JP2001300591A - Method for simply coagulating muddy material decreasing volume thereof and stabilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method which subjects hydrophilic muddy material such as dredged sludge, sludge and various waste sludge to coagulation treatment easily even for muddy material of high or low water content by using a simple tool/ apparatus, enables decreasing the volume in the short term by solar drying and provides hard aggregate similar to neutral sandy soil which is stable without returning to the muddy state at a low cost. SOLUTION: An active silicate sol 4b which is acidic is prepared by mixing silicate substance aqueous solution incorporated with metals of high ionization tendency which is mainly composed of bivalent iron and mineral acid. An alkaline diluted silicate substance aqueous solution 4a ad the active silicate sol 4b are added to the muddy material 3 which is charged into a bag having excellent water permeability or the muddy material 3 which is directly charged into an upper part opening type tank 1 and are stirred and mixed, thereby the muddy material 3 is made to be the neutral gel-like hydrous coagulated material. The hydrous coagulated material is temporarily hung down as it is charged in the bag, is subjected to simple dehydration, thereafter, the upper part of the bag is opened, is sun-dried, or is directly taken out of the tank and is subjected to solar drying without using the bag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to finely particulate mud having good hydrophilicity, such as sludge, construction sludge, side sludge, and various kinds of wastewater sludge generated in factories, which are deposited on seas, rivers, lakes, lakes and ponds. The sludge is solidified by adding and mixing a silicic substance-based coagulant without using any special mechanical equipment, and the sludge is solidified. The present invention relates to a simple solidification and volume reduction stabilization method for a mud which stabilizes its capacity, facilitates the handling of the residue, and hardens and stabilizes the mud to a sandy soil and sand-like shape that can be reused.

[0002]

2. Description of the Related Art Mud-like substances of this type have a specific viscosity and fluidity in a high water content state, and sometimes contain harmful substances such as harmful heavy metals and emit off-flavors to cause environmental pollution. Therefore, curing and stabilizing various kinds of mud is to prevent waste pollution, and various treatment measures are proposed and implemented in response to requests for environmental purification and recycling of waste mud. ing.

[0003] Conventionally, as a method for treating this kind of muddy substance, a method of performing a heat treatment or a method of forcibly reducing the volume of dehydration using a dehydrator is known. In addition, in the case of mud with high water content, the mud that has been subjected to coagulation using a coagulant is placed in a double-type bag, suspended, the method of reducing the volume of dewatering by the weight of the mud, and the method of coagulation and separation mud. A method of dehydrating a product using a dehydrator or coagulating and sedimenting in a sedimentation tank to remove separated supernatant water, followed by drying in the sun is also used. On the other hand, a method in which lime, cement, or the like is used as a solidifying agent to directly solidify and discard mud, or a method in which sunlight is dried outdoors are also known. As described above, a method of solidifying a highly watery mud using these solidifying agents with the separated supernatant water removed is also being implemented.

[0004]

However, the methods described in the prior art have many problems that require the following solutions for each method.

[0005] In the method by heat treatment, the amount of treatment in the form of fine particles is large, the heating time is extended as the water content increases, the equipment for heat treatment and a large heat energy source are required, and the heating temperature is set to a predetermined value. Equipment and the like for maintaining the value are required, which greatly impairs economic efficiency. Moreover,
Not only the generation of excess heat energy, but also the problem of environmental pollution due to gasification ore dispersion of harmful substances in the muddy matter will occur.

The method of directly dehydrating mud using a dehydrator requires a complicated mechanism for dehydrating hydrophilic mud having a high water content, an apparatus for pretreatment, and the like. or,
Since the dehydrated product is not in a physically and chemically stable state as in the case of being solidified by the solidifying agent, there is a possibility that the dehydrated product absorbs moisture and becomes muddy again. Furthermore, due to the physical properties of the muddy substance, even when a flocculant is used and the dewatering process is performed by a dehydrator after performing floc formation, the processed material generated is not physically stable. In addition, there is a possibility that the mud may be formed again, and the viscosity of the mud may increase, dehydration efficiency may be reduced, and the solid-liquid separation surface may be clogged. And nails, glass fragments,
If contaminants such as empty cans, stones, and vinyl are mixed, dehydration becomes impossible, and a pretreatment facility for removing the contaminants is required. The dewatering equipment generally has a complicated structure and a lot of peripheral devices, and the cost of the entire equipment is high, and the dewatering ability is not so good despite the high maintenance cost.

[0007] In the method of putting the mud which has been subjected to coagulation using a coagulant into a double-type bag, suspending the mud, and reducing the volume of dewatering by the weight of the mud, the mud having a high water content is removed. Has an effect as an initial water separation, but in order to further reduce the volume of dehydration, it is necessary to wait for natural drying after that, it takes a lot of days, and in the case of natural drying outdoors Then
In the case of rain, etc., due to the moisture that penetrates through the bag,
There is a risk of mud. In addition, since the effect of the flocculant cannot be expected for muddy substances having a low water content, the effect of initial moisture separation is also lost.

[0008] The coagulation separation supernatant water is removed using a coagulant,
After that, a method of drying in the sun or a method of directly drying in the untreated state can be considered.However, it takes not only a very long time to reduce drying, but also When it rains, it becomes muddy again. In such a situation, it is difficult to determine the number of days during which the dried product can be obtained, and it is necessary to take measures against the outflow of muddy substances and the treatment of turbid water during rainfall.

[0009] In the method of directly solidifying mud with a low water content using a solidifying agent such as lime or cement, the weight and volume of the processed material to be produced are reduced by the amount of the solidifying agent mixed. This means that the volume will not be reduced, and it is necessary to take measures against alkali spillage until the completion of the final solidification. Further, for a mud having a high water content, a very large amount of a solidifying agent is required, which impairs economic efficiency. Further, since the weight and volume of the processed material increase, it is not easy to carry or transport the processed material.

[0010] In the conventional method, as for the sludge containing harmful substances, in the treatment process and after treatment, measures for elution of the harmful substances contained and separation water separated are taken as a post-process. Required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to remove a mud-like substance in a high water content state and a low water content state without using special mechanical equipment. Even in the form of solids, it is possible to produce hard aggregates that are physically and chemically stable for a long period of time in a short time, on a short day, and at low cost. The purpose of the present invention is to provide a method for stabilizing the solidification and volume reduction of mud which can be effectively used for various purposes.

[0012]

In order to achieve the above object, in the method for stabilizing solidification and volume reduction according to the present invention, it is put into a bag having good water permeability placed in a tank having an open top. Acidic activity obtained by mixing a silicic acid aqueous solution containing a highly ionizable metal and a mineral acid with a muddy substance or a muddy substance directly charged into a tank with an open top. A step of adding a silicic acid sol and an aqueous solution of an alkaline diluted silicic acid substance to a mud and stirring and mixing the mud to a neutral hydrated coagulate. Perform primary dehydration by the method used, and then, by the dehydration reaction from the hydrated coagulate accompanying the condensation reaction by the coagulation reaction and the secondary dehydration by the solar drying step, easily, in a short time, Reduced volume of physically and chemically stable neutralized non-remudified sand In which it was included the step of allowed to generate a hard crumb similar to system earth and sand.

The present invention has excellent characteristics as described above because an acidic active silicate sol and an alkaline aqueous solution of a diluted silicate substance are added to a slurry, and the mixture is stirred and mixed. The silicic acid adjusted by summing
It is an active species that crosslinks and cures through silanol condensation reactions and dipole interactions. This makes the silica sol effective as a mud coagulant and turns the mud into a neutral hydrated coagulate.

This water-containing coagulated material has a volume-reducing property, is physically and chemically stable, and has a three-dimensional network structure formed by siloxane bonds, so that harmful substances are hardly eluted. Is a solidified product. In addition, since this coagulated material is physically and chemically stabilized for a long period of time, it does not deteriorate due to freezing or heating, and even when it rains,
Again, there is no danger of muddy.

The hydrated coagulum promotes silanol condensation with the lapse of time after the coagulation, further develops a three-dimensional network structure, breaks siloxane bonds, and grows into a silicic acid polymer having a stable structure. , Contains and solidifies mud particles. In these reaction processes, the water in the hydrated coagulate is gradually discharged as syneresis water, and the coagulate itself has the property of reducing its volume. Further, the coagulated structure is in a state where harmful substances are hardly eluted into syneresis water.

Regardless of whether the mud is high or low water content, the active silicate sol and the diluted silicate material are added, and the mixture is stirred and mixed. As a result, when the PH becomes neutral, the coagulation activity starts. It becomes a gel-like neutral hydrated coagulated product in a short time. Also,
Even for muddy substances with bad odor, the coagulated matter has a deodorizing effect by being treated in the neutral region, and the ammonia odor and hydrogen sulfide odor, which are typical odor gases in the muddy substance, The ammonia odor is fixed as ammonium sulfate by the activated silica sol added to the mud, and the hydrogen sulfide odor is converted to iron sulfide by metals with a high ionization tendency, mainly ferrous iron mixed in the aqueous solution of silica. In addition to the deodorant effect of the neutral region treatment, it also has a large deodorant effect.

The bag placed in the tank is made of a nonwoven fabric of linen cloth and rayon cotton and a cloth for nylon stocking, so that it is extremely excellent in water permeability.
The rayon cotton, which has a thickness of 5 to 2 mm and is randomly overlapped, is a cloth processed in a process of being entangled with linen with a comb-shaped pin, and the gap between the fibers of the rayon serves as a water permeator. Because of this, there is no hole, and together with the liquid crystal filtration effect of using a nylon stocking cloth together, the fine solid matter in the mud does not pass through.
Azabu has the role of reinforcing rayon cotton,
This nonwoven fabric has a tensile strength of 6.3 kgf / cm ² .

The above bag is not sewn in a bag shape, but is made of a single piece of circular cloth, with a string passing through the outer periphery of the circle, and the string is passed through. By squeezing the string, it becomes a bag-like shape, and when the squeeze is warmed, it becomes a single flat circular cloth.

By arranging the circular cloth along the inside of the container, the container becomes a cloth container and can receive the mud without losing its shape even when the mud is introduced. or,
By replacing this circular cloth even with one container, the receiving of mud can be smoothly and sequentially performed.

The above-mentioned hydrated coagulum is taken out together with a bag arranged along the tank and suspended, whereby static pressure dehydration is performed using the own weight of the coagulate as an external force, and a considerable amount of water is rapidly discharged. Can play a role as primary dehydration. The suspension time is 3 to 4 hours, during which time the coagulate will develop further a three-dimensional network due to siloxane bonds.

After the above-mentioned primary dehydration, the bag is moved to the ground or a gantry, the upper portion of the bag is opened, and solar drying is performed, so that a neutral hard aggregated state having a greatly reduced volume is obtained in a short period of time. . In the case of solar drying, drying is further promoted with the effect of a condensation reaction of the coagulated product. This is 4-7 days after coagulation.
In addition, since these operations are performed in the above-described bag, all the movement is easy, and the bag is hardly clogged due to the solidification state, so that the bag can be reused many times. Also,
All the work up to about 40 litters can be easily performed manually, and the time required to complete the coagulation is as short as 15 to 20 minutes. When the sludge amount that is difficult to move with human power is processed at once, only the equipment at the time of movement is sufficient.

The hydrated coagulated material obtained when the mud is directly poured into a tank or the like and subjected to coagulation treatment is taken out of the tank, raised to a certain thickness, and dried by the sun in the outdoors. It is dried for a short period of time without being affected by the weather, and becomes a neutral hard aggregated state similar to sandy soil with greatly reduced volume. In this step, by raising to a certain thickness, the lower part is subjected to static pressure dehydration using the own weight of the upper coagulated substance as an external force, and it is possible to rapidly discharge a considerable amount of water, as a primary dehydration Have a role. Furthermore, during sun drying, drying is further promoted with the effect of a syneresis reaction due to a condensation reaction of the coagulated product. This number of days
6-14 days after coagulation.

The processed material thus obtained is a hard aggregate having good physical and chemical stability for a long period of time and no adverse effect on the environment, and can be reused for various purposes. Furthermore,
Processing can be easily performed without requiring special mechanical equipment.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In the case of using a bag having good water permeability inside the tank as equipment for the method for stabilizing the solidification and volume reduction of mud according to the present invention, an open-top tank 1 schematically shown in FIGS. , A water-permeable nonwoven bag 2, a stirring and mixing rod 5, a primary dehydrating hanging column 7, and a drug measuring container 4. The introduction of the muddy substance may be arbitrary such as direct introduction from a generation source, introduction of a pump, or the like, and medicine measurement may be medicine and measurement by an automatic dispensing device. In addition, the bag containing the hydrated coagulated material may be manually or mechanically moved.

In the solidification of the mud according to the present invention, sodium silicate No. 3 containing a metal having a high ionization tendency, mainly ferric iron, is used. (Addition amount of 0.4 to 1.5% based on the amount of No. 3), and acidic sodium sulfate is used as a mineral acid. First, a 40% to 50% diluted sodium silicate aqueous solution 4a is prepared by diluting sodium silicate 3 with diluted water. And this diluted sodium silicate aqueous solution 4
a is directly added to the slurry 3 to be treated and mixed with stirring, and the same amount of this diluted aqueous sodium silicate solution is mixed with an aqueous solution of 10% or less of acidic sodium sulfate to adjust the pH to 1.5 to 1.5%.
2. Prepare a strongly acidic activated silica sol 4b of 2.2. The adjusted active silicate sol 4b is added to the slurry 3 to be treated, to which the diluted aqueous sodium silicate solution is added and mixed, and the mixture is stirred and mixed. As a result, the mud becomes a neutral region having a pH of about 6.5 to 8, and if the mud is left for a while in such a state, the mud 3 becomes gel-like in a short time (about 10 to 40 minutes). It becomes a water-containing coagulated product. A diluted sodium silicate aqueous solution and an acidic sodium sulphate
The ratio of the aqueous solution of 0% or less is 1: 0.9-1.
0.

The diluted aqueous sodium silicate solution 4a is directly added to the slurry 3 in advance, and is diffused in the slurry 3, so that the acid active silica sol 4b to be added thereafter is a small amount. Even if it is present, the mud 3 can be surely neutralized to obtain a hydrated coagulated product. As described above, since the dilute sodium silicate aqueous solution 4a is added in advance to the mud, even when the strongly acidic active silicate sol 4b is added, generation of odor due to sulfides and the like is suppressed, and the mixed metal The compounds form iron sulfide, which exerts a further suppressing effect. Further, since the contained ammonia odor is fixed as ammonium sulfate by the active silicic acid sol 4b, the malodor after the treatment is extremely reduced.

In order to exhibit the initial effects of the present invention, the active silicic acid sol as a coagulant needs to be treated in terms of the muddy properties of the mud to be treated, the workability, the properties of the resulting treated material, economy, purpose and the like. The concentration and the amount of addition are selected accordingly, for example, the addition amount is 2.5 to 30% with respect to the mud to be treated, and the mixture is left for about 10 to 40 minutes.

The stirring and mixing of the added drug in the mud is carried out by moving the stirring and mixing rod 5 in FIG.
Facilitates uniform mixing of mud with different concentrations of drug.
The stirring and mixing rod 5 has a shape like a bath scraper. In addition, since the stirring and mixing is required to be stirred and mixed as much as possible up and down, as long as the stirring and mixing can be easily performed even with a rod other than the stirring and mixing rod 5, it is used regardless of the mechanical equipment and the manual stirring. .

After the solidification of the mud is completed, the bag binding string 2a shown in FIG.
As shown in FIG. 6, it becomes a bag shape enclosing the hydrated coagulated material 6. The bag is taken out of the container 1 and moved. At this time, the binding string makes the movement easier.

Water-permeable nonwoven bag 2 wrapped with hydrated coagulated material
Is taken out of the container, and the suspension column 7 for primary dehydration in FIG.
The weight of the hydrated coagulated material acts as a static pressure, and the dewatering of the hydrated coagulated material is performed temporarily, although temporarily, using the water-permeable nonwoven fabric bag as a solid-liquid separation surface.
In this case, most of the easily separated water in the coagulated matter is discharged in 1 to 2 hours, so this primary dehydration operation is performed in about 3 to 4 hours. The suspension time, whether shorter or longer, is less affected by the end effect. During this time, the siloxane bond in the coagulate promotes further development of the three-dimensional network structure.

After the primary dehydration, the bag is moved, the binding cord 2a at the top of the bag is warmed on the ground surface or a gantry as shown in FIG. In this case, in addition to evaporation and air permeability of moisture due to sunlight, a condensation reaction accompanying solidification promotes further drainage of moisture in the solidified product. In addition, since the coagulated material is extremely stable physically and chemically, there is no need to worry about solids flowing out and muddy again due to rainfall in the course of drying in the sun, and extremely low outside air temperature. There is no need to worry about freezing and deterioration.

In the bag 2 shown in FIG. 5, a string 2a is passed through the outer periphery of the circle, and the string is squeezed to form a bag. The squeezing by the string is heated, and the bag is opened to form a circular sheet. Therefore, the drying of the coagulated material on the sheet is promoted during the solar drying. In addition, by using such a bag, it is possible to easily move the processed material at each time.

The agent to be used for coagulation is sodium silicate 3 previously mixed with metals having a high ionization tendency, mainly ferrous iron.
Appropriate amounts of a prescribed diluted aqueous solution of the above and an aqueous solution of 10% or less of mineral acid are prepared, and these aqueous solutions are charged, measured, and added to the medicine measuring container 4 marked on the container at the time of execution.

When the mud is directly charged into a tank or the like,
The muddy substance 3 is put into the tank 1a shown in FIG. This tank may be an excavated pond or a box-type tank made of steel or a mixer. FIG. 7 is a diagram showing a state in which the muddy substance 3 is put into the box-shaped tank 1a.

FIG. 8 shows that a sodium silicate No. 3 is prepared with a diluted water to prepare a 40-50% diluted sodium silicate aqueous solution 4a, stored in a chemical measuring container 4, and a mud 3 is diluted with a diluted sodium silicate aqueous solution 4.
a, and mixed by stirring. Next, the activated silicic acid sol 4b adjusted and stored in the medicine measuring container 4 is charged, and the whole is thoroughly stirred and mixed. After the stirring and mixing are completed, the mixture is left gently for about 10 to 40 minutes to produce a gel-like hydrated coagulated product. The stirring and mixing are required to be mixed up and down as much as possible.

The hydrated coagulated product 6 thus generated is taken out of the tank 1a, and is raised to a predetermined thickness on the ground as shown in FIG.
Hard aggregates 8 similar to chemically stable neutral sandy sediment can be produced on short days. In this case, the hydrated coagulate 6
The lower part is subjected to static pressure dehydration using the own weight of the upper coagulated material as an external force, and a considerable amount of water is temporarily suddenly discharged, thereby promoting drying. With. FIG. 10 illustrates such a process of discharging water.

[0038]

As described above, the present invention provides the following effects as a simple solidification volume reduction stabilization method for mud.

[0039] The muddy material is a simple operation that does not require skill,
Reduce and stabilize mud volume on relatively short days, and
Easy handling of residue. Furthermore, regardless of the physical properties of the mud, the volume reduction stabilization process can be easily performed without using special equipment except for some tools or simple equipment.
The volume of mud can be easily reduced and stabilized.

By using the water-permeable nonwoven bag, the movement between the respective working steps can be performed very smoothly. Furthermore, since this water-permeable nonwoven bag is excellent in water permeability, it also has a temporarily effective dewatering effect.

With the activated silicate sol and the diluted sodium silicate,
After the mud is turned into a neutral gel-like hydrated coagulate, the volume is reduced by dehydration and drying in the sun. Aggregates are also harmless and do not adversely affect the environment. Furthermore, since the coagulated material is physically and chemically stable for a long period of time, there is no danger of the coagulated material flowing out due to freezing or rainfall and re-mudification even in solar drying. In addition to being able to obtain stabilized hard aggregates with a large volume reduction in a short period of time, the work schedule can be grasped. Moreover, the obtained hard aggregates can be effectively used.

Experiment. Based on Notification No. 13 of the Environment Agency in 1973 and No. 44 Notification of the Environment Agency in 1982, leaching tests of hydrated coagulates, formed hard aggregates, and separated water were conducted. The test results were satisfactory.

One entire working process for the stabilization of the solidification and volume reduction of the mud requires 4 to 14 days, but the actual working time in the meantime requires only 1 to 2 hours, and heat and large-scale machines, Since no special machine is used, energy consumption is low, which leads to further economic efficiency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an example of the implementation of the muddy solidification of the present invention before muddy solidification.

FIG. 2 is a schematic diagram of addition of a drug and stirring and mixing.

FIG. 3 is a schematic diagram of hanging primary dehydration of a hydrated coagulated product.

FIG. 4 is a schematic diagram of solar drying after primary dehydration.

FIG. 5 is a schematic plan view of a water-permeable nonwoven fabric bag and a configuration diagram of a water-permeable nonwoven fabric.

FIG. 6 is an explanatory view of a primary dehydration action of a water-containing coagulated product suspended by a water-permeable nonwoven bag.

FIG. 7 is a state diagram before solidification in which mud is put into a tank, schematically showing two examples of execution of mud solidification according to the present invention.

FIG. 8 is a schematic diagram of drug addition and stirring and mixing.

FIG. 9 is a schematic view of embankment to a predetermined thickness and solar drying.

FIG. 10 is an explanatory diagram of a process of discharging water content by drying a water-containing coagulated product by sunlight.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top-open tank 1a Tank 2 Water-permeable nonwoven bag 2a Water-permeable nonwoven bag binding cord 3 Mud 4 Drug measuring container 4a Dilute sodium silicate aqueous solution 4b Active silica sol 5 Stirring and mixing rod 6 Water-containing coagulated material 7 Primary dehydration Suspended pillar 8 Generated hard aggregate

Claims (1)

[Claims] Claims 1. A hydrophilic mud such as dredged sludge, sludge, and various kinds of wastewater sludge is put into a bucket or a bag having good open permeability installed inside a tank or an open top tank, An acidic activated silicate sol obtained by directly charging a bucket or open-top tank, etc., and mixing an aqueous solution of a silicate substance mixed with highly ionizable metals such as ferrous iron and a mineral acid. And a process of adding an alkaline dilute silicate aqueous solution and mixing with stirring to make this hydrophilic muddy substance into a neutral hydrated coagulated product, and taking out the hydrated coagulated product in a bag and temporarily suspending it. By lowering, or by directly taking out the hydrated coagulated material and stacking it to a predetermined layer thickness, forcible primary dehydration using the hydrated coagulated material static weight is performed. The top is fully open and the ground Alternatively, if the bag is not used and the bag is left on the gantry, it can be left standing for a short period of time due to the syneresis reaction from the hydrated coagulated product due to the condensation reaction due to the coagulation reaction and the secondary dehydration by the solar drying process. Producing hard aggregates similar to sandy soil that does not re-pulverize in a neutral region where the volume is reduced physically and chemically stable, Stabilization method.