Aerobic biological decomposition and stabilisation of landfill by oxygen injection - takes place after sealing surface simultaneously while extracting gas for treatment by biological filter and draining of fluids whilst treated levels may be excavated for extraction of metals and local reuse

(42) Date of commencement of the patent: 15. 7.1997 (45) Date of issue: 25. 2.1998

<td>(56) Documents:</td><td>(73) Patent owner:</td>

<td>AT 395686B AT 395859B</td><td>PORR ENVIRONMENTAL TECHNOLOGY AKTIENGESELLSCHAFT A-1031 VIENNA (AT). (72) Inventor: RAUSCHER CHRISTIAN DIPL.ING. VIENNA (AT).</td>

(54) METHODS OF MICROBIOLOGICAL DECOMPOSITION AND / OR STABILIZATION OF AT LEAST TEMPORARY ANAEROB-FERICINATED MIXTURES

CQ (57) Process for the degradation of at least temporarily anaerobically fermented mixtures with aerobic microbiologically degradable organic substances of an upper and / or underground deposit, eg. B. landfill wherein an oxygen-containing gas is supplied to the mixture in the deposit via Auidleitungen (11) and gaseous fluids are withdrawn from upper fluid conduits (12) and the anaerobic fermentation is at least partially converted into an aerobic fermentation, whereupon the mixtures are mechanically degraded to the respective lower area of ​​the Auidleitungen (11; 12) and spent, wherein the surface (7) created by the degradation before and / or after the laying of Auidleitungen (11,12) is sealed substantially fluid-tight and fed again oxygen-saturated gas and an Auid is subtracted.

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AT 403 480

CTRaraeiß

AT 403 480 B

The invention relates to a method for the microbiological degradation and / or stabilization of at least temporarily anaerobically fermented mixtures with aerobic microbiologically degradable substances, an upper and / or underground deposition of waste.

With increasing prosperity of a population, an increase in the amount of waste material occurs, in particular municipal waste has a high proportion of microbiologically degradable organic substances. Originally, the world did not pay due attention to the rapidly increasing amount of waste, but rather landfill that does not meet the current scientific and technical standard. So underground dumps were built in former gravel pits, which were partially dug into the groundwater area, but also aboveground landfills. These landfills have generally exhibited no seal against the ground so that water-elutable substances enter the groundwater. Furthermore, such landfills have a slight air supply, so that, if any rotting occurs, an anaerobic fermentation is present. This results in combustible, highly explosive and usually toxic gas mixtures, the main component of which is methane. In addition to the risk of explosions of such gas mixtures additionally occurs an odor, since the rotting products also cause the formation of mercaptans. The anaerobic fermentation is usually very slow, so that such landfills in the long term pose a threat to groundwater and an odor and toxic load, especially for the residents. A removal of such landfills is contrary, however, that with the removal of an extreme odor and toxic impairment of the population is given. To rehabilitate such landfills has already been proposed to freeze the garbage and thus the odoriferous substances, for example, with liquid nitrogen, and then to spend the waste at a suitable landfill site. Thus, although the waste can be spent to a landfill, which takes into account the need to seal against the groundwater, but the impairment of gaseous odors and toxins still exist.

For the rehabilitation and relocation of a landfill in Vienna, a procedure was developed in which, according to Austrian patents no. 395,686 and no. 395,859. Hiebei is the garbage, softer in a thickness of up to 10 m, via pipelines, z. B. Lances, which are driven into the ground, air, especially enriched with oxygen supplied. The lances extend in a vertical direction to the lower edge of the landfill. About these lances, the air can be fed intermittently, so intermittently, the compressed gas pulses are up to 10 bar. About its own other lances is then sucked from the landfill gas, with a larger amount of gas sucked as the landfill is supplied. This prevents on the one hand that odoriferous substances can escape from the landfill and on the other hand, the anaerobic fermentation process is converted into an aerobic fermentation, whereby a rearrangement of the landfill without odor nuisance and toxic endangerment can be achieved.

The object of the present invention is therefore to provide a method which allows od landfills. Like. Abolume with any height or thickness without toxic and odor stress. Furthermore, a transfer of the landfill should be possible without environmental or odor nuisance. Another object of the invention is that the once mechanically, z. B. with machines, degraded substances of landfill a safe disposal can be supplied.

The invention is of a prior art, as given by AT-395,859-B.

Despite the high number of above-ground landfills, which are to be referred to as hills and mountains and are located in the vicinity of cities, so far no process has been found that allows to reduce these high deposits and at the same time to avoid any odor nuisance but also health impairment. Obviously, there was already a prejudice to reduce a landfill in terms of height. Such landfills were usually secured against the groundwater that accordingly deep around the landfill sheet piling were arranged, at the same time auxiliary wells were provided so that contamination of the groundwater was thereby avoided. One cause, which precludes the mining of landfills, is that the waste is deposited with an upward sloping slope angle. Waste, as long as no fermentation occurs, although inhomogeneous but structured so far that a mass is present, which has a relatively high dimensional stability in itself. Over time, a degradation or an embrittlement of the constituents solidifying the structures, so that later in succession a smaller angle of repose would have to be maintained than in the construction of the Doponie took place. Now, if a landfill is reduced, so must be taken with particular care to crumble or decrease in pressure on the lower areas of the landfill Avoid falling from the edge of the landfill.

The inventive method for microbiological degradation and / or stabilization of at least temporarily anaerobically fermented mixtures with aerobic microbiologically degradable organic substances

AT 403 480 Β an upper and / or underground deposit, eg. B. landfill of waste, rubble, Municipal waste, Waste industry, wherein the mixture in the deposit via fluid lines, in particular via pipes, which protrude downwards from the surface of the deposit, an oxygen-containing gas, preferably air, especially enriched with oxygen, is fed and via fluid lines, in particular via pipes, which protrude from the surface down, gaseous fluids are withdrawn and the anaerobic fermentation is at least partially converted into an aerobic fermentation, whereupon the mixtures mechanically up to the respective lower area of ​​the fluid lines, preferably by machine, be removed and spent locally, consists essentially of that the surface created by the ablation is sealed in a substantially fluid-tight manner before and / or after the laying of fluid lines, after which the fluidic lines, especially pipes, which protrude downwards from the surface created by the erosion, be relocated into the mixture, whereupon an oxygen-containing gas, preferably air, especially enriched with oxygen, supplied to the mixture and via fluid lines, especially pipes, which protrude from the surface down, gaseous fluids are withdrawn and the anaerobic fermentation is converted to an aerobic fermentation, whereupon the mixtures are removed mechanically up to the respective lower area of ​​the fluid lines and are transported locally, and, if appropriate, the surface created by the removal before and / or after the relocation of the fluid lines is sealed substantially fluid-tight.

By sealing the obtained by the removal of the mixture surface of the deposit, for. B. Landfill, on the one hand, the escape of toxic or Odor nuisance substances simply avoided, while the forced ventilation via the fluid lines and a withdrawal of the gases from the landfill od. like. can be made particularly effective, since no false air is sucked in and thus can be done in small volumes of volumes of an efficient transfer of the anaerobic fermentation in an aerobic fermentation. It is opened by this method, the possibility to perform a height-wise sectional removal, depending on the thickness of the landfill or Desired depth of the Beund venting can be performed. The on-site fluid lines can each be disassembled and then re-used and sent to a stationary gas source or Vacuum source to be connected. The method with sealing the surface and previous or nachgängigen laying the fluid lines can until the degradation of the deposit, z. B. Landfill, to be repeated as often as you like. A fluid is flowable media, e.g. B. Gases, liquids.

It was quite surprising that during the degradation of the waste, which has already been converted into an aerobic fermentation, the odor nuisance of the present under an anaerobic underlying fermentation avoided or so much can be kept in check that there are no real impairments. Hiebei it is not necessary that large layers of the transferred in aerobic fermentation waste remain on the residual landfill, but it is already achieved with the degradation, for example by the machines, a densification of the surface so that not large amounts of gas from mercaptans u. like. escape. It was therefore unlikely that a process which had already been proven in practice could also be carried out in several stages in succession, since it was rather to be feared that the waste not yet converted by the injection of oxygen-containing gas would become an extreme Odor and environmental pollution would lead.

If a surface layer of the deposit is removed before supplying the oxygen-containing gas, and then the surface is sealed in a substantially fluid-tight manner, so the near-surface areas, which were usually subject to an aerobic fermentation, be broken down without toxic and odor stress, wherein at the same time a drivable substantially flat surface can be created, which is suitable as a work surface for fluid-tight sealing and as a work surface for the laying of fluid lines.

If the surface created by the ablation is compacted substantially in a fluid-tight manner by compaction, then a toxic or odor-laden environmental impact can be avoided in a particularly simple manner, and at the same time no increase in the landfill volume is caused.

If the surface is sealed with a layer of loam, plastic foams, bitumen, humus substantially fluid-tight, so particularly porous or inhomogeneous mixtures can be converted with a relatively thin layer to the required tightness, the humus can also be obtained from the landfill itself. The plastic foam is in particular for sealing the transverse to the horizontal surfaces, z. B. flanks of the landfill, suitable.

If the surface created by the removal with a film, preferably a polypropylene film reinforced with a non-woven, sealed substantially fluid-tight, so can with very little

Effort a seal to be carried out, regardless of the weather, for example, embrittlement from the sun, flooding by rain u. Like., Over the required time periods

AT 403 480 Β allows a seal without additional controls, whereby a multiple use of the films is usually possible.

If only the approximately horizontally extending surface, which was created by the ablation, sealed fluid-tight, so either existing seals the flanks of both an upper and an underground deposit can be used advantageously, or there is a possibility that in these areas by the suction line air is sucked directly from the atmosphere, so that fewer lines for introducing the oxygen-containing gases are required.

If after the mechanical removal of the aerobically fermented mixture for the surface created a slope angle is maintained, which is less than the largest slope angle of the deposit in the respective corresponding height, it can be in a particularly simple manner untargeted slippage and thus toxic or odor stress Environment are avoided. The landfills generally have a depending on the height of the landfill slope angle, which decreases from top to bottom, since the landfill material on the one hand undergoes a microbiological decomposition and on the other hand is additionally destroyed due to the weight pressure. Thus, all those substances that allow solidification of the landfill, progressively degraded from top to bottom.

If an area of ​​the deposit intended for subsequent erosion, to which an oxygen-containing gas is supplied, prior to supplying these gases with fluid conduits for removing fluids from the deposit, especially provided opposite the horizontally adjacent areas, so on the one hand an untargeted leakage of fluids from the deposit can be effectively avoided and, on the other hand, it is possible to extract gases of combustible concentration from the areas still in anaerobic fermentation, which are not diluted by the air or other oxygen-containing gases supplied to the landfill.

If, as is known, the oxygen-containing gas with pressure peaks, in particular intermittently fed to the mixture, so a particularly effective gas exchange in the deposition can be performed because the standing under normal pressure gas is displaced in the landfill by the pressure peaks, so that also in capillary spaces od. Like. A gas exchange can be carried out particularly effective, whereby a rapid transfer of anaerobic fermentation in an aerobic fermentation can be achieved.

If volumetrically more than 10.0% by volume to 30.0% by volume of gaseous fluid is withdrawn via fluid lines in volume over time than is supplied to oxygen-containing gases, escape of gases from the deposit can be avoided particularly effectively on the one hand On the other hand, a particularly effective gas exchange can be carried out.

If the oxygen-containing gas is loaded with water vapor and / or water droplets, drying out of the same and hence a standstill of the fermentation can be avoided in a particularly effective manner even with long-term aeration of the landfill.

The water content of the landfill is of particular importance, since on the one hand by desiccation of the landfill a termination of the fermentation can be brought about, this dehydration may not be too far out, on the one hand the risk of fire or to prevent spontaneous combustion and on the other hand to avoid dust, especially when removing the landfill. On the other hand, too high a moisture content in the landfill causes the oxygen supply to be prevented at least to individual areas and anaerobic fermentation occurs with the corresponding odor and toxic load.

If the oxygen-containing gas is loaded with microorganisms, then a targeted fermentation process can be carried out, whereby furthermore the generation sequence during a fermentation is also taken into account.

If the gaseous fluid is withdrawn continuously, then the largest possible amount of gas can be withdrawn with a device of specific capacity, wherein constant flow conditions can be maintained during the suction in the deposit.

When the gaseous fluid is withdrawn from the deposit during non-supply of the oxygen-containing gas, the exposure times of the oxygen to the mixture can be particularly easily and effectively controlled.

If the gaseous fluid of the deposition with negative pressure peaks, in particular intermittently withdrawn, so particularly turbulent flow conditions can be met in the landfill, so that the gas exchange itself does not take place at the interfaces alone by diffusion processes.

If the gaseous fluid withdrawn from the deposit is mixed via biofilters, preferably with bentonite, in particular into the deposit, it is possible to use particularly low energy

Use odorous substances and pollutants are degraded or bound.

AT 403 480 Β

If the gaseous fluid from the deposit passed through an activated carbon filter, then the, in particular at the beginning of the extraction of a gas, hydrocarbons withdrawn from the deposit, fluorinated hydrocarbons u. Like. Particularly simple and effective, so that no additional toxic and / or odor stress and explosion hazard is conditional.

If the gaseous fluid withdrawn from the deposit is treated thermally and / or catalytically, in particular oxidized, the gaseous fluid can be supplied to a desodination or detoxification with a particularly low volumetric expenditure.

If the removed mixture mechanically and optionally separated magnetically and the non-ferromagnetic fraction with a particle size smaller than 60 mm, in particular less than 45 mm, fed to a landfill, so can by precipitation of a coarse fraction, which is usually of an inorganic nature, a significant reduction of subsequent landfill volume can be achieved.

When the oxygen-containing gas is fed to the mixture along the vertical of the fluid lines, aerobic fermentation may be performed along the entire area of ​​the mixtures impinged by the fluid lines.

If, viewed in the vertical direction, more oxygen-containing gas per unit time is fed into the lowermost third region than in the subsequent upper third region, the different admission of oxygen by the preceding introduction of oxygen in the upper region and the diffusion processes associated therewith are taken into account particularly advantageously.

If the gaseous fluid is sucked out of the mixture along the vertical of the fluid line, then particularly small flow paths within the mixture can be achieved, whereby a particularly high gas exchange can be achieved with little expenditure of energy and time.

If viewed in the vertical direction, in an upper two-thirds area more gaseous fluid withdrawn per unit time than in the lowermost third area of ​​the fluid line, so a vertical gas equalization and thus a vertical flow of the deposit for quick transfer into an aerobic fermentation is taken into account.

If the gaseous fluid is additionally withdrawn below the area to which the oxygen-containing gas is supplied, not only a horizontal, but also a vertical boundary of the mixture to be transferred into an aerobic fermentation is taken into account.

If any water or aqueous solution present in the deposit is drawn off by suction, the desired water balance can also be set quickly at the beginning of the ventilation of the landfill, whereby undesired water sites are easily removed by aspirating the water or the aqueous solution from different horizons and can be effectively eliminated.

Pressure peaks are also pressure pulse peaks to understand.

In the following the invention with reference to the drawings and the example will be explained in more detail:

Show it:

1 is an above-ground landfill in a schematic representation from the front,

2 is an above-ground landfill in the view from above,

Fig. 3 is an above-ground landfill, which is already partially inferior to a removal and Figure 4 shows a schematic representation of additional facilities for ventilation of a landfill.

The above-described landfill 1 shown in Fig. 1 has a height of 50 m and may also od under the ground, for example, in a gravel pit. Like. Extend. Dash-dotted the individual levels are shown with 10 m, where in the top of the range 2 dashed that portion of the landfill is shown, which can be degraded without additional ventilation, as an aerobic fermentation has already taken place due to the surface.

Such a landfill is, as shown in FIG. 2 can be seen particularly clear that constructed with the waste a spiral terrace, the supply of a plateau surface 3, 4, 5, 6 to the other, as with the arrows a, b, c, shown, allows. As can be seen in Fig. 1, the slope angle α₂, α₃, α₄, a₅ rising from the ground to the top plateau surface 3. The organic substances present in the landfill are subject to anaerobic fermentation because there is no corresponding supply of oxygen.

In the in Fig. 3 shown schematic section, the upper portions 2 of the deposit have already been mechanically degraded. A supply of oxygen was not required in this near-surface area. The created by the degradation surfaces 7 and 8 were covered with a layer 9, so that no gaseous odoriferous substances and toxic substances could escape. The layer 9 is made of loam, but, if, for example, particularly unfavorable weather conditions, be replaced by a thin bituminous layer or by a plastic film. The angle a₆ is lower than the minimum angle originally present in the landfill a₅, so that a slipping of the deposited substances is avoided with some certainty. This flank surface can

AT 403 480 Β particularly good with plastic foam, z. B. sealed with urea. From the space which is partially enclosed by the newly created surface 8, can be withdrawn via the fluid lines 10 gas, the concentration of combustible substances is so high that recovery by burning, even by operating an explosion engine, is possible. On the substantially horizontal surface 7, which was also obtained by the mining removal of waste, a layer 9 is also provided, which allows a substantially fluid-tight sealing of the landfill. Through this seal through fluid lines 11, z. B. Lances, laid over which oxygen-enriched air is introduced either continuously or preferably pulsed into the landfill. The vertically arranged fluid lines 11 end above the dash-dotted Höhenkote. The fluid lines 12, z. B. Lances, which are also arranged vertically in the waste, serve to extract the gases introduced in the landfill and the resulting gases. The vertical fluid conduits 12 terminate below the end of the vertical fluid conduits 11, through which the oxygen is supplied, thus limiting the area in which the anaerobic fermentation is to be converted into an aerobic fermentation. The vertically arranged suction fluid suction ducts 12 have holes at their lower half of the surface. For this purpose, the vertical fluid lines to the supply line have different openings, and more oxygen is supplied in the lower third region than in the subsequent third region. Both the fluid lines 11 and the fluid lines 12 are connected via their own supply lines 13 and discharges 14. The leads 13 are connected via a pressure source 15, u. tw. a compressor, supplied with compressed air. In addition, gaseous oxygen is introduced into the compressed air via the oxygen tanks 16, so that an oxygen concentration of 35.0% by volume in the gas supplied to the landfill can be maintained. The gas is under a pressure of 18 bar, and the vertical fluid conduits 11 have at their upper end a windkessel with valve which opens every five seconds for a duration of 1/1000 second, causing pressure surges of oxygen enriched air in the landfill , The air can additionally be moistened with water and optionally loaded with microorganisms. For simultaneous or time-delayed extraction of initiated from the landfill or The vertical fluid lines 12 are connected via the discharge line 14 to the resulting gases, the vacuum pump 18 producing a negative pressure of 0.4 bar. Such pumps are known in the mining industry, and they must be designed so that they are on the one hand explosion-proof and on the other hand can withstand the corrosive gases. The total length of the vertical fluid lines for both gas supply and gas extraction is approx. 10 m, and there are per hour and m³ Landfill 0,2 m³ fed to oxygen-enriched gas and 0.3 m³ Gas sucked off. The extracted with the vacuum pump gases reach either through a biofilter 17 to the outside, which instead of the biofilter and a return of the gases in the landfill is feasible, or it can also be burned gases, for example, oxidized with a catalyst. The ventilation of a landfill section with simultaneous suction is carried out until the content of methane falls below 2.5 vol .-%. Optionally, the COi content can be used as a further indicator.

If the fermentation of the relevant landfill section is essentially transferred from the anaerobic phase to the aerobic phase, the vertical fluid lines 11, 12 can be pulled and the corresponding connecting lines can be partially dismantled. Then a mining mechanical removal, z. B. with machines, the corresponding landfill area without toxic and odor stress possible, and it can landfill, for example, after separation of ferromagnetic materials and a coarse fraction, eg. B. over 60 mm or 45 mm, be returned to a landfill.

In the separation of the already removed landfill materials, a light fraction, for example by air classification but also by the sink-swimming method, can be obtained.

To seal the surface, in addition to the compaction of the surface obtained by the removal and compost, humus od. Like. Are used, which can preferably be obtained directly from the degraded landfill mixtures.

For the detoxification or deodorization of the extracted fluids also bioscrubbers, chemical scrubbers, natural or artificial ion exchangers can be used.

If duckweed are present in the deposit, the water, z. B. via suction lances, are withdrawn with openings at different heights. The lances can have a perforated tube on the outside and a tube on the inside that reaches almost to the lowest area. Also, approximately horizontally arranged suction lines can be used.

AT 403 480 Β