RU2712526C1 - Method of recycling domestic and industrial wastes - Google Patents

Abstract

FIELD: recycling.

SUBSTANCE: invention relates to a method of recycling organic and mineral wastes, which can be used, for example, in recycling wastes from poultry factories or pig-breeding complexes, as well as in recycling sewage wastes. Method consists in that wastes are removed to the landfill and stored in a solid mass, wherein the wastes are first subjected to grinding and stabilization, for which they are mixed with a neutral filler. Degree of grinding, composition and amount of filler is selected so that produced mixture has limited gas and water permeability, and thickness of backfill of mass is selected such that at depth equal to or less than 1/3 of thickness of filling, pressure accumulated as a result of decomposition of garbage gases exceeded water column pressure to backfill surface.

EFFECT: method provides higher environmental friendliness of the landfill, in particular, due to high density of embedded organics.

5 cl, 2 dwg

Description

It is proposed (according to claim 1) a method of disposing of household and industrial waste in the region by transporting it to a landfill (landfill) and storing it in a continuous massif, which consists in the fact that the waste is first subjected to grinding and stabilization, for which a certain proportion is mixed with a neutral filler characterized in that the degree of crushing of the garbage, the composition and amount of filler are selected so that the resulting mixture has limited gas and water permeability, and the thickness of the backfill of the array is chosen such that and at a depth equal to or less than 1/3 of the thickness of the backfill, the pressure of the gases accumulating as a result of decomposition of the waste exceeds the pressure of the water column to the backfill surface. Let's see what distinguishes the traditional, loose waste dump and the array of shredded and mixed with soil waste. First of all, specific gravity and degree of permeability to water and gases. In our case, small rubbish mixed with earth hardly passes gases, anaerobic conditions are already created at a depth of one meter, the partial pressure of oxygen decreases, other microorganisms live in the decomposing organic matter, fewer foul-smelling gaseous substances are released, processes occur at a lower temperature, more slowly and evenly. With increasing depth, the pressure of landfill gases increases and at around 4-5 meters it begins to exceed the pressure of the water column to the surface. This means that water seeping from above after rain will not go lower, but will mainly flow down the slope of the relief. Of course, capillary mechanisms will moisten the entire array of waste, but there will be no continuous flow of rainwater and leaching of harmful impurities from garbage into groundwater, as happens in a normal landfill. Gas is released continuously and also continuously leaks up, a certain dynamic equilibrium arises and is maintained. Thus, a phenomenon arises when almost the entire volume of buried waste is protected from running water - precipitation from above and groundwater around the perimeter. While there is gas evolution, and the process of decomposition of plastic will continue for decades, organic toxins and soluble minerals will remain at the burial site. The deeper the array is laid and the thicker the layer of waste, the better for the environment. Let us illustrate with an example. Suppose crushed garbage is mixed with soil in a volume ratio of 3/1 (the density of the garbage is reduced to the state compressed inside the embankment), then the density of the mixture will be approximately 1.3 g / cm3. If the embankment is 50 meters thick, then due to the excavated soil it will be 20 meters deep. What are the conditions at the bottom of the pit. The pressure from above the underlying rock will be 6.5 atmospheres, the pressure of landfill gas, consisting mainly of methane, can rise to the same value. At the same time, the pressure of groundwater along the periphery of the landfill is equal to the pressure of a water column of 20 meters, i.e. two atmospheres. The gas cushion reliably isolates the internal buried mass of garbage, water will not get there.

The next difference (according to claim 2) of the proposed method is that, as a result of the limited permeability of the mixture of garbage and filler in the thickness of the formed array, a dynamic interface is formed that rain and groundwater cannot overcome, and where favorable anaerobic conditions are created for the decomposition of garbage . Subject to the technological regime, in each volume intended for the burial of the mixture, there will be enough small particles to create tangible resistance to the slow but continuous flow of landfill gas, making its way from the depth of the landfill to the surface and edges. The magnitude of this resistance depends, first of all, on the degree of moisture in the mixture: the more moisture the soil absorbs, the more difficult it is for rainwater to penetrate deep into the direction of the gas moving towards it. The gas pressure at any depth tends to approach the weight of the soil column at this depth, and the water pressure is equal to the current weight of the water column. And since the specific gravity of the mixture is greater than the specific gravity of water, even in the case of heavy rain, when the entire overlying layer is saturated with moisture, a dynamic interface will arise, beyond which precipitation will not penetrate. For persuasiveness, let’s do such a thought experiment. A grid is fixed in the middle of a long glass cup, filter paper is laid on it, a layer of fine soil is poured on top and water is poured. Water seeps and drips to the bottom of the glass. If air is now supplied to the lower part of the glass through the outlet under a slight pressure, the liquid filtration will stop. Even if, as a result of capillary seepage, a certain amount of water gets to the bottom of the pit, it will be squeezed out into groundwater, which is under much lower pressure. Moreover, atmospheric oxygen cannot penetrate the seeping landfill gases into the garbage, and ideal anaerobic conditions are created for the decomposition of garbage.

The next difference (according to claim 3) of the proposed method is that local soil is used as a neutral filler, as well as pre-ground construction and other industrial wastes of the region. The following requirements are imposed on the filler: it must have a mineral origin, a higher specific gravity in comparison with garbage and contain a sufficient percentage of the fine fraction. Since this filler is consumed in large quantities, it is advisable to obtain it at the location of the landfill, taking out, in particular, the soil underlying the formed dump. In addition, construction waste that needs to be disposed of appears in the region, contaminated soils taken out during the repair of communications are removed, there are ash-and-slag waste from thermal power plants and other non-toxic industrial waste. All this, after some refinement, can be used as a neutral filler for mixing with crushed garbage.

The next difference (according to p. 4) of the proposed method is that the soil used to stabilize the mixture is taken directly at the place of formation of the landfill, and some of it is removed from the underlying bulk array of the horizon, and part is taken from the foundation pit formed along the dump mass; This pit is used as a reservoir - sedimentation tank, performing damping, drainage and fire fighting functions. As explained earlier, rainfall and groundwater do not penetrate the bulk of the stored waste, however, harmful substances that damage the environment are removed from the surface and peripheral zones of the formed array. To minimize this harm, a foundation pit breaks out along the forming landfill, the depth and location of which is determined by the peculiarities of groundwater movement in the area. The pool is filled with groundwater and soluble or liquid wastes removed from the pile are drained into the created artificial reservoir. It is convenient to inspect them and, if necessary, take decontamination measures, for example, conduct aeration or dosed chlorination of a reservoir. Such a measure will prevent the further spread of infected organics along the groundwater flow chain. In addition, the formed pool-settler is convenient to use as a fire reservoir, as well as a source of water for wetting the landfill in dry years.

The next difference (according to p. 5) of the proposed method is that along with household waste, local organic waste from poultry farms, pig-breeding complexes, as well as sewage waste and sludge residues are simultaneously disposed of; this specific waste is mixed in a balanced manner with household waste. Organic waste of this class is not accepted at ordinary landfill sites due to their viscous consistency. Municipal wastewater treatment plants are usually engaged in sewage leachate and silt sludge from aeration pools. They are either burned or buried in trenches at their own landfills. Livestock farms are also not going to pay landfills for the disposal of their manure - they allegedly use it to fertilize the soil, but in reality they spill it near the complex. For a long time, nature has not been able to adapt this viscous concentrated mass, revitalized with every rain. The named organic waste fits perfectly into the technology of this method. Mixing them with soil and crushed garbage in a convenient proportion, we get a high-quality mixture for laying in the dumped array.

In our country, the most common way of disposing of household waste is direct storage in specially designated areas near settlements. At the same time, unstable, fire and environmentally hazardous formations are formed that require constant maintenance costs for a long time and cause serious concern to the local population.

удельный вес, обладает предсказуемой водо - и газопроницаемостью и пригодна для однократной и окончательной укладки в массив большой толщины. При этом с воздухом находится в контакте лишь незначительный процент отходов, а

их часть сразу попадает в анаэробные условия, где подвергается медленному и равномерному разложению. Профиль полигона формируется единовременно, равномерно проседает, не требует последующей рекультивации и, соответственно, отчуждает меньшую площадь.Uneven in composition, the garbage sags as it decomposes, new portions of waste are laid on the encircled area, the landfill surface must be constantly leveled and compacted with bulldozers, otherwise spontaneous combustion occurs. As a result, a large surface of rotting waste is in contact with the atmosphere at the same time, which causes additional air pollution. According to the proposed method, the waste coming to the landfill is pre-crushed and mixed with a neutral component - soil, construction waste or other inorganic waste. The resulting mixture has

specific gravity, has predictable water and gas permeability, and is suitable for single and final laying in an array of large thickness. At the same time, only a small percentage of waste is in contact with air, and

part of them immediately falls into anaerobic conditions, where it undergoes slow and uniform decomposition. The landfill profile is formed at a time, evenly sags, does not require subsequent reclamation and, accordingly, alienates a smaller area.

It is interesting to look at how the problem of disposing of household waste in other countries of the world is being solved. Here, the best experience is the technology of incineration and deep processing of household waste. With a high population density, incineration is the only way to radically reduce waste. This technology requires the use of complex high-temperature furnaces with exhaust gas treatment devices. Burning plastic at a low temperature is unacceptable - harmful hydroxyl, peroxide, carbonyl and ether groups are formed, but at a high temperature dangerous inorganic impurities appear - nitric oxide, hydrogen chloride and carbon monoxide, which have to be chemically neutralized at the outlet of the furnace. In this case, in any case, all carbon goes into dioxide, a greenhouse gas, which, when it enters the atmosphere, adversely affects the environment.

The deep processing of household waste also creates many problems. The process of complex processing is poorly automated, the use of manual labor in this not prestigious and harmful work is ineffective, processing products, with the exception of metals, are not of sufficient value. Attempts at complete thermal destruction of the organic component of household waste up to carbon with the isolation and integrated use of the resulting organic products have not yet gone beyond the scope of experiments.

According to the proposed method, manual sorting is completely excluded from the technological process — after the waste is shredded, non-ferrous and ferrous metals are automatically separated, and the remaining mass is mixed with the neutral component and laid in a pile at the place of constant burial. It is assumed that plastic, wood pulp and paper do not represent value justifying the cost of sorting. The processing technology maintains a constant ratio between the organic and neutral components of the mixture, which contributes to the slow and uniform decomposition of garbage under anaerobic conditions created in the massif to be laid. A significant content of the inorganic component, as well as the difficult access of oxygen to the mixture mass, exclude the possibility of ignition and allow the formation of significantly more powerful dumps (50-100 m) than is now accepted.

Since the proportion of plastic in modern materials and products is constantly growing, and its operating time is insignificant, this material inevitably ends up in a landfill, in fact, this is the main waste of modern civilization. Compared to household organic waste, plastic disintegrates very slowly, so under the influence of time and pressure, anthropogenic rock similar to shale forms in the landfill site, which preserves the potential greenhouse gas in the form of relatively relatively stable carbon compounds. Harmful chemical elements such as chlorine or fluorine will be gradually excluded from the composition of plastics as the technology for their manufacture improves, because nature manages to create much more valuable biopolymers such as cotton, cellulose or wool without such aggressive elements.

When preparing garbage for storage, an important and difficult technological operation is its grinding. The incoming waste varies greatly in nature, consistency and size - you will have to apply different methods of influencing the material, such as crushing, loosening, tearing, cutting, sieving, magnetic and induction separation of metals. This will require appropriate mechanisms and flexible production lines, but there is no doubt that the process lends itself to complete automation and the elimination of manual waste sorting.

Another costly component is excavation for the extraction and delivery of local soil to the mixing point. It is important to use a conveyor method of moving soil and garbage, as well as to avoid double overloading of the ground mass, - material removed from the pit should be immediately used. In a region rich in precipitation, where a reservoir at one time is formed - a sump, excavation can be carried out by the method of hydraulic washing, and the rock to the mixing place is fed through pipes in the form of pulp. In “dry” regions there is no need for a reservoir, and the soil removed from the pit is immediately replaced by the mixture prepared for burial.

The depth of the pit and, accordingly, the laying of garbage depends on the volume of mineral waste brought for utilization, as well as on the volume of soil removed from the pit if the layer being developed contains useful materials such as sand and clay. With this approach, the landfill can be partially used as a raw material quarry, which will lead to a deeper laying of the shoulder, and also favorably affects the economic performance of the enterprise.

As an example of a specific implementation of the method, consider a landfill designed to receive one million cubic meters of organic waste per year or 3000 cubic meters per day, which is about a hundred large garbage trucks. For every three cubic meters of compressed waste brought for recycling, one cubic meter of soil will have to be removed, i.e. 1000 cubic meters of soil per day; for a 3 cc excavator - this is the daily rate. Over 25 years, the size of the landfill with a mixture laying thickness of 50 m will be 500 per 1000 m, while only a growing frontal zone of 500 m wide is “active”, the “old” sections are closed with soil taken from the upper layer of the quarry being developed as it sags. If there is a reservoir, its width will be about 100 meters throughout the landfill at a depth of 10 m.

In the figure of FIG. 1 shows the layout of the landfill, shows the mechanisms for its maintenance, conveyor lines for the shipment of soil and the reception of garbage mixture.

The layout of the landfill preparation plot is shown in FIG. 2. Wastes coming to the landfill are divided into three categories: silt sludge from a water utility and manure from livestock enterprises - site 17, ordinary household waste - site 18 and industrial waste - site 19. Sludge-like waste is finely dispersed in nature, it is fed to a vibrating screen and then directly into the drum of the mixer 27. Extraneous inclusions remaining on the vibrating screen are sent through a magnetic separator 33 to a ball mill 26.

Household waste is the most diverse in structure and therefore difficult to grind. The vibrating grating 20 with large cells divides the garbage into two streams, - the small garbage passes into the plate crusher 23, and the large fragments encountered go into the jaw crusher 21. Then the vibrating screen 25 passes the finely divided garbage through itself, and a viscous, cohesive component, for example, a film, the fabric, the fibers are separated and fall on the separation brush machine 28, where metal brushes tear the material apart. Sufficiently shredded debris passes through the induction and magnetic separation device 34, where non-ferrous and ferrous metals are separately extracted.

Industrial and construction waste, as well as utilized contaminated soil go in a separate stream, since they consist mainly of mineral raw materials. They fall onto the vibrating grating 20, a small fraction wakes up, and large pieces, such as bricks, concrete, crumble onto small gravel in a jaw crusher 21.

The crushed garbage ultimately ends up in a mixer - a drum type dispenser 27, where soil is added to it in the required proportion, taken out at the same landfill and additionally mixed in a drum 30. The finished mixture is fed through a conveyor to the landfill directly to the place of laying in the bead. The described method of crushing garbage is illustrative, does not pretend to be original, and aims to show that the task of ensuring automatic acceptance and preparation of garbage for disposal is not difficult.

The list of positions in the figures of FIG. 1 and FIG. 2

1. the body of the dumped shoulder

2. ground level in the landfill

3. excavation area

4. device for laying the mixture in an array

5. excavator

6. bottom of the pit

7. soil receiver

8. conveyor belts for soil

9. conveyor belts for the mixture

10. direction to the site of preparation of the mixture

11. pond - sedimentation tank

12. fire boat

14. sludge waste

15. household waste

16. receipt of industrial and construction waste

17. sludge waste buffer area

18. domestic rubbish dump

19. buffer pad for industrial and construction waste

20. vibrating grill

21. jaw crusher

22. substandard inclusions

23. plate crusher

24. crushing rollers

25. vibrating screen

26. ball mill

27. mixer - drum type dispenser

28. separating brush machine, tearing a viscous fraction

29. the output of the mixture to be sent to the shoulder

30. normalizing drum

31. ground buffer pad

32. soil intake

33. magnetic separator

34. device for induction and magnetic separation.

Claims (5)

1. The method of disposal of household and industrial waste by removal to the landfill and storing them in a continuous array, which consists in the fact that the waste is subjected to preliminary grinding and stabilization, for which it is mixed with a neutral filler, characterized in that the degree of grinding of garbage, composition and amount of filler selected so that the resulting mixture had limited gas and water permeability, and the thickness of the backfill of the array is chosen such that at a depth equal to or less than 1/3 of the thickness of the backfill, the pressure accumulating As a result of decomposition of gas debris, it exceeded the pressure of the water column to the backfill surface. 2. The method according to p. 1, characterized in that by limiting the gas and water permeability of the mixture of garbage and filler in the thickness of the formed array, they form a dynamic interface that rain and groundwater cannot overcome, and where favorable anaerobic conditions are created for the decomposition of garbage. 3. The method according to p. 1, characterized in that as a neutral filler using local soil, as well as pre-ground construction and industrial waste. 4. The method according to p. 1, characterized in that the local soil used to stabilize the mixture is taken directly at the place of formation of the landfill, and part of it is removed from the underlying bedrock array, and part is taken from the foundation pit formed along the bed massif, the foundation pit is used as a settling pond, performing damping, drainage and fire-fighting functions. 5. The method according to p. 1, characterized in that along with household waste, local organic waste from poultry farms, pig farms, as well as sewage and sludge residues are simultaneously disposed of, while these specific wastes are balanced in a balanced manner with household waste.

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