JP2002001395A - Process and facility for treating organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic sludge treatment process in which a material containing phosphorus and nitrogen components necessary for the growth of agricultural products, are effectively recovered from the organic sludge consisting of food industrial waste or the like and utilized as a fertilizer or a soil conditioner. SOLUTION: This organic sludge treatment process involves indirectly heating organic sludge which is derived from an activated sludge process and particularly contains a large amount of phosphorus components, with a heating cylinder 22 placed on the outer periphery of a rotary circular-cylindrical body 21, to subject the organic sludge to carbonization and/or ashing treatment and to obtain the objective treated material having a high phosphorus or phosphorus compound content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for treating organic sludge, and more particularly to a technique for treating an organic sludge containing a large amount of phosphorus and nitrogen components by activated sludge treatment so that it can be reused as a soil conditioner or a fertilizer. And a processing facility.

[0002]

2. Description of the Related Art It is well known that organic sludge, for example, organic sludge composed of food industry waste, contains a large amount of nitrogen group elements such as phosphorus (phosphorus compound) and nitrogen. Moreover, it is also known that when treated by the activated sludge method, these components in the sludge are further increased.

[0003] Attempts have been made to process the organic sludge containing the nitrogen group element to reuse it as a resource.

[0004] As a method of recycling, there are known a method of removing and using a nitrogen group element contained therein, and a method of reusing by utilizing the qualities of the contained element.

In the former, for example, when used as a raw material for cement, it is necessary to remove phosphorus. Organic sludge is carbonized in a closed heating furnace, and the carbonized product is heated in another closed heating furnace. (1000 ° C. to 1250 ° C.) to volatilize phosphorus and remove it from the treated ash, and use this as a raw material for cement (JP-A-11-3140).
98).

On the other hand, effective use of nitrogen group elements contained in organic sludge is to remove food residue from food factories and organic residue such as paper slush from paper mills in an almost closed incinerator. A method of carbonizing with a complete combustion gas filled in the furnace and using the carbide as a soil improving material (Japanese Patent Laid-Open No. 10-330745).

Or an organic sludge containing a nitrogen component;
A method is known in which a phosphorus compound having a hygroscopic property is mixed, dried, and used as a fertilizer (Japanese Patent Application Laid-Open No. 10-2482).

[0008]

As described above, organic sludge is used as a soil improving material or a raw material for fertilizers by utilizing components necessary for growing agricultural products, such as phosphorus, phosphorus compounds, and nitrogen contained in the organic sludge. It is proposed to use it, but in practice, the starting sludge has various qualities and contains a large amount of useful substances, but may contain harmful substances (such as heavy metals). Therefore, to use JIS K
If it is necessary to confirm that the amount of harmful substances specified by the dissolution test specified in No. 0102 is not more than a certain amount, or if the starting material is sewage sludge, the resources obtained by regenerating this are fertilizer The fact is that there is considerable resistance to reusing it as it is and it has not been actively accepted.

[0009] In this regard, it is becoming common practice to recycle food residues into compost at each home and reuse them as fertilizer.

[0010] That is, it is necessary to recognize the current situation in which the recycling tends to be easily performed if the qualities of the starting materials are acceptable.

The present invention has been made on the basis of the understanding of the current situation. In particular, organic sludge free of heavy metals, which has been treated by the activated sludge method containing a large amount of phosphorus and phosphorus compounds, is dried, carbonized or dried. By the incineration treatment, phosphorus, a treated product containing a large amount of a phosphorus compound is obtained, and this is used as a soil improving material,
It is an object of the present invention to provide a processing method and a processing facility that can be reused as fertilizer.

[0012]

When various types of sludge such as sewage sludge are subjected to biological treatment using microorganisms (activated sludge method), phosphorus and phosphorus compounds increase from the initial amount due to the activity of microorganisms. Is known.

There are two types of sludge, one containing heavy metals such as sewage sludge, and the other sludge containing no heavy metals, such as food industry waste. When these sludges are treated by the activated sludge method, phosphorus, The present invention has been made by paying attention to the fact that the phosphorus compound is contained in a larger amount than the initial amount.

The present inventors have found that, as a result of the experiment, those containing heavy metals remove heavy metals in the sludge below the safety standard value, and sludge that does not contain heavy metals does not contain these heavy metals because it is safe in itself. Heat treatment of sludge obtained by treating sludge by the activated sludge method yielded a treated product containing a large amount of phosphorus and a phosphorus compound, and found that a fertilizer and a soil improving material that can be used safely were obtained.

In the experiment, sludge obtained by treating the food industry waste containing no heavy metal from the beginning (specifically, waste sludge after extraction of oil and fat products) by the activated sludge method was used as a sample. (Water content: 73.64%) was prepared and subjected to a drying treatment and a carbonization treatment under the following temperature conditions, and to a case where the carbide after the carbonization treatment was ashed.

Temperature condition (1) Drying process Starting weight 50.63 g Water content 73.64% Drying condition Room temperature to 110 ° C for 10 minutes Keep at 110 ° C for 180 minutes Weight after drying 13.20 g (2) Carbonizing process Starting weight 60.63 g Moisture content 73.64% Carbonization conditions Room temperature to 600 ° C. Gradually increase the temperature, keep 60 minutes at 600 ° C. for 45 minutes Weight after carbonization 3.08 g (3) Ashing treatment Starting weight 3.08 g * Carbonization Ashing conditions Room temperature to 850 ° C for 60 minutes Keep at 850 ° C for 60 minutes Weight after ashing 0.97g Put the above sample in a crucible, put it in a closed electric furnace equipped with vent holes After heating under the temperature conditions of
Analysis was performed by a semi-quantitative analysis method using a PMA (electron beam microanalyzer). The results of the analysis were as shown in Table 1. The measurement points are obtained by measuring two arbitrary points on the sample.

[0017]

[Table 1]

From the results of Table 1 and micrographs (not shown), it was observed that the distributions of P, Ca, C, and O, which are the main components, overlapped. I found out.

That is, in the case of a compound, it is presumed that the compound constitutes any one of primary, secondary and tribasic calcium phosphates. The forms of the primary to tricalcium phosphates each have the following properties. (1) Soluble in calcium monophosphate Ca (H ₂ PO ₄ ) ₂ water Possible as fertilizer (2) Dibasic calcium phosphate CaHPO ₄ Almost insoluble in water Main component of dry sludge (3) Tricalcium phosphate Ca ₂ (PO _{4 2} ) Insoluble in water Main component of carbonized sludge and incinerated sludge Therefore, it was found that using commonly used phosphate ore instead of monobasic calcium phosphate is more efficient.

The main component of the phosphate ore is calcium hydroxide phosphate (3Ca ₃ (PO ₄ ) ₂ .Ca (OH) ₂ ), which is insoluble in water. ), The dibasic calcium phosphate and the tricalcium phosphate can be changed to water-soluble monobasic calcium phosphate.

A mixture of the obtained calcium phosphate monobasic, gypsum, and other components (for example, CaSO ₄ .2H ₂ O) can be used as a fertilizer. 15-20 when converted as ₂ O ₅
%include).

Another method using sulfuric acid is a method in which a phosphate ore and a rock rich in soda ash and alkali silicate are heated to 1100 ° C. to 1200 ° C., semi-melted, and pulverized. There is burnt phosphorus fertilizer.

Further, as means for converting insoluble phosphorus to soluble phosphorus, in addition to the above, generally known various methods can be suitably applied, and the means can be selected in consideration of economics such as production equipment and cost. it can.

[0024] As a method for removing heavy metals in sludge, for example, Japanese Patent Application Laid-Open Nos.
-33594, JP-A-11-696, JP-A-10-25
8300, JP-A-10-225698, JP-A-10-1
65994 and the like.

The present invention has been made based on the above experimental results. Means for solving the above-mentioned problem is to heat-treat sludge containing no heavy metal treated by the activated sludge method,
A dried, carbonized or ashed treatment containing phosphorus or a phosphorus compound is obtained.

Further, the treated product obtained by the above-mentioned method is used to obtain a soluble phosphorus compound by chemical reaction means.

The above-mentioned sludge which does not contain heavy metals includes food industry waste and sludge subjected to heavy metal removal treatment below the safety standard value.

A part or all of the soluble phosphorus compound obtained by the above-mentioned chemical reaction means can be used as a fertilizer or a soil improving material. This chemical reaction means is preferably a sulfuric acid treatment.

The organic sludge treatment facility includes a conveying means for conveying the organic sludge to a heat treatment means in a later stage, and a heating or carbonization or incineration and carbonization of the conveyed organic sludge by indirect heating. Heat treatment means for obtaining a treated material containing phosphorus or a phosphorus compound by performing incineration treatment; a heating source for heating the heat treatment means; a combustion means for burning and treating a decomposition gas generated from the treatment object; and combustion. Means for purifying and discharging the subsequent exhaust gas.

[0030]

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

According to the present invention, an organic sludge to be treated is indirectly heated in a low-oxygen atmosphere by carbonization and / or incineration to carry out a treatment containing a nitrogen group element, particularly phosphorus, a phosphorus compound. It is to get things.

FIG. 1 is a conceptual diagram of an organic sludge treatment facility according to the present invention. The treatment facility uses two heat treatment furnaces having the same configuration, and transports and carries out a drying and processing function to a first heat treatment furnace 10. This is the case where the second heat treatment furnace 20 is provided with a carbonization and / or ashing treatment function.

The first heat treatment furnace 10 includes a rotatable cylindrical body 11 having a blade 11a (see FIG. 2) for moving an object to be processed while being stirred, and a gas duct on the outer periphery of the cylindrical body 11. A heating cylinder 12 that is formed and heats the cylindrical body 11 by introducing a hot gas; a supply port 13 provided at one end of the cylindrical body 11 to supply an object to be processed into the cylindrical body 11;
A discharge port 14 is provided at the other end of the cylindrical body 11, and the cylindrical body 11 is rotationally driven by a rotation driving unit 15. The rotation driving means 15 is a driving motor 15
a, a driving gear 15b, and a driven gear 15c provided on the cylindrical body 11.

16 is a supply duct surrounding the supply port 13 side, 17 is a discharge duct surrounding the discharge port 14 side, 18
Is a dynamic seal (mechanical seal) for sealing ducts 16 and 17 (not shown) in contact with the outer periphery of the cylindrical body 10 and a contact portion with the heating cylinder 12.

Reference numeral 19 denotes a support roller for rotatably supporting the cylindrical body 11 at both ends.

The second heat treatment furnace 20 has the same basic configuration as the first heat treatment furnace 10 described above. Therefore, in the same or equivalent part, one digit of 20 is set to the same number (for example, 21 is a cylindrical body, 22 is a heating cylinder, 29 is a supporting roller).
Description is omitted.

Reference numeral 30 denotes a hopper, which feeds an object to be processed and supplies it into the cylindrical body 11 through a supply port 13 of the cylindrical body 11. Examples of the material to be treated include organic sludge, sludge that does not contain heavy metals and is processed by the activated sludge method, such as food industry waste containing nitrogen-group elements such as nitrogen and phosphorus (residues after processing foods of agricultural products, foods, etc.). Sludge that has been treated by the activated sludge method with sludge that has been treated to remove heavy metals from sludge or residue sludge.

The cylindrical body 11 of the first heat treatment furnace 10 and the cylindrical body 21 of the second heat treatment furnace 20 are arranged vertically, and the discharge side duct 17 and the supply side duct 26 of the cylinder 11
Is communicated via a rotary valve 32, and
Discharge side duct 27 of cylindrical body 21 of second heat treatment furnace 20
Discharges the carbide or treated ash after the heat treatment through a rotary valve 33.

Reference numeral 35 denotes a gas-fired furnace as a heating source.
A fuel such as G or LPG is burned to generate hot gas.
This hot gas is supplied into a heating cylinder 22 provided on the outer periphery of the cylindrical body 21 and heats the cylindrical body 21, and then is sent into the heating cylinder 12 of the cylindrical body 11 through the communication pipe 37, and Is heated and then discharged from the discharge pipe 38. It is desirable to reuse the discharged hot gas as a heat exchanger, a drying means, or a heat source for hot water supply without directly discharging the hot gas.

A series of heat treatments in the first heat treatment furnace 10 and the second heat treatment furnace 20 are performed in a low oxygen atmosphere. In particular, the carbonization and incineration treatment in the second heat treatment furnace 20 results in steaming and thermal decomposition by indirect heating in a low oxygen region.

Reference numeral 41 denotes a gas combustion furnace, which is a first heat treatment furnace 1
Exhaust gas generated during the heat treatment in the 0th and second heat treatment furnaces 20 is introduced through the exhaust gas pipes e ₁ and e ₂ , and is subjected to the combustion treatment.

After burning and removing combustible components such as harmful substances and tar components contained in the gas in the gas combustion furnace 41,
The bag filter 42 is cooled to a suitable temperature for use in the heat exchanger 40 and sent to the bag filter 42, where it is cleaned and discharged from the chimney 43. It is preferable to use a heat exchanger for cooling while utilizing waste heat.

Reference numeral B denotes an exhaust blower that sucks exhaust gas from the discharge side duct 17 through the gas combustion furnace 41, the heat exchanger 40, and the bag filter 42, and discharges the exhaust gas from the chimney 43.

The gas combustion furnaces 35 and 41 may be shared. In this case, the exhaust gas pipes e ₁ and e ₂ are connected to the gas combustion furnace 3.
5, the gas combustion furnace 41 side may be omitted, and the discharge pipe 38 may be connected to the heat exchanger 40.

Next, a series of processing methods for an object to be processed will be described.

First, the second heat treatment furnace 20 (hereinafter, referred to as a carbonization / ashing treatment furnace) and the first heat treatment furnace 10 (hereinafter, referred to as a carbonization / ashing treatment furnace) in a state where the object to be treated is not introduced (the state may be introduced).
The heating operation of the transfer / drying furnace is started.

That is, the gas combustion furnace 35 and the exhaust gas combustion furnace 41
Burns fuel such as LNG, and heats each furnace.

The hot gas generated in the gas combustion furnace 35 is supplied to the heating cylinder 22 of the carbonization / ashing furnace 20 and heats the cylindrical body 21.
2 and heats the cylindrical body 11.

At this time, the heating temperature of the carbonization / ashing furnace 20 is set to a temperature at which the object to be treated is carbonized (200 ° C. to 600 ° C.) or a temperature at which the object is incinerated (700 ° C. to 900 ° C.).

When each furnace reaches this temperature, the object to be processed is supplied from the hopper 30 into the transfer / drying furnace 10. The supplied processing object is dried by evaporating water while being conveyed to the discharge port 14 side. The dried object is sent to the carbonization / ashing furnace 20 through the discharge duct 17, the rotary valve 32 and the supply duct 26, where it is carbonized or incinerated. It is discharged to the outside via the valve 33.

The temperature of the carbonizing / ashing furnace 20 is controlled by controlling the amount of fuel supplied by the gas combustion furnace 35, and the temperature of the transfer / drying furnace 10 is controlled by controlling the amount of temperature-regulated air 36 supplied to the connecting pipe 37. That can be done.

On the other hand, the steam and exhaust gas generated in the transfer / drying furnace 10 and the carbonization / ashing furnace 20 are introduced into the gas combustion furnace 41 from the gas discharge pipes e ₁ and e ₂ and burned. Since the combustion in the gas combustion furnace 41 is performed at 850 ° C. so as not to generate dioxins, 800 ° C. to 900 ° C. close to this temperature is desirable.

After the combustible components such as tar components and the remaining harmful substances are removed by burning in the gas combustion furnace 41, the exhaust gas is cooled to a temperature suitable for use of the bag filter 42 in the exhaust gas cooling section 40, and is passed through the bag filter 42. And is discharged from the chimney 43.

In the above embodiment, the heating gas is used as the heating means for the indirect heating. However, the heating means is not limited to the heating gas, but may be electric heating (resistance heating, induction heating, microwave heating, etc.). In this case, the gas combustion furnace 35 and the heating cylinders 12 and 22 as heating sources are not required.

[0055]

The present invention has the following effects. (1) Since the treatment is performed by indirect heating, it is possible to effectively obtain a treated product containing 30% or more of a nitrogen group component (phosphorus in an experimental example), and it can be used as it is in a soil improvement material, a fertilizer, or other components. It is suitable as an additive to a fertilizer that requires, or a base material to be added. (2) It is particularly effective for recycling food industry waste. (3) If the starting sludge is a raw material provided for food, there is no resistance of re-users (agricultural producers, gardeners, etc.) to use the processed material, and the re-use rate Can be expected to improve.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an object heat treatment facility for explaining a heat treatment method of the present invention.

FIG. 2 is a sectional view of a rotating cylinder.

[Explanation of symbols]

 10, 20 ... heat treatment furnace 11, 21 ... cylindrical body 12, 22 ... heating cylinder 13, 23 ... supply port 14, 24 ... discharge port 15, 25 ... rotation drive means 16, 26 ... supply side duct 17, 27 ... discharge Side duct 18 Dynamic seal 19 29 Support roller 30 Hopper 31 32 33 Rotary valve 35 Gas combustion furnace 36 Temperature controlled air 37 Communication pipe 38 Discharge pipe 40 Heat exchanger 41 Gas Combustion furnace 42 ... Bag filter 43 ... Chimney

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[Procedure amendment]

[Submission date] August 28, 2000 (2008.2.
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

Temperature condition (1) Drying process Starting weight 50.63 g Water content 73.64% Drying condition Room temperature to 110 ° C for 10 minutes Keep at 110 ° C for 180 minutes Weight after drying 13.20 g (2) Carbonizing process Starting weight 5 0.63 g Moisture content 73.64% Carbonization conditions Room temperature to 600 ° C. Gradually increase the temperature and keep at 600 ° C. for 60 minutes for 45 minutes Weight after carbonization 3.08 g (3) Ashing treatment Starting weight 3.08 g * Use carbonized material Ashing conditions Room temperature-850 ° C for 60 minutes Keep at 850 ° C for 60 minutes Weight after ashing 0.97g Put the above sample in a crucible and put it in a closed electric furnace equipped with vent holes After heating under the above temperature conditions, E
Analysis was performed by a semi-quantitative analysis method using a PMA (electron beam microanalyzer). The results of the analysis were as shown in Table 1. The measurement points are obtained by measuring two arbitrary points on the sample.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F23G 7/04 ZAB F23G 7/04 ZAB 601 601J 603 603Z // C09K 101: 00 C09K 101: 00 F term (reference) 4D059 AA05 BB05 BB14 BD11 BD22 BK30 CA14 CC01 CC10 DA33 4H012 HA03 4H026 AA03 AA18 AB04 4H061 AA02 AA03 BB30 BB44 CC51 GG18 GG19 GG24 GG28 GG30

Claims (6)

[Claims] 1. An organic material characterized in that sludge free of heavy metals treated by the activated sludge method is heat-treated to obtain a dried, carbonized or ashed treated material containing phosphorus or a phosphorus compound. Sludge treatment method. 2. A sludge containing no heavy metal, which has been treated by the activated sludge method, is subjected to a heat treatment to obtain a dried, carbonized or incinerated treated product containing phosphorus or a phosphorus compound, and the treated product is subjected to chemical reaction means. A method for treating organic sludge, wherein a soluble phosphorus compound is obtained. 3. The method for treating organic sludge according to claim 1, wherein the sludge that does not contain heavy metals is food industry waste, sludge that has been subjected to heavy metal removal treatment below a safety standard value. 4. The method for treating organic sludge according to claim 1, wherein part or all of the soluble phosphorus compound is used as a fertilizer or a soil conditioner. 5. The method for treating organic sludge according to claim 2, wherein the chemical reaction means is a sulfuric acid treatment. 6. A transport means for transporting the organic sludge to a heat treatment means in a subsequent process, and heating the transported organic sludge by indirect heating to carbonize and / or incinerate the phosphorus or phosphorus compound. Heat treatment means for obtaining a treated material, a heating source for heating the heat treatment means, a combustion means for burning and treating a decomposed gas generated from an object to be treated, and a means for purifying and discharging exhaust gas after combustion. An organic sludge treatment facility characterized by comprising: