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The main goal of progressive technology is to find a way to produce something useful from waste. D.I. Mendeleev 6.1. A brief history of waste management Household waste poses a certain risk to human health, as it contains rapidly decomposing organic matter, pathogens, fly larvae and helminth eggs. Reducing or eliminating the negative impact of household waste on people and the environment is one of the important tasks of sanitary cleaning of cities. Analysis of the composition of municipal solid waste (MSW) shows the presence in them of a number of components that can be used immediately after their extraction or as a result of certain processing. In this regard, MSW should not only be neutralized, but also used in most cases. In prehistoric times, waste consisted of campfire ash, wood, bones, vegetable waste, which served as compost to improve the soil. More than 2,500 years ago, the world's first municipal waste landfill was opened in Athens. Authorities have decreed that the waste must be removed at least a mile outside the city gates. In the Roman Empire, there were strict regulations regarding the removal of solid and liquid waste from cities. With the fall of the Roman Empire, its harsh laws ceased to apply, in particular regarding waste, and as a result, a plague appeared. Catastrophe struck the cities of medieval Europe. The plague destroyed a third of the population of Europe. In Italy, half of the population died, in England - 90%, in the Russian city of Smolensk almost 100%. The reason for these disasters was the unsanitary state of medieval cities: the accumulation of garbage, waste, excrement on the streets.
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Residents dumped waste into garbage heaps, threw it out through the windows onto the street. The huge numbers of rats in the cities led to the rapid spread of the plague. The spread of other dangerous diseases - cholera and smallpox - also caused dire consequences. In the eighteenth century, a technical revolution began, contributing to new discoveries and the development of machines. However, the increased productivity laid the foundation for mass production and led to an increase in industrial waste. In 1809, Nicholas Appert invented the first packaging - storing food in glass bottles with cork plugs. For more than a century, glass, wood and paper have been used for packaging. By the end of the nineteenth century, in many European countries, household waste was collected daily in mobile waste bins. Waste was sorted manually. A large proportion of the waste was recycled: glass and metal were returned to sellers, and ash from waste incineration was used to produce building materials. In 1929, aluminum foil and cellophane were used for packaging. Packaging has come to play an important role in retail. In the 1930s, the production of synthetic materials from petroleum products began. For the first time, polymeric materials and plastic appeared in the composition of household waste. During World War II, the need to provide food for American troops in Europe sparked a flood of inventions that marked the “Great Frontier” in trade — industrial packaging, improved canning and disposable beverage containers. In the post-war years, European countries faced the problem of huge unsanitary and uncontrolled dumpsites, especially around large cities. In 1947, England passed the Towns and Towns Planning Act, which gave the authorities the ability to organize landfills, which were built in the most convenient places. However, this did not take into account their impact on the environment, on the consequences of pollution of water sources.
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The composition and concentration of inorganic and organic pollutants in the filtrate is determined by the chemical composition of the stored waste, the processes of anaerobic and aerobic decomposition occurring in the waste column, the permeability of the waste layer, the intensity of precipitation, and the ambient temperature. The filtrate may contain bacteria of intestinal infectious diseases, tuberculosis, tetanus, gas gangrene, anthrax. The constant use of polluted groundwater leads to a sharp decrease in the body's immunity and the development of leukemia in humans and domestic animals. At the same time, the concentration of many substances may not reach the values at which living things die at the same time, and accumulate in small doses in bottom sediments, in biota, and in the human body. Many chemical compounds (heavy metals, polycyclic aromatic and organochlorine compounds) have cumulative properties, that is, they can accumulate in humans and animals for a long time without visible damage, leading then to such tragic consequences as tissue degeneration, genetic abnormalities, and decreased immunity. Heavy metals are carcinogenic and mutagenic. Waste from non-ferrous metal, a broken battery can, after a few years, cause a malignant tumor - cancer or mutagenic changes through a nearby pond from which vegetable gardens are watered. Most of the household waste contains various organic materials, including food residues and paper. In landfills, anaerobic conditions are rapidly formed, in which the bioconversion of organisms takes place. As a result of this process, biogas (landfill gas (LF)) is formed, the macrocomponents of which are methane (40-70%) and carbon dioxide (30-60%). Usually, gas generation ends in a landfill body within 10-50 years, while the specific gas yield is 120-200 m3 per 1 ton of solid waste. The most intensive process of formation of landfill gas proceeds during the first 5 years, during which about 50% of its total reserve is released.
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Landfill gas also contains nitrogen, oxygen, hydrogen, and dozens of different compounds can be included as trace impurities. It is toxic at certain concentrations and usually has a pungent, unpleasant odor. Landfill gas is combustible and has a heating value of approximately 20,000 kJ / m3. Abroad, SG is considered as an alternative source of energy. In the United States, its production is considered commercially viable; there are the world's largest plants for producing biogas from urban waste. For example, in the suburbs of New York, such a station produces up to 110 million m3 of gas per year. In Germany, biogas extraction and processing systems operate at 35 solid waste landfills. In Great Britain, the number of biogas fields is 25. Free spread of landfill gas in the environment can cause a number of negative consequences: create explosive and fire hazardous conditions in buildings located near solid waste burials; cause solid waste fire in places of their storage. In calm weather, landfill gas can accumulate in significant quantities in the surface layer of the atmosphere, creating a dangerous situation for people in this area. Landfill gas has a negative effect on vegetation, the reason for this is the saturation of gas in the pore space of the soil and the displacement of oxygen from it. In addition, landfill gas belongs to the so-called "greenhouse" gases, which makes it the object of close attention of the world community. The negative impact of landfill gas on the environment has led to the fact that the legal norms of most developed countries require landfill owners to prevent the spontaneous spread of landfill gas.
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When plastics and organics are burned in the flue gases of incinerators and in fly ash, compounds of the dioxin class are formed. Dioxin is a powerful poison that is stable in the external environment. In soil, it decomposes within twenty years, and in water - up to two or more years. Dioxins are supertoxicants, their toxicity is tens of thousands of times greater than the toxicity of potassium cyanide. These substances are incomparably more dangerous than known carcinogens such as benzo (a) pyrene. They have a destructive effect on the endocrine and hormonal systems of humans and animals, disrupt the development of the immune system, which increases the body's sensitivity to infectious diseases. Dioxins have properties, like radiation, to accumulate in the human body, which leads to mutations at the genetic level. One molecule of this substance is capable of disrupting normal cellular activity and causing a chain of reactions that disrupt the functions of the body. Dioxins affect human immunity: the body's susceptibility to infections increases, the frequency of allergic reactions, cancer and other serious diseases increases. Toxic gases from landfills can spread over long distances in the direction of prevailing winds, as well as react with gaseous emissions from industrial facilities, exacerbating the ecological situation. Domestic and foreign experience shows that there is not and cannot be one universal technology capable of absolutely ecologically safe way to recycle the growing waste stream. In industrialized countries, an environmental policy regarding solid waste has been formed, which is based on two provisions. 1. In modern conditions, uncontrolled formation of the amount and composition of household waste, as well as the ways and technologies for their processing, is unacceptable. These issues should be an integral part of the state's environmental and economic policy.
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2. Modern technologies for processing household waste should ensure maximum regeneration of energy and material resources spent on waste generation with their complete safety for the population and nature. 6.3. General characteristics of waste 6.3.1. Production and consumption waste Production and consumption waste (waste) is usually called the remains of raw materials, materials, semi-finished products, other products or products that were formed in the process of production or consumption, as well as goods (products) that have lost their consumer properties. The problem of waste management is a historically important task, since waste is “production residues suitable for some purpose” (Explanatory Dictionary of the Russian Language by SI Ozhegov). Indeed, the boundaries between the concepts of "raw materials - waste - secondary resources" are conditional and move apart depending on the technical and economic levels of production, economic feasibility and technological possibility of complex processing and use of natural raw materials. Wastes containing harmful substances that have hazardous properties (toxicity, fire and explosion hazard, high radiation activity) or contain pathogens of infectious diseases, as well as posing a potential hazard to the environment and human health on their own or when they come into contact with other substances are called hazardous waste. The waste management process required the introduction of a number of specific concepts and definitions into practice. Let's take a look at some of them. Waste management is an activity during which the collection, sorting, transportation and placement of waste, their use and disposal is carried out.
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Waste disposal is their storage and disposal. In turn, waste storage is a set of works that ensure the maintenance of waste in disposal facilities for the purpose of their subsequent burial, neutralization or use, and waste disposal is the isolation of waste that is not subject to further use in special storage facilities that exclude the ingress of harmful substances into the surrounding natural environment. Wednesday. Waste management involves the use of waste for the production of goods (products), performance of work, provision of services or for the production of energy. Waste disposal is the treatment of waste in special installations, including incineration in order to prevent harmful effects on human health and the environment. A waste disposal facility should be understood as a specially equipped facility designed for waste disposal, for example, solid waste landfills or storage facilities. Wastes generated in the course of the activities of enterprises and other economic facilities that have hazardous properties are subject to mandatory certification. A hazardous waste passport is drawn up on the basis of data on the composition and properties of hazardous waste, indicating the waste code according to the Federal Classification Catalog of Wastes. Waste impact on the environment depends on their qualitative and quantitative composition. Waste is a heterogeneous chemical composition, complex multicomponent mixtures of substances with a variety of physicochemical properties. The uncertainty of the chemical and material composition of waste is due to the interaction of components, biological decomposition and assimilation of substances. In fig. 6.1 shows the characteristics of wastes that allow them to be assessed as harmful and hazardous to the biosphere.
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Rice. 6.1. Main characteristics of hazardous waste
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The hazard of waste to the environment increases in cases where production and consumption waste has characteristics that facilitate the migration of its components in the environment: volatility, high reactivity, etc. 6.3.2. Classification and characteristics of solid household waste According to the Federal Classification Catalog of Wastes, solid household waste corresponds to the group code 91000000 00 00 0 "Solid municipal waste", which includes waste from dwellings, industrial waste, similar to municipal waste, garbage from household premises of organizations and construction, waste kitchens and catering establishments, waste (garbage) from cleaning the territory and premises of wholesale and retail trade in food and industrial goods, waste (garbage) from cleaning the territory and premises of educational, cultural and sports institutions and entertainment events, waste from cleaning territories cemeteries, columbariums, as well as waste of a complex combined composition in the form of products, equipment, devices (electrical equipment, appliances, devices and their parts, battery waste, lamps (incandescent, fluorescent, electronic, etc.), insulated wires, cables and other insulated electricity conductors). In cities and towns, there is an intensive accumulation of solid household waste, which, if it is not timely removed and neutralized, can pollute the environment of urban settlements. By morphological characteristics, solid waste is divided into the following components: paper (cardboard), food waste, wood, metal (black and non-ferrous), textiles, bone, glass, leather, rubber, stones, polymeric materials, other (unclassified parts), screening (street estimates - less than 15 mm in size), as well as, in some cases, medicines and waste from medical institutions.
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The morphological composition of municipal solid waste varies significantly for different countries and climatic zones. Table 6.1 presents comparative data on the morphological composition of solid waste in Russia and the USA. It follows from the table that there is less paper and cardboard in landfills in Russia than in the United States (20-36% and 40%, respectively), while there is much more food waste (20-38% and 7.4%, respectively). Seasonal changes in the composition of MSW in Russia are characterized by an increase in the content of food waste from 20-25% in the spring to 40-55% in the fall, which is associated with an increase in the consumption of vegetables and fruits in the diet. In winter and autumn, the content of small dropouts (street estimates) decreases from 20% to 7% in the cities of the southern zone and from 11% to 5% in the middle zone. In recent years, there has been a tendency for the composition of solid waste in large cities of Russia to approach the composition of solid waste in Western countries. The share of non-ferrous metals in MSW has significantly increased due to the appearance of aluminum cans for drinks, the content of plastic packaging materials has increased. With the change in the quality of food products in recent years, the composition of food waste has changed: if until 1991 the bulk of food waste was potatoes, cabbage and their cleaning (up to 70%) and only 10% was waste and fruit cleaning (and only in summer and autumn), then at present, with improved storage conditions for potatoes, the content of potato peelings has decreased and the share of peelings of fruits (oranges, bananas, etc.) has increased. This pattern is observed in all seasons of the year. At the same time, the ratio of the total content of organic matter, including wood waste, to the total mass of MSW has practically not changed and fluctuates within 56-72%. However, the heat of combustion of MSW is quite low and ranges from 5000 to 7000 kJ / kg. The moisture content of solid waste depends mainly on the content of food waste in them and is 40-50%.
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Table 6.1. Morphological composition of municipal solid waste in Russia and the United States (percent) It should be noted that a significant part of municipal solid waste is packaging waste. In the late 80s - early 90s of the XX century in Russia per capita there was only 9 kg of packaging, while in Germany - 150 kg, in the USA and Japan - 250 kg. With the advent of the packaging industry in Russia and a significant increase in imported finished products from abroad, the volume of packaging waste in solid household waste is currently 70-80%.
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The granulometric composition of solid waste affects the collection technology, transportation, and the choice of equipment for waste processing plants. Table 6.2 shows data on the granulometric composition of solid waste in Moscow.
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6.3.3 Standards for the accumulation of solid household waste The amount of solid household waste in Russia as of 2005 amounted to more than 35 million tons. The bulk of solid waste is transported from urban settlements to landfills and solid waste landfills, which occupy over 40 thousand hectares of land in the country; in addition, about 50 thousand hectares is the area of closed (filled) landfills and landfills for solid waste. Annually, about 1 thousand hectares are alienated for burial of solid waste, which is undoubtedly unprofitable for the state's economy. The amount of waste significantly depends on the standard of living of the population. The standard of living of the population can be characterized by the waste index (the ratio of the mass of household waste to the total amount of waste in society) WI (Wastes Index). This index for different countries has the following indicators: Germany - 0.26; England - 0.26; USA - 0.23; France - 0.23; Japan - 0.19; Poland - 0.030; Russia - 0.025. These data show that when the standard of living in developed countries is reached in our country, the amount of household waste can increase 10 times. The accumulation rate is the amount of waste (kg, l, m3) generated per unit of account (for the housing stock - 1 person, hotels - 1 place, shops and warehouses - 1 m2 of retail space, etc.) per unit of time (day , year). Accumulation rates are calculated separately for residential buildings and institutions and public enterprises (catering, educational, entertainment, hotels, kindergartens, etc.). The following factors influence the value of the accumulation rate: the degree of improvement of the housing stock (the presence of garbage chutes, gas, water supply, sewerage, heating systems); number of storeys of buildings; type of fuel for local heating; development of public catering and trade culture; the level of well-being of the population; climatic conditions; specifics of nutrition, etc.
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For large cities, the accumulation rates are slightly higher than for medium and small cities. The accumulation rates of institutions and public enterprises in large cities are 30-50% of the accumulation rates for residential buildings. Actual rates of solid waste accumulation are determined for each specific settlement. The average daily rate of solid waste accumulation in Russian cities is 0.52 kg / person in comfortable residential buildings, or 0.96 m3 / person at a density of 0.2 t / m3. The maximum coefficient of daily irregularity in the accumulation of solid waste (irregularity of supply to containers) is 1.26. Table 6.3 and 6.4 show the approximate standards for the accumulation of solid waste in Russia for residential buildings and public facilities. The average rate of food waste collection from the population is 30 kg / person per year.
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Accumulation rates are introduced based on the decision of local authorities. It is advisable to update the MSW standards every 5 years. The rate of accumulation of solid waste increases annually by about 0.3-0.5% by weight and by 0.6-1.2% by volume.
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6.3.4. Physical properties of solid household waste An important indicator of the physical properties of solid household waste is its density. The density of solid waste in a comfortable housing stock in the spring-summer season (in containers) is 0.18-0.22 t / m3; in the autumn-winter period - 0.20-0.25 t / m3. For different cities, the average annual density of solid waste ranges from 0.19 to 0.23 t / m3. Specific heat capacity of MSW and compost Stbo, J / kg C °), depends on moisture W,% and is determined by the formula: Stbo = 21.9W + 2000 (6.1) wire, etc.) and adhesion due to the presence of wet sticky components. Due to the cohesion, solid waste is prone to lump formation and does not spill into a fixed lattice with cells less than 20-30 mm (critical cell size). Solid household waste can stick to a metal wall with an angle of inclination to the horizon up to 65-70 °. Due to the presence of solid ballast fractions (ceramics, glass), MSW is abrasive, that is, the ability to abrade surfaces in contact with them. Solid household waste has a caking capacity, that is, with prolonged immobility, it loses its flowability and becomes compacted (with the possibility of separating the filtrate) without any external influence. With prolonged contact with metal, MSW has a corrosive effect on it due to high humidity and the presence of solutions of various salts in the filtrate. When designing installations for pressing solid waste, it is necessary to know the compression characteristics of the material, that is, the dependence of the degree of compaction of solid waste on the applied pressure. Depending on the load, the properties of MSW change as follows. When the pressure rises to 0.3-0.5 MPa, various kinds of boxes and containers are broken.
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The volume of solid waste (depending on its composition and moisture content) decreases 5-8 times, the density increases to 0.8-1.0 t / m3. Pressing devices used in the collection and disposal of solid waste operate within this stage. When the pressure rises to 10-20 MPa, an intensive release of moisture occurs (up to 90% of all moisture contained in MSW). The volume of solid waste decreases by another 2-2.5 times with an increase in density by 1.3-1.7 times (Table 6.5). Table 6.5. Compression characteristic of solid waste
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The material compressed to such a state stabilizes for some time, since the moisture contained in the material is insufficient for the vigorous activity of microorganisms and the access of oxygen to the mass is difficult. 6.4. Waste management 6.4.1. Integrated Waste Management Integrated Waste Management (IWM) starts with a change in the way we think about what household waste is. Renowned waste expert Paul Connett has a short aphoristic formulation that expresses this new view: "Garbage is not a substance, but an art - the art of mixing together various useful things and objects, thereby defining their place in a landfill." Traditional approaches to the problem of MSW focused on reducing the dangerous impact on the environment by isolating the landfill from pound water, cleaning up the emissions of an incinerator, etc. An unconventional view of the problem is that it is much easier to control what goes to the landfill than that ends up in the environment from the landfill. The basis of the concept of integrated waste management is based on the fact that the components of household waste should not ideally be mixed with each other, but should be disposed of separately from each other in the most economical and environmentally friendly ways. The waste management system being formed and developing in the Russian Federation at the moment is based on the main management methods, mutually complementing each other. The complex application of control methods forms the basis of an environmentally oriented socio-economic policy of the state (Fig. 6.2).
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Legal and regulatory framework for waste management The basis of any management system is the regulatory framework that determines the algorithm of activity. In the case of waste management, such an algorithm is environmental legislation. The main document governing environmental protection activities is the Federal Law “On Environmental Protection”, in the development of which the RF Law “On Production and Consumption Wastes” was adopted. Legal regulation in the field of waste management is also carried out by laws and other regulatory and legal acts of the constituent entities of the Russian Federation. The law of the Russian Federation "On production and consumption waste" for the first time formulates the following basic principles of state policy in the field of waste management: a scientifically grounded combination of environmental and economic interests of society; the use of the latest scientific and technical achievements in order to implement low-waste and non-waste technologies; the use of methods of economic regulation of activities in order to reduce the amount of waste and involve it in economic circulation; access to information in the field of waste management. Consequently, one of the priority areas of activity in the field of waste management is to reduce their amount. In addition, the law separates the powers of the Russian Federation and its constituent entities. At the same time, it is envisaged to strengthen the role of local self-government bodies. The legislative procedure defines the conditions for the regulation of state accounting and reporting, formulates the basic principles of economic regulation and defines the procedure for state, industrial and public control. Liability has been established for violation of the legislation of the Russian Federation in the field of waste management.
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Economic Methods of Waste Management Under the conditions of market mechanisms for regulating economic relations, each enterprise that handles waste must form a management system that ensures high efficiency and environmental safety. Among the economic levers and regulators of environmental protection, the main place is occupied by payments for environmental pollution. Pollution payment is a form of compensation for economic damage from emissions and discharges of pollutants into the environment, as well as for waste disposal on the territory of the Russian Federation. Pollution charges reimburse the following costs: compensation for the impact on nature of pollutants; stimulation of reduction or maintenance of emissions and discharges within the limits of standards; recycling; design and construction of environmental protection facilities. To determine the amount of payments for harmful emissions into the environment, the basic standards of payment for emissions and discharges of pollutants and the placement of production and consumption waste have been established, which include: standards for payments for emissions of pollutants into the atmosphere from stationary and mobile sources; payment standards for the discharge of pollutants into surface and underground water systems; standards of payment for waste disposal. The following types of basic payment standards have been established: for emissions, discharges of pollutants, other types of harmful effects within the limits of permissible standards (MPE, MPD);
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for emissions, discharges of pollutants, waste disposal, other types of harmful effects within the established limits (temporarily - agreed standards). The basic standards of payment for waste disposal are determined by multiplying the unit costs for the placement of a unit (mass) of waste of IV toxicity class by indicators that take into account the toxicity classes of waste and by the indexation coefficient of the payment. The indicators of the relative hazard of substances Аj are calculated on the basis of the normative documents "Maximum permissible concentrations of pollutants in the atmospheric air of populated areas" and "Sanitary rules and norms for the protection of surface waters from pollution": Аj = MPCj (6.2) where MPC: for atmospheric air - the maximum allowable concentration average daily (MPCss), and for water bodies - the maximum permissible concentration in the water of fishery reservoirs (MPCrh); j - index of a polluting hazardous substance. Payment for environmental pollution is undoubtedly collected from enterprises, institutions, organizations and other legal entities, regardless of their organizational and legal form of ownership, on which they are based. Payments for environmental pollution are the most important elements of the overall system for regulating the state of the environment. They must have a strict target purpose, be closely linked with environmental restrictions and regulations of environmental management regimes, and act as economic levers for achieving the goals of environmental programs.
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The most important lever of economic regulation is the stimulation of activities in the field of waste management. For this, the following measures are provided by law: lowering the amount of payment for waste disposal for individual entrepreneurs and legal entities carrying out activities in the process of which waste is generated, when they introduce technologies that reduce the amount of waste; the use of accelerated depreciation of fixed assets associated with the implementation of activities in the field of waste management; application of incentive prices and additives for environmentally friendly products; introduction of special taxation of environmentally harmful products; application of concessional lending to enterprises that effectively protect the environment. Organizational and managerial methods of waste management Organizational and managerial methods of waste management are based on the aspect of sustainable development of the Russian Federation. In this regard, it is necessary to develop and implement waste management programs for each region and integrate these programs in the development of state policy in the field of waste management. Organizational structures, mechanisms for developing and making decisions at various levels of management should be focused on the appropriate priorities, taking into account the following criteria: no economic activity can be justified if the benefits from it do not exceed the damage caused; environmental damage should be as low as can reasonably be achieved, taking into account economic and social factors.
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In fig. 6.3 presents the ideology of building a waste management system, which is based on the general laws of building such systems and is implemented in a number of regions of the Russian Federation. The control decision-making scheme is a multi-level scheme (Fig. 6.4). The level of assessing the situation is based on determining the economic efficiency of the implementation of environmental protection measures and assessing the economic damage caused to the environment. Rice. 6.4. Hierarchy of Integrated Waste Management
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In some cases, it is also necessary to assess the risk to public health. Decision-making in complex issues, as a rule, is preceded by a systematic analysis of the impact of economic activity on the ecosystem, which makes it possible to optimize the decision. Within the framework of the integrated waste management program, it is assumed that a settlement or urban district chooses approaches to solving the MSW problem depending on their specific local conditions and resources. However, in any case, when defining the objectives of the program and planning the strategy for waste management, it is advisable to be based on a certain hierarchy of integrated waste management. This hierarchy implies that primary waste reduction should be considered first, followed by secondary reduction: reuse and recycling of the remainder of the waste. In the last place, measures for the disposal or disposal of those wastes that could not be avoided and that cannot be recycled are considered (see Fig. 6.4). Primary waste reduction is “at the source” waste reduction at the very top of the integrated waste management hierarchy. Reduction means not only a decrease in the total amount of waste, but also a decrease in their toxicity and other harmful properties. Waste reduction is achieved by reorienting producers and consumers towards products and packaging that result in less waste. Recycling (including composting) is the second step in this hierarchy. Recycling (recycling) not only saves landfill space, but also improves the efficiency of incineration by removing non-combustible materials from the general waste stream.
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The lowest level in the hierarchy is landfill and solid waste incineration. Incineration reduces the amount of waste ending up in landfills and, in some cases, can be used to generate electricity. While waste incineration for disposal is a thing of the past, modern incinerators equipped with emission control systems and used in combination with other methods can help manage the flow of waste, especially in densely populated areas. 6.4.2. Waste management system The term "waste management" is broader than the concepts of "recycling", "disposal" and "waste management", as it includes the organization of waste collection, recycling, incineration, disposal, as well as measures to reduce the amount of waste. The principles of integrated waste management are as follows: 1. MSW consists of various components, to which different approaches to their management should be applied. 2. For disposal of each component of solid waste, its own technology should be used, but technologies should be developed in a complex, complementing each other. 3. Municipal solid waste disposal system should be developed taking into account specific local problems. The participation of city authorities, as well as groups of the population, that is, waste producers, is a necessary element of any program to solve problems with solid waste. In fig. 6.5 shows a block diagram of consumer waste management (solid domestic waste).
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Collection of municipal solid waste In recent years, the amount of garbage has been growing at an enormous rate. In industrially developed countries, there is a growing desire to produce short-lived items, especially of one-time use. Diapers, bags, cans, bottles and other disposable paper items, cheap short-lived shirts, and out-of-fashion dresses quickly fill up trash cans. The mass of such garbage, thrown away annually, for example, by the French, is 600 times the mass of the Eiffel Tower. Waste collection is an expensive component of the recycling process, so organizing it correctly can save you a lot of money. The main system for the collection and disposal of solid waste is the container system of "replaceable" and "non-replaceable" containers. With the container "swap" system, the waste is removed along with the containers, and empty, clean containers are installed in their place. With a "non-removable" system, waste is discharged directly into garbage trucks, and the containers, after emptying, are placed in place. Collection and disposal of household waste in cities and towns of Russia is carried out by special enterprises within the time frame stipulated by the norms. The system of collection and disposal of solid waste includes: preparation of waste for loading into a collecting garbage truck; organization of temporary storage of waste in households and waste transfer stations; collection and removal of solid waste from the territories of households and organizations. The frequency of disposal of solid waste is determined depending on the season of the year, climatic zone, epidemiological situation, agreed with local institutions of sanitary and epidemiological supervision and approved by the decision of local administrative bodies.
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As a rule, the following terms for the removal of solid waste are established: from the territories of households - at least 1 time in 3 days; from the territories of households with a special regime or in the southern zone - every day. Frequency of sanitization of collections: for the northern (summer period) and middle zones - once every 15 days; for the southern zone - once every 10 days. Washing of collections should be carried out by housing maintenance and other organizations. Separate collection of waste A product becomes garbage when it is mixed with other products. A container filled with empty bottles is not garbage, but a commercial product - raw materials for the industry. The way out of the "garbage crisis" is to reduce the mass of stored waste by organizing their complex processing. Household waste contains 20-40% waste paper, up to 40% food waste, 2-5% non-ferrous and ferrous metals and 4-6% glass, plastics and textiles. In the USA, it is calculated that metals extracted from solid waste can meet the national demand for iron by 7%, aluminum - by 8%, and tin - by 19%. The costs of collecting and sorting solid waste are several times lower than for the extraction and processing of raw materials, from which paper, textiles, polymeric materials and various metals contained in waste are obtained. Modern technologies make it possible to recycle up to 80% of household waste and reduce the cost of their disposal. The next step in solving the "garbage" problem is the organization of processing of individual components of household waste.
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Possible approaches to waste separation fall between two positions: "technical" and "social". The first position is a kind of ideal factory, at the entrance of which there is an unassembled stream of solid waste, and at the exit there is a flow of materials that meet the requirements of the market, and a flow of materials that goes to a landfill. The second position is that the population itself separates its waste, brings the recyclable part to market condition (washing bottles, removing caps, etc.), after which the waste is handed over for recycling. The first path in its pure form is very difficult to carry out. Sorting the solid waste stream is suitable as a method of obtaining enriched fuel for incineration plants (WIP) and solves the problem of recovering recyclable materials (for example, metals), but as a method with the main purpose of separating recyclable materials from the general waste stream, it is not always suitable. It is very difficult to separate plastic from paper, bottle glass will be mixed with window glass, etc. The quality of materials obtained from a common wet and dirty mixture will be low. From a purely technical point of view, it is possible to qualitatively separate the waste stream using machine technology or by manual disassembly, but then the process will be expensive and this will make such an activity unprofitable. The costs with this method of separating waste will be lower if the waste is separated or, more precisely, not mixed from the beginning of its path to the places of processing or storage. In developed countries, waste separation by producers is considered more acceptable than technological separation for the following reasons: less waste treatment costs; a high probability of obtaining a commercial product from waste; direct producers of waste take part in solving the problem of solid waste.
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Sorting waste at the source of accumulation eliminates the possibility of mixing waste and impact on nature during burial at the landfill of hazardous waste generated in everyday life of used electrical batteries, paints and varnishes, mercury-containing household appliances, etc. The system of separate (selective) collection of MSW components is developed in European countries - Denmark, Holland, Germany, etc. The formation of the environmental initiative of the population is considered as one of the determining factors in the development of the selective collection system. Developed countries legislate to introduce obligations for the collection of certain types of waste. For example, in France, since 2002, it has been prohibited to accept unsorted waste for any kind of processing and disposal. The Netherlands has introduced a ban on the disposal of organic waste to improve the efficiency of separate collection and subsequent composting. However, the recycling of waste components is growing slowly due to its technological complexity. Among European countries, by the end of the 90s of the last century, the percentage of recycled waste ranged from 6 in France to 39% in the Netherlands. An important and fundamental aspect of the indicated problem is the formation of markets for products from waste, which becomes the main limitation of recycling as the materialization of the idea of selective collection. If there is no market for secondary raw materials and materials, then the system of separate collection will not develop. Incentive programs and public awareness of the problem are needed to foster the formation of markets with the involvement of private entrepreneurship. In Russia, there is a widespread opinion that it is impossible to carry out selective collection of household waste. The main reason for this is called the national peculiarities of the mentality.
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If this idea were a utopia, then the pragmatic West would not follow it. Facing the threatening growth of solid waste in the early 70s of the last century, Western countries began to pursue a targeted policy, fostering a sense of responsibility for the environment, including instilling the skills and habit of selective waste collection. There are various ways of separating waste by the public. In many states of the United States, separate waste collection is provided in two containers: in the first - waste that can be used as recyclable materials, in the second - all the rest. Recyclable waste is transported to special factories for sorting into categories. Involving the population in the separation of solid waste is the most difficult task for public utilities. Foreign experience shows that to ensure active participation of the public in recycling programs, the following conditions must be met: constant educational work among the population; an appeal to the population with an explanation of questions about the time and place of collection of recyclable materials, preparation of waste for collection; organization of a clear regular work of the services of export, sale and processing of recyclable materials. Technical means for the collection and removal of waste In domestic practice, metal collectors-containers of various capacities from 100 to 800 liters are used for the collection of solid waste. Containers with a capacity of 55 and 75 liters are usually stationary. Containers with a capacity of 30, 60 and 80 liters have wheels and can be installed under the garbage chute. Abroad, the most widespread are plastic containers with a capacity of up to 240 liters. The service life of such collections is 8 years. Collectors with a capacity of 1100 liters with wheels and a lid are made of galvanized steel sheet.
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Areas for containers should be removed from residential buildings and childcare facilities at a distance of at least 20 and not more than 100 m. The sites should have a flat asphalt or concrete surface with a slope towards the roadway and be fenced. Garbage removal is carried out by special vehicles, which also include machines for washing and disinfecting containers, various garbage trucks, as well as machines for removing liquid household waste. Today, the vast majority of European garbage trucks are traditional rear-loading vehicles. In addition to the driver, they are served by 1-2 people standing behind on special footrests. Recently, garbage trucks with side loading and one driver-operator have become widespread. In Russia, the most widespread are garbage trucks of the brands KO, MKZ, MKM, MKT, MS "Sokol" on automobile chassis GAZ, KAMAZ, ZIL. Garbage trucks of type KO of various modifications are intended for mechanized loading of solid waste from standard containers into the body, their compaction, transportation and mechanical unloading. Garbage trucks with compaction devices such as Norba BM-500, RIKO, FAUN are widely used. In world and domestic practice, there is a tendency to replace the direct removal of solid waste with a two-stage one using waste transfer stations. This technology is being actively implemented in large cities, where solid waste landfills are located at a considerable distance. The two-stage system includes the following technological operations: collection of solid waste in places of accumulation; removal of solid waste by collecting garbage trucks to the waste transfer station (MPS); reloading solid waste into heavy vehicles; transportation of solid waste to the places of their burial or utilization; unloading of solid waste.
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The use of the MPS allows you to: sort solid waste; reduce the cost of transporting solid waste; reduce the number of collecting trucks; to reduce the total emissions into the atmosphere from garbage transport; improve the technological process of storage of solid waste. MPS can be with and without compaction of waste. The layout diagrams of the Ministry of Railways with the use of stationary compactors provide for two-tier structures: an upper platform for unloading collecting garbage trucks and a lower platform with a compactor and a container body. This type of MPS with the use of pressing equipment operates in Moscow. Two-level stations were built in Perm, Krasnodar, Vladimir. Sorting of municipal solid waste It can be considered that all consumption waste is potentially secondary material resources. The main problem in recycling is not the lack of recycling technologies (modern technologies allow to recycle up to 90% of the total waste), but the separation of recycled components from garbage and separation of garbage ingredients. The recovery of recyclable materials from the generated waste stream is the most expensive and difficult. Small non-automated manual sorting lines for 5-20 sorters abroad cost about $ 500,000, and powerful automated plants cost up to $ 1.5 million. In the countries of Europe and North America, the disposal of solid waste costs on average a little more than $ 100 per ton. In the USA, the total fee for the removal and disposal of solid waste is more than $ 200 per ton. Currently, the following methods of separation of solid household waste are used: magnetic separation, used to extract ferromagnets; electrodynamic separation for the extraction of non-ferrous metals;
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aerodynamic separation based on different densities of solid waste constituents for the recovery of waste paper, textiles, plastic films and similar materials; ballistic separation, based on different elasticity of MSW components, to extract, for example, glass; hydroseparation (flotation method). To increase the efficiency of separation methods, the waste is crushed and sieved using special devices - screens. Serial production of sorting equipment for waste processing stations (MPS) in Russia was mastered in the early 70s of the last century, but the total volume of recycled waste is no more than 1% of the generated waste. In our country, a technology is widely used that provides for the division of the entire mass of solid waste into two parts: organic and the rest. The organic part of MSW is subjected to industrial composting, the main product of which is organic fertilizer containing at least 1% nitrogen, 0.6% phosphorus, 0.3% potassium and 2.5% calcium. Non-compostable waste is subject to thermal destruction. The Russian enterprise "Ecotekhnika" produces a complex of sorting equipment with a capacity of 40,000 tons per year, which makes it possible to separate metal, glass, paper, scrap, plastic, food waste, and construction waste from household waste. The technology includes the following main operations: preliminary drying at 130 ° C, ultraviolet disinfection, manual sorting, packaging or grinding of the selected components. In fig. 6.6 is a schematic diagram of sorting solid waste.
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To organize the disposal of traditionally recyclable components of household waste and if the region has technical capabilities for their processing, it will be necessary to solve the following problems of their preparation for processing. Scrap metal. Household waste contains 4-5% iron. Scrap for steelmaking must contain at least 90% iron, and scrap recovered from garbage contains only 60-70% iron. Therefore, in order to use iron recovered from waste in metallurgy, special shredding (separation) installations are required for cleaning scrap and the use of roasting to remove organic impurities (oil, fat, etc.). Tin. Tin extracted from household waste can be used to make containers and utensils. However, landfill cans are usually dirty, clogged with rotting food waste. Obtaining tin from solid waste abroad is carried out by heat treatment in rotary kilns, freezing in liquid nitrogen, magnetic and centrifugal separation using chemical and electrolytic methods. Over the past 20 years, these technologies have been improved in developed countries, and now they allow recovering 75% of the tin. Plastic. MSW contains more than a dozen types of plastics. In the West, processing of only two is widespread: polyethylene terephthalate and high density polyethylene. Recycling of other types is not practiced. A significant number of plastic packaging includes several materials: plastic (often of several types), foil, cardboard. Such packaging is practically not recyclable. Organic waste. In all European countries where organic waste is released, it is disposed of through composting (aerobic digestion of the organic part of the waste). The proportion of compostable waste ranges from 1% in the UK and Norway to 17% in Spain. Leaves, grass, waste of fruits, vegetables, eggshells can be used as compost, but meat, bones, fat, etc. cannot be used. There are technologies for composting only food waste.
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Waste briquetting Solid waste briquetting is a relatively new method of waste management. Briquetting can significantly reduce the volume of solid waste and reduce the area of the territory required for the placement of solid waste. During pressing, municipal solid waste is compressed to a density of 1-1.1 t / m3 and decreases in volume by about 3 times. Briquettes tied with wire with a size of 1.1x1.1x2.0 m and a mass of 2.4-2.5 tons are obtained from compressed waste. Briquettes "live" longer than unpressed primary material, since they contain little air due to their high density and almost no water. The pressing station can be located both directly at the landfill, and at the waste transfer station located on the territory of an urban settlement. Garbage compaction can be viewed as a temporary, but very effective way to solve the problem of cleaning cities from solid waste and save space at landfills. 6.5. Technical methods of solid waste management 6.5.1. Choosing a method for neutralizing and recycling solid waste The choice of the optimal method for neutralizing and processing solid household waste for a particular region is determined by solving the problem of environmental protection, public health, as well as the economic efficiency of the use of land resources. Taking into account climatic, geographical, urban planning conditions and the number of the served population plays an essential role in solving the problem of neutralization and disposal of solid household waste for specific conditions. There are more than 20 known methods of neutralization and disposal of solid waste (Fig. 6.7). For each method, there are 5-10 types of technology, technological schemes, types of structures. According to the final goal, the methods of decontamination and processing of solid waste are divided into: liquidation (they mainly solve sanitary and hygienic problems); utilization (solve, in addition, the problems of the economy - the use of secondary resources).
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Technologically, the methods are subdivided into biological, thermal, chemical, mechanical, and mixed. The most widespread in our country and abroad are such methods as storage at landfills (liquidation biological and mechanical), incineration (liquidation thermal) and composting (disposal biological). Rice. 6.7. Classification of technical methods for neutralization and disposal of solid waste
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Analysis of the composition of municipal solid waste in large cities shows that all the above methods can be used for their neutralization and utilization. Municipal solid waste contains enough nutrients to produce compost. An increase in the heat of combustion of solid waste is predicted, which will increase their value as a fuel. The content of polymeric materials in MSW will not reach a level by 2010 that would prevent composting or incineration of waste. The considered areas (storage at landfills, incineration, composting, mechanized sorting) allow you to neutralize and dispose of solid household waste, observing the standards of environmental protection requirements. According to foreign data, specific capital costs for the implementation of various options for handling solid waste in US dollars per ton are: storage at landfills - 50; composting - 90; sorting with composting - 100; complex processing - 240. 6.5.2. Recycling The earth is becoming a dumping ground for disposable goods. The buy-use-throw away consumer scheme is becoming more and more popular around the world. According to Tom Wirhail, editor of the online edition of Productscan, today society's desire for everything disposable is a rapidly growing trend, people want to get everything ready to eat and use, and disposable products are quite satisfying in this regard. In Russia today, after a single use, 2/3 of aluminum, 3/4 of steel, a huge amount of paper, a very large part of plastic products are thrown away. If the “one-off” use is replaced by the ethics of recycling resources, there will be less environmental pollution.
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Smelting aluminum from scrap metal requires 20 times less energy than smelting it from bauxite ore. For steel remelted from scrap metal, the savings are 2/3 of the primary cost, while air pollution is reduced by 85%, water pollution by 76%. The production of paper from waste paper requires 25-60% less energy than its primary production from cellulose, while harmful emissions to the atmosphere are reduced by 75%, and emissions to water bodies - by 35%. Remelting glass saves up to 1/3 of the energy required to produce the original product. Glass is usually processed by grinding and remelting, with the original glass being matched to the same color. Low grade broken glass is used after grinding as a filler for building materials. Waste paper is used for the manufacture of pulp - raw materials for paper. Mixed or low-grade waste paper can be used to make toilet paper, wrapping paper and cardboard. Waste paper can be used in construction for the production of thermal insulation materials and in agriculture - instead of straw. Recycling plastics in general is expensive and complex. Some plastics, such as 2- or 3-liter clear beverage bottles, can produce high-quality plastic. Other plastics, such as PVC, can be used as building materials after processing. In Russia, plastic recycling is very limited. The formation of markets for secondary raw materials should take place under the auspices of the state with the active involvement of enterprises engaged in waste processing and the population. Processing of plastics Currently, there are the following directions of utilization of polymer raw materials: combustion for the purpose of obtaining energy; thermal decomposition; recycling.
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When polymers are burned, there is an irreversible loss of valuable chemical raw materials and pollution of the environment with toxic components of flue gases. Thermal decomposition as a way of converting the initial product into low-molecular compounds by pyrolysis and catalytic thermolysis should become an alternative to the incineration of secondary polymer raw materials. Pyrolysis is the thermal decomposition of organic substances in order to obtain useful products. At temperatures up to 600 ° C, liquid products are formed, and above 600 ° C, gaseous products up to carbon black. The pyrolysis of PVC together with propylene ethylene (PE), propylene polystyrene (PP) and propylene styrene (PS) at a temperature of 350 ° C and a pressure of up to 3 MPa in the presence of a Friedel-Crafts catalyst and by treating the mixture with hydrogen makes it possible to obtain valuable chemical products with a yield of up to 45% benzene , toluene, propane, cumene, alpha-methylstyrene, etc., as well as hydrogen chloride, methane, ethane. Catalytic thermolysis is thermal decomposition at lower temperatures than pyrolysis. Gentle modes make it possible to obtain monomers that are used as raw materials in polymerization and polycondensation processes. In the USA, from used bottles made of polyethyl phthalate (PET), scarce monomers - dimethyl phthalate and ethylene glycol - are obtained, which are used for the synthesis of PET in the production of bottles. Recycling of polymer waste is widespread in many countries. Mixed waste from polymeric materials is processed into products for various purposes (building panels, decorative materials, etc.). In the USA, where the use of PET containers is especially high, the level of recycling of PET bottles reaches 25-30%.
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Recycling of used car tires The volume of used car tires (OAP) in the world is estimated in hundreds of millions of tons per year. In all countries, tire dumps are considered extremely hazardous to the environment. From the point of view of environmental feasibility, among the numerous and varied methods of disposal of used automobile tires, the following directions are considered priority in the hierarchy: reducing the formation of tires; recycling tires; recycling of tires; fuel use and thermal degradation of tires; burial of tires. The main ways to reduce the formation of used car tires are to increase their service life and restore their performance. For example, the transition from bias to radial tire design has increased the service life of a passenger car tire by 3.5 times. An increase in the service life of automobile tires can be achieved as a result of an improvement in their operating conditions and, above all, by improving the quality of road surfaces. Recycling waste car tires can include the creation of artificial spawning grounds, buffers in port facilities, decorative fences, sound-absorbing screens and safety barriers. So, for the manufacture of 1 km of sound-absorbing screen "Acia1" (France) 3 m high, 20 thousand tires are required. In road construction, tires are laid in retaining walls, used as mats for earth embankments in the foundations and embankments of roads passing through marshy areas.
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The main direction of recycling used car tires is the production of reclaimed tires for the tire industry, which requires grinding tires to a crumb state. In addition, crumb rubber of various sizes is used in road construction as a shock-absorbing underlay for asphalt pavement and as an ingredient in the composition of the top pavement. The widespread use of this area is hindered by its high cost and environmental hazard - during the thermal decomposition of rubber heated together with asphalt, toxic substances are released. The efficiency of burning used car tires is not comparable to the consumption of non-renewable natural resources and energy for their manufacture (the production of a car tire takes 32 liters of oil, and its combustion is equivalent to burning 6-8 liters of oil). The rubber component of tires is characterized by low ash content (2-3%) and high calorific value (30,000-35,000 kJ / kg), which determines their value as fuel. World experience shows that it is most expedient to burn OAP together with coal in the furnaces of coal-fired boilers with a small addition to coal in the amount of 2-4%. This increases the calorific value of the fuel and does not significantly affect the composition of the flue gases. Thermal treatment of used car tires (pyrolysis, hydrogenation, gasification, depolymerization) makes it possible to obtain 32-57% of oil products, 34-50% of solid residue and 9-18% of gaseous products. The properties of petroleum products are close to those of diesel fuel and light oil fractions. High concentrations of benzene, xylene, styrene, limonene were found in the composition of gaseous products. The solid residue (carbon black) can be used as fuel or adsorbent.
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Composting of organic components of solid household waste Composting is a biothermal method for neutralizing and disposing of household, agricultural and some industrial waste. The mechanism of the basic reactions of composting is the same as for the decomposition of any organic matter: more complex compounds decompose and transform into simpler ones. The essence of the method lies in the course of the biochemical reaction of oxidation of the organic component of the waste (cellulose) to obtain carbon dioxide and water. In this case, a significant amount of heat is released, and the final product is compost. The heat heats up the compostable material. Diverse, mainly thermophilic, microorganisms actively grow and develop in the mass of the waste, as a result of which it self-warms up to 60-70 ° C. At this temperature, many pathogens and pathogens die. In the practice of industrial composting, the following methods can be distinguished: field composting (composting in piles); mechanized composting in special installations - fermenters (composting in installations with controlled conditions). Field (open) composting of waste in stacks is carried out in natural conditions on specially designated areas - composting fields. Stacks can be arranged both on the ground (on the surface of the earth) and in combination with shallow (up to 0.5 m) ditches or trenches. For aeration, peat, humus, matured compost from previously laid piles or other materials with a layer of 10-15 cm are placed in the base of the stacks.The stacks are placed in parallel rows with 3 m wide aisles between them. at the bottom 3-4 m, at the top 2-3 m, height 1.5-2 m (in the northern regions of the country up to 2.5 m), length 10-25 m.For air access, waste is stacked without compaction at full height with a gradual build-up in length.
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There are various technologies for this composting method. Minimal technology. Compost heaps up to 4 m high and 6 m wide are turned over once a year. The composting process takes one to three years, depending on the climate. Low level technology. Compost heaps up to 2 m in height and 3-4 m in width are turned over for the first time after a month and then every 10-11 months. Composting takes 16 to 24 months. Mid-range technology. The heaps turn over daily. The compost is ready in 4-6 months. Capital and operating costs in this case are the highest. The mechanized method of biothermal compost preparation is carried out, as a rule, in horizontal rotating drums or in louvered towers for 1-6 days. Non-crushed waste is fed into horizontal rotating drums, the sorting of which is limited to the extraction of black scrap metal. Wastes that have necessarily passed preliminary separation and crushing are fed to the louvered towers for processing. Crushed waste is transported by a conveyor system or grab to the upper, usually the sixth floor. Every day the pallets (interfloor floors) rotate around their axis, and the compostable mass is poured onto the next floor. Compost obtained as a result of biothermal decontamination of solid waste should not be used in agriculture and forestry, as it may contain impurities of heavy metals. Its use is limited to the cultivation of non-food crops, landscaping of roadside strips, land reclamation of closed solid waste landfills. The choice of composting methods is determined by the optimal combination of cost, the achieved effect of utilizing compostable waste and the availability of a market for the product.
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The disadvantage of composting is the need for sorting solid household waste, neutralizing or processing the non-compostable part of the source material. This problem can be solved by the method of incineration, pyrolysis or disposal of waste to landfills for solid waste. Biodegradation of organic waste It is generally accepted that biological methods of decomposition of organic pollution are considered the most environmentally acceptable and cost effective, as evidenced by the indicators of various waste processing processes, given in table. 6.6. Table 6.6. Indicators of waste processing processes, USD / t
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Vermiculation In recent years, one of the varieties of ecological biotechnology has become widespread - the cultivation of vermiculture, that is, the cultivation of cellulose-containing components of Californian worms on waste. For the first time, the idea of industrial breeding of earthworms appeared and was embodied in the USA in the state of California in the 50s of the XX century. For cultivation, the productive population of the worm Eiseiafoctida obtained by selection, called the "red Californian worm", is used. In Europe, the red Californian worm is known by another trade name "Tennessee Wigler". Vermite technology is developing on an industrial scale in Germany, Italy, Japan, Great Britain, France, and Switzerland. A small 10 cm worm has the unique ability to devour any organic material - sawdust, paper, cardboard, rotten vegetables, sewage sludge, food processing waste, bones, animal entrails, etc. In the UK, worms purify sewers. By processing waste, they release an extremely valuable organic fertilizer - biohumus. During the day, Californian worms eat garbage more than their weight (about 1 g) and produce about the same amount of vermicompost. Concentrated vermicompost makes it possible to obtain the following products: complete natural feed for poultry and fish farms, protein component for compound feed; growth stimulants; medicines (for example, the "Epaolay" remedy) that regulate the level of cholesterol in the blood; preparations for the cosmetic industry. The high cost of the worm population hinders the widespread use of vermite technology.
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6.5.3. Waste incineration Waste incineration methods Waste incineration is the most developed and widespread method of solid waste processing in the world practice. Its main advantage is the reduction of waste volume by more than 10 times. Burning also eliminates unpleasant odors, pathogenic bacteria, and also obtains heat energy. However, incineration of waste containing hydrocarbon and chlorine substances at temperatures below 1200 ° C produces dioxins, which are very toxic compounds. Waste incineration is a complex and high-tech option for waste management and can be considered as one of the components of a comprehensive recycling program. The incineration of an undivided waste stream is considered extremely hazardous. Therefore, pre-treatment of solid waste is required. When separating, large fractions, metals, plastic, power cells, batteries are removed from the solid waste. It should be borne in mind that MSW contains potentially hazardous elements characterized by high toxicity: compounds of halogens (fluorine, chlorine, bromine), nitrogen, sulfur, heavy metals (copper, zinc, lead, cadmium, tin, mercury). Table 6.7 shows a comparative content of a number of elements in solid waste and the earth's crust. The table shows that the content of halogens, sulfur and heavy metals in MSW is 1-2 orders of magnitude higher than in the earth's crust. The choice of technological and thermal schemes for a waste incineration plant, such as a reactor, heat-using equipment and devices for gas purification is largely determined by the chemical composition and physical properties of the waste. To date, a certain amount of experience has been accumulated to assess the combustibility of solid waste. According to the data, the lower limit of the heat of combustion of solid waste, at which they can be burned without additional fuel, ranges from 3.35 MJ / kg to 4.19 MJ / kg. Fuel combustion is usually subdivided into low-temperature (600-900 ° C) and high-temperature (1250-1450 ° C).
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Table 6.7. The content of elements in solid waste and the earth's crust
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During low-temperature incineration, as a rule, this process is carried out in incinerators (incineration plants), highly toxic compounds are formed, which limit its use. The first incinerator was built in England in 1874. In 1995, there were 2,400 waste incinerators in the world. The attitude towards the incineration of solid waste changed in the 80s of the last century after the establishment of the fact of the formation of highly toxic substances in the process of their incineration. Even in the presence of highly efficient gas cleaning systems, emissions from incinerators contain dioxins, furans and heavy metal compounds, the concentration of which is 10-100 times higher than the toxicity of smoke from coal combustion. Currently, the level of incineration of municipal waste in individual countries is different. So, of the total volume of household waste, the share of incineration fluctuates in countries such as Austria, Italy, France, Germany, from 20 to 40%; Belgium, Sweden - 48-50%; Japan - 70%; Denmark, Switzerland - 80%; England and the USA - 10%. In our country, only about 2% of household waste is incinerated so far, and in Moscow - about 10%. Modern incinerators are very expensive and pay off no more than 60%. Capital costs for incinerators in the USA range from 80 to 100 thousand dollars per ton of solid waste. Operating costs are about $ 20 / t. A third of the operating costs of the incineration plant goes to pay for the burial of ash generated during the incineration of waste, which is a more environmentally hazardous substance than the solid waste itself. However, incineration has a number of indisputable advantages over waste storage at solid waste landfills. Therefore, at present, there has been an increase in the number of incinerators in the world. In France and Germany, incinerators are becoming the main means of recycling solid waste.
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High-temperature fuel combustion methods are divided into: processes in which the oxidation of solid waste occurs in the so-called fluidized bed of thermal furnaces; processes in which the oxidation of solid waste occurs in a layer of molten slag. For high-temperature combustion, it is necessary to have a metallurgical or construction-technological complex with special equipment (metallurgical furnaces, cement kilns, etc.). In addition, there is oxygen-free processing of solid waste in reactors, for example, in blast furnaces, at temperatures of 1650-1750 ° C without access to air. Waste processing technology "Piroxel" The method of high-temperature waste processing, called "Pyroxel", is based on a combination of the processes "drying" - "pyrolysis" - "incineration" - "electrometallurgical treatment" - "chemical-thermal neutralization of gases" and provides for the appropriate hardware design (fig. 6.8). High temperatures and multistage heat treatment allows achieving complete neutralization of toxic components contained in waste, preventing their secondary formation and reducing the content of harmful impurities in waste gases to the level of European standards. The proposed technology for neutralization and disposal of waste has a number of advantages over other methods of thermal destruction of waste and provides: the possibility of high-temperature processing of various types of waste with high (up to 50%) humidity without their preliminary selection; prevention of the formation of toxic compounds (dioxins, furans, etc.); effective cleaning of exhaust gases from dust, chlorine and fluorine compounds, sulfur oxides, nitrogen;
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absence of by-products of processing, subject to subsequent burial; transfer of the mineral and metal components of waste into a melt, followed by obtaining a useful product in the form of granular slag, metal and products based on them; blockiness and completeness of equipment, the possibility of its placement at existing industrial sites (boiler rooms or other areas with equipment tied to local conditions). The secondary product of this process - slag, can be used as follows: in its natural form as crushed slag and aggregate in road and other types of construction; in the form of a porous aggregate (pyrosite) in the production of lightweight concrete for wall products and other building structures. The Piroxel technology is used for processing production and consumption waste of various composition (Table 6.8). Table 6.8. Morphological composition of waste before sorting
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Despite the possibility of processing unsorted waste, for household waste it is advisable to pre-sort with the selection of up to 50% of useful raw materials for secondary use. The Piroxel technology allows you to “recycle”: waste from medical institutions (used bandages, cotton wool, disposable syringes, needles, ampoules, vials, blood transfusion systems, rubber tubes, plastic products, gloves, medicines, etc.); some types of industrial waste (any paper, cardboard, glass, wood pulp and container); waste from public utilities (used sanitary devices, sinks, toilet bowls, taps, waste paint, plaster, various wooden products, broken glass); waste from car service stations (rags, rusty small units and parts (metal), car wash residues); waste electrical products (wires, cables, wiring accessories, etc.). Using the energy of solid waste incineration Improving the efficiency of incineration plants can be achieved by introducing well-known technologies for utilizing the heat of waste gases generated during waste incineration. The main method of heat recovery is the classic method of generating steam in waste heat boilers (UC). It is known that the production of heat energy at the incineration plant is due to a sharp fluctuation in the flow of waste and their calorific value. Therefore, certain difficulties arise to ensure the year-round use of the energy generated at the incineration plant. The presence of centralized sources of power supply presupposes the creation of special schemes for the joint operation of the recovery plants of the incineration plant with plants operating on fossil fuels: district boilers, combined heat and power plants and power plants.
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Depending on the consumers, utilization boiler houses are designed as industrial heating or pure heating. In order to maintain stable parameters of heat carriers, it is planned to burn, along with solid waste, fossil fuel, which dampens all fluctuations in parameters caused by the specifics of solid waste combustion. The UK can supply steam or hot water to the heat supply system. Parameters of steam generated in utilization boiler houses, as a rule, are P = 1.4-2.4 MPa, t = 250 ° C. The schemes of utilization boiler houses and heat supply depend on the nature of the consumer, the type of heat carrier and its parameters; heat consumption regime in daily and seasonal periods. 6.5.4. Disposal of household waste Disposal of consumer waste is a widely practiced method of waste disposal. However, the disposal of waste generates a host of environmental and sanitary and hygienic problems. Therefore, reducing the volume of waste to be buried is one of the most important tasks that can be solved by reducing its formation, reuse, processing and energy production. The most optimal method of disposal of residual waste is to create landfills for solid domestic waste (sanitary landfills). Solid waste landfills are complexes of environmental structures designed for centralized collection, neutralization and disposal of solid waste, preventing the ingress of harmful substances into the environment, pollution of the atmosphere, soil, surface and ground waters, preventing the spread of rodents, insects and pathogens.
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Depending on the morphological composition of waste, landfills are subdivided into two classes: 1) landfills of 1st class solid waste are intended for receiving: household waste, the content of organic matter in which should not exceed 25% of waste from medical institutions; 2) landfills for solid waste of the 2nd class are intended for the reception of waste with an organic matter content of more than 25%, as well as: construction waste, including wood construction; solid industrial waste of IV hazard class, in agreement with the authorities and institutions of the sanitary-epidemiological and municipal services, in an amount not exceeding 30% of the mass of accepted solid waste; soils and soils, solid industrial grade IV hazardous waste containing radionuclides in quantities not exceeding the limits established for radioactive waste. It is prohibited to take to the landfills of solid domestic waste: construction waste containing asbestos slag (waste), slag, ash, waste asbestos, waste of soft roofing; industrial waste of I, II and III hazard class; radioactive waste. The number of solid waste landfills and productivity are determined by the feasibility study for the construction of the landfill and environmental conditions, taking into account the master plans for the development of urban and rural settlements.
Slide 60
The ecological safety of solid waste landfills is ensured by geotechnical measures, which include: the installation of barriers that prevent the spread of contamination into the ground, groundwater and airspace and represent a geocompositional system of waterproofing and gas-insulating elements in the protective screens of the base and surface of the landfill; reducing the risk of environmental pollution due to the destruction of the source of pollution or a decrease in the level of its toxicity. The placement of solid waste landfills is envisaged in the development of territorial integrated schemes of urban planning for the development of territories and must meet the conditions of social well-being of the population and the concept of minimizing environmental damage to the environment. The placement of landfills is excluded: on the territory of the natural reserve fund of the Russian Federation; within the districts of sanitary protection of resort and health-improving zones; on the territory of green zones of cities and industrial settlements; on lands occupied by green spaces performing environmental, sanitary and hygienic and recreational functions; on agricultural land with a cadastral estimate above the average district level; on lands of historical and cultural purposes; within the water protection zones of water bodies; within the I and II zones of sanitary protection zones of water bodies used for domestic and drinking water supply; within the city limits; in the territory contaminated with organic and radioactive waste;
Slide 61
In areas with difficult geological and hydrogeological conditions (developed slope processes, suffusion-unstable soils; wetlands and flooding zones, etc.). Solid waste landfills are placed taking into account the requirements of urban planning, and the hygienic requirements for the design and maintenance of landfills are determined by sanitary rules. The sanitary protection zone for solid waste landfills, counting from the border of the landfill, is 500 m. The landfill territory is divided into production and administrative zones. The production area includes: a solid waste storage area with soil cavaliers (warehouses) for intermediate isolation of solid waste, a waste sorting area, a composting area for wood and vegetable waste, treatment facilities and evaporation ponds, biogas utilization facilities. At the landfill along its perimeter, starting from the fence, the following objects should be sequentially located: administrative and utility rooms, a laboratory, a warm parking lot for special vehicles, a workshop for repairing special vehicles and mechanisms, a fuel storage, truck scales, a checkpoint, a boiler room, a control - a disinfectant bath, a fire-fighting tank, a transformer substation, an artesian well (reservoir for drinking water), treatment facilities (if necessary), a site for radiation control of waste. The landfill for burial of waste along the perimeter must have a fence with a height of at least 1.8 m, and then successively the following structures: an annular canal for intercepting rain and melt water; ring road with high quality hard surface; rainwater trays along the road or ditches. In addition, trees will be planted, utilities (water supply, sewerage), and electric lighting masts will be installed along the perimeter of the landfill on a strip 5-8 m wide.
Slide 62
Calculation of the capacity of the landfill. The projected capacity of the landfill is carried out to substantiate the size of the area required for organizing a solid waste storage site, taking into account the number of people served by the landfill, the estimated service life of the landfill, the degree of compaction of solid waste at the landfill, as well as the strategy for the development of the waste management system adopted in this territory. The projected capacity of the landfill can be calculated using the formula (6.3): where U1, U2 are the specific annual rates of solid waste accumulation by volume, respectively, for the first year of operation, m3 / person; Q1, Q2– the number of the population served by the landfill, respectively, for the first and last year of operation, people; T is the estimated service life, year; K1 is the coefficient taking into account the compaction of solid waste during the operation of the landfill for the entire period, for approximate calculations it is taken equal to 2.5-3.0; K2 is the coefficient taking into account the volume of the outer insulating soil layers, both intermediate and final, for approximate calculations is taken equal to 1.25. The calculation of the required area of the land plot for the rectangular shape of the solid waste storage site is calculated by the formula (6.4): where a is the coefficient taking into account the steepness of the slopes, when the outer slopes are laid 1: 4, a = 3; H is the projected height of the landfill, m.
Slide 63
The solid waste storage area occupies the main (up to 95%) landfill area. It is divided into operation queues, taking into account the provision of waste reception for 3-5 years. Table 6.9 shows the approximate area of the landfill storage area for an estimated service life of 15 years. Table 6.9. The minimum area of the site, hectares. storage of a solid waste landfill Constructive solutions for the construction of landfills depend on the terrain. There are high-rise, trench, ravine and quarry polygons. Polygons of high-rise and trench types are placed on flat terrain. High-rise polygons are edged with a dam. The height of the dam and the width of its upper platform must ensure the safe operation of equipment (garbage trucks, rollers, bulldozers). Trench landfills are created by laying trenches 3-6 m deep and 10-12 m wide at the top. temperatures below 0 ° С - for the entire period of soil freezing.
Slide 64
The selected soil is used to cover the individual layers of the stored waste. Gully polygons are organized in ravines and in worked-out clay quarries. After the end of the operation of the landfills, they are covered with a layer of soil up to one and a half meters thick and the soil is reclaimed. Solid waste landfills must ensure environmental protection according to six indicators of hazard: organoleptic, general sanitary, phytoaccumulation (translocation), migration-water, migration-air and sanitary-toxicological. The organoleptic indicator of harmfulness characterizes the change in the smell, taste and nutritional value of phytotest plants in the adjacent areas of the operating landfill and the territories of the closed landfill, as well as the smell of atmospheric air, taste, color and odor of ground and surface waters. The general sanitary indicator reflects the processes of changes in biological activity and indicators of self-cleaning of the soil of adjacent areas. Phytoaccumulation (translocation) indicator characterizes the process of migration of chemicals from the soil of nearby areas and territories of reclaimed landfills into cultivated plants used as food and fodder (into marketable mass). The migration-water hazard indicator reveals the processes of migration of chemicals in the solid waste leachate into surface and ground waters. The migration-air index reflects the processes of emission of emissions into the atmospheric air with dust, vapors and gases. The sanitary-toxicological indicator summarizes the effect of the influence of the factors acting in the complex.
Slide 65
A special monitoring project is being developed for the solid waste landfill, which includes the following sections: monitoring the state of underground and surface water bodies, atmospheric air, soil and plants, noise pollution in the area of possible adverse impact of the landfill. The content of ammonia, nitrites, nitrates, hydrocarbonates, calcium, chlorides, iron, sulfates, lithium, COD, BOD, pH, magnesium, cadmium, chromium, cyanides, lead, mercury, arsenic, copper, cadmium, barium, methane is monitored , hydrogen sulfide, carbon monoxide, benzene, trichloromethane, carbon tetrachloride, chlorobenzene and other pollutants. The monitoring system should include constant monitoring of the state of the soil in the area of possible influence of the landfill. For this purpose, the quality of soil and plants is monitored for the content of exogenous chemical substances (ECP), which should not exceed the MPC in the soil and the residual amounts of harmful ECP in the vegetable commodity mass are above the permissible limits. The operation of solid waste landfills is carried out in accordance with the current regulatory and instructive documents.
View all slides
One of the main problems of our time is the disposal and processing of solid waste - solid household waste. It is still difficult to talk about fundamental changes in this area in our country. As for the European countries and the USA, people there have long come to the conclusion that the resource potential of solid waste should not be destroyed, but used. You cannot approach the problem of solid waste as a fight against waste, setting the task to get rid of it at any cost. It is no longer news to anyone that multicolored containers for the selective collection of waste (glass, waste paper, etc.) are installed on the streets of Western European cities. At the same time, the duties and responsibilities of the parties are clearly allocated, taking into account the total profit. Almost all countries banned the sale of food in non-degradable plastic casing. In the USA in 1998, for example, America Recycles Day was held. The prize for the most effective participation was a $ 200,000 home made entirely from recycled materials. Since 1990, the UK government has been implementing a pan-European directive: at least 70% of food plastic containers (bottles, glasses, bags, blister packs, etc.) must be recycled. One of the latest decisions is to achieve in 2000 the recycling of all produced household and industrial plastic waste.
1 slide
THE PROBLEM OF HOUSEHOLD GARBAGE Executor: Beltyukova O.A. MBOU-SOSH № 36 Yekaterinburg
2 slide
3 slide
From the history of garbage disposal 200 thousand years BC NS. The first trash heaps found by archaeologists. 400 BC NS. The first ever municipal landfill is established in Athens. 200 A municipal garbage collection service was established in Rome. 1315 After a long hiatus, garbage collection resumed in Paris. 1388 The English Parliament forbids throwing rubbish on the streets. 1775 The first garbage cans appeared in London. 1800 New York City Council ordered pigs to be thrown onto the streets to eat trash. 1897 The first waste sorting and recycling center opens in New York. 1932 Garbage pressing machines are invented in the USA. 1942 Mass collection of garbage for military processing begins in the USSR and the USA. 1965 US Congress passes the Solid Waste Disposal Act. 2000 EU countries set a target to achieve recycling and reuse of 50% of waste.
4 slide
The reasons for the increase in the amount of garbage. growth in disposable production; ... an increase in the number of packaging; ... raising the standard of living, allowing usable things to be replaced with new ones.
5 slide
MSW: paper, glass, food waste, plastics, fabrics, metal objects. In addition to all this, large-sized solid waste (garbage - old furniture, out-of-order household appliances, car tires, etc.)
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Burial is the most anti-ecological option In an ordinary landfill, toxic infiltration water flows out of it, and methane enters the atmosphere, which enhances the greenhouse effect (today, methane "takes over" 20% of the effect of climate warming)
11 slide
Burial - a landfill for storing solid waste is a "bath" with a bottom and sides made of clay and polyethylene film, in which compacted layers of solid waste are sprinkled with layers of soil. The volume of garbage is growing so quickly that in a few years any landfill is full and a new one needs to be built.
12 slide
Incineration of solid waste. 1 ton of garbage can give 400 kWh. However, even with the most advanced combustion technology, these plants pollute the atmosphere.
13 slide
Sorting and recycling - the most environmentally friendly option for handling solid waste Recycling requires investment to make waste recycling plants economically viable. It is profitable to recycle solid waste; there is always a demand for secondary raw materials - paper, glass, plastic, aluminum, non-ferrous metals, etc.
14 slide
Recycling of solid waste in Russia is no more than 2% one of the reasons is the insufficient ecological culture of the population
15 slide
Unauthorized landfill 1. Disfigures the landscape. 2.Creates a threat to human health: - breeding rodents are carriers of infectious diseases; - toxicological hazard from emitted methane, sulfur dioxide. 3. The released biogas creates an explosive and fire hazardous situation. 4. Contamination of soil and groundwater with compounds of arsenic, cadmium, chromium, lead, mercury, nickel.
16 slide
When arranging a waste site, it is taken into account: rose, winds in the landfill area; distance from settlements, water protection and nature protection zones; water permeability of soils; the area of the landfill (the area must be sufficient to receive garbage for a long time); location convenient for transport
17 slide
Special waste: 1. Industrial waste - cannot be destroyed together with household waste, pesticides, mercury and its compounds - chemical industry waste; radioactive waste generated at nuclear power plants; arsenic and its compounds - wastes from metallurgical industries and thermal power plants; lead compounds - wastes from the oil refining and paint and varnish industries, etc.
18 slide
Special waste: 2. Household waste - which after their use becomes special waste, Batteries; unused medicines; residues of plant protection chemicals (pesticides); residues of paints, varnishes and adhesives; the remains of cosmetics (eye shadow, nail polish, nail polish remover); residues of household cleaning products (cleaning agents, deodorants, stain removers, aerosols, furniture care products); mercury thermometers.
Description of the presentation for individual slides:
1 slide
Slide Description:
2 slide
Slide Description:
Solid household waste (MSW) - waste of unnecessary materials and products that accumulate in everyday life and in institutions - garbage, garbage, food waste, waste paper, worn out clothes, out-of-order household appliances, etc. - everything that does not apply to industry and sewage waste. Waste disposal is the use of waste in industry as additional raw materials and in agriculture as feed or fertilizer.
3 slide
Slide Description:
Utilization of solid waste is a headache for most of the subjects of our country. It is MSW that make up the lion's share of the w / w, causing irreparable harm to air, soil and groundwater. In almost every settlement in Russia today you can see a huge landfill. According to science, these "traces of human activity" will remain in nature for several thousand years.
4 slide
Slide Description:
Annually in the cities of Russia about 130 million m3 of solid waste is generated, which is approx. 200 kg per person per year. On the territory of Russia today there are 7 waste incineration plants that process about 3% of solid waste, 9% is exported from cities to more than 1,000 landfills for household waste. The rest of the waste (88%) goes to landfills. A significant number of 88% ends up in unauthorized landfills, the number of which is constantly growing.
5 slide
Slide Description:
The main problem of MSW processing is their unsorted quality, high humidity, low calorific value and, as a result, the impossibility of observing environmentally friendly technologies for storage at landfills, composting, and waste incineration.
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Slide Description:
paper (cardboard); food waste; wood; black metal; non-ferrous metal; textile; bones; glass; leather and rubber; Classification of solid waste According to the qualitative composition, solid waste is subdivided into: stones; polymeric materials; other components; screening out - small fragments passing through a 1.5 cm grid; dangerous solid waste!
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Slide Description:
Hazardous solid waste Hazardous solid waste includes: batteries and accumulators, electrical appliances, varnishes, paints and cosmetics, fertilizers and pesticides, household chemicals, medical waste, mercury-containing thermometers, barometers, tonometers and lamps. They pose a threat to the environment if they enter waterways through sewers or are washed out of landfills and into ground / surface water. Batteries and mercury-containing devices will be safe as long as their casing is not damaged; then mercury, alkali, lead and zinc will become elements of air pollution, groundwater and surface water.
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Slide Description:
Correct disposal of solid waste does not imply their complete destruction. Most of the waste will go to recycling, which will save on the production of many goods. In European countries, this problem was solved a long time ago: there are separate containers for each type of waste. After all, glass, metals, wood and even biological waste can become raw materials for the manufacture of new materials.
9 slide
Slide Description:
In world practice, more than 20 methods of processing solid waste are known, which, according to the final goal, are divided into: liquidation (based on sanitary and environmental problems) utilization (use of secondary resources)
10 slide
Slide Description:
There are two main methods of MSW processing: Mechanical and biological methods: waste composting, waste sorting by recycling facilities Thermal methods: waste incineration, pyrolysis, waste gasification, combined thermal methods
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Slide Description:
Most of the above methods have not found significant distribution due to their technological complexity and high cost of processing solid waste. The most widespread practice is: storage at a landfill (dump); incineration (incinerators); aerobic biothermal composting; a composting and incineration or pyrolysis complex.
12 slide
Slide Description:
1. Specially equipped landfills This should take into account: wind rose in the landfill area; distance from settlements, water and nature protection zones; water permeability of soils; the area must be sufficient to receive garbage for a long time; location convenient for transport access; etc. It is not possible to arrange a specially equipped landfill in any place. Specialists of different directions are involved in solving this problem - geologists, hydrologists, ecologists, etc.
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Slide Description:
You have to spend a lot of money on the delivery of waste to the landfill, because they all have to move away from the cities - by 50 - 100 km. In addition, they occupy large areas, which are useful for agriculture. Specially equipped landfills are not the best way to get rid of garbage, although today you cannot do without them. In our country approx. 90% of solid waste is disposed of in landfills, which occupy more than 20 thousand hectares in the country as a whole.
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Slide Description:
The territory for the landfill is chosen so that harmful waste water does not get into rivers and groundwater. Compliance with technological standards for disposal leads to the fact that the buried waste practically does not have a harmful effect on the environment. Moreover, enclosed in a special huge "sandwich", the garbage undergoes natural utilization (decomposition) and in a few decades will become completely safe for nature.
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Slide Description:
Landfills themselves create a lot of complications. Here, rodents, insects, birds reproduce in large numbers, which can become a source of various infectious diseases. Landfills are also dangerous because the biogas emitted there creates an explosive and fire hazardous situation.
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Slide Description:
2. Sanitary earth filling Microbiological processes develop in the strata of solid waste. In the upper aerobic layer (up to 1 - 1.5 m), due to microbial oxidation, MSW is gradually mineralized to CO2, H2O, nitrates, sulfates and a number of other simple compounds. In the transition zone, nitrates and nitrites are reduced to gaseous nitrogen and its oxides - the process of denitrification. In the lower anaerobic zone, gases and volatile organic substances are formed. The central process is the formation of methane. A constant t = + 30… + 40 ºС is optimal for the development of methane-forming bacteria. Solid waste neutralization technology based on the production of biogas and its use as a fuel, solid waste is covered with a layer of soil 60 - 80 cm thick in a compacted form. Biogas landfills are equipped with ventilation pipes and containers for collecting biogas. 1 ton of solid waste emits at least 100 m³ of biogas. The use of biogas is possible in 5 - 10 years after the creation of the landfill, and profitability is manifested when the volume of solid waste is more than 1 million tons.
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Slide Description:
3. Incineration Incineration of solid waste reduces their volume and weight, allows you to get additional. energy resources that are used for heating and electricity production. Disadvantages - the release of harmful i / v into the atmosphere and the destruction of valuable organic and other components contained in MSW. A type of MSW utilization, in which waste is incinerated, and the ash formed during the incineration process is buried in special landfills. Incineration is a widespread method of MSW destruction, which has been used since the end of the 19th century. The complexity of MSW disposal is due to their multicomponent nature and increased sanitary requirements for the recycling process. In this regard, incineration is still the most common way of utilizing solid waste. When solid waste is incinerated, 28 - 44% of ash and gaseous products (CO2, H2O vapors, various impurities) are obtained. Combustion occurs at t = 800 - 900 ºС, therefore, gases contain aldehydes, phenols, dioxins, furans, heavy metals. This mixture is more dangerous than the military gases mustard and sarin.
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Slide Description:
Currently, the level of incineration of solid waste in individual countries is different: Austria, Italy, France, Germany - 20 - 40%; Belgium and Sweden - 48-50%; Japan - 70%; Denmark and Switzerland - 80%; England and the USA - 10%. In our country, approx. 2% household waste. Waste incineration is advisable to be used in cities with a population of at least 15 thousand inhabitants with a furnace capacity of about 100 tons / day. Each ton of waste produces approx. 300 - 400 kW / h of e / energy.
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Slide Description:
5. Pyrolysis The method of utilization of solid waste by pyrolysis is known quite little, especially in our country, because of its high cost. Irreversible chemical change of garbage under the influence of temperature without oxygen access By the degree of temperature effect on the garbage substance, pyrolysis as a process is conventionally divided into low-temperature (up to +900 ° С) and high-temperature (over +900 ° С).
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Slide Description:
5.1. Low-temperature pyrolysis The advantages of pyrolysis: Recycle solid waste, difficult to recycle - car tires, plastics, waste oils and sludge waste; does not leave biologically active substances, therefore, underground storage of pyrolysis waste does not harm the natural environment; the resulting ash has a high density, which sharply reduces the volume of waste; there is no recovery of heavy metals; the resulting products are easy to store and transport; does not require large capital investments. Pyrolysis is used in Denmark, USA, Germany, Japan and other countries. The process by which the crushed waste material undergoes thermal decomposition. It has several options: pyrolysis of the organic part of solid waste under the influence of temperature in the absence of air; pyrolysis in the presence of air, providing incomplete combustion of solid waste at t = + 760 ° C; pyrolysis using O2 instead of air to obtain a higher calorific value of the gas; pyrolysis without separating solid waste into organic and inorganic fractions at t = + 850 ° С.
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Slide Description:
The technological chain of pyrolysis consists of 4 successive stages: selection of bulky items, non-ferrous and ferrous metals from garbage using an electromagnet and by means of induction separation; processing of prepared waste in a gasifier to obtain synthesis gas and by-product chemical compounds - chlorine, nitrogen, fluorine, sulfur, cyanides and slag when melting metals, glass and ceramics; purification of synthesis gas to improve its environmental properties and energy consumption, its cooling and flow into a scrubber for cleaning with an alkaline solution from polluting I / O; combustion of purified synthesis gas in waste heat boilers to produce steam, hot water or electricity. 5.2. High-temperature pyrolysis The method of utilizing solid waste is essentially nothing more than gasification of garbage. The technological scheme of pyrolysis involves obtaining synthesis gas from the biological component of solid waste in order to use it to produce steam, hot water and electricity.
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Slide Description:
The problem of waste and ways
deliverance
from them became one
of serious problem
Relocation to cities and their development
led to a different structure
consumption:
for better transportation
food and other
products needed packaging;
new artificial and
synthetic materials that
absent in nature;
society of many developed countries
turned into a "society
consumption ", where the quantity
"Necessary" things are immeasurable
increased.
What is waste?
Waste - substances found unsuitable forfurther use within existing
technology, or after household use
products.
MAIN WASTE TYPES:
household (utilities);
industrial (production waste);
dangerous (toxic);
radioactive
Household waste
the share of foodwaste, wood, ferrous and
non-ferrous metals;
the share of waste is increasing
packaging materials
made from
difficult to decompose substances;
is growing rapidly
number of served
household appliances,
used cars
batteries, etc.
Solid household waste is a source of environmental hazard:
Municipal solid waste is a sourceenvironmental hazard and:
MSW spreads an unpleasant odor and
are breeding grounds
pathogenic bacteria, insects and
rodents - carriers of infectious
diseases;
incineration poses a serious hazard
MSW (especially synthetic materials
and substances) in bins and garbage cans, so
how are they released into the air
toxic substances that quickly
enter the respiratory system of others
of people;
scattered everywhere (in the entrances, on
street, in playgrounds) garbage is
shame of our society, characteristic
the level of our everyday culture, the environment in
which we all live.
The waste problem is compounded by the fact that the natural decomposition of various materials takes a certain amount of time.
Paperfrom 2 to 10 years
Tin
90 years
Cigarette filter
100 years
Polyethylene
plastic bag
200 years
Glass
1000 years
Burial of waste at solid waste landfills
Solid waste landfills are nothing more than officialname of authorized landfills.
Waste at landfills
unloaded from containers
or bodies and leveled
through dedicated
technology.
A layer of debris defined
thickness periodically
cover with soil, after
which is again filled with waste.
Waste containing a lot
organic substances,
start gradually
rot
Burial of toxic waste
Toxic solid industrial wasteneutralized at special landfills and
structures. To prevent pollution
soil and groundwater waste is exposed
curing with cement, liquid glass,
bitumen, processing with polymer binders and
etc.
Burial, disposal of toxic solid
industrial waste is produced at
specialized territories.
Waste,
incoming
on
factories,
first of all, they pass control on
radioactive isotope content
Manually from
large
battery
wheels
beds and
masses of solid waste are removed
subjects
–
cast iron
central
heating,
cars,
iron
etc.
Selection of secondary raw materials -
waste paper,
colored
metals,
cullet.
Items from
plastics and polyethylene. Of them
it turns out
secondary
raw material
–
plastic
chit,
which
sorted
on
color
and
packaged.
The main stages of waste processing
Coming out of the trash with magnetsrelease ferrous scrap
(consisting mainly of
cans and corks from
beer bottles). This scrap metal
pressed into bales and sent to
remelting
on
metallurgical
production of other factories.
Car tires also
subject to a separate
processing; of them get
pyrocarbon - black powder,
widely used for
rubber production,
plastics, waste water treatment
and soil from herbicides.
Biocomposting
Mechanized processingsorted solid waste is produced by
biocomposting technologies
organic part with obtaining
compost.
Waste is fed into rotating
biothermal drums 60 m long
and a diameter of 4 m each.
Bio-drums activate
vital activity of microorganisms,
in the trash, as a result
what happens naturally
biological decomposition process
organic matter at
temperature 50 ° C.
In 48 hours from waste to
bio-drum compost is formed
- moist crumbly dark gray mass. Purified from
impurities (polyethylene
films, etc.) compost is
good fertilizer,
containing mineral and
organic matter.
Incineration of waste
Waste incineration is a thermalrecycling and disposal of solid
household and industrial waste. V
as a result of this process, the waste is not
are only rendered harmless, but they can
be the source for receiving
electrical and thermal energy.
There are also several groups of waste, incineration
for which it is necessary to apply. This is waste
who may be infected: medical
- dressings, syringes, overalls,
medical instruments, organic
postoperative waste; bioorganic waste from forensic services,
carcasses of animals; waste of catering units. They must
be subjected to immediate thermal
neutralization
Burial of toxic waste
The generation of toxic waste is inevitablethe result of industrial and construction
production in cities.
In 1970 in St. Petersburg for burial
toxic waste landfill was opened "Red
Bor "(30 km from St. Petersburg and 6.5 km
from Kolpino).
From several options was chosen
territory corresponding to the following
requirements:
large strata of Cambrian clays
performs the role of an absolute waterproofing
(liquid waste does not seep into
The groundwater);
the territory is not flooded by floods
waters.
Along the perimeter of the landfill,
annular intercept channel
surface water from adjacent
territories.
1. WASTE PREVENTION:
a key factor in any waste management strategy.
If it becomes possible to reduce the number of produced
waste and reduce their toxicity by reducing hazardous
constituents in the final product, then waste disposal
will automatically become
more simple. Prevention
waste generation is closely related to the improvement
production technologies and impact on consumers,
which should demand more environmentally friendly
products with less packaging.
THREE PRINCIPLES OF WASTE MANAGEMENT IN THE EU
2. RECYCLING AND RECYCLING:if the generation of waste cannot be prevented, then
use as many materials as possible
reused, preferably by recycling.
European
Commission
identified
several
specific 'waste streams' to be devoted to
special attention in order to reduce their overall negative
environmental impact. These include: packaging waste,
out of order vehicles, batteries,
electrical and electronic waste. Today the EU requires
member countries to enact legislation to collect
waste, their reuse,
processing and
recycling. Several EU countries have already
recycle
recyclable up to 50% of packaging waste
THREE PRINCIPLES OF WASTE MANAGEMENT IN THE EU
3.Improvement
technologies
final disposal and monitoring:
where possible, waste that cannot be
reused or recycled, must
be burned;
landfill disposal should be applied
as the last possible alternative.
Both of these methods need careful
control because of its potential danger to
environment.
Basic technological solutions for waste management
PRINCIPAL APPROACHES TO WASTE RECYCLING
There are four options for recycling:1. burial at landfills;
2.combustion, less often pyrolysis and others
high temperature processes;
3. composting;
4.sorting for recycling purposes,
disposal and recycling.
Each of these types has its own advantages and
disadvantages. The presentation used
materials:
dy-1 / Ispolzovanie-otkhodov.html
http://900igr.net/prezentatsii/ekologija/Otkho
dy-2 / Pererabotka-otkhodov.html
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