.

It is difficult to evaluate the efficiency in a non-stationary mode, which is typical for the operating conditions, as the loading and speed modes are constantly changing, and the value of mechanical losses in the friction pairs is also changing. In this case, it is advisable to evaluate the efficiency with regard to fuel and power consumption for mechanical losses in friction pairs, that is, according to indicator parameters – the specific fuel consumption and indicator power. The value of the hourly fuel consumption and the average indicator power depends on the design parameters of the tractor, the size of the transported cargo, the average speed and operating conditions. The character is determined by the transfer function U(s) – the dynamic characteristic of the engine speed. Guaranteed by the manufacturer of the engine, the hourly and specific fuel consumption and power differ from the actual values at operation of the tractor in the whole range of loading and speed modes. Experimental researches of different types of engines with the subsequent approximation by analytical expressions of amplitude-frequency characteristics of crankshaft rotation frequency have allowed to receive a transfer function of rotation frequency, which in turn gives an opportunity to consider mechanical losses in engine friction pairs in a non-stationary mode at estimation of economic efficiency of a forestry industrial tractor.

The issue of expanding the range of road-building materials used on forest roads is one of the most critical in the Russian Federation. This fact is connected with both the environmental and economic aspects, as well as with the wide geography of the country. A significant part of the forests are located in the permafrost zone, which requires the availability of materials with higher performance characteristics. The study considers the use of nepheline sludge as an alternative mineral binder in order to improve the physical and mechanical characteristics of the material for the construction of forest roads. X-ray phase, chemical, granulometric analysis of the material was carried out, as well as the study of the effect of the fractional composition of nepheline sludge on the physical and mechanical characteristics of the material. The materials presented in the study comply with standard in terms of their physical and mechanical characteristics.

The aim of the study is to develop a classification of wheeled forwarders, taking into account an extended list of operational characteristics. The material for the classification is the information provided via official websites of manufacturers Ponsse, Rottne, Komatsu, John Deere, Ecolog, HSM. In total, data on 39 forwarder models with were used for the analysis. The proposed classification bases on the results of the objects clustering using k-means method. For the clustering, the main components obtained as a result of a linear transformation of the original feature space were used. The calculations were performed in Maple 2017 program. Based on the data obtained, it is proposed to subdivide the forwarders into 4 classes, taking into account the values of 14 operational parameters, with the following approximate values of the main ones: “light forwarders”, weight of the machine is 11–15 tons, with a carrying capacity of 7–11 tons; engine power is approximately 120–130 kW, machines are equipped as standard with wheels with a tire width of 500–710 mm with a diameter of 1171–1340 mm; «medium forwarders», the weight of the machine is 15–20 tons, with a load capacity of 9–15 tons; engine power from 120 to 210 kW, machines are equipped as standard with wheels with a tire width of 600–710 mm with a diameter of 1171–1340 mm; «heavy forwarders», the weight of the machine is 19–24 tons, with a carrying capacity of 14–20 tons; engine power from 190 to 240 kW, machines are equipped as standard with wheels with a tire width of 710–780 mm with a diameter of 1340–1525 mm; «especially heavy forwarders», the weight of the machine is 22–29 tons, with a carrying capacity of 18–25 tons; engine power from 200 to 240 kW, machines are equipped as standard with wheels with a tire width of 710–780 mm with a diameter of 1340–1525 mm.

To analyze surface phenomena during the formation of adhesive joints, the mutual arrangement of pores on the wood substrate and the depth of penetration of liquid glue into wood, electron microscopy methods, atomic force and scanning tunneling microscopy are used, which make it possible to assess the influence of factors characterizing the interaction between liquid glue molecules and a porous surface. wood. An effective way to improve the quality of plywood that meets the requirements of the consumer is to modify its binder, i.e. purposeful change in physicochemical properties, technological and operational indicators, and often giving special specific properties to synthetic resins. The use of electron microscopic methods, atomic force and scanning tunneling microscopy will allow a comprehensive approach to the study of adhesive joints in general, and in particular to the description of the processes that occur at the stage of formation and destruction of an adhesive joint. The nature of the SEM images indicates the interaction of liquid adhesives modified with cellulose production wastes with wood, the penetration depth of the adhesive is 20–30 μm, which is consistent with the general concepts of the molecular adsorption theory of liquid polymers in interaction with wood. Due to the effect of consolidation, the practical application of the theory of fractals in the production of glued materials, in particular plywood, can be as follows: an increase in the strength characteristics of plywood based on modified urea- and phenol-formaldehyde adhesives is explained. The adsorption capacity of porous bodies (in particular wood) with respect to molecules of different sizes (free formaldehyde, water) will be determined by the fractal dimension of the pores, due to the molecular sieve effect, shungites, as a representative of a wide group of zeolites, absorb free formaldehyde of the urea-formaldehyde oligomer, thereby reducing its content in the finished product. Considering the macrostructure of the adhesive joint, it can be imagined that in the frozen state, the adhesive layer formed without heating is subject only to additional compressive stresses from cell cavities filled with water, while in adhesive joints formed during heating, the adhesive-wood zone, which includes themselves as well as cell cavities, weakened by the additional pressure created in them.

The purpose of the work is to substantiate the use of a less energy-consuming circulating lubrication system consisting of two options for installing rotameter blocks. Compact (rotameters are installed in one block on the front and drive side of the drying section) and distributed (four rotameter blocks are installed on the front and drive side of the drying part). To achieve this goal, the following tasks were solved: measurement and analysis of the temperature of the operating compact system of circulating lubrication of drying cylinders and grid-carrying shafts of the drying section; calculation of the length of pipes of small internal diameter dv = 8 mm of oil supply from the rotameters to the bearings of drying cylinders and grid-carrying shafts of the operating (compact) and grouped drying part of rotameter installations; determination of the loss of the amount of heat carried out by the circulating oil from the zone of the heat-insulating hood of the drying part with a compact and distributed in groups of the drying part of rotameter installations. Experimental studies have established that the oil temperature in the pipes, with a compact installation of rotameters, increases in the area from the entrance to the zone of the heat-insulating hood of the drying part to the entrance to the bearing supports of the drying cylinders and cloth shafts by 27...29 C and reaches an average of 67 C. The estimated length of the oil supply pipes to the bearing supports when the rotameters are located in front of the drying groups is shorter than the same length of pipes with a compact arrangement of rotameters by 1501.52 m. Reducing the length of pipes in the zone of the heat-insulating hood of the drying part, with a steady operating mode, significantly reduces the heating of oil and the removal of thermal energy from the drying zone of the paper web. The calculation of the reduction in the amount of heat carried out from the boiler part when the rotameters are arranged in groups in comparison with the compact arrangement is performed. It was found that during an hour of operation of the drying part, the amount of heat carried out by heated oil is reduced by 74844 kJ.

To reduce the toxicity of particle boards, urea-formaldehyde resins with a low molar ratio of formaldehyde to urea are used, – 1.0 or less. Plates based on these resins have reduced strength and water resistance and increased pressing time. These shortcomings are explained by the features of the new resins. In the oligomer molecules, formaldehyde binds to urea by predominantly methylene bonds, and contains a small number of hydroxymethyl groups necessary for curing the resin. Since there is a little amount of free formaldehyde in the resin, – 0.05...0.10%, the hardener is forced to react with hydroxymethyl groups. Oligomer molecules without hydroxymethyl groups become unstable in an aqueous medium and precipitate. The oligomer, which is notsoluble in water, slows down significantly the curing process of UFR. In addition, it is not involved in the formation of a spatially cross-linked polymer and the formation of adhesive bonds. New resins contain a lot of unbound urea. An aqueous solution of urea has a weakly alkaline character and neutralizes part of the hardener. To eliminate these shortcomings, it is proposed to use the addition of formaldehyde in the form of its aqueous solution – formalin. It must protect hydroxymethyl groups and increases the amount of acid formed. The curing time of industrial resin with a formaldehyde to urea ratio of 0.85:1.0 with a modifier content of 1.0% is reduced from 63.2 to 38.0 s or by 39.9%. Particle boards on this resin with 1.0% formaldehyde in the hardener have increased strength and water resistance compared to plates without additives. The content of formaldehyde remains at the same level, – 5.68 against 5.70 mg/100 g. Tensile strength perpendicular to the plate layer increases by 30%. This is due to the acceleration of the heating of the inner layer of the plate, which is carried out as a result of the mass transfer of steam and gases. In aqueous solutions of acids, free urea is unstable and begins to decompose when heated above 50 ° C into ammonia and carbon dioxide. Provided that the content of the binder acid increases, this process is accelerated. When the plates are pressed at a temperature of 210...220 C, water vapor is heated to a maximum of 130 ° C, and gases – to the pressing temperature. Moreover, the steam moves into the carpet of the plate step by step, condensing on cold chips. Heating with gases is more effective. The invariability of the toxicity index of the plates is explained by the fact that the residues of free formaldehyde are bound to urotropin by ammonia formed from urea. A formulation and technology for the synthesis of an innovative urea-formaldehyde resin with a mole resin has been developed. The ratio of formaldehyde to urea is 0.9:1.0. Plates on this resin with 1% formaldehyde in the hardener have a formaldehyde content of 3.7 mg/100 g. This meets the requirements of emission class E0.5.

According to the latest studies, 24% of the currently available opportunities to reduce energy consumption in the production cycle of pulp and paper enterprises, as well R&D, are in the rebuild of design, technology and the correct configuration of equipment and related systems of the dryer part of the paper machine. Conducted thermotechnical studies suggest that in order to obtain the maximum productivity of the paper machine and minimize the specific heat consumption for drying paper, it is necessary to redistribute the cylinders into steam groups in accordance with the drying periods and ensure the redistribution of the steam flow across the cylinders according to the calculated steam flow. In this context, it seems reasonable to optimize drying temperatures, and there is a need for research on the effect of drying temperatures on paper properties. Therefore, the aim of this work was to study the effect of drying temperature on the strength and structural-dimensional properties of paper made from sulphate softwood and hardwood pulp. The analysis showed that an increase in the drying temperature from 80 to 140 ºС has the greatest effect on the growth of the structural and dimensional properties of paper made from a pulp with higher beating degree using both sulphate BHKP, BSKP and UBSKP as a raw material. At the same time, an increase in the drying temperature from 80 to 140 ºС has the greatest effect on the strength properties of paper (tensile strength, burst, tear) made from a pulp with lower beating degree when used as a raw material both BHKP and BSKP. Increasing the drying temperature from 80 to 140 ºС has a greater effect on the change in the structural and dimensional properties of paper, made from softwood compared to hardwood pulp, which is recommended to be considered when optimizing drying temperatures with the available fiber composition.

The article presents comparative results of scientific studies of the structural and morphological properties of the waste paper stock after flotation with preliminary wet and dry pulping. Newsprint and printed office paper were used as waste paper. It is known that these types of waste paper differ significantly in quality and price, since the paper pulp obtained on their basis differs in paper-forming properties, which are mainly determined by the morphological characteristics of secondary fibers. The pulping of waste paper by the wet method was carried out in a disintegrator, dry pulping – in a rotary-vortex mill. Cleaning of the waste paper stock by flotation was carried out on a laboratory installation by a standard method. It was found that the dry pulping of newspaper waste paper before flotation, compared with wet, significantly reduces the average fiber length from 0.92 to 0.56, while the amount of small change increases by 2 times from 2.57 to 4.82%. Dry pulping of newspaper waste paper can be recommended in the manufacture of paper products by casting using binders. With dry pulping of office waste paper in comparison with wet does not lead to a decrease in the average length of the fiber, it is 0.96 mm. With dry pulping, the amount of the shortest fraction of the trifle increases to 76%, with wet 60%, the twisting of the fibers increases (7.3 with wet – 10.7 with dry dissolution). The curvature and twisting of the fibers leads to an increase in the thickness and a decrease in the density of paper, may lead to a decrease in mechanical performance, but an increase in absorbency, therefore, dry pulping of office waste paper before flotation can be recommended for the production of absorbent types of paper and cardboard.

Chloride ions in the electrolyte significantly affect the corrosion of metals, cooking and heat exchange equipment of chemical processing of wood. Commercially produced Cl-ion-selective electrodes (Cl-ISE) with polycrystalline membranes made of pressed AgCl and Ag2S powders are chemically unstable in highly acidic media, insufficiently sensitive and selective for potentiometric determination of Cl––ions, in the presence of strong reducing agents and oxidants. The aim of the study was to determine the acid resistance and the possibility of ionometric application of Ag–ISE with monolithic membranes made of Ag–Ge (As)–S system glasses, as well as AgAsS2 and Ag3AsS3 single crystals as indicators of the end of potentiometric titration of Cl––ions in solutions of formic, acetic and nitric acids. Ion-conducting glassy materials for Ag–ISE sensor membranes were synthesized in evacuated quartz ampoules from especially pure elemental substances at 650 or 950 C and hardened in air. The acid resistance of sensor materials was determined by gravimetric method according to GOST 7343-41 in 10% aqueous solutions of НСОOH, CH3COOH and HNO3 at 17 ± 1 C for 250 h. Potentiometric measurements with an accuracy of ± 0.5 mV were carried out using an Ag–ISE electrochemical cell Ag–ISE | test solution¦1M NH4NO3 ¦ 1M KCl | AgCl, Ag. Potentiometric titration was performed using a microburet with a volume measurement accuracy of ± 0.01 ml. Homogeneous Ag+– sensor membranes made of Ag–Ge (As)–S system glasses or Ag3AsS3 single crystal are chemically stable in 10% aqueous solutions of formic, acetic and nitric acids (the dissolution rate at 17 C is less than 10 micrograms· cm–2 · h–1). Ag–ISE with acid-resistant glassy membranes Ag20Ge29S51 and AgAsS2 have a stable electrode potential and a gradient of the electrode function of 52–58 mV/ рAg at рAg = 1–5 and can be successfully used in solutions of formic, acetic and nitric acids with a concentration of up to 6 mol/ l for the determination of chloride ions by the method of potentiometric precipitation titration.