JPH11347593A - Construction sludge closed type recycle treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable 100% recycle by concentrating wastewater by flocculation/ precipitation after classifying/selecting gravel from construction sludge, separating the concentrated slurry into dewatered cake and separated water by a dewaterer, solidifying the dewatered cake by a solidifying agent and reusing, and using the separated water as a supply water when the gravel is washed. SOLUTION: Construction sludge charged in a receiving hopper 1, gravel is classified by a vibrating screen 2, and sludge which passed through the screen 2 is washed by a high-mesh separator 5. Wastewater which passed through the separator 5 is stored in a raw water pit 7. It is conveyed to a flocculant addition tank 8, after being added with a flocculant and precipitated/separated in a concentration tank 9, and concentrated slurry is stored in a slurry tank 10. Next, the slurry is conveyed to a flocculation tank 12 and molded into blocks again. Dewatered cake which was dewatered by a dewaterer 13 is conveyed to a kneader 15 and added with part of a solidifying agent. Treated soil kneaded by the kneader 15 is pressurized by an extruder 16 and molded into column-shaped treated soil by a die 17.

Description

Description: BACKGROUND OF THE INVENTION [0001] The present invention relates to a method for treating construction sludge that does not contain harmful substances. Sand and gravel that can be reused from sludge are classified and separated. The mud is concentrated by a thickener, separated into water and a dewatered cake by a dehydrator, and the mud is reused as an improved soil using a polymer-type / cement-type solidifying agent and quicklime. The supernatant water from the thickener and the dewatering from the dehydrator are used as pumping mud and washing water for sand and gravel. Classified and separated sand and gravel contain water, and are used as makeup water when granulating and solidifying dewatered cakes and dewatered cakes with a low moisture content. [Prior Art] Construction sludge is classified into slurry (muddy water), sludge (mud), cake (filtration residue), etc., and various types of processing apparatuses are used for each purpose, with the aim of reusing sand and gravel. However, all of them, including the final dewatered cake, are landfilled. When solidifying (modifying) muddy water or muddy soil with cement or quick lime, etc., and using it as a backfill material or soil improvement material, the water content of muddy water to be accepted is limited and the amount of solidifying agent added must be large. In addition to the non-uniformity of the improved soil due to the variation of the water content, sand and gravel contained in the sludge are also objects to be solidified at the same time, so that the equipment was in severe wear. In addition, it is difficult for one system to handle sludge of all properties, and the acceptance must be restricted. With regard to the treatment of construction sludge, there is a need for reuse, and it has been necessary to develop a system that is small, rational, and 100% reusable. [Problems to be Solved by the Invention] In recent years, the number of remaining years of a waste management type landfill site for landfilling waste is limited, and in addition, it is difficult to construct a new landfill site due to lack of suitable land on topography and social issues. Difficult because of the typical environment. In spite of the fact that recycling of construction sludge has been pointed out, sand and gravel are separated from construction sludge as resources, the raw material for improved soil is extracted from the remaining mud, and the generated water is used for washing sand and gravel. The purpose of the present invention is to provide a closed recycling system that eliminates wastewater. [MEANS FOR SOLVING THE PROBLEMS] A system according to claim 1 which meets the above-mentioned object is characterized in that, when construction sludge is recycled, sand and gravel are recycled by a vibrating shaker, a separator, a trommel or the like. Separate and separate to required size. Muddy water is concentrated by coagulation sedimentation, and then separated into dewatered cake and dewatering by a dehydrator. The dewatered cake is reformed and solidified mainly with quick lime or cement-based solidifying agent and then recycled, and the dewatering of the coagulated sedimentation supernatant water and the dehydrator is carried out by pumping sludge, washing sand and gravel, and adjusting during solidification. It is a closed type treatment system that eliminates wastewater because it is used as water.
% Recyclable processing system. Claim Item 2
Since wastewater and mud are reformed and solidified from the input hopper or raw water pit, and the dewatered cake is reformed and solidified by a kneader, crusher or reactor, it can be used as a system that can receive and treat any property. Means Claim Item 3
Is an invention on the structure of the concentration tank, which was devised in order to improve the processing capacity with a compact size.After adding the above flocculant according to the properties of the slurry, a floc is formed and the sedimentation and separation is performed in the concentration tank. By improving the ordinary outlet to improve the separation efficiency, it became possible to prevent the vortex and increase the sedimentation efficiency. Claim 4 is a claim relating to the balance of water in this system. Regarding the water contained in the construction sludge, it is usually heated and dried, or the water is evaporated by a hydration reaction by the heat of quick lime, or water treatment. In this system, the water contained in the construction sludge is used for washing sand and gravel, and adheres to sand and gravel as a resource. Since it is used for pumping from the hopper and replenishing the water content of sludge with a low moisture content, the system does not generate drainage. Item 5 relates to the modification and solidification of the dewatered cake, which is usually solidified by pozzolanic reaction and hydration hardening by directly pouring a polymer / cement or quicklime into muddy water. Especially for quick lime, the hydration reaction is used to evaporate and solidify water, so depending on the moisture content, solidification is impossible or even if solidification is required, a large amount of quick lime is required, so running costs are high and processing is high. There is a problem that the hydrogen ion concentration of the material is high and it takes time to stabilize. This system uses a dehydrator to dewater the concentrated slurry after classification and separation of sand and gravel, so the properties of the dewatered cake are stable. Therefore, there is an advantage that the addition amount of cement or quick lime required for the reforming and solidification is small, and the fluctuation range is small. At the same time as adding added value to the modified treated soil, it is shaped into a sphere or the like for future use of the treated soil, but the diameter of the sphere can be freely changed by changing the shape of the die of the extruder. Is possible. In addition, in order to reduce running costs and stabilize the properties of the product, 5-30% of the total amount of the solidifying agent is added after shaping to add a carbonation reaction (quick lime) and hydration hardening of the surface after the treatment. (Cement-based solidifying agent). In claim 6, a solidifying agent is added in order to solidify the dewatered cake in the kneading machine in claim 5, but using a dryer or a baking facility, a horticultural water retention material, a landscape / aesthetic material, or a steel mill is used. When it is used as a heat insulator or the like, clay, alumina, silicon dioxide (silas), fly ash or other materials may be mixed and added in place of the solidifying agent. [0005] The construction sludge which can be recycled here refers to slurry (mud water), sludge (dirty soil), cake (filtration residue), etc., which are inorganic and do not contain harmful substances. Not suitable. There are various methods for classifying and separating sand and gravel, such as a single-stage or multi-stage vibrating shaker, high-mesh separator, trommel, and the like. Moisture contained in construction sludge or water used for pumping / washing becomes muddy water, which is stored in raw water pits and then coagulated and settled in a concentration tank. Agent or a combination thereof. As inorganic coagulant, aluminum sulphate _{Al 2 (SO 4) 3 ·} 18H 2
O (bansulfate) is a typical example. Judging from the hydrogen ion concentration of muddy water, iron salts such as iron sulfate (I
It is preferable to use aluminum, such as aluminum sulfate, sodium aluminate, or basic aluminum chloride, rather than using I), iron (III) chloride, iron (III) sulfate, chlorinated copper salt, or the like. At this point, it is necessary to adjust the PH. As organic polymer flocculants, sodium alginate, CMC sodium salt, sodium polyacrylate, partially hydrolyzed salt of polyacrylamide, maleic acid copolymer, cationic polymer, water-soluble aniline resin
As polythiourea, polyethyleneimine, polyvinylpyridines, and nonionic polymers, there are polyacrylamide, polyoxyethylene, and the like, but it is necessary to select an appropriate flocculant by judging from a hydrogen ion concentration suitable for flocculation. Both cement and lime have JIS standard products.
There are cement-based and lime-based solidifying agents using this as a base material.
In recent years, a moderate cement-lime composite solidifying material has been developed. In addition, there are water glass / colloid cement and ultra-fast curing cement. Cement-based solidifying agents include gypsum to help generate ettrine guides that take in large amounts of water as bound water, slag and fly ash to promote the porazone reaction, alumina cement and jet cement to increase the solidification performance, Alternatively, when selecting a solidifying agent, for example, a special clinker whose components are adjusted and fired is used, it is necessary to determine the properties after examining the properties of the object and the properties of the processed material. The dehydrator is a general term for a belt press, a filter press, a centrifuge, a vacuum dehydrator, a wire barrel system, and the like, and needs to be selected according to the properties of the object. The concentration tank is a tank that sediments and separates and concentrates after the addition of a flocculant. Since the sedimentation speed differs depending on the floc formed by the Stoke method, it is necessary to select the shape in consideration of the selection of the flocculant and the capacity of the dehydrator. The reason is that the stirrer is removed by improving the muddy water outlet after adding the flocculant,
This is because it became possible to make the shape compact. The raw water tank is a pit where sludge is poured into the hopper and temporarily stored before classification and separation of sand and gravel before sedimentation and separation by the thickener.After pumping up the thickener quantitatively from the raw water tank and adding the flocculant, Settle and separate in the concentration tank.
Dewatering of the dehydrator and washing water of the belt press are also guided to the raw water tank depending on the water quality. The Shimizu pit is a pit where the supernatant in the concentration tank is neutralized and stored. The kneading machine is a machine for mixing a dehydration cake with a cement-based solidifying agent or a solidifying agent such as quicklime, and the type thereof is not particularly limited as long as sufficient stirring is possible. Selection should be based on the ability. Extrusion molding machines require a vacuum extrusion molding machine or the like when high density processing is required in the pre-treatment for sizing.However, when the purpose is to use as backfilling / improved soil, Extrusion molding machines and the like can also be used. A sizing machine is a machine that changes the shape from a columnar shape to a spherical shape by rotating the treated soil formed by an extruder with a rotary drum. doing. In the upper part of the granulator (close to the entrance), there is provided a spraying device for the solidifying agent such as quick lime of the fine powder of claim 5. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; Here, FIG. 1 is an example of a processing flow diagram of the construction sludge closed type recycling system of the present invention, and FIGS. 2A to 2C are explanatory diagrams of the structure of the outlet of the concentration tank. FIG. 3 illustrates the flow of water in the construction sludge closed type recycling system of the present invention. As shown in FIG. 1, the construction sludge put into the receiving hopper 1 is classified into gravel by a vibrating shaker 2 and separated by a conveyor belt 3.4 into gravel of each size. Sludge that has passed through the vibration shaker 2 is washed with a high mesh separator 5 for sand, and is conveyed on a conveyor 6. The sewage that has passed through the high mesh separator 5 is temporarily stored in a raw water pit 7, transported to a flocculant addition tank 8 by a required amount pump, and the muddy water with the flocculant added is settled and separated in a concentration tank 9 and concentrated. Slurry tank 1
Store temporarily at 0. Stirring is performed by the stirrer 11 to such an extent that the precipitate does not solidify, but low-speed and minimum stirring is performed so that the formed floc is not broken. The slurry is conveyed from the slurry tank 10 to the coagulation tank 12 and reblocked. The dehydrated cake dehydrated by the dehydrator 13 is transferred to a conveyor belt 14.
, And a part of the solidifying agent is added thereto. The treated soil sufficiently kneaded by the kneader 15 is pressurized by an extruder 16 and formed into a cylindrical processed soil in the shape of a die 17. The treated soil formed into a cylindrical shape
By being rotated by the sizing machine 19, it is shaped into a sphere while falling, and at the same time, a part of the solidifying agent is added from the fine powder addition pipe 18 to form a dense layer on the surface of the shaped article. It is possible to do. [0008] As shown in FIG. 2 (a), the sludge in which floc is formed by a polymer flocculant or PAC (polyaluminum chloride) in the flocculant addition tank is settled and separated in the concentration tank 22. , From the inlet 20 and out of the outlet 21. Generally, the outlet has a shape of 25 or 26 as shown in (b) and (c). In the case of 25, a vortex is generated in the fresh water separation tank 23, and the sedimentation separation speed is reduced. In the case of 26, the water flows out to the bottom of the concentration tank, and repulsion generates turbulent water upward. Therefore, by changing the direction of the outlet 21 to 180 degrees with the concentrated slurry valve 24, the turbulence of the slurry in the concentration tank is minimized to increase the sedimentation speed. It has a compact diameter of 2 and improved sedimentation separation efficiency. The diameters of the outlet 21, the inlet 20, and the tube diameter of the concentration tank 22 are not limited here, but the diameter 20 and the diameter 21 are set so that the diameter 21 ≧ the diameter 20. FIG. 3 illustrates the water balance of the construction sludge closed type recycling system according to the present invention.
All arrows show the flow of water. The construction sludge is composed of sewage (slurry) 27, soil 28 and dewatered cake 29 depending on the moisture content.
Are roughly divided into Sewage 27 and soil 28 are gravel 41 and sand 4
The wastewater enters the raw water pit 32. A flocculant such as a polymer flocculant PAC is pumped up from the raw water pit 32 and sedimented and separated by the concentration tank 33. After the supernatant is neutralized by the neutralization device 38,
Will be stored temporarily. The concentrated slurry is stored in the slurry tank 3
Stored temporarily at 4. The slurry is sent from a slurry tank 34 to a dehydrator 35 by a monomer pump or the like, and is dehydrated. Dewatering is returned to the raw water pit 32.
The dehydrated cake is modified and solidified using quick lime or cement-based solidifying material, shaped into a spherical shape by a sizing machine 37, and shipped as a solidified product. The material received as the dewatered cake or the dewatered cake 29 by the dewatering 35 varies depending on the type of dehydrator or the drying condition. However, those having a low water content have a high water content for improving the granulation property or for the hydration reaction. Addition is required. In this case, it is replenished from the Shimizu pit 39. The increase in water balance is due to the
This is the water contained in soil and dewatered cake. Increasing substances are used to reduce the amount that adheres to sand and gravel at the time of classification / separation and are discharged from the processing line or contained in dehydrated cakes, as well as spontaneous evaporation or replenishment water for granulation. It has been demonstrated that the relationship of moisture content ≤ decreasing moisture content. Accordingly, the water balance is reduced, resulting in a closed treatment system. In the case where the dehydrated cake is modified and solidified with quick lime, after granulation according to claim 5 of the present invention, the granulated granules are sieved from a cylindrical shape to a spherical shape. In order to promote the stabilization of the chemical properties of the granules, a device for adding quicklime is installed above the inlet. The amount of quicklime added by this apparatus varies depending on the diameter of the sphere, but is between
About 0% to 50%, 20 g to 1 per kg of dehydrated cake
00g is good. The whole surface of the sphere is coated with quick lime, and a fine powder is used so that a uniform reaction can be achieved. Those having a particle size of 300 mesh or less are suitable. Quicklime is 15.2 Kc due to the hydration reaction between water in the dehydrated cake and Chemical Formula 1.
al / mol. The heat of the reaction evaporates the water content of the dewatered cake and lowers the water content of the dewatered cake. Therefore, immediately after the treatment, a high hydrogen ion concentration is exhibited. After that, it reacts with carbon dioxide in the air accompanied by an ion exchange reaction and a pozzolan reaction, and causes a chemical reaction 2 from the surface. The carbonation reaction proceeds gradually to the inside to form calcium carbonate, and the hydrogen ion concentration becomes neutral. When changed to slaked lime Ca (OH) ₂ , the solubility in water becomes 0.1.
The solidified dewatered cake is reduced to 12%, and the whole dehydrated cake becomes hydrophobic. Further, when calcium carbonate is formed, the solubility in water becomes extremely low at 0.0014%, and re-mudification does not occur. Accordingly, the fine powder quicklime adhered to the surface in the process of sizing in claim 5 is due to the hydration reaction /
It was designed to promote the carbonation reaction on the surface of the sized product, prevent re-mudification, and promote the neutralization of water cable ion concentration. The use of a solidifying agent is not preferred in the case of performing high-temperature drying or calcination in the process of treating a material having properties that can be solidified without heating or low heating and can be reused. In the carbonation reaction, slaked lime (Ca
(OH) ₂ ) Alternatively, calcium carbonate is formed to form a hydrophobic substance, but when heated, it returns to quick lime again,
It can be expected that re-alkalization or shape destruction will occur due to the absorption of moisture. Claim item 6 particularly describes a case where a firing step is performed. Other inorganic materials such as clay, aluminum oxide, silicon dioxide, and pottery stone are used. Depending on the purpose, the additives can be kneaded during the granulation process. For example RO group: rise when refractoriness For reduction BaO electrical conductivity of MgO _R 2 _{O 3} groups: _Al 2 _{O 3} when increasing RO ₂ groups increases, the thermal expansion coefficient of mechanical strength: For ZrO ₂ In the case of P ₂ O ₅ as an increase in acid / base resistance, etc. In the case of SiC, in the case of SiC In the case of SiC, the mechanical strength is increased. Can be changed. When treating construction-based sludge as a claim in the present invention, dewatered cake is generated and solidified in quicklime-based, cement-based, and polymer-based, and partially reused, but is not limited to the solidifying agent. It means that it can be commercialized by baking with or without the addition of the above-mentioned additives, if necessary, without sintering or sintering. [Effects of the Invention] In the construction soil treatment system according to claims 1 to 5, regardless of the water content of the received slurry (sewage), sludge (soil), cake (filtration residue) and the like. , Processing is possible. In addition, the sand and gravel that can be effectively used are classified and separated from the incoming materials, and the muddy water is coagulated and settled, and then classified into water and dewatered cake by a dehydrator. Until now, dehydrated products have been finally disposed of at landfill sites. It was also confirmed that a solidifying agent could be added to the dewatered cake and mixed as a backfill material or crushed stone powder to be reused. For the supernatant liquid during coagulation sedimentation and dewatering of the dehydrator, the closed type without drainage has been made possible by using it for pumping the received material, washing sand and gravel, and making up water for solidification. Harmless construction sludge received as waste is
This plant makes it 100% reusable and basically becomes a completely closed recycling system. Claims 5 and 6 are proposals for a method of solidifying a sewage cake. The sewage cake has a relatively small spherical shape to increase the air contact area, and by adding fine powder during sizing.
This means that the reaction can be promoted and that the strength as a lump can be improved. Also, without using quicklime / cement-based or polymer-based solidifying agents, other additives are mixed according to the purpose, and baked or dried at high temperature. Many uses can be found, such as timber, civil engineering construction, lightweight aggregates, and heat insulators in steelworks.

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[Procedure amendment] [Submission date] July 23, 1999 [Procedure amendment 1] [Document name to be amended] Description [Item name to be amended] Brief explanation of drawings [Amendment method] Addition [Amendment content] [ BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a processing method of a construction sludge closed type recycling system of the present description. FIGS. 2A to 2C are diagrams showing flows of wastewater in a concentration tank. FIG. 3 illustrates the flow of water in the machine. [Description of Signs] 1 Hopper 2 Vibrating Sieve 3 Conveyor Belt 4 Conveyor Belt 5 High Mesh Separator 6 Conveyor Belt 7 Raw Water Pit 8 Condensant Addition Tank 9 Concentration Tank 10 Slurry Tank 11 Stirrer 12 Coagulation Tank 13 Dehydrator 14 Conveyor Belt 15 Kneader 16 Extruder 17 Dice 18 Pipe for adding fine powder 19 Granulator 20 Inlet 21 Outlet 22 Concentration tank 23 Fresh water separation plate 24 Concentrated slurry valve 25 Eddy current in fresh water separation tank 26 Turbulence in fresh water separation tank Indicate the generation state of the flow Indicate the generation state 27 Sewage (slurry) 28 Construction sludge (sludge) 29 Dewatered cake 30 Gravel classification and separation 31 Sand separation 32 Raw water pit 33 Concentration tank 34 Slurry tank 35 Dehydration 36 Granulation 37 Granulation 38 Medium Japanese 39 Shimizu pit 40 Solidified soil (improved soil), etc.

Claims (1)

[Claims 1] After classification and separation of sand and gravel from construction sludge, muddy water is concentrated by coagulation sedimentation. The concentrated slurry is separated into dewatered cake and dewatered water using a dehydrator. The dewatered cake is reused after solidification using a solidifying agent, and the dewatering is used not only for washing sand and gravel, but also as replenishment water during sludge pumping and solidification, and it is included in sand, gravel and dewatered cake, so there is no drainage Combination system featuring complete reuse of sludge. [Claim 2] Construction sludge is separated into slurry (mud water), sludge (soil), cake (filtration residue), etc.
The sludge having different physical properties such as water content and soil / viscosity distribution can be introduced from the middle of the process according to claim 1 and flocculated by a solidifying agent, and then dewatered to be dewatered. A processing system that can stabilize the quality of recycled products with little fluctuation. [Claim 3] Sand and gravel are classified and separated and reused. The muddy water according to claim 1 or 2 is supplied to the thickening tank for about 1 hour.
As a pretreatment for sedimentation separation in a tank, a polymer flocculant and the like are added to form flocs, and then sedimentation and separation are performed in a concentration tank. A system with an outlet structure to increase the separation efficiency. Item 4 The water contained in the construction sludge is collected in a raw water tank as mud after sand and gravel are classified and separated. The collected mud is polymer coagulant PAC (poly aluminum chloride)
Then, the coagulant is added and the mixture is concentrated to about 1/3 in a concentration tank. The slurry in the concentration tank is separated into water and dewatered cake using a dehydrator such as a belt press, filter press, and centrifuge. The dewatering is transferred to the raw water tank or the Shimizu pit. Closed structure that does not generate drainage from this system because the water in the freshwater pit is used for pumping sludge, washing sand and gravel, and for replenishing water to sludge with a low moisture content. A system having: [5] This system is a treatment system capable of 100% recycling of construction sludge, and has a mechanism for reforming and solidifying mud after dehydration. Using a quicklime-based / cement-based solidifying agent or a polymer-based solidifying agent as a solidifying agent, or a combination thereof, and kneading with a conventional kneading machine to produce an improved soil,
After kneading, the system can change the shape of the molded product by changing the shape of the die using an extrusion molding machine. In this state, it is cylindrical, but it is possible to granulate it spherically by using a sizing machine. When granulating with a sizing machine, this system has a mechanism to mix a solidifying agent such as fine lime, in order to reduce the strength of the processed product, reduce the time required to prevent re-mudification and stabilize, and prevent adhesion of the processed products. Item 6 The dewatered cake generated in Items 1 to 5 does not contain sand, gravel, etc., and although its composition and properties vary depending on the soil properties of the construction site, it has a fairly uniform water content and particle size. Since it has a distribution, granulation at the time of modifying and solidifying by adding a polymer flocculant, a cement solidifying agent, or quick lime, etc. becomes easy, and the amount of the additive is less varied. or,
Add clay, alumina, silicon dioxide, fly ash, and other materials at the time of kneading, and dry or incinerate to create mud that can be used for other purposes, such as water retention materials for horticulture, materials for improving landscape and beauty, etc. Grain processing system.