1.3. The main processes of engineering environmental protection
Organizational and technical methods of environmental protection can be conditionally divided into active and passive.
Active methods of environmental protection are technological solutions for the creation of resource-saving and low-waste technologies.
Passive methods of protecting the environment are divided into two subgroups: the rational allocation of pollution sources; localization of pollution sources. Rational accommodation implies the territorial rational allocation of economic objects, reducing the burden on the environment, and localization is essentially a phlegmatization of pollution sources and a means of reducing their emissions. Localization is achieved through the use of various environmental technologies, technical systems and devices.
The physical and chemical essence of the main processes of ecobio-protective technologies is studied in the theoretical foundations of environmental protection technology, based on the general laws of physical and colloid chemistry, thermodynamics, hydro- and aerodynamics. This systematic approach allows us to make generalizations on the theory of environmental protection processes, apply a single methodological approach to them.
Depending on the main regularities characterizing the course of environmental protection processes, the latter are divided into physical; mechanical; hydromechanical; mass exchange, chemical; physical and chemical; thermal; biochemical; processes, complicated by a chemical reaction.
In physical processes only the form, size, aggregate state and other physical properties of substances change. Their structure and chemical composition are preserved. Physical processes dominate the crushing, grinding of minerals, in various ways of metal working with pressure, during drying and in other similar cases.
Mechanical processes based on mechanical action on solid and amorphous materials include grinding (crushing), sorting (classification), pressing and mixing of bulk materials. The driving force of these processes are the forces of mechanical pressure or centrifugal force.
Hydromechanical processes, based on hydrostatic or hydromechanical effects on media and materials, include mixing, sedimentation, filtration, centrifugation. The driving force of these processes is hydrostatic pressure or centrifugal force.
Mass transfer (diffusion) processes, in which the transition of matter from one phase to another due to diffusion plays an important role along with heat transfer, include absorption, adsorption, desorption, extraction, rectification, drying and crystallization.
The driving force of these processes is the difference in the concentrations of the transition substance in the interacting phases.
Chemical processes that occur with a change in the physical properties and chemical composition of the initial substances are characterized by the transformation of some substances into others, a change in their surface and interfacial properties. These processes include the processes of catalysis, neutralization, oxidation and reduction. The driving force of chemical processes is the difference between chemical (thermodynamic) potentials. Chemical processes change the physical properties of the raw material and its chemical composition. With their help, metals, alcohols, fertilizers, sugars and the like are obtained, which are not present in the pure form in the raw materials. Chemical processes are the basis of production in metallurgy, the chemical industry and in many other branches of the national economy. Chemical phenomena in technological processes often develop under the influence of external conditions (pressure, volume, temperature, etc.) in which the process is realized. In this case, non-stoichiometric transformations of some substances into others, a change in their surface, interfacial properties, and a number of other phenomena of a mixed (physical and chemical) nature take place.
Physicochemical processes are characterized by an interrelated set of chemical and physical processes occurring in a material substance. Physicochemical separation processes based on physical and chemical transformations of substances include coagulation and flocculation, flotation, ion exchange, reverse osmosis and ultrafiltration, deodorization and degassing, electrochemical methods, in particular, electrical gas cleaning. The driving force of these processes is the difference between the physical and thermodynamic potentials of the separated components at the phase boundaries. Physico-chemical processes are widely used in the enrichment of minerals, in metallurgy, in basic chemical production technologies, in organic synthesis, in energy, but especially in environmental technologies (dust and gas collection, wastewater treatment, etc.).
Thermal processes, the basis of which is the change in the thermal state of interacting media, include heating, cooling, evaporation and condensation. The driving force of these processes is the difference in temperatures (thermal potentials) of interacting media.
A specific group consists of biochemical processes - chemical transformations that take place with the participation of wildlife and constitute the basis of vital activity of all living organisms of the plant and animal world. Biochemical processes, which are based on catalytic enzymatic reactions of biochemical transformation of substances in the process of life of microorganisms, are characterized by the course of biochemical reactions and the synthesis of substances at the level of a living cell. A significant part of agricultural production and food industry, for example, biotechnology, has been built on their use. The products of biotechnological transformations occurring with the participation of microorganisms are substances of inanimate nature. The driving force of these processes is the energy level (potential) of living organisms.
The above classification is not rigid and unchanged. In reality, many processes are complicated by the flow of contiguous-parallel processes. For example, mass-exchange and chemical processes are often accompanied by thermal processes. Thus, rectification, drying and crystallization can be attributed to combined heat and mass exchange processes. The processes of absorption, adsorption are often accompanied by chemical transformations. The chemical processes of neutralization and oxidation can simultaneously be regarded as mass-exchange processes. Biochemical processes are accompanied simultaneously by heat and mass transfer, and physicochemical processes are accompanied by mass-exchange processes.
In a separate group, the processes of protection against energy impacts are highlighted, mainly based on the principles of reflection and absorption of excess energy of the main technological processes of nature management. An important place in the protection and protection of the environment is taken by methods and methods of protection against energy impacts, including protection against acoustic pollution (noise, infra- and ultrasound, vibration vibrations), protection from electromagnetic fields and radiations (permanent and alternating electric and magnetic fields, studies of the optical range, ionizing radiation).
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