KR100945232B1 - Method of treating sludge for recycled soil - Google Patents

Abstract

PURPOSE: A method for processing sludge landfill covering is provided to reduce sludge treatment processing time by inputting a sludge-solidifying material to a mixer, and to enhance moisture removing efficiency of the sludge. CONSTITUTION: A device for sludge landfill covering includes a mixer agitating sludge and processing materials for sludge solidification, and a curing device with a plurality of hot wind nozzles which are used for drying moisture inside mixtures after receiving the mixtures. A method for processing the mixer includes a step for putting the processing materials into the mixer(210), a step for inputting sludge(230), and a step for mixing the sludge and the processing materials(250).

Description

{Method of treating sludge for recycled soil}

The present invention relates to a cover treatment method for treating a waste called sludge or sludge generated in a sewage treatment plant and the like to be used as a useful resource such as landfill cover material or building materials.

Sludge refers to a mud-like substance that is sedimented and separated in the process of treating sewage and wastewater. The sludge has high water content and high organic content, which is easy to rot and difficult to treat. In the past, most of these sludges were buried underground or treated with ocean dumping, and some treatment methods such as incineration, drying, composting, and solidification have been attempted.

In particular, since sewage sludge has been banned from landfills since July 2003, about 5,120 tons, or 77.1% of the 6,645 tons generated per day at the end of 2004, have been dumped at sea.

Sludge offshore dumping is being banned internationally in accordance with the London Treaty (1972), and in order to prevent future sludge offshore dumping, various efficient treatment measures are being taken.

However, incineration of sewage sludge is difficult to install incineration facilities due to high environmental investment, such as high initial capital investment costs and secondary pollutants generated during treatment. In addition, some composting has been attempted, but it is difficult to secure the use of the produced compost, so there is a limit to composting a large amount of sludge.

On the other hand, the Waste Management Act Enforcement Rule suggests that the landfill site criterion should be applied daily by compacting the soil to less than 10 centimeters by using soil that has low permeability, solidified materials or construction waste recycled after completion of the landfill operation. It is. Low water permeability according to the requirements of landfill materials on landfills, less than elution standards for hazardous substances, less than 35% of soil moisture content so as not to stick to equipment, more than 0.5kgf / ㎠ compressive strength Requirement such as not to be presented.

However, in the conventional sewage sludge solidification treatment technology, an alkali-based solidifying agent such as quicklime, cement, and fly ash is mixed and cured into sewage sludge. The bad odor problem was serious, and such composition did not facilitate curing, so the compressive strength, permeability coefficient, etc. could not meet the requirements for covering or filling soil according to related laws.

Recently, processes are developed to cover sewage sludge by using a basic material and an acidic material together as a solidifying agent and using cement or quicklime as a binder for curing.

However, these theoretical process methods work well at small and laboratory levels, but often do not yield satisfactory results on high volume processing equipment. For example, if you apply a laboratory method at a large facility level that has tens of tonnes of treatment at a time and hundreds to thousands of tonnes of treatment a day, then the treatments that have the same particle size and water content as soils will be Occasionally there is a very small particle size and water content that cannot be used as cover.

Therefore, in particular, there is a need for an efficient sludge treatment apparatus capable of sufficiently considering the nature of sludge and treating a large amount of sludge at a low cost in a short time, and a treatment method capable of having an optimum effect by such an apparatus.

The present invention is to eliminate the problems in the conventional sludge covering apparatus and its operation method described above, it is possible to cover the soil through a large amount of sludge treatment of several hundred tons to thousands of tons per day, and also based on the same capacity It is an object of the present invention to provide a method for shortening the treatment time and increasing the water removal rate in the sludge as compared with the method of.

The present invention for achieving the above object,

A container-type mixer having a stirrer inside to mix the sludge introduced downward through the mixer opening and a mixture mixed in the mixer and introduced downward through the curing unit opening, and a plurality of nozzles are used to dry the water in the mixture. In the operating method of the sludge cover device having a container-type curing machine is provided with a hot air pipe is distributed in the interior space,

The treatment in the mixer is characterized in that the treatment material input step, the sludge input step of injecting sludge, the mixing step of mixing the input treatment material and sludge is sequentially made.

In the method of the present invention, the treatment in the curing machine, while the hot air is injected through the hot air nozzle, the mixture mixed in the mixer is continuously fed down through the curing machine opening, while the bottom is dried by hot air It can be made in a flow manner to continuously discharge the dropped mixture.

In particular, in a state in which a plurality of pipes are distributed inside the curing machine and hot air is injected through a plurality of nozzles formed in the hot air pipe, the mixture mixed in the mixer is continuously introduced downward through the curing machine opening, In this case, it can be achieved by continuously discharging the dropped mixture while being exposed to hot air.

In the present invention, the treatment material in the mixer can be added to the hardening agent and the hardening agent including a substance that generates heat in contact with water and absorbs moisture to change the crystal structure and particle size, more specifically, the solidifying agent is powdered as the main material Quicklime (calcium oxide: CaO), calcined gypsum (calcium sulfate hemihydrate: CaSO ₄ 1 / 2H ₂ O), ferrous sulfate (FeSO ₄ ) may be used, and the hardener is fortunelan cement, quicklime and mixtures thereof. Can be used.

According to the present invention, a large amount of sludge can be treated in a short time to cover the soil, and in addition, the treatment time can be shortened compared to the existing method, and the water removal rate in the sludge can be increased to increase the efficiency of the sludge cover.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Figure 1 is a simplified block diagram showing an embodiment of the apparatus for the sludge cover of the present invention, Figure 2 is a flow chart showing the steps of an embodiment of the sludge cover treatment method of the present invention.

1 and 2, first, sludge such as sewage treatment sludge is introduced into a storage hopper of a sludge storage 10 of a sludge treatment plant (100). Sludge is first mechanically pressed in a sewage treatment plant to remove some water, and the water content is about 75% to 85%, which contains about 80% of the average, and the organic content is about 50% when dried. The introduced sludge is introduced into the mixer 25 by the conveying device 11 to start the mixer step 200.

The mixer 25 is, for example, a kind of large container having an effective capacity of about ³ m ³ , and a paddle stirrer is installed inside the mixer to mix chemicals of 1 to 2 tons. Usually, a pin mill (not shown) is provided on the stirrer for pulverizing agglomerated materials among the input materials. The upper portion of the mixer is opened so that the treatment material for sludge and sludge treatment is introduced through the opening (210). Sludge treatment materials have been developed and used in the past.

In the present embodiment, as a treating material, a solidifying agent and a hardening agent are used, and as a solidifying agent, powdery quicklime (calcium oxide: CaO), calcined gypsum (calcium sulfate hemihydrate: CaSO ₄ 1 / 2H ₂ O), ferrous sulfate (FeSO ₄ ) Is mainly used, and as a hardener, cement such as porcuran cement may be used alone or in a state where cement and quicklime are mixed, but quicklime is used here. The solidifying agent and the curing agent are introduced into the mixer 25 through a meter in the solidifying agent reservoir 21 and the curing agent reservoir 23, respectively.

In general, the most important reactions in sludge cover work are the hydration of quicklime, the hydration of acidic substances in solidifying agents, the neutralization of basic and acidic substances, the hydration of cements, and curing.

Hydration of Quicklime

CaO + H 2 O → Ca (OH) 2 + 15 ㎉ / mol

Quicklime contained in the solidifying agent plays a role of primarily reducing moisture in sewage sludge by hydration reaction when mixed with sewage sludge. Absorbs about 320g of water per kilogram of quicklime and releases about 280㎉ of heat to evaporate 450g of water.

Hydration reaction of cement (water content decrease, strength and dissolution inhibition)

2 (3CaO SiO2) + 6H2O → 3CaO 2SiO2 3H2O + 3Ca (OH) 2

Cement becomes hydrated when it comes into contact with water, turning it into a silica material. At this time, moisture in sewage sludge is absorbed, the strength of solids is gradually increased, and elution of sewage sludge is also suppressed.

Neutralization

H + (αｑ) + OH- (αｑ) → H2O (ℓ)

Neutralization reaction is a reaction in which a low pH acid and a high pH base react to neutralize the pH. The acid component in the solidifying agent and the alkali component in the solidifying agent react to change into neutral compounds, and the produced moisture is changed into water vapor due to the heat of reaction.

Basically, in order to be used as cover material in the state treated with hardener and hardener, certain requirements related to acidity (ph concentration) must be satisfied, and hardener and hardener to keep the environment workable by preventing severe odor even in the process of treatment. The chemical composition and its dosage should be controlled. Many components and compositions are already known for treatment materials for sludge treatment. In this embodiment, a basic treatment material and an acid treatment material are used together, and a solidifying agent 250t to 300t and quicklime 50t to 100t produced by Korea Pozotech Co., Ltd. are used for 1000t (ton) of daily treatment capacity sludge in the loaded state. .

Treatment material is first introduced into the mixer 25, and the sludge is transferred and introduced in the state (230). Since the amount of sludge once introduced into the mixer 25 is more than 1 ton, the sludge input time takes 2 to 4 minutes, and during this period, the water of the sludge first introduced is treated while reacting with the treatment material to generate heat. The change of the ash state and the change of the sludge state begin. The type of treatment material and sludge in the mixer is not a continuous method in which the input and discharge are continuously performed, but a batch type. In other words, a predetermined amount of material is added to the mixer and mixed, and the lower part is opened to discharge the mixture at once, empty the mixer, and then prepare the next mixing.

When the sludge is added, the paddle stirrer is operated at a speed of about 30 revolutions per minute, and the sludge and the treated material are stirred at an average of 30 seconds for 20 to 40 seconds (250). This agitation is to mix the treatment material powder and sludge, thereby making the whole state of the mixture relatively uniform, and reducing the treatment time to a realistic range, thereby allowing treatment.

Typically, the base material to be treated in the treatment apparatus through chemical stirring is put first, followed by the treatment chemicals to be stirred. However, in the present invention, in consideration of the characteristics and throughput of the sludge, the treatment material is added first, and the sludge is added later. Since the sludge has a large amount of water to be introduced into the mixer at one time, the present invention fully considers the type of sludge input that takes some time to input, and the sludge contains physical properties such as mud dough containing about 80% of water. Considered.

When the sludge is added first, the reaction time between the water and the treated material of the sludge reacts for a few minutes and the heat released is small. The temperature of the mixture is low and the particle size in the mixture is generally finer. Moreover, the agitation degree is also easy to fall by the characteristic of the conventional apparatus in which a stirring blade is lower. To compensate for this, increasing the agitation time causes the treatment powder to mix with the sludge so evenly that the treatment material absorbs moisture, making it difficult to form hydrate crystal grains larger than the original powder, and the mixture is still mud-kneaded. In this state, it becomes very difficult to contain moisture in the process and becomes very difficult to process. Therefore, there is a limit to simply increasing the stirring time of the sludge and the treated material.

The inventor of the present invention, if the treatment material is first introduced as in the present invention, it is possible to earn time for reacting the moisture and the treatment material even before stirring while the sludge is added, and at this time, the stirring temperature due to the release of calories can be increased, and the stirring time It has been found that it is possible to form a suitable state of agitation, such as clay dough or lumps, which are brittle, rather than mud dough, while retaining moisture, without increasing the particle size.

The sludge, treatment material mixture is transferred from the mixer to the mixture storage hopper 31 as a whole, and is partially transferred from the mixture storage hopper 31 through the conveying means 33 such as a screw conveyor and a belt conveyor (300). It enters the inlet or opening at the top of the vital part. In the process of transport, the mixture develops widely, giving the opportunity to release internal moisture and gases, the moisture in the treatment and sludge continues to react after mixing, and the mixture contains moisture which can be differentiated slightly from mud dough. It becomes a state of soil, and its heat releases some water and gaseous components of the sludge. Storage hoppers and transport means are installed in compartments to prevent odors from being released into the open atmosphere, in which the space is filled with gases and vapors released from the sludge. By quickly venting and removing vapors and gases from this space, on the one hand there is an opportunity to lower the water content of the sludge and, on the other hand, it is possible to prevent the gas from being released into the atmosphere untreated. To this end, an exhaust pump is installed in the mixture conveying space as a separate exhaust device and the exhaust gas can be condensed and deodorized while lowering the internal pressure.

In the present embodiment, the mixture is introduced into the curing machine 41a in which hot air is injected by the nozzles dispersed in a state of about 60% to 65% of water content by the transfer means 33 (400). The curing machine 41a has an inlet or an opening through which the sludge mixture is introduced, and a steam outlet through which water vapor and gas are discharged. A discharge pump is installed in the steam outlet so that steam is forced out quickly, and preferably, the inside of the steam outlet is made to have a negative pressure to increase the steam discharge efficiency. Inside the curing machine, a plurality of pipes provided with a plurality of hot air spray nozzles are arranged horizontally or vertically in several layers in order to evenly contact the hot air to the mixture. The hot air is supplied through the pipe via the blower and the heater 43a. Blower inlet air is air at 20 ° C ambient temperature and 60% relative humidity of the atmosphere, and the temperature of hot air is controlled at 100 ° C mainly in the range of 80 ° C to 100 ° C. The air emitted from the curing unit becomes air with a relative humidity of 95% at a temperature of 65 ° C. This requires a continuous supply of air at a capacity of 280 m ³ to 300 m ³ per minute.

The sludge introduced at the inlet of the curing machine 41a is in a state similar to a moist soil (soil or lump of soil), and falls down in a state where the mass is divided into small pieces by the resistance of the air while descending from the upper side. It may also fall while being dispersed in smaller lumps or particles while colliding with pipes distributed in the inner space during a fall, and hitting upward hot air. The surface area exposed to the outside air of these mixtures is further increased, and the moisture on the surface becomes water vapor in large part due to the hot air, so that the moisture content of the mixture is lowered and drying occurs.

The curing machine 41a is not a device in which the processed materials are continuously introduced and discharged on the other hand in the original flow method, and hot air is dried in a state in which a certain amount of the mixture is added together in a batch processing method, and after a predetermined time The mixture was treated for the process to discharge all at once. However, in this way, the hot air is discharged in contact with a small area of the mixture only in a certain path when the mixture is filled with mud dough, and the sludge itself is contained due to the nature of containing moisture in the mud dough. It has been found that the efficiency of draining off moisture is not high. Thus, by using a curing apparatus in which the existing hot air nozzles are dispersedly arranged in a flow manner, on the one hand, the mixture is dispersed while dropping the mixture from above, and the hot air removes moisture from the mixture of the wide surface, and the dried or solidified mixture is It is to be discharged to the next step.

The curing device 41a is formed in a container shape having a height (6 m to 8 m) higher than the average width (for example, 4 m x 4 m) or the diameter of the container such as a tower so that the mixture can be sufficiently separated while the mixture falls. It is preferable. In addition to the hot air pipes, separate components, such as shreds, may be installed at the beginning of the curing machine to distribute the sludge-treatment mixture falling from the opening to the entire area of the curing machine in a wide, particulate or small mass, but in this case, It is necessary to make the scale of the scale large enough so that it does not accumulate. The hot-air nozzle made of a hole formed in the hot-air pipe may be open as it is, but a cover member having a cap shape having a pointed top at a state spaced apart from the hot-air nozzle on the pipe on which the hot-air nozzle is formed so as to prevent the injected mixture particles from clogging the hole ( May be installed over the pipe.

The curing may be passed only once but the mixture may be subjected to two or more times for sufficient drying. In such a case, a treatment more suited to the mixture or solidified object may be performed by varying the size (height) of the primary curing device 41a and the secondary curing device 41b, the hot air temperature, and the amount of air flowing through the nozzle. can do.

The mixture with a moisture content of 35 to 40% dropped below by drying by hot air can be collected by a continuously rotating conveyor belt 45b or a funnel structure with a slope, which can be collected and discharged out of the curing machine continuously ( 500). In the present invention, the drying process in pure curing is consumed in a short time of several minutes, whereas the curing process is conventionally filled with a mixture, which takes 4 hours + 8 hours. If there is no delay in the next hopper or conveying means, the chemical reaction of the mixed material at the moist limit may continue to occur in the curing state and further reduce the moisture content even in the solidified mixture state.

Meanwhile, steam and gas generated at all stages of sludge treatment, such as the original sludge, mixer, and curing machine, are harmless to the environment through a separate deodorization tower 61 and a condenser (not shown) for condensation and deodorization treatment. May be discharged. Derivative 63 represents a wastewater reservoir for storing condensate obtained through the condenser.

The solidified mixture discharged from the curing machine 41b is collected in the discharge air hopper 51, and the discharge air hopper 51 opens the lower discharge port to load the mixture on a vehicle or the like as shown in FIG. At this time, as can be seen from Figure 3, the solidified mixture discharged from the curing machine has a very small and fragile particle group or is taken out as a soil consisting of a single particle, it is easily broken even if there is a lump.

The solidified mixture loaded on the vehicle forms the soil covering the surface of the landfill, as shown in FIG.

In the above embodiment, in order to increase the sludge throughput, the processing capacity of the mixer, curing machine, and conveying device can be largely designed, and the individual devices having a certain processing capacity can be connected in parallel to design an appropriate capacity for each step so that there is no difficulty. Even sludge treatment may be possible.

1 is a simplified block diagram showing an embodiment of the apparatus for the sludge cover treatment method of the present invention,

Fig. 2 is a flow chart showing the steps of an embodiment of the sludge cover treatment method of the present invention.

Fig. 3 is a photograph showing a state in which the solidified mixture obtained experimentally according to the method of the present invention is loaded on an unloading truck in the form of individual particles or small, brittle masses.

FIG. 4 is a photograph showing a site where the solidified mixture loaded on a truck is used for cover work in a landfill as in FIG. 3.

Claims (6)

A container-type mixer with a stirrer inside to mix the sludge put down through the mixer opening and the treatment material for solidifying the sludge, and a mixture mixed in the mixer and put down through the curing machine opening to receive moisture inside the mixture. In operation of the sludge cover device comprising a container type curing machine having a plurality of hot air nozzles dispersed in the The treatment in the mixer, the sludge solidification method, characterized in that the sludge solidification treatment material input step, the sludge input step for introducing the sludge, the mixing step of mixing the added sludge solidification treatment material and sludge in sequence is provided. The method of claim 1, While the hot air is injected through the hot air nozzle, the mixture mixed in the mixer is continuously fed downwardly through the curing unit opening, while the lower part continuously discharges the dropped mixture while being dried by hot air. Sludge covering method, characterized in that consisting of. The method of claim 1, The sludge solidification treatment material is made of a material that changes the crystal structure by absorbing moisture to generate heat in contact with water, the sludge cover method comprising a basic treatment material and an acid treatment material together. The method of claim 3, wherein The treatment material for the sludge solidification is made of a hardener and a hardener, 250t to 300t of solidifying agent and 50t to 100t of hardener are mixed with 1000t of sludge having 75% to 85% moisture content, The solidifying agent includes powdered quicklime (calcium oxide: CaO), calcined gypsum (calcium sulfate hemihydrate: CaSO ₄ 1 / 2H ₂ O), ferrous sulfate (FeSO ₄ ), The hardening agent is a sludge cover method characterized in that it is used containing fortunelan cement, quicklime or a mixture thereof. The method of claim 1, The mixture discharged from the container-type mixer and introduced into the container-type curing machine passes through a conveying means in a space partitioned with outside air, and the partitioned space is provided with an exhaust device for forcibly discharging water vapor and gas therein. Slurry cover method. The method according to any one of claims 1 to 5, The sludge dosing step is made over 2 to 4 minutes, Sludge covering method characterized in that the mixing step is performed for 20 to 40 seconds.

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