WO2013150660A1

WO2013150660A1 - A treatment device for waste matter containing heavy metals and a method for treating waste matter containing heavy metals using same

Info

Publication number: WO2013150660A1
Application number: PCT/JP2012/059822
Authority: WO
Inventors: 松井　三郎
Original assignee: Ｇ－８ＩｎｔｅｒｎａｔｉｏｎａｌＴｒａｄｉｎｇ株式会社
Priority date: 2012-04-04
Filing date: 2012-04-04
Publication date: 2013-10-10
Also published as: JPWO2013150660A1; JP6872101B2

Abstract

Provided are a simple, low-cost treatment device and treatment method for waste matter containing heavy metals, the treatment device comprising: a sealed container having a closed space for storing a Ca component material and a SiO₂ component material in an amount sufficient for forming 5CaO•6SiO₂•5H₂O crystals (tobermorite) for sealing, inside a crystal structure, waste matter containing heavy metals or at least the heavy metals undergoing treatment; a steam jetting means for jetting high-temperature, high-pressure steam into the closed space; a cooling means for cooling and liquefying the vapor inside the closed container after treatment; and a separation and recovery means for discharging a mixture of the waste matter containing tobermorite in which the treated heavy metals are sealed, and a liquid containing the liquefied components, and then separating both from each other. Waste matter containing heavy metals can thereby be safely treated using high-temperature, high-pressure steam, the heavy metals are immobilized to inhibit elution, and the mixture containing a liquid and waste matter in which the heavy metals have been immobilized can be separated and recovered using a simple operation.

Description

Waste treatment apparatus containing heavy metals and waste treatment method using heavy metals using the same

The present invention treats waste containing heavy metals such as sewage sludge, industrial sludge, medical waste, household waste, and industrial waste using high-temperature and high-pressure steam, and after the treatment, it is treated and fixed. The present invention relates to an apparatus for treating waste containing heavy metals and a method for treating waste containing heavy metals using the same, which discharges and separates a mixture containing a waste containing heavy metals and a liquid. .

As a method for treating organic waste, for example, a method of treating waste in high-temperature and high-pressure steam in a sealed container is known (see, for example, Patent Document 1). In the conventional method of treating waste with steam, there is almost no generation of harmful nitrogen oxides, sulfur oxides, etc. as in the case of incineration treatment, and there is no problem of environmental pollution and safe waste The process could be expected.
However, after processing, the processed solid matter and liquid are in a mixed state, and there is a problem that transportation and storage after taking out the processed waste is inconvenient and difficult to handle, and Separation of solids and liquids processed using a separator after processing requires a complicated process and requires a lot of labor. The processing takes a long time. The reaction vessel and the separator are installed separately. There was a problem that it was necessary to secure a wide site for the purpose.
For this reason, a processing apparatus has been proposed that can safely process waste using high-temperature and high-pressure steam with a single device, and that can separate and recover the processed waste and liquid following this processing. (See Patent Document 2). However, this processing apparatus is composed of a reactor composed of a sealed container for treating waste in high-temperature and high-pressure steam, and another recovery sealed connected to the reactor composed of the sealed container for recovering separated liquid. Since a container is required, there are problems such as high equipment costs and complicated operations.
On the other hand, for example, sewage sludge discharged from sewage treatment facilities contains pathogenic microorganisms and heavy metals, and in order to avoid environmental risks caused by them, it can be treated and treated by various methods such as concentration, digestion, dehydration, composting, incineration, and melting. Disposal has been done. However, any of these treatment methods is a method of reducing or discarding, a consumption type technology that inputs a large amount of electric power or thermal energy, and a method that has a large impact on the environment, such as being a greenhouse gas emission source. This is a cause of squeezing the local economy because of high maintenance costs rather than processing according to the principle of resource recycling.
At present, there are problems of accumulation due to the heavy metals contained in sewage sludge, infectious contamination such as harmful chemical substances, pathogenic microorganisms and viruses, and effective utilization of sewage sludge is not progressing. Against this background, in recent years, the direction of “sewage sludge recycling” policy has been directed (see Non-Patent Document 1).
On the other hand, a soil purification method by solidifying heavy metals has been proposed by treating inorganic waste with lime addition and processing under subcritical water conditions (see Non-Patent Document 2).
However, for the purpose of concrete resource regeneration, it is safe to process and immobilize the heavy metals to suppress elution, simplify the structure of the processing equipment, and it seems easy to operate and low cost. New resource recycling technology has not been introduced.

JP 2000-33355 A Japanese Patent No. 4864884

The present invention has been made in view of the above-described conventional problems, and a first object of the present invention is to safely treat waste containing heavy metals using high-temperature and high-pressure steam with a single device. The heavy metal is immobilized to suppress elution, and after the treatment, the mixture containing the waste and liquid in which the heavy metal is immobilized can be discharged and separated and recovered by a simple operation. It is an object of the present invention to provide an apparatus for treating waste containing heavy metals that is simple, easy to operate, and low in cost.
Furthermore, a second object of the present invention is to provide a mixture containing waste and liquid, in which waste containing heavy metals is simply treated using high-temperature and high-pressure steam, and the heavy metals are immobilized to suppress elution. It is an object of the present invention to provide a method for treating waste containing heavy metals that can be discharged and separated and recovered by a simple operation.

The invention according to claim 1 of the present invention for solving the above-mentioned problems is characterized in that a waste containing heavy metals is contained therein, and at least the heavy metals are treated with a 5CaO · 6SiO ₂ · 5H ₂ O crystal (tobermorite) structure. A sealed container having a closed space for containing a sufficient amount of Ca component raw material and SiO ₂ component raw material to form 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) for containment in the sealed container, Steam ejection means for ejecting high-temperature and high-pressure steam for treating the waste, the Ca component raw material and the SiO ₂ component raw material, and cooling means for cooling and liquefying the steam in the sealed container after the treatment; Waste and liquefaction containing a tobermorite containing a discharge port provided on the bottom side in a sealed container and having an opening and closing mechanism, and the heavy metals treated from the discharge port A waste treatment apparatus containing heavy metals, comprising: a separation / recovery means for separating the waste and the liquid from the discharged mixture. Separates and collects the waste and the liquid while moving by separating and collecting means for separating the waste and the liquid after the mixture is once collected in a collection container and / or supplying the mixture to a belt conveyor device. It is a waste processing apparatus containing heavy metals, which is a separation and recovery means.
In the invention according to claim 2 of the present invention, when processing waste containing heavy metals in a sealed container having an openable and closable discharge port and having a closed space while jetting high-temperature and high-pressure steam, A sufficient amount of 5CaO.6SiO ₂ .5H ₂ O crystals (tobermorite) to be contained in the 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) structure during the treatment with After the treatment is performed in the presence of the Ca component raw material and the SiO ₂ component raw material, the treatment is cooled and treated with the treated liquid containing the water-soluble compound of the heavy metal liquefied and the tobermorite in which the heavy metal is contained. A method for treating waste containing heavy metals, characterized in that separated waste is collected.
The invention according to claim 3 of the present invention is the treatment method according to claim 2, wherein the content of the Ca component (A-1) and the content of the SiO ₂ component (A) previously contained in the waste containing heavy metals. -2) is analyzed, and 5CaO · 6SiO ₂ · 5H ₂ O crystals (tobermorite) are formed during the treatment to contain at least the heavy metals in the 5CaO · 6SiO ₂ · 5H ₂ O crystal (tobermorite) structure. The amount of Ca component (B-1) and the amount of SiO ₂ component (B-2) sufficient to be calculated are calculated, and the waste containing heavy metals is calculated by the following formulas (1) and (2). The addition amount (C-1) of the Ca component raw material to be added and the addition amount (C-2) of the SiO ₂ component raw material are obtained, and the Ca component raw material (C-1) and the SiO ₂ component raw material ( C-2) is added to the treatment It is characterized by performing.
[(B-1)-(A-1)] = (C-1) Formula (1)
[(B-2)-(A-2)] = (C-2) Formula (2)
According to a fourth aspect of the present invention, in the treatment method according to the second or third aspect, the heavy metal is at least one selected from chromium, lead, cadmium, arsenic, mercury, zinc, copper, and nickel. Since the heavy metals are contained in the 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) structure in the waste after treatment, the waste after treatment is classified into water environment standard, soil environment standard, It is characterized by satisfying at least one selected from special fertilizer standards and food safety standards.
According to a fifth aspect of the present invention, in the treatment method according to any one of the second to fourth aspects, the treatment is performed at 120 to 250 ° C. and 1.1 to 2.1 MPa. It is characterized by performing time.

The invention according to claim 1 of the present invention includes a waste containing heavy metals therein, and 5CaO · for containing at least the heavy metals in a 5CaO · 6SiO ₂ · 5H ₂ O crystal (tobermorite) structure during processing. A closed container 12 having a closed space S1 for storing a sufficient amount of Ca component raw material and SiO ₂ component raw material for forming 6SiO ₂ .5H ₂ O crystal (tobermorite), and the waste stored in the closed container 12 Vapor jetting means 14 for jetting high-temperature and high-pressure steam for treating the product, Ca component raw material and SiO ₂ component raw material, cooling means 70 for cooling and liquefying the vapor in the sealed container 12 after the treatment, and sealing A discharge port 16 provided on the bottom side in the container 12 and having an opening / closing mechanism 26; and a tobermorite containing the heavy metal treated from the discharge port 16 A waste treatment apparatus 10 containing heavy metals, comprising a separation and recovery means 18 for discharging a mixture of waste and liquid containing liquefied components and separating the waste and liquid from the discharged mixture. The separation / recovery means 18 recovers the mixture into a recovery container 50-1 or 50-2 and then separates the waste and the liquid and / or the mixture into a belt conveyor device 80. -1 or 80-2 is a separation and recovery means for separating the waste and the liquid during the movement, and is a waste treatment apparatus containing heavy metals, and only by one apparatus , Wastes containing heavy metals are treated safely using high-temperature and high-pressure steam, and the heavy metals are immobilized to suppress elution. Including The product can be discharged and separated and recovered by a simple operation. The structure is simple, the operation is simple, and the cost is low.
The processing apparatus 10 of the present invention has a simple configuration, a simple operation, and a low-cost structure, and can satisfactorily separate and collect processed waste and liquid.
Further, the entire apparatus is not enlarged and can be manufactured at low cost. In addition, waste collected separately from liquid is in a state of low moisture, which is convenient for handling, transportation, management, etc. For example, carbonized waste is processed into fuel, soil conditioner, etc. in a short period of time. obtain.
The shape of the airtight container 12 may be, for example, a rectangular box shape, a three-dimensional polygonal cylinder shape, a cylindrical shape, a barrel shape, a drum shape, or any other arbitrary shape, but using gravity from the discharge port 16 provided on the lower surface side. A shape that is discharged is preferred. It is preferable that the lower surface of the sealed container 12 is provided in a downward slope toward the discharge port 16.
The processing apparatus 10 of the present invention also separates and collects the mixture from the waste and the liquid after the mixture is once collected in the collection container 50-1 or 50-2 and / or removes the mixture from the belt conveyor device 80. -1 or 80-2, and separation and recovery means 18 for separating the waste and the liquid during movement.
As shown in FIG. 1 and FIG. 3A, once the mixture of the waste and the liquid treated in the vicinity of the discharge port 16 is recovered in the recovery container 50-1, the bottom of the recovery container 50-1 is formed. The liquid is separated by a stainless steel mesh 56 that does not allow the waste to pass through but allows the liquid to pass through, and is recovered in another recovery container 50-3 disposed below the recovery container 50-1.
Since the waste material is separated and remains on the stainless steel mesh 56 of the recovery container 50-1, the waste is driven by a controlled driving device (not shown) around the rotating shaft 52 when taken out. Rotate 56 in the direction of the arrow to release the locking portion 53 and drop it downward by gravity to collect the waste in a collection container (not shown). In addition to a simple configuration, the waste and liquid that have been processed can be separated and recovered satisfactorily with a simple and low-cost structure.
In the invention according to claim 2 of the present invention, when processing waste containing heavy metals in a sealed container having an openable and closable discharge port and having a closed space while jetting high-temperature and high-pressure steam, A sufficient amount to form 5CaO.6SiO ₂ .5H ₂ O crystals (tobermorite) to contain at least the heavy metals in the 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) structure during the treatment with After the treatment is performed in the presence of the Ca component raw material and the SiO ₂ component raw material, the treatment is cooled and treated with the treated liquid containing the water-soluble compound of the heavy metal liquefied and the tobermorite in which the heavy metal is contained. Waste material containing heavy metals, characterized by separating and recovering the collected waste, and waste containing heavy metals with only one device Is treated safely and simply using high-temperature and high-pressure steam to immobilize the heavy metals to suppress elution, and after treatment, the heavy metals treated continuously are cooled with the immobilized waste. As a result, it is possible to separate and recover the liquefied liquid containing the water-soluble compound of the heavy metal by a simple operation.
The invention according to claim 3 of the present invention is the treatment method according to claim 2, wherein the content of the Ca component (A-1) and the content of the SiO ₂ component (A) previously contained in the waste containing heavy metals. -2) is analyzed, and 5CaO.6SiO ₂ .5H ₂ O crystals (tobermorite) are formed during the treatment to contain at least the heavy metals in the 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) structure. A sufficient amount of Ca component (B-1) and SiO ₂ component (B-2) are calculated, and the waste containing heavy metals is calculated by the above formulas (1) and (2). The addition amount (C-1) of the Ca component raw material to be added and the addition amount (C-2) of the SiO ₂ component raw material are obtained, and the Ca component raw material (C-1) and the SiO ₂ component raw material ( C-2) is added to the treatment This is characterized in that the heavy metal can be efficiently contained.
According to a fourth aspect of the present invention, in the treatment method according to the second or third aspect, the heavy metal is at least one selected from chromium, lead, cadmium, arsenic, mercury, zinc, copper, and nickel. Since the heavy metals are contained in the 5CaO.6SiO ₂ .5H ₂ O crystal (tobermorite) structure in the waste after treatment, the waste after treatment is classified into water environment standard, soil environment standard, It is characterized in that it satisfies at least one selected from special fertilizer standards and food safety standards, and efficiently contains the heavy metals to satisfy at least one selected from the standards There is a further remarkable effect of being able to.
According to a fifth aspect of the present invention, in the treatment method according to any one of the second to fourth aspects, the treatment is performed at 120 to 250 ° C. and 1.1 to 2.1 MPa. 5CaO.6SiO ₂ .5H ₂ O crystals (tobermorite) are efficiently generated during the treatment in the first closed vessel 12, and the heavy metal is contained in the crystal structure. There is a further remarkable effect that the species can be contained.
It is good also as having the stirring means 30 which stirs a waste in the airtight container 12. FIG. In addition, by having a configuration having a stirring means for stirring the waste, the waste can be processed quickly without unevenness.
Further, the sealed container 12 is formed in a side-down barrel shape in which the discharge port 16 is provided on the bottom side of the left and right center part, and the diameter is gradually reduced from the left and right center part toward both left and right sides. Includes a rotating shaft 49 that is provided horizontally in the sealed container 12 and rotatably supported, and a stirring blade 48 that is attached to the rotating shaft 49 and has a portion that extends in the circumferential direction of the rotating shaft 49. The length from the rotating shaft 49 of the stirring blade 48 to the tip of the blade is long at the central position in the longitudinal direction of the rotating shaft 49 corresponding to the sideways barrel shape of the sealed container 12, and gradually decreases toward both ends. It is good also as having been formed.
By setting it as such a structure, when taking out the waste in a 1st airtight container, it can take out easily using gravity. At the same time, it is possible to reliably stir the waste uniformly, corresponding to the shape of the sealed container.
Further, the steam jetting means 14 includes a rotary shaft / steam jet pipe 28 constituted by forming the rotary shaft 49 as a hollow tube and forming a plurality of steam jet holes 44 on the peripheral surface of the hollow tube. Also good.
By adopting such a configuration, high-temperature and high-pressure steam can be directly ejected to the waste for efficient waste disposal, and the efficiency of the steam ejection means and the stirring means in the first sealed container A good arrangement configuration can be realized.

FIG. 1 is a cross-sectional explanatory view of an example of a waste treatment apparatus containing heavy metals according to an embodiment of the present invention.
FIG. 2 is an enlarged partial cross-sectional explanatory view of the vicinity of the discharge port of the waste processing apparatus containing heavy metals of FIG.
FIG. 3A is an explanatory diagram for explaining a part of the separation / recovery unit shown in FIG. 1, and FIG. 3 (b) is an explanatory diagram for explaining another example of the separation / recovery unit shown in FIG. FIG. 3C is an explanatory view for explaining an example of a separation and recovery means for separating the waste and the liquid during the movement by supplying the mixture to the belt conveyor device, and FIG. It is explanatory drawing explaining the other example of the isolation | separation collection | recovery means shown to 3 (c).
FIG. 4 is an explanatory diagram schematically illustrating the layered crystal structure of the tobermorite formed.
FIG. 5 is an explanatory diagram for explaining a state in which chromium and lead ions are taken in and contained in the layered crystal structure of tobermorite.
FIG. 6 is an explanatory diagram for explaining a reaction region when performing a subcritical water reaction.
FIG. 7 is an explanatory diagram showing the relationship between the types of heavy metals and the average value and standard deviation of the solidification rate by subcritical water treatment (the ratio of the decrease in the concentration of treated sludge to the concentration of heavy metals in the raw sewage dewatered sludge).

Hereinafter, an example of a waste treatment apparatus containing heavy metals and a method for treating waste containing heavy metals according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional explanatory view of an example of a waste treatment apparatus including heavy metals according to an embodiment of the present invention as will be described later.
Waste containing heavy metals in the sealed container 12 having the openable / closable discharge port 16 and the closed space S1 shown in FIG. 1 and the heavy metals are converted into 5CaO · 6SiO. ₂ ・ 5H ₂ 5CaO · 6SiO for containment in O crystal (tobermorite) structure ₂ ・ 5H ₂ A sufficient amount of Ca component raw material and SiO to form O crystals (tobermorite) ₂ Component raw materials (hereinafter referred to as waste containing heavy metals and the Ca component raw materials and SiO ₂ Waste containing component raw materials may be referred to as waste for short) and processing while blowing high-temperature and high-pressure steam (120 to 250 ° C, 1.1 to 2.1 MPa, 1 to 8 hours) (Hereinafter, it may be referred to as subcritical water reaction or hydrothermal reaction.) Then, during treatment under saturated water vapor pressure, the Ca component previously contained in the waste by the following formula (3) or newly added Ca component and disposal SiO contained in advance ₂ Components and newly added SiO ₂ The component reacts hydrothermally to produce stable calcium silicate (tobermorite: 5CaO · 6SiO ₂ ・ 5H ₂ A mineral crystal called O) is formed.
6SO ₂ + 5CaO + 5H ₂ O → 5CaO ・ 6SiO ₂ ・ 5H ₂ O ... Formula (3)
As shown schematically in FIG. 4, the tobermorite crystal is composed of a Si—O tetrahedral layer, a Ca—O octahedral layer, and a Si—O tetrahedral layer, and the Si—O tetrahedral layer and the Si—O tetrahedral layer are repeated. In this structure, calcium ions are grown in a layered manner intercalated.
In the process of forming the layered crystal structure, heavy metals are substituted into the layered crystal structure by substituting calcium ions with the calcium ions by an ion exchange reaction. Heavy metals are incorporated and contained in the layered crystal structure of tobermorite, which suppresses elution.
The subcritical water reaction conditions (temperature, pressure, time) are important. The layered crystal structure of tobermorite is formed by treating the waste, and in the process of forming the layered crystal structure, heavy metals replace calcium ions by ion exchange reaction with calcium ions, and are taken into the layered crystal structure of tobermorite and containment It is important to use such subcritical water reaction conditions.
FIG. 5 shows a case in which contaminated soil containing chromium and lead as heavy metals is mixed with SiO contained in the contaminated soil in advance. ₂ Using the components, SiO 2 is newly added to satisfy the above formula (3). ₂ When CaO is added as a component and a new Ca component, and hydrothermal reaction treatment is performed while jetting high-temperature and high-pressure steam as described above, chromium and lead are taken in and contained in the layered crystal structure of tobermorite. It is explanatory drawing explaining a state.
When treated with steam at a high temperature and high pressure as described above (120 to 250 ° C., 1.1 to 2.1 MPa for 1 to 8 hours), chromium and lead become chromium ions and lead ions, and newly added CaO is added. Becomes calcium ions and is pre-contained in contaminated soil ₂ Components and newly added SiO ₂ The component becomes silica ions and moves to the surface reaction layer 81 of the soil particles 80 to undergo a hydrothermal reaction, and the tobermorite layered crystal layer 82 is formed on the surface of the soil particles 80. In this layered crystal structure formation process, chromium ions and lead ions are replaced by calcium ions and exchanged with calcium ions to be incorporated into the tobermorite layered crystal structure.
Thus, silica (SiO2) in the soil and newly added SiO ₂ Tobermorite was synthesized by chemically reacting components and additives with lime (CaO) at a relatively low temperature (120 to 250 ° C) (1.1 to 2.1 MPa for 1 to 8 hours). Elution can be suppressed by growing a stable and strong crystal and confining heavy metals in the layered crystal.
In the case shown in FIG. 5, SiO contained in the contaminated soil in advance. ₂ Using the components, SiO 2 is newly added to satisfy the above formula (3). ₂ The example which added CaO newly as a component and Ca component, and performed the hydrothermal reaction was shown.
According to the formula (3), the molar ratio (theoretical value) of Ca / Si is about 0.8.
However, when the hydrothermal reaction is performed, SiO ₂ Part of the component dissolves in water to form silicate ions, and this SiO ₂ In some cases, the component does not contribute to tobermorite layered crystal formation. Therefore, SiO satisfying the formula (3) ₂ It is preferable to add a larger amount to the component in advance.
However, if added too much, the silicate ion concentration becomes high and heavy metals cannot be confined in the tobermorite layered crystal as will be described later.
The inventors have determined that the SiO / Si molar ratio is in the range of 0.6 to 0.8. ₂ Increasing the ingredients, SiO ₂ It has been found that when the component and the Ca component are blended, the confinement ratio of heavy metals in the tobermorite layered crystal can be kept high.
In this way, since heavy metals can be confined in a strong tobermorite crystal, it is possible to suppress elution of heavy metals such as chromium, lead, cadmium, arsenic, mercury, zinc, copper, nickel, which has been difficult to process in the past. Become.
For example, when compared with soil contaminated with lead and arsenic, the amount of lead elution will increase compared to the soil of the raw material because the treated soil becomes highly alkaline in cement solidification by the conventional method. Elution of both lead and arsenic is effectively suppressed, and the elution standard stipulated in the Environmental Agency (Old) Notification No. 46 can be cleared.
When the waste is treated while jetting high-temperature and high-pressure steam as described above, most heavy metals are taken in and contained in the layered crystal structure of tobermorite as described above. For example, in the waste, When a chloride ion, a silicate ion, a carbonate ion, a sulfate ion, a phosphate ion, or the like is present as an anion, it may dissolve in water vapor or dissolve in water.
Therefore, the present invention treats waste in the sealed container 12 while ejecting high-temperature and high-pressure steam, and then cools the sealed container 12 by the cooling means 70 to liquefy the water vapor in the closed space S1, A treated liquid containing the water-soluble compound of heavy metals is used, and the liquid and the treated waste containing tobermorite containing the heavy metals are separated and recovered.
As shown in FIG. 1, the cooling means 70 for cooling the sealed container 12 is a hollow metal chamber that is installed so as to integrally cover and fix most of the outer surface of the sealed container 12, A cooling medium, such as water or oil whose temperature is adjusted as necessary, or a gas such as air or nitrogen, supplied from a cooling medium source (not shown) flows inside the metal chamber and exchanges heat with the sealed container 12. It is configured to cool.
Although an example of a metal chamber that is integrally covered is shown, the present invention is not limited to this example, and a cooling device that is installed by covering and fixing most of the outer surface of the sealed container 12 with a plurality of metal chambers, A hollow metal pipe fixedly installed on the outer surface of the hermetic container 12 and supplied from a cooling medium source (not shown), such as water, oil, air, nitrogen, etc., temperature-controlled as necessary A cooling device in which the cooling medium flows through the inside of the metal pipe and exchanges heat with the sealed container 12 for cooling, or a hollow metal pipe fixedly installed on the inner surface of the sealed container 12, A cooling medium such as water, oil, gas such as air or nitrogen, which is supplied from a cooling medium source (not shown) and whose temperature is adjusted as necessary, flows inside the metal pipe and exchanges heat with the hermetic container 12 for cooling. Such as a cooling device It can gel. Two or more of these can be used in combination.
The waste processing apparatus containing heavy metals of the present invention includes, for example, a syringe made of synthetic resin, a gauze with blood attached, a disposable diaper, a medical waste discarded from a medical organization such as a visceral organ operated, a garbage Waste from household waste, food processing waste, agricultural and fishery waste, various industrial product waste, industrial waste such as sewage sludge, etc. Is a device that processes high temperature and high pressure steam. Furthermore, the waste containing the tobermorite encapsulated in the heavy metals obtained from the treatment and the liquid liquefied as described above are effectively separated by a simple operation, and the waste and the liquid are recovered separately. It is a device that can.
1 and 2 show an embodiment of a waste treatment apparatus containing heavy metals of the present invention (hereinafter also simply referred to as “treatment apparatus”). As shown in FIG. 1, the processing apparatus 10 according to the present embodiment includes a sealed container 12 that contains waste therein, a steam ejection means 14 that ejects high-temperature and high-pressure steam into the sealed container 12, and the sealed container 12. And a separation and recovery means 18 for separating and recovering the treated waste and liquid.
As shown in FIG. 1, the sealed container 12 is a closed container having a closed space S <b> 1 that accommodates waste to be processed therein, and is a container that processes waste in the closed space S <b> 1 under high temperature and high pressure. .
In the present embodiment, the sealed container 12 is supported by the support legs 13 so as to be disposed at a certain height from the ground. The sealed container 12 is formed in a side-down barrel shape whose diameter is gradually reduced from the central portion in the left-right direction toward the end walls 12a on the left and right ends. The sealed container 12 is formed, for example, by processing a metal plate so as to have heat and pressure resistance, and waste is about 2 m. ³ It is provided with a size that can be accommodated. The closed container 12 is provided with an input part 20 above the center part and a discharge part 22 at the bottom side of the center part, and is provided to be opened and closed by opening /

closing mechanisms

24 and 26, respectively.
In the present embodiment, a steam ejection pipe 28 constituting the steam ejection means 14 and a stirring means 30 for stirring the waste are disposed in the closed space S1 of the sealed container 12. The sealed container 12 is provided with a safety valve 32 that can release the internal steam when the internal pressure becomes higher than a set value, for example, the set pressure can be adjusted. Further, a silencer / deodorant / heavy metal recovery device 34 is provided in the middle of the exhaust pipe connected to the safety valve 32, and the steam exhausted through the safety valve 32 is silenced, deodorized, Heavy metal compounds are collected and discharged to the outside air side.
In this embodiment, as shown in FIGS. 1 and 2, the discharge port 16 is opened on the bottom surface side of the left and right central part of the sealed container 12, and is provided with the treated waste discharged in a downward direction. ing. In the present embodiment, the diameter of the discharge port 16 is, for example, about 300 mm.
In the present embodiment, the discharge port 16 is connected to a discharge tube 36 projecting downward to form a discharge path R1 for the treated waste, and is provided in the middle of the discharge path R1. An opening / closing mechanism 26 for opening and closing the discharge port 16 is provided.
That is, in the present embodiment, the discharge unit 22 includes the discharge port 16, the discharge tube 36, and the opening / closing mechanism 26. In the present embodiment, the opening / closing mechanism 26 has, for example, a ball-shaped valve body 38 provided with a through-hole 37 communicating with the discharge path R1 at the center around a rotary shaft 40 provided in a direction orthogonal to the discharge path. And an opening / closing valve such as a ball valve that opens and closes the discharge path R1.
Since the sealed container 12 is laid sideways and formed into a barrel shape, the waste inside easily gathers toward the center where the discharge port 16 is provided due to gravity, and is simply processed by simply opening the opening / closing mechanism 26. Waste can be discharged from the discharge port 16.
In the present embodiment, in the present embodiment, the closing opening 12 is opened on the upper side of the sealed container 12, and a loading cylinder 43 protruding upward is attached to the loading opening 42 to open and close the loading cylinder 43. For example, an opening / closing mechanism 24 such as a ball valve is provided.
Waste including heavy metal, the Ca component raw material, and SiO are opened through an opening / closing mechanism 24. ₂ The component raw materials can be charged into the sealed container 12 and closed during processing to maintain the closed state of the closed space S1 in the sealed container 12.
In the present embodiment, the steam ejection means 14 ejects high-temperature and high-pressure steam into the sealed container 12, puts the sealed container 12 into a high-temperature and high-pressure state, and processes the waste through the steam.
In the present embodiment, as shown in FIG. 1, the steam ejection means 14 includes a steam ejection pipe 28 that is a hollow pipe disposed in the sealed container 12 and formed with a large number of steam ejection holes 44 on the peripheral surface side, A steam generator 46 such as a boiler, and a steam feed pipe 47 that supplies steam from the steam generator 46 into the steam ejection pipe 28 are included.
The steam ejected from the steam ejection means 14 into the sealed container 12 is 5CaO · 6SiO during processing in the sealed container 12. ₂ ・ 5H ₂ The high temperature and high pressure are set so that O crystals (tobermorite) can be efficiently produced and the heavy metals can be contained in the crystal structure. In the present embodiment, for example, the steam ejected from the steam ejection pipe 28 has a temperature of 120 to 250 ° C. and a pressure of 1.1 to 2.1 MPa. The inside of the sealed container 12 is set to a temperature of 120 to 250 ° C. and a pressure of about 1.1 to 2 MPa, and the treatment is performed for 1 to 8 hours.
If the temperature is less than the lower limit, there is a risk that tobermorite crystals will not be formed, and if the temperature exceeds the upper limit, other crystals that are not tobermorite crystals may be formed.
If the pressure is less than the lower limit, the tobermorite crystals may not be formed, and if the pressure exceeds the upper limit, other crystals that are not tobermorite crystals may be formed.
If the treatment time is less than the lower limit, a tobermorite crystal may not be formed, and there is no upper limit, but if the treatment time is too long, it becomes uneconomical.
When processed within the above range, 5CaO · 6SiO ₂ ・ 5H ₂ O crystals (tobermorite) can be efficiently produced, and the heavy metals can be contained in the crystal structure.
In the present embodiment, the steam ejection pipe 28 is long in the lateral direction at a substantially central position in the vertical direction of the sealed container 12, and is rotatably supported via bearings 45 provided on both end walls 12 a of the sealed container 12. ing. That is, the steam ejection pipe 28 is adapted to directly apply the steam to the waste while rotating radially around the horizontal axis and ejecting the steam radially.
Note that the steam ejection pipe 28 is rotated by obtaining a rotational driving force from a rotational driving device 51 such as a motor via a chain or the like. Furthermore, in this embodiment, the stirring blade 48 is attached to the steam ejection pipe 28, and the steam ejection pipe 28 also serves as the rotating shaft 49 of the stirring means. That is, in the present embodiment, the steam jetting unit 14 is a rotary shaft that is configured by forming the rotating shaft 49 of the stirring unit 30 as a hollow tube and forming a plurality of steam jetting holes 44 on the peripheral surface of the hollow tube. It also includes a steam jet pipe 28.
In addition, the vapor | steam ejection means 14 is not restricted to the structure of this embodiment, For example, the structure which ejects a vapor | steam from the front-end | tip of the pipe | tube inserted in the airtight container 12, the structure which has arrange | positioned several vapor | steam ejection pipes, etc. The structure of may be sufficient.
The stirring unit 30 is a unit that stirs the waste to be processed in the sealed container 12 and can process the waste at an early stage without unevenness. In the present embodiment, the stirring means 30 includes a rotating shaft 49 composed of the steam ejection pipe 28 and a stirring blade 48 attached to the rotating shaft 49 and having a portion extending in the circumferential direction of the rotating shaft. In the present embodiment, the stirring blade 48 is formed of a right-handed spiral blade 48a and a left-handed spiral blade 48b that are provided in a reversely wound manner at approximately the center position in the axial direction of the rotating shaft 49.
The stirring blade 48 is provided such that the length from the rotation shaft 49 to the blade tip is gradually reduced from the left and right central portions toward both ends. As a result, the waste can be reliably agitated corresponding to the barrel shape of the closed container 12. Furthermore, a certain gap H is provided between the blade tip and the inner wall of the sealed container 12.
In the present embodiment, the

spiral blades

48a and 48b agitate the waste while crushing the solid waste while conveying the waste from the center toward the both end walls. In the present embodiment, the waste is finally provided by the stirring means 30 so as to be crushed to about 0.3 to 0.8 mm, for example.
The waste conveyed to the both end walls 12a side by the stirring blades 48 is pushed by the waste conveyed later on the end wall 12a side, passes through the gap H along the inner wall of the sealed container 12, and then enters the center. It is transported back.
The agitation means 30 is not limited to the one in the present embodiment. For example, the agitation means 30 is agitated with a plurality of plate-like or wing-like agitation blades or rods attached to the rotary shaft 49, or a pressure fluid such as steam. Any other configuration such as a configuration to be used may be used. Moreover, you may set arbitrarily the magnitude | size of the crushed waste.
In the present embodiment, 5CaO · 6SiO is obtained by processing for a required time, for example, about 1 to 8 hours, while stirring in the sealed container 12 under high temperature and high pressure as described above. ₂ ・ 5H ₂ O crystals (tobermorite) can be efficiently produced, and the heavy metals can be contained in the crystal structure.
In the above-described processing, for example, decomposition of PCB contained in waste can be expected. For example, when wastes mixed with transformer oil or the like are processed, it has been confirmed that the PCB concentration of 80 ppm before the processing has decreased to about 0.005 ppm after the processing.
After processing the waste in the sealed container 12 while jetting high-temperature and high-pressure steam, when the sealed container 12 is cooled by the cooling means 70 and the water vapor in the closed space S1 is liquefied, the water solubility of the heavy metals is increased. The treated liquid containing the compound accumulates, and the liquid and the treated waste containing tobermorite containing the heavy metals are mixed.
Next, the separation / recovery means 18 will be described.
One example of the separation and recovery means 18 is shown in FIGS. 1 and 3A as described above. FIG. 3A is an explanatory view for explaining a part of the separation and recovery means shown in FIG.
The mixture of the waste and the liquid processed in the vicinity of the discharge port 16 is once recovered in the recovery container 50-1. The waste forming the bottom of the recovery container 50-1 is not allowed to pass through, but is separated from the liquid by the stainless steel mesh 56 that allows the liquid to pass through, and the other recovery container 50 disposed below the recovery container 50-1. -3.
Since the waste material is separated and remains on the stainless steel mesh 56 of the recovery container 50-1, the waste is driven by a controlled driving device (not shown) around the rotating shaft 52 when taken out. Rotate 56 in the direction of the arrow to release the locking portion 53 and drop it downward by gravity to collect the waste in a collection container (not shown). In addition to a simple configuration, the waste and liquid that have been processed can be separated and recovered satisfactorily with an easy operation and a low cost structure.
FIG. 3B is an explanatory view for explaining another example of the separation and recovery means shown in FIG.
As shown in FIG. 3B, the waste and liquid mixture treated in the vicinity of the discharge port 16 is once recovered in a recovery container 50-2. Then, the liquid is driven by a controlled driving device (not shown) around the rotation shaft 54 installed on the side wall of the recovery container 50-2 to rotate the recovery container 50-2 and tilt the liquid to another recovery container 50-. 4 to collect. The waste from which the liquid has been separated remains in the collection container 50-2.
FIG. 3C is an explanatory diagram illustrating an example of a separation and recovery unit that supplies the mixture to the belt conveyor device and separates waste and liquid during movement.
As shown in FIG. 3C, the waste and liquid mixture treated in the vicinity of the discharge port 16 includes a belt formed of a stainless steel mesh 56 that does not allow the waste to pass but allows the liquid to pass. Supplied to one end of the belt of the belt conveyor device 80-1. Then, the liquid is separated by the stainless steel mesh 56 and collected in another collection container 50-5 disposed at the lower part of the belt conveyor device 80-1.
The waste material is separated by gravity at the end of the belt conveyor device 80-1 in the traveling direction of the belt, falls down, and is collected in a collection container 50-6.
FIG. 3D is an explanatory view for explaining another example of the separation and recovery means shown in FIG.
As shown in FIG. 3 (d), the waste and liquid mixture treated in the vicinity of the discharge port 16 includes a belt made of synthetic rubber or the like disposed at an angle θ with respect to the horizontal direction. Supplied to one end of the belt of the belt conveyor device 80-2.
Then, since the liquid is inclined by the angle θ as described above, the liquid is separated from the mixture by gravity, and flows down faster than the waste as indicated by an arrow toward the end in the traveling direction on the belt. It collect | recovers in the collection | recovery container 50-7.
Since the angle θ depends on the physical properties of the mixture, the waste, the liquid, the material of the belt, the moving speed of the belt, and the like, the liquid is separated from the mixture by gravity, and the end of the traveling direction on the belt It is preferable to test and determine in advance an angle θ that flows faster than the waste as indicated by an arrow.
55 is scraping means, and the belt is disposed above the belt with a gap (not shown) through which the liquid passes. Then, the waste from which the liquid on the belt has been separated is scraped off by the scraping means 55 as indicated by an arrow, and recovered in the recovery container 50-8.
Thereby, the liquid in a state containing bacteria, malodorous components and the like contained in the waste at the same time as the waste can be treated with high-temperature and high-pressure steam. The liquid separated and recovered after the treatment contains water-soluble compounds of heavy metals, but malodors and harmful components can be recovered in a decomposed state, so that the separated and recovered liquid needs to be subjected to secondary treatment. This eliminates the need for labor and saves time.
However, when it is necessary to separate the water-soluble compound of heavy metals from the liquid, it is necessary to perform a secondary treatment.
Next, the operation of the waste treatment apparatus including heavy metals according to the present embodiment will be described together with the liquid recovery method according to the embodiment. In this embodiment, the waste containing heavy metals to be treated includes, for example, blood discharged from hospitals, universities, other medical institutions such as laboratories, internal organs after surgery, cotton wool, disposable diapers, and blood supply. Medical waste such as tubes, infusion containers, and plastic syringes.
In addition, metals such as injection needles and those made of glass are separated and removed in advance. With the opening / closing mechanism 26 of the discharge port 16 closed, the opening / closing mechanism 24 of the inlet 42 of the sealed container 12 is opened, for example, 2 m ³ Waste containing heavy metals and the Ca component raw material and SiO ₂ Ingredient raw materials are charged. With the open / close mechanism 24 of the inlet 42 closed and the sealed container 12 closed, a high-temperature and high-pressure steam set to, for example, about 250 ° C. and about 25 atm from the steam ejection pipe 28 of the steam ejection means 14 in the sealed container. Erupt.
Due to the jetted steam, the inside of the sealed container 12 is in a high temperature and high pressure state of, for example, about 250 ° C. and about 2.1 MPa.
In the sealed container 12, the waste is treated while being stirred and crushed by the rotating stirring blade 48 under high-temperature and high-pressure conditions.
When treated, the Ca component previously contained in the waste or the newly added Ca component and the SiO contained in the waste in advance. ₂ Components and newly added SiO ₂ The component reacts hydrothermally to produce stable calcium silicate (5CaO · 6SO ₂ ・ 5H ₂ A crystal having a layered structure of mineral called O tobermorite is formed, and in the process of forming the layered crystal structure, heavy metals are taken into the layered crystal structure and contained.
Most heavy metals are taken in and contained in the layered crystal structure of tobermorite as described above, but when anions are present in the waste, they are dissolved in water vapor or dissolved in water.
Further, pathogens contained in (or adhering to) the waste are sufficiently sterilized and treated while decomposing malodorous components.
Further, during the treatment, the moisture contained in the waste is also treated with high-temperature and high-pressure steam at the same time as the waste. When such treatment is performed for a required time, for example, about 40 minutes, the organic matter in the waste is processed into a charcoal state crushed into particles of, for example, about 0.3 to 0.8 mm.
After the waste is treated as described above, when the airtight container 12 is cooled by the cooling means 70 and the water vapor in the closed space S1 is liquefied, the treated liquid containing the water-soluble compound of the heavy metals is collected, Since this liquid and the treated waste containing tobermorite containing the heavy metals are mixed, the separation and recovery means 18 can, for example, as shown in FIG. 1 and FIG. Once the mixture is recovered in the recovery container 50-1, the liquid is separated by the stainless steel mesh 56 that does not allow the waste forming the bottom of the recovery container 50-1 to pass but allows the liquid to pass. -1 is recovered in another recovery container 50-3 arranged at the lower part of -1. Since the waste material is separated and remains on the stainless steel mesh 56 of the recovery container 50-1, the waste is driven by a controlled driving device (not shown) around the rotating shaft 52 when taken out. Rotate 56 in the direction of the arrow to release the locking portion 53 and drop it downward by gravity to collect the waste in a collection container (not shown).
The treated waste is, for example, liquid separated, organic matter is charcoal, tobermorite containing heavy metals and treated soil particles, etc. Can be recovered in a state that is easy to handle.
Thereby, it is possible to separate and collect the waste and the liquid together with the disposal of the waste with only one device. In addition, it is not necessary to take out unwieldy waste mixed with liquid, and it can be separated and recovered by simple operation directly from the sealed container continuously after processing. Also, the separation and recovery configuration is simple and can be manufactured at low cost. Each open / close mechanism may be configured to open and close manually, or may be configured to open and close by mechanical operation using electricity or the like.
Since the subcritical water reaction described above uses only high-pressure steam as the driving force of the reaction, it can be said to be the safest treatment technology without using any artificial materials such as chemicals. The subcritical water reaction (temperature of about 100 to 374 ° C., pressure of 0.1 to 22.1 MPa) has various reaction regions as shown in FIG. 6 depending on the temperature and pressure conditions of water vapor.
For example, the subcritical water treatment conditions used for recycling sewage sludge are regions where the main reaction is a “hydrolysis reaction” at a temperature of about 200 ° C. and a pressure of 1.2 to 1.6 Mpa. Utilize the same reaction principle as the decomposition reaction performed by fermenting microorganisms. Sewage sludge is reduced in molecular weight by hydrolysis, and the fiber is hydrolyzed to glucose and oligosaccharides, the protein is hydrolyzed to amino acids and peptides, and the lipids are hydrolyzed to organic acids. For this reason, it becomes possible to introduce into a multipurpose resource reproduction system, such as direct material utilization of processing sludge, and efficiency improvement of methane fermentation.
In addition, it can sterilize and destroy pathogenic microorganisms, viruses, etc., and can ensure various environmental safety such as decomposition of harmful chemical substances such as agricultural chemicals and suppression of elution by solidification of heavy metals.
Regarding sewage sludge, it can be used as various recyclable resources as follows.
(1) Agricultural land soil improvement material: Subcritical water treatment of sewage sludge can be stably hydrolyzed and can be generated in a granulated state, so that it can be a highly convenient green agricultural land soil improvement material.
(2) Sludge organic fertilizer: Sewage sludge can be used as a kind of “ordinary fertilizer” if it can be dried and fermented to confirm the safety of fertilizer components and agricultural standards for heavy metals.
(3) Pretreatment function of methane fermentation
Since the macromolecular organic matter is hydrolyzed, the rate of microbial decomposition, that is, primary fermentation is increased, and at the same time, the gas yield is increased. For example, in the case of methane fermentation, the yield of methane gas is enhanced by about 1.5 to 2.8 times, and the material and energy recovery rate can be enhanced.
It can also be mixed with household waste, food waste, etc., and when it is jointly treated at a sewage treatment plant, it can also be used as a power and heat source self-sustained system by methane fermentation power generation.
As described above, there are various utilities, but in any case, ensuring the safety of heavy metals is an important issue.
The heavy metal solidification characteristics of sewage dewatered sludge containing heavy metals by subcritical water treatment were tested.
(1) Test apparatus: The subcritical water treatment apparatus shown in FIG. 1 is of a practical type and has a reaction volume of 2 m. ³ This is a batch processing type. A boiler with a boiler capacity of 500 kg / h was used.
(2) Test conditions: The subcritical water region in which hydrolysis of organic substances is the main reaction has a temperature of around 200 ° C., and the pressure is a saturated vapor pressure at the temperature of 1.2 to 1.6 MPa. If the temperature and pressure conditions are higher than this, it will be over-decomposed, resulting in a loss of nutrients. Therefore, the temperature is in the range of 180 to 200 ° C.
(3) Test procedure: Ca component and SiO ₂ Sewage dewatered sludge (water content of about 78% by mass), which is known to have a small amount of components, is contained in the tobermorite crystal structure at least in 300 kg of sewage dewatered sludge during treatment in the subcritical water treatment device. A sufficient amount of Ca component raw material [CaO)] 10 Kg and SiO to form tobermorite for ₂ Component raw materials [silica (SiO ₂ )] 13 kg added, Ca component raw material and SiO ₂ The component raw material was mixed well with sewage dewatered sludge, and after adding and mixing the raw material, steam was injected until the subcritical water reaction conditions were reached, and subcritical water treatment was performed for the required time while maintaining the predetermined conditions. This reaction time ranges from 30 min to 1 hour. After completion of the reaction, the mixture is cooled to room temperature, degassed and returned to normal pressure, and then 10 kg of liquid containing the liquefied component is separated. Then, about 300 kg of sludge containing tobermorite containing the heavy metals (saturated steam hydration) The reaction occurred and the weight increased slightly).
About 30 samples of raw sewage dewatered sludge, liquid containing liquefied components, and sludge containing tobermorite containing the heavy metals, general organic components including fertilizer components, heavy metals and trace chemical substances by the following analysis method The physicochemical analysis was conducted.
For the treated sludge, the results are summarized and the solidification rate by subcritical water treatment (the ratio of the decrease in the treated sludge concentration to the heavy metal concentration in the raw sewage dewatered sludge) is calculated, and the average value and standard deviation range are calculated. This is shown in FIG.
MPa analysis method:
It conformed to the heavy metal dissolution test method based on Prime Minister's Ordinance No. 5 in 1973.
Tables 1 and 2 show two examples of analysis results of sludge containing tobermorite in which the heavy metals are contained.

On the other hand, Table 3 shows the results of a survey conducted by the Public Works Research Institute of the Ministry of Land, Infrastructure, Transport and Tourism (“Environmental Standards Concerning Soil Contamination” Environmental Agency Notification No. 46, August 1991). Indicates heavy metal concentration.
From the results of the national survey on sewage sludge, if the maximum value of the soil environmental standards listed in Table 3 can be cleared by subcritical water treatment, the safety of sewage sludge heavy metals can be secured nationwide.

From Table 3, the maximum value of Cr is about 650 mg · kg. ^-1 And applying the average solidification ratio of 45% shown in FIG. 7 to about 360 mg · kg after the subcritical water treatment. ^-1 Therefore, the fertilizer standards shown in Tables 1 to 3 are satisfied.
From Table 3, the maximum value of Pb is about 180 mg · kg. ^-1 When the average solidification rate of Pb shown in FIG. 7 is 45%, it is about 99 mg · kg after the subcritical water treatment. ^-1 And 100mg / kg ^-1 However, it is below the fertilizer reference value shown in Tables 1 to 3.
From Table 3, the maximum value of Cd is 7.4 mg · kg. ^-1 When the average solidification rate of Cd of about 58% shown in FIG. 7 is applied, about 3.1 mg · kg after the subcritical water treatment ^-1 It is below the fertilizer standard value shown in Tables 1 to 3.
From Table 3, the maximum value of As is 101 mg · kg. ^-1 Assuming that the average solidification rate of As shown in FIG. 7 is about 57%, it is about 44 mg · kg after the subcritical water treatment. ^-1 Therefore, the fertilizer standards shown in Tables 1 to 3 are satisfied.
Similarly, from Table 3, the maximum value of Hg is 7.3 mg · kg. ^-1 Assuming that the average solidification rate of Hg shown in FIG. 7 is about 78%, it is about 1.6 mg · kg after the subcritical water treatment. ^-1 Therefore, the fertilizer standards shown in Tables 1 to 3 are satisfied.
From Table 3, the maximum value of Zn is 3020mg · kg ^-1 When the average solidification rate of Zn shown in FIG. 7 is about 75%, it is about 755 mg · kg after the subcritical water treatment. ^-1 However, zinc and copper are based on soil concentration, not fertilizer, and when mixed with soil after application of sewage sludge as fertilizer, 120 mg · kg ^-1 It is required to become. With careful application, the soil environmental standards shown in Tables 1 to 3 can be observed.
From Table 3, the maximum value of Ni is 417 mg · kg. ^-1 Assuming that the average solidification rate of Ni shown in FIG. 7 is about 60%, it is about 167 mg · kg after the subcritical water treatment. ^-1 Therefore, the fertilizer standards shown in Tables 1 to 3 are satisfied.
From the above, it is considered possible to produce sludge resource recycling products that can satisfy the agricultural land standard value (fertilizer standard) by solidification of heavy metals in sewage sludge nationwide by subcritical water treatment.
In addition, since zinc is an effective monitoring substance for the purpose of preventing soil contamination, a management standard for zinc concentration of 120 ppm has been established based on the naturally existing amount of agricultural land soil (such as “heavy metals in soil on agricultural land”). "Regarding the management standards related to the prevention of accumulation of water," the Environmental Agency Water Quality Conservation Bureau Director General in November 1984). This is set for the purpose of minimizing the accumulation of harmful substances such as cadmium and arsenic by using zinc as an index. It should be noted that the value of 120 ppm is a management concentration related to the soil after being sprayed on the farmland.
The elution standards (soil environmental standards) listed in Table 3 are set for the purpose of preventing heavy metal groundwater contamination. This is set as a standard that is safe to drink groundwater containing heavy metals for a lifetime, and is determined by performing a certain elution operation and measuring the concentration of the eluate.
As described above, it was confirmed that all heavy metals were below the elution standard value after the subcritical water treatment.
It was found that by treating sub-critical water for all samples, organic fertilizers (including compost) that are safer than heavy metals and less than agricultural standards can be used.
It was shown that by applying "subcritical water treatment technology" to sewage sludge, heavy metals can be solidified to a detoxification level and elution suppression can be achieved. In other words, it was demonstrated empirically that the heavy metal content standard for agriculture can be satisfied even with sewage sludge of the past maximum concentration, and that safe sludge fertilizer can be directly produced in a short time.
Regarding the separated liquid, an example in which physicochemical analysis of general organic components including fertilizer components, heavy metals, and trace chemical substances was performed by the above-described analysis method is shown below.
92.7 mass% in the liquid was water having a pH of 4.8. The organic carbon in the solid content in the liquid was 3.6% by mass.
The fertilizer content and heavy metal content in the liquid are shown below.
Total nitrogen 6.700mg / L
Total phosphoric acid (P ₂ O ₅ ) 2.100mg / L
heavy metal:
Cr 0.3mg / L
Pb 0.01mg / L
Cd less than 0.01 mg / L
As 0.27mg / L
Hg less than 0.0005 mg / L
Zn less than 43.05 mg / L
Cu 2.1mg / L
Ni 0.6mg / L
The separated liquid is subjected to appropriate water treatment and drainage according to the drainage standards because it contains environmental contaminants and drainage standards for water related to heavy metals and also contains water pollutants other than heavy metals. In the sewage treatment plant, it is returned to the water treatment system for treatment before being discharged into the public water area.
Next, the economics of the subcritical water treatment facility will be described.
As shown in FIG. 1, the subcritical water treatment equipment is composed of (1) a high-pressure steam boiler, (2) a pressure tank (with a stirrer), (3) a temperature and pressure control panel, and (4) raw materials and treatment. There are four types of equipment for introducing, transferring and storing products.
The main input resources are boiler fuel (A heavy oil, etc.), drive motor and water. These energy consumptions are about 20 L / t of water and power consumption of about 25 kwh / t per processing amount.
Compared with the case of conventional carbonization equipment, the energy input is about 1/3 and the construction cost is about 1/3 to 1/4.
As described above, it was shown that sewage sludge can be made a safe organic resource by subcritical water treatment. In Japan, due to the decline in the agricultural economy, idle farmland is expanding along with a decrease in the number of farmers. Agricultural production is important as a basic industry that supports daily life, and measures to improve regional production are important. For this purpose, it is important to revitalize agricultural soil and create soil with regenerative production capacity.
In addition, since it is possible to produce compost with high functionality, it is possible to achieve an efficient agricultural economy in combination with improved quality of agricultural products. In addition, improvement of organic soil is important for the restoration of farmland soil such as abandoned farmland in Japan. Promoting active and effective use of sewage sludge that has been made safe by subcritical water treatment is a cost-effective aspect. Is strongly desired.
The above-described waste metal-containing waste processing apparatus and heavy metal-containing waste processing method of the present invention is not limited to the configuration of the above-described embodiment alone, and the present invention described in the claims. Any modification may be made without departing from the essence of.

The waste treatment apparatus containing heavy metals of the present invention is a single device that safely treats waste containing heavy metals using high-temperature and high-pressure steam to immobilize and elute the heavy metals. Suppressed and treated, the waste material and the liquid fixed with the heavy metals processed continuously can be separated and recovered by a simple operation, the structure is simple, and the cost is low. There is no need to take out mixed waste that is difficult to handle, and it can be separated and recovered directly from the first sealed container that has been processed, and the operation can be performed easily and smoothly. Low-cost, waste collected separately from liquid is in a state of low moisture, convenient for handling, transport, management, etc. For example, carbonized waste can be improved in fuel and soil in a short period of time. It has a remarkable effect that it can be processed into materials, etc. In, high utility value on the industry.

DESCRIPTION OF SYMBOLS 10 Waste processing apparatus containing heavy metals 12 Sealed container 14 Steam ejection means 16 Discharge port 18 Separation and recovery means 18-1, 18-2 Belt conveyor device 26 Opening / closing mechanism 30 Stirring means 50-1 to 50-8 Recovery container 70 Cooling means

Claims

Inside, wastes containing heavy metals, and at least the heavy metals to 5CaO · 6SiO 2 · 5H 2 O crystals (tobermorite) structure 5CaO · 6SiO 2 · 5H 2 O crystals for containing during during processing (tobermorite) is A sealed container having a closed space containing a sufficient amount of Ca component raw material and SiO 2 component raw material to be formed;
Steam ejection means for ejecting high-temperature and high-pressure steam for treating the waste, the Ca component raw material, and the SiO 2 component raw material contained in a sealed container;
A cooling means for cooling and liquefying the vapor in the sealed container after the treatment;
A discharge port provided on the bottom side in the sealed container and having an opening and closing mechanism;
Separation and recovery means for discharging a mixture of a waste containing tobermorite containing the heavy metals treated from a discharge port and a liquid containing a liquefied component, and separating the waste and the liquid from the discharged mixture An apparatus for treating waste containing heavy metals, comprising:
The separation and recovery means collects the mixture once in a recovery container and then separates and collects the waste and the liquid, and / or supplies the mixture to a belt conveyor device and moves the waste and the An apparatus for treating waste containing heavy metals, which is a separation and recovery means for separating a liquid.
When processing waste containing heavy metals in a sealed container having an openable and closable discharge port and a closed space while jetting high temperature and high pressure steam,
5CaO · 6SiO 2 · 5H 2 O crystals (tobermorite) are formed to contain at least the heavy metals in the 5CaO · 6SiO 2 · 5H 2 O crystal (tobermorite) structure during the treatment in the sealed container. After performing the treatment in the presence of a sufficient amount of Ca component raw material and SiO 2 component raw material,
A waste containing heavy metal, characterized by separating and recovering the treated liquid containing the water-soluble compound of the heavy metal liquefied and the treated waste containing tobermorite in which the heavy metal is contained How to handle things.
The content (A-1) of the Ca component and the content (A-2) of the SiO 2 component contained in the waste containing the heavy metals in advance are determined by analysis, and at least the heavy metals are treated with 5CaO · A sufficient amount of Ca component (B-1) and SiO 2 component to form a 5CaO · 6SiO 2 · 5H 2 O crystal (tobermorite) for containment in a 6SiO 2 · 5H 2 O crystal (tobermorite) structure The amount (B-2) is calculated, and the addition amount (C-1) of the Ca component raw material added to the waste containing heavy metals and the addition of the SiO 2 component raw material according to the following formulas (1) and (2) The amount (C-2) is obtained, and the treatment is performed by adding the Ca component raw material (C-1) and the SiO 2 component raw material (C-2) to the waste containing heavy metals. The processing method described.
[(B-1)-(A-1)] = (C-1) Formula (1)
[(B-2)-(A-2)] = (C-2) Formula (2)
The heavy metal is at least one selected from chromium, lead, cadmium, arsenic, mercury, zinc, copper and nickel, and the heavy metal is a 5CaO · 6SiO 2 · 5H 2 O crystal in waste after treatment. (Tobermorite) Since it is contained in the structure, the waste after treatment satisfies at least one selected from water environmental standards, soil environmental standards, special fertilizer standards, and food safety standards. The processing method according to claim 2 or 3.
The treatment method according to any one of claims 2 to 4, wherein the treatment is performed at 120 to 250 ° C and 1.1 to 2.1 MPa for 1 to 8 hours.