DD296010B5 - Process for the complex dumping of pollutants with water-soluble fractions - Google Patents

Abstract

The invention relates to a method of dumping pollutants with water-soluble constituents in complex landfills. The object of the invention is to provide a safe way for the landfill disposal of pollutants with multiple protection, where points of damage can be concretely localised and eliminated. According to the invention this is accomplished when, parallel to the fabrication of blocks after a pollutant analysis and categorisation, the landfill chamber is produced in such a way that its walls (1 - 4) are formed by excavation with subsequent infilling with a suspension of fly ash and/or fly ash/cement containing broken aggregates and/or textile reinforcement, and the bottom (5) thereof is coated after the inside excavation with a layer (5) of a fly ash and/or fly ash/cement suspension provided with textile reinforcement, after which the landfill chamber filled with blocks (6) is infilled on all sides with fly ash and/or fly ash/cement suspension and sealed, including the textile reinforcement. <IMAGE>

Description

For this 1 page drawings

The invention relates to a process for the complex dumping of pollutants with water-soluble fractions. Pollutants with a high proportion of water pollutants are inertized or stored in various forms in order to prevent inadmissible high pollutant levels cause adverse health effects by water-dissolution reactions. Thus, the long-term interim storage in closed buildings is known. Likewise, the storage in barrels and in foil as well as in currently dense residual holes is known. All these solutions pose a long-term danger as a "time bomb", since destruction of the current protection as a non-excludable hazard can cause a radical contamination which can not be corrected by nature's "self-detoxification forces" and could cause permanent damage. By contrast, the known methods of pollutant incorporation by cementation are safer. Often, however, these methods are insufficient due to insufficient degree of incorporation (too high a temporal emission of pollutants) alone or the binder pollutant reactions cause insufficient long-term stability under consideration of the effects of weathering. The high proportion of expensive binders (cement, etc.) often makes such environmental technologies a costly affair, with the need for long-term open landfill to incur additional costs. A method for producing a water-impermeable container for landfills, wherein in a prepared terrain formation, a water-impermeable layer is prepared, which is produced using fly ash (DD-PS 234374) is known. The digestion of the fly ash is done with an excess of water, with an alkaline excitation is required. These landfill containers have due to the low alkaline excitation no frost resistance and are due to their brittleness (low work capacity of dormant bound alkali-stimulated water-saturated fly ash) not fracture and settlement safe, creating dangers of uneven and insufficient landfill underground compaction and / or uneven loading or loading of the Container with pollutants despite high container wall thickness (high costs!) Long term are not excludable.

Also known is a method for the hazardous disposal of waste materials, wherein solid, dissolved or suspended waste materials are mixed with water to a homogeneous, mushy consistency and harden to a water-impermeable mass (DD-PS 201649). It is possible to introduce pollutants, e.g. Dilute acids with simultaneous sealing function of the fly ash consolidated layer against leachate.

The deficiencies in DD-PS 234374 regarding long-term container safety and / or resistance to breakage of the solidified pollutants also apply to this method. In addition, in the absence of a "neutral envelope" of the attached pollutant-bound body or layers, leakage of pollutants in the event of moisture and / or rain by capillary action (gradual leaching) is generally unavoidable, although only a low flow value can be observed. This method is effective only with sufficient reaction water of the pollutant to be solidified due to the chemical-physical Schadstoffverfestigung (integration) is known a method for the disposal of pollutant-laden materials and use of the product thereby produced, with the addition of an at least latent hydraulic ash under adjustment inerting of the pollutants with protection against leaching and leaching takes place (DE-OS 3,634,650), the embedded pollutants are formed into solid dumpable bodies u nd stored.

However, this is only possible with minimum water contents of 25 to 35% by weight, based on the total mixture, in order to ensure complete hydration. Despite low water permeability, leaching, destruction, freezing, sanding, etc. of the landfillable body would result in leaching and surface pollutant crystallization by capillary action, which in turn would not preclude pollutant leakage into aquifers.

For this application, a safe landfilling of liquid and / or pasty pollutants, which can not be provided with the mixing water required for setting the ash (no miscibility with water, such as in dry cleaning residues), not possible.

DE-AS 2 426 641 describes a method for detoxifying waste in which it is mixed in the presence of water with fly ash and a Portland cement, wherein the resulting slurry is allowed to harden to a rock-like material. It can be found no indication of how this material should be deposited long-term safe.

DE-OS 3 347 377 describes a method for producing a water-impermeable container for landfills of fly ash, cement and water. In this material, however, there is a risk of cracking, so that liquid pollutant-containing components leave the landfill space and can penetrate into the soil. According to DE-OS 3,044,436, landfills are to be sealed by a mixture of ash and water, such that a mushy consistency is achieved. The material should additionally be mechanically compacted. Here, an extremely low water permeability is achieved. However, this is not sufficient for a secure long-term landfill, so that there is a risk of leakage of liquid pollutant-containing materials from the landfill because of lack of waterproofing.

The aim of the invention is to provide a pollutant leaching preventing long-term stable and cost-effective landfill for solid, liquid and pasty pollutants.

The invention has for its object to provide a way to landfill of pollutants, which has a multiple protection, in the damaged areas are specifically localized and eliminated.

This is inventively achieved in that parallel to the block production after a pollutant investigation and categorization of the landfill space is prepared such that its walls by a Erdaushub and with subsequent filling with a broken aggregates and / or a textile reinforcement having fly ash or fly ash cement suspension formed and the soil is digested after the inner excavation with a textile-reinforced layer of fly ash or fly ash cement suspension, after which filled with blocks landfill by fly ash or fly ash cement suspension filled on all sides and incorporating textile reinforcement is closed. The invention ensures the occurrence of shrinkage-free solidification reactions of strained deworming active activated fly ashes in suspension form for landfill bodies, which allow for curing water permeabilities of <10-9m / s, if the compaction behavior, a solid storage density of> 1.3 kg / dm ³ of dewatering compliant suspension guaranteed, whereby densities and strengths of such mixtures by mixing cement (100-300kg / m ³ compressed mixture) can be increased according to the respective requirements (water permeabilities of <10-12 and strengths of> 50 N / mm ² achievable). The hardening mechanism of such fly ash / cement mixtures unfolds optimally under tension conditions, which are filled by fly ash-cement mixture diaphragm walls as vertical lateral landfill boundaries (internal landfill excavation after significant trench wall consolidation) and / or interference or splintering of broken aggregates (chippings , Gravel) and / or textile reinforcement (nets with anchoring, mixed crack-resistant resistant textile fibers) can be realized.

Taking into account the landfill storage size, the landfill body floor must be provided so deep that a gradual moisture penetration and / or leaching of stored pollutants can be ruled out by high ground or layer water levels (location issue) and at least 1% inclination in the direction of the flow direction of the underlying ground - or Schichtwassers is recorded. Due to size, layer thickness, mixture consideration as well as substrate choice (location question) a cracking is excluded, which is why textile-reinforced fly ash-cement mixtures with low Ε-module (<4000kp / cm ² ), with high deformation strengths (> 20MPa), limited Sohlflächenausdehnung (<20000 m ² ) and minimum thicknesses of 4cm should be used. In order to avoid plastic "mixture tearing off" and subsidence with low structural safety or carrying capacity of the substrate, preference should be given to vertical embankment walls as diaphragm walls, which are to be executed as the first technological step of landfill body installation which allows the abovementioned conditions at> 5 N / mm ² final strength if the slot depth does not exceed 3 m

 Otherwise, the mixture quality for the slot filling in terms of stability by strength increase

(Cement admixture in suspension) and / or additional reinforcement (eg., Textilschnitzeleinmischung of 30 ... 60kg / m ² -compressed mixture) to improve to guarantee the highest levels of security. The mixture filling of the diaphragm wall has to be done so that the depth is at least 20cm lower than the projected depth of the bottom of the landfill body, the upper one

Mixture of the diaphragm wall must be provided parallel to the projected sole with slope and a minimum depth to

must have surrounding terrain of 50cm.

After stability of the so-filled diaphragm wall, the inner earth excavation takes place under consideration of the gradient for o.g. Landfill body, which with o.g. Mixture made connected to the vertical cleaned slope slot wall connected

becomes.

The blocks are produced according to different variants:

1. In solid blocks (minimum technological strength:> 2 MPa) castable or cuttable pollutants, which, provided with a sealing paint system (eg cold paint), no solution products in the blocks in the landfill space dense and mutilating mixture (active Fly ash suspension with minimum water requirement, in which gravel sand or sand is mixed in order to achieve a good stiff Vermörtelungskonsistenz) are stored in secure buildings, to fill the landfill by the above Blockvermörtelung completely or to an acceptable Teilabschluß (vertical Vermörtelungswand) at upper cover by sealing layer analogous sole and heaped up plant-active soil is possible, the block size of the existing technological possibilities (hoists, storage room size, etc.) is adjusted. The closed landfill space can be achieved in a block filling process (preferred solution) or by gradual "growth" (coverage is greater at each block landfill operation).

The paint systems need only be effective for a short time to prevent replacement of solution products in the fresh wet mortar mixture. After mortar drying and closed landfill space is a pollutant leaching by inflowing upper water (rain, etc.) is no longer possible anyway by water impermeability of the mortar and the even denser upper sealing layer. Prevent the solution products of the solid contaminants so this temporary protection function can also Ölpapier-, Dachpappe- or foil envelope or the like take place, the protective function of the paint system.

2. As chunks with non-uniform grain size accumulating solid pollutants are in stiff fly ash cement mix (eg Vermörtelgemisch with low cement stimulation) analogous to a conventional aggregate, so that at most per m ³ emerging, compressed to the block fresh mixture 90% of the bulk density volume from loose purged pollutants (complete pollutant embedding and pollutant coating). After solidification and drying, these blocks are handled like solid blocks according to point 1.

3. Liquid and pasty pollutants with water contents which are large enough to permit chemical water binding for hydrate phase formation of active fly ash (about 10% water in relation to fly ash weight) are rendered inert to mixtures with slow mixing of fly ash into the liquid pollutant. until sufficient mixture stiffness is present, with no significant air porosity (<1%) must be recorded in now stiff mixture. To control the strength can be done at the end of a minor cement mixture.

After more than 20 days' hardening time, the solidified and dried blocks are handled like solid blocks according to point 1.

4. Liquid and pasty pollutants with insufficient proportions of water according to point 3, obtained subsequently admixed for the amount of binder (hydrate phase formation) required amount of water and are otherwise treated as described in point 3.

5. Completely water-soluble solids (eg powder) can be handled as a water-saturated solution like a liquid pollutant according to point 3.

In front of the closed landfill space in the flow direction of the groundwater or stratum water, a control well to be constantly monitored (for comparison, the initial value was taken before landfill occupation) was carried out. With trench wall as an embankment provided landfill space can string together, with a good complex monitoring is possible. If, for unforeseeable reasons or as a result of technological or mixture errors at a control point, a maximum permissible measured value is exceeded, it can additionally be provided by a separate diaphragm wall sealing the base or layer water, which after pumping in of liquid fly ash / cement mixtures simultaneous continuous extraction of water after solidification and compaction has occurred further penetration of polluted water and thus prevents a width distribution, whereby a greater environmental damage can be avoided and the pollutant is limited, a temptation can be excluded. The landfill is a solidified chamber system made of a non-contaminated, well-functioning scaffold, which is completely enveloped. In this are located at full contact pressure on the chamber walls of permanently integrated into blocks and solidified pollutant. This chamber system ensures increased long-term safety of the landfill. Reference to an embodiment of the invention will be explained in more detail below. It shows

Fig. 1: the schematic diagram of a contaminant landfill, Fig. 2: the landfill in cross section.

Before a safe disposal of the resulting pollutants can take place, a classification of the pollutants must be made in hazard categories that are formed as follows and influence the type of disposal:

a) unproblematic pollutant

- Pollutant contains enough water for hardening reactions and is thin enough (low viscosity) to mix without makeup water with fly ash at a pollutant content of> 0.5 (pollutant mass / fly ash), pumped and decaffeination compliant (eg: Excess pollutant extraction in vacuum compression) to be compacted to be made as a mold block or form body on respective intermediate sealed landfill level or parked.

- Body / block with high fresh mix strength exhibits normal fly ash-cement mix behavior.

- Hardened body / block is water, pollutant and space resistant.

- Hardened body has extremely low water permeability (generally: <10 " ⁹ m / s) when using suitable fly ash.

- ³ tons of fly ash are needed per m ^{3 of} pollutant (mean value).

- 1 m ³ causes body / block volume of about 2.2 m ³ (mean).

- Pollutant example: car wash residue

b) slightly problematic pollutant

- Pollutant with enough water for hardening reactions is provided with 10-40% make-up water to then be processed as described in category a) and to provide the same effects.

- For every ³ pollutants, about 4 tons of fly ash are needed (mean value).

- Pollutant example: neutral sludge

c) medium problematic pollutant

- Pollutant contains enough fly ash-cement water of reaction.

- Pollutant fly ash mixture is not vacuumable (liquid withdrawal), which is why always use intensive compulsory mixing (from thin to thick gradually mix) to produce a rigid homogeneous mixture and is parked by Intensiwerdichtung as body / block.

- After normal curing effects as in category a).

- For every ³ pollutants 2-31 fly ash is needed.

- 1 m ³ causes body / block volume of about 2 m ³ (mean).

- Pollutant example: oil separator residues

d) problematic pollutant

- pollutant as in category a) ... c) with hardening, which, however, does not lead to permanently stable body / block products, but to products which are partially envelopable with fly ash suspension (protective casing), without the bodies / blocks being damaged during protective casing production and hardening decay.

- Jem ³ Emission be about 3.21 fly ash required (average).

- 1 m ³ causes body / block volume of about 2.3 m ³ (mean).

- Pollutant example: sulfidic solution products

e) highly problematic pollutant

- Pollutant is not dilutable with water and also does not contain enough mixing water for its own hardening reactions.

- Pollutant can solidify after intensive mixing and compaction as category c) to bodies / blocks high fresh mix strength, but no own hardening takes place, but an envelope analogous to category d) is feasible.

- For every ³ pollutants, about 2-3 tons of fly ash are needed (mean value).

- 1 m ³ causes body / block volume of about 2.0 m ³ (mean).

- Pollutant example: Dry cleaning residue

f) - Pollutant is not completely protected by leaching with fly ash-cement mixture against leaching.

- Pollutant is mixed with fly ash, stiffened, is provided with a fly ash-cement protective cover in accordance with category a) ... e) and then deposited in protective sheath (eg foil bags).

- per m ^{3 of} pollutant about 2-3t fly ash are needed (mean).

- 1 m ³ causes body / block volume of approximately 2.5m ³ (mean).

In a large-scale chemical operation, 40000 tons of active fly ash accumulate annually in the company-owned heating house, whose solids storage density after maximum condensation-compliant compression of the corresponding fly ash-water reaction is 1.35 kg / l, whereby ultimate tensile strengths of about 8 MPa can be achieved after stress moisture storage. These fly ashes are to be landfilled anyway and need a landfill space of about 35000 m ² as humid landfill (humidification and mixture).

Furthermore, about 5,000 annually, in each case one m ³ castable solid pollutant blocks, accumulates in the above-mentioned operation. The potted pollutant blocks have an intrinsic strength of about 6N / mmB. Other liquid pollutants in the order of 7000000l / a must also be fed to an inerting, because a further backfilling in assumed tight residual holes is no longer possible and a free landfill would also lead to the above effects. In addition, pulverized pollutants of the order of 2000 t / a are produced, which can be considered and dumped with 3200 m ^{3 of} other contaminated water dissolved as an additional 200 t / a of liquid pollutants, with a BOD of up to 4 000 mg 02 / l is. For the inerting of the 7 000000 l / a liquid pollutants a fly ash amount of 21000t is required, from which about 14000 blocks ä 1 m ³ manufacture, stack and can be temporarily protected after curing and drying with cold paint. For the inerting of the powdery solution product 12000t / a fly ash are required, where about 7000 blocks ä 1 m ³ to produce, stack and after curing and drying are temporarily protected with cold paint. Thus, in this large-scale chemical operation, 26,000 blocks per 1 m ^{3 of} inertized landfill would have to be deposited each year, with 156,000 m ³ smooth surfaces being provided with cold paint and a fly ash amount of 33,000 t / a already being used for the inerting. The remaining 7000t / a fly ash are required for diaphragm wall, sole, Vermörtelgemisch and upper sealing cover, taking into account a total cement requirement of about 1000t and a

Textile fiber needs of about 10t (from own residues used for mixed reinforcement) about 500Om ³ fly ash-cement mixtures

for the landfill body covering the 26000 m ³ pollutants (total landfill body about 31000 m ³ ) are provided. This results in an annual construction and closure of a 31000m ³ large landfill space with an area requirement of approx.

15000m ² at a landfill depth of 2.5 ... 3m (taking into account the slope with proven groundwater safety ⁾ and a minimum effective soil coverage of 50cm, with the landfill areas closed on all sides

landscaped are usable and monitored by control holes in groundwater flow direction before landfill space.

The pollutant landfill to be constructed has walls 1-4, the bottom layer 5, the inertized blocks 6, the envelope 7, the Closure layer 8, the earth cover 9 and the control bore 10 (Fig. 1 and 2). The bottom layer 5 and the Closure layer 8 are executed in a gradient to the groundwater flow direction 11. In case of insufficient stability of the

an additional stiffening 12 is not yet arranged by inerted blocks 6 supported walls.

An increase in the biological oxygen demand is not recorded. Without lasting and disadvantageous landscape damage results for the enterprise with the annual Abfallsanfall of

about 40000t fly ash

about 5000 m ^{3 of} solid potted pollutants

about 7000m ³ liquid pollutants

about 2000t powder pollutant

a closed material cycle, whereby annually controlled a landfill space of 31000m ³ , closed and

landscaped on 15000 m ² and where "environmental disasters" are excludable and claimed

Landfill volume does not exceed the anyway required for the fly ash disposal landfill space. The cost of the identified complex landfill is well below the cost of incompletely effective biological Methods of purification, whereby wastewater and / or fines are omitted and negative long-term effects with Radical contaminants are excludable. The landfill is a solidified chamber system made of a non-polluted, all-effective Scaffold is, which is completely enveloped. In it are at full contact pressure on the chamber walls to Blocks permanently incorporated and solidified pollutant. This chamber system ensures an increased Long-term safety of the landfill. List of used reference numbers

1 wall 2 wall 3 wall 4 wall 5 soil layer 6 inertized blocks 7 wrapping 8th sealing layer 9 Ground cover 10 inspection hole 11 Groundwater flow direction

Claims (10)

1. A process for the complex dumping of pollutants with water-soluble fractions, wherein the pollutants are rendered inert by incorporation in water-saturated fly ash, formed with possible addition of cement as alkaline exciters into blocks and stored in a landfill, characterized by the combination of the following features in that, parallel to the block production after a pollutant investigation and categorization, the landfill space is produced in such a way that its walls (1-4) are filled with fly ash or fly ash cement suspension by excavation and subsequent backfilling with a broken aggregate and / or textile reinforcement and whose bottom (5) after the inner excavation is purged with a textile-reinforced layer (5) of fly ash or fly ash cement suspension, after which the landfill space filled with blocks (6) is conveyed by fly ash or fly ash. Cement suspension available on all sides and closed with the inclusion of textile reinforcement. 2. The method according to claim!, Characterized in that the bottom and the closure layer (8) of the landfill space with a slope in the flow direction of the ground or layer water (11) are executed. 3. The method according to claim 1 and 2, characterized in that in the flow direction of the groundwater and layer water (11) a constantly monitored control bore (10) is introduced. 4. The method according to claim 1, characterized in that liquid pollutants are used instead of normal mixing water for the suspension. 5. The method according to claim ^, characterized in that as surface protection for the blocks (6) a protective coating and / or an oil paper, roofing felt or film wrapping is used. 6. The method according to claim 1, characterized in that between the individual block layers (6) in the landfill space a layer of dewaterable material is introduced. 7. The method according to claim 6, characterized in that fly ash, cement or textile reinforcement is used as the drainable material. 8. The method according to claim 1 to 7, characterized in that the closed landfill is provided with a Erdabdeckung (9). 9. The method according to claim 1 to 8, characterized in that the next landfill space is created in parallel in direct reference to the preceding. 10. The method according to claim 1, characterized in that a capillary-breaking layer is introduced before the surface closure of the filled landfill with fly ash or fly ash cement suspension.