JPH1034135A - Wastewater treating auxiliary and wastewater treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently utilize organic sludge generated by wastewater treatment, to attempt the reduction of a coagulant injection ratio and the property improvement of the coagulated sludge, and to provide a wastewater treatment auxiliary which can reduce waste and a treatment method. SOLUTION: In a wastewater treatment auxiliary made from active carbon powder which is obtained by the carbonization treatment and/or the activation treatment of organic sludge generated from various wastewater treatment facilities or the mixture of the organic sludge and a component adjusting agent of an organic carbon material, the organic sludge is mixed organic sludge in which two or more kinds selected from excrement residue, raw sludge, excess sludge, coagulated sludge, and aquatic plants propagated in a water channel or these and physico-chemically treated sludge are mixed. The component adjusting agent is composed of at least one kind selected from tar, pitch, starch, and waste molasses, and 0-20wt.% of the organic sludge can be added. The treatment auxiliary can be used as an organism carrier in an organism treatment process and a coagulation treatment auxiliary in a physico-chemical treatment process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment technique, and more particularly to a wastewater treatment aid and a wastewater treatment method for effectively utilizing organic sludge generated from a wastewater treatment facility.

[0002]

2. Description of the Related Art The flow of various wastewater treatment facilities is not uniform due to the quality of wastewater, but after removing BOD (biological oxygen demand), nitrogen and the like by biological treatment, phosphorus and difficulties in physicochemical treatment. In general, a method of removing biodegradable COD (chemical oxygen demand) and further removing remaining COD and chromaticity by ozone treatment, granular activated carbon treatment, or the like when there is still remaining COD and chromaticity. As described above, the flow of a general wastewater treatment facility includes various processes such as biological treatment, physicochemical treatment, ozone treatment, and granular activated carbon treatment.
Among them, the role of the physicochemical treatment is to remove the phosphorus component and the hardly biodegradable COD component that could not be removed by the biological treatment in the former stage, and reduce the load on the ozone treatment and granular activated carbon treatment in the latter stage. is there. This physicochemical treatment includes
The coagulation-sedimentation process has been the mainstream, but in recent years, a method using a membrane treatment as a separation method after the coagulation process has been adopted.

[0003] Wastewater containing a large amount of organic matter requires a large amount of coagulant. For example, in the treatment of human waste, in the case of aluminum sulfate, addition of several hundred to several thousand mg / liter may be required. A high coagulant addition rate is not preferable because it leads to an increase in the amount of generated sludge and a deterioration in the sludge settling property and the sludge dewatering property, in addition to the problem of the treatment cost. The coagulant injection rate can be reduced by using a commercially available powdered activated carbon in combination, but since the commercially available powdered activated carbon is expensive, the treatment cost is significantly increased. For sludge generated from various wastewater treatment facilities, sludge containing a large amount of organic matter, such as human waste treatment, is treated by composting, etc.
It is used as a soil amendment material in a very small number of cases, but is generally incinerated or landfilled as waste.

[0004]

DISCLOSURE OF THE INVENTION In view of the above prior art, the present invention aims to reduce the coagulant injection rate and improve the properties of coagulated sludge by effectively utilizing organic sludge generated by wastewater treatment. An object of the present invention is to provide a wastewater treatment aid and a method capable of reducing generated waste.

[0005]

In order to solve the above-mentioned problems, the present invention provides a method for carbonizing organic sludge generated from various wastewater treatment facilities or a mixture of the organic sludge and a component modifier comprising an organic carbon material. It is a wastewater treatment aid comprising powdered coal or powdered activated carbon obtained by the treatment and / or the activation treatment. In the above auxiliary agent, as organic sludge, sewage, raw sludge, excess sludge, agglomerated sludge, one or more selected from aquatic plants and the like that flourished in waterways, or a mixed organic sludge obtained by mixing these with physicochemically treated sludge And at least one selected from tar, pitch, starch and molasses can be added as a component adjuster, and the amount of addition is preferably 0 to 20% by weight based on the organic sludge. . The carbonization is performed at a carbonization temperature of 400 to 600 ° C. and an oxygen concentration of 0 to 10% by volume, and the activation is performed at a temperature of 600 to 900 ° C. and a partial pressure of steam of 10 to 40% by volume, or 9
The reaction can be carried out at 00 ° C. and a zinc chloride content of 5 to 25% by volume.

In the present invention, the wastewater treatment aid is added to a biological treatment step and used as a biological carrier when treating wastewater, and / or is added to a subsequent physicochemical treatment step. This is a wastewater treatment method used as a coagulation treatment aid. Furthermore, in the present invention, the organic sludge generated from the wastewater treatment facility is subjected to low-temperature pyrolysis treatment in a gasification furnace attached to the wastewater treatment facility, and the generated gas is used as a resource, and the generated pulverized coal or the pulverized coal is used. The obtained activated carbon is to be used in the wastewater treatment facility as a wastewater treatment aid, and the organic sludge is introduced into a carbonization furnace attached to the wastewater treatment facility, and the resulting pulverized coal or the pulverized coal is used. The obtained activated carbon is used as a wastewater treatment auxiliary as a wastewater treatment aid, and is guided to the coagulation step of the wastewater treatment facility. In this treatment system, it is preferable to use the whole amount of pulverized coal produced from organic sludge or activated carbon obtained from the pulverized coal in the wastewater treatment facility.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has the effect of processing sludge with a high content of organic substances generated in a biological treatment step and the like, improving the organic substance removal performance in the physicochemical treatment step, and reducing the amount of coagulant injected. It provides a processing aid that can be used. Therefore, sludge, which was conventionally only waste, can be effectively used as a raw material for producing coagulation treatment aids, and the amount of coagulant injected can be reduced, and waste generated from wastewater treatment facilities can be limited. And can approach zero. Therefore, the sludge is preferably one in which the whole amount is activated carbonized by powder to form an auxiliary. However, since the amount of organic sludge increases or decreases according to the change in the amount of sewage treatment, surplus activated carbon may be generated or some external carbon may be introduced. In the present invention, generated from various wastewater treatment facilities, sewage, raw sludge, excess sludge, coagulated sludge, organic sludge such as aquatic plants that flourished in waterways, and mixed organic sludge mixed with these and physicochemically treated sludge, Alternatively, a mixture of these organic sludges and component adjusters such as tar, pitch, starch, molasses, etc. is used as a raw material, and a dried product such as the sludge containing these organic carbon bodies is carbonized and / or activated to form a carbonized product. This imparts the ability to adsorb and remove COD components in water, and pulverizes and adjusts the particle size to obtain powdered activated carbon.

[0008] The mixing ratio of waste residue, raw sludge, surplus sludge, coagulated sludge, and physicochemically treated sludge is to be adjusted according to the actual operation status of the night soil treatment facility, and is not particularly limited. The addition of component modifiers such as tar, pitch, starch, molasses, etc. is intended to increase the fixed carbon content of the product and increase the adsorption performance of the COD component. Any tar, pitch, starch, and molasses may be used without limitation. The mixing ratio of the component adjuster is also not particularly limited, but since the component adjuster is used for the purpose of increasing the fixed carbon, it is natural that increasing the mixing ratio increases the adsorption performance. In addition, it leads to an increase in manufacturing cost.
Is appropriate. For aquatic plants that thrive in waterways, for example, aquatic plants such as water hyacinth should be actively cultivated using organic matter, phosphorus, etc. remaining in biologically treated water, and used as an effective carbon source. Is also possible.

In the case of only the carbonization treatment, the product adsorption performance is low, but the product yield is high. When the activation treatment is carried out, the adsorption performance of the product is high, but the yield is low. Therefore, the carbonized product and the activated product have advantages and disadvantages, and the production method must be appropriately selected depending on the application and purpose. The conditions for the carbonization treatment are not particularly limited.
It is appropriate to set the temperature to about 00 to 600 ° C. and the oxygen concentration to about 0 to 10% by volume. As a method of the activation treatment, steam activation or chemical activation using zinc chloride or the like is appropriate. The activation treatment is generally performed on a carbonized material, but a manufacturing method in which the carbonization treatment is omitted and only the activation treatment is performed is not excluded. The conditions for steam activation are not particularly limited, either.
It is appropriate to set the temperature to about 00 to 900 ° C and the partial pressure of water vapor to about 10 to 40% by volume. The chemical used for activating the chemical using zinc chloride or the like and the activating conditions are not particularly limited. However, as an embodiment, a zinc chloride content is 5 to 25% by volume, and 400 to 900 ° C.
Is appropriate.

The processing time of the carbonization treatment and the activation treatment is not particularly limited. However, as an industrial activated carbon production method, both the carbonization treatment and the activation treatment time are about 20 to 90 minutes. It is common. In addition, the powdered activated carbon produced by the present invention is applied to a coagulation sludge generated by applying the same to a processing aid, and may be mixed with another organic sludge and the like, and used again as a part of the raw material for producing powdered activated carbon. However, it is also possible to perform incineration separately from this, and to use the heat generated here as a part of the heat source in the drying, carbonization and activation steps in the powdered activated carbon production process.

Next, a specific wastewater treatment system using the present invention will be described. First, a system for performing carbonization using a gasification furnace will be described with reference to FIG. FIG. 1 is a process diagram of the treatment system. In FIG. 1, wastewater 1 such as night soil is introduced into a biological treatment process 3 through a pretreatment process 2 and biologically treated. Processing step 4
To form purified treated water 5. that time,
The residue 8 from the pretreatment step 2, the excess sludge 9 from the biological treatment step 3, and the flocculated sludge 10 from the flocculation treatment step 4 are introduced into the gasification furnace 7 together with another sewage sludge 6 and the like, and subjected to low-temperature pyrolysis treatment. The generated gas is effectively used separately as a fuel and a raw material, and the pulverized coal 11 obtained here is introduced into a coagulation treatment step and used as a coagulation aid. As the gasification furnace, any type such as a fluidized bed furnace and a rotary kiln can be used.

In this system, sludge or the like before entering the gasification furnace 7 may be provided with a known concentration and dehydration step such as centrifugation and pressing. Activated carbon can also be obtained by the activation treatment described above. The low-temperature pyrolysis treatment of the gasification furnace is preferably performed at a carbonization temperature of 400 to 600 ° C. and an oxygen concentration of 0 to 10% by volume, which is the above-described carbonization treatment.
It is particularly preferable to use it in the aggregation treatment step. When carbonization is performed using a carbonization furnace, the carbonization can be performed according to the process diagram shown in FIG. In FIG. 2, the process of converting the wastewater 1 such as human waste into purified water 5 is the same as that of FIG. 1, but the waste 8 and excess sludge 9 obtained from the treatment process are separately separated together with sewage sludge and the like. The resulting coal is introduced into a carbonization furnace 13 and carbonized, and the obtained coal powder is used as a coagulation aid in the coagulation processing step 4, and the obtained coagulated sludge 10 is subjected to thermal decomposition heat recovery in an incinerator 14 to carbonize the generated heat 15 Used as an external heat source of the furnace 13.

[0013] Powdered charcoal or powdered activated carbon produced by any of the above methods, or an acid aqueous solution is added to the powdered activated carbon,
The pH adjusted to acidic to neutral is subjected to a biological treatment step and / or
Alternatively, it is added as a processing aid for physicochemical treatment. When added to the biological treatment process, it acts as a biological carrier, so it can enhance the BOD removal effect and the nitrification-denitrification effect, reducing the load on the subsequent treatment equipment and improving the sedimentation of activated sludge. It is valid. When added to physicochemical processing equipment, it acts as an agglomeration processing aid, which enhances the COD / chromaticity removal effect and helps to reduce the amount of coagulant injected, reducing the load on subsequent processing equipment and coagulation. It is extremely effective in reducing sludge generation and improving settling and dewatering properties. As a result, sludge generated from various wastewater treatment facilities can be effectively used, and at the same time, it is possible to contribute to reduction of treatment costs such as chemical costs, and as a result, waste generated from the wastewater treatment facilities is reduced to almost zero. be able to.

[0014]

The present invention will be described below in more detail with reference to examples. Example 1 A mixed sludge of raw sludge, surplus sludge, and coagulated sediment sludge from the night soil treatment plant A was granulated and dried, and then an oxygen atmosphere of 5% and 400 to 550 ° C.
The activated carbon powder produced by performing a carbonization treatment for 1 hour under the conditions described above and further pulverizing the powder to 200 mesh or less with a roller mill had an iodine adsorption performance of 200 mg / g. The produced powdered activated carbon was used in the coagulation sedimentation step as follows. The coagulation and sedimentation step involves aluminum sulfate,
Then, a polymer flocculant (about 1 mg / liter) is added and mixed for 2 to 5 minutes, and then floc is grown by gentle stirring for 10 to 30 minutes to precipitate and separate the floc.
Prior to the addition of aluminum sulfate, the powdered activated carbon 1000
When a contact time of 30 minutes was provided by adding mg / l, it was possible to reduce the amount of aluminum sulfate added from 4000 mg / l to 1500 mg / l.

Example 2 After drying the excess sludge in the B sewage treatment plant, the oil pitch was 20 wt.
%, And carbonized for 30 minutes under the conditions of oxygen atmosphere 5% and 400 to 550 ° C., and then activated by steam at 700 to 800 ° C., the iodine adsorption performance of the powdered activated carbon is 800 mg / g. And 100 in the coagulation sedimentation step.
When 0 mg / L was added, the amount of aluminum sulfate added could be reduced from 600 mg / L to 150 mg / L.

Example 3 A mixed sludge of raw sludge, excess sludge and coagulated sediment sludge from a human waste treatment plant C was dried, and then mixed with 5 wt% of zinc chloride to obtain a mixture of 400 to 5%.
The powdered activated carbon produced by performing the carbonization treatment at 50 ° C. for 1 hour has an iodine adsorption performance of 500 mg / g. When 500 mg / l is added in the coagulation precipitation step, the amount of aluminum sulfate added is 2000 mg / g. It was possible to reduce from liter to 1000 mg / liter.

Example 4 A mixed sludge of raw sludge, surplus sludge and coagulated sediment sludge in a human waste treatment plant C was dried, and then mixed with 5 wt% of zinc chloride to obtain a mixture of 400 to 5%.
Powdered activated carbon produced by performing a carbonization treatment at 50 ° C. for 1 hour has an iodine adsorption performance of 500 mg / g, and diluted sulfuric acid is added thereto to form a suspension aqueous solution having a pH value of 3.
When 500 mg / L was added in the coagulation sedimentation step, the amount of aluminum sulfate added was increased to 2000 mg / L.
It was possible to reduce from liters to 500 mg / liter.

Example 5 D Mixed sludge of raw sludge, excess sludge, and coagulated sediment sludge from a night soil treatment plant was granulated and dried, and carbonized at 600 ° C. for 1 hour, and then ground to 200 mesh or less by a roller mill. When the produced powdered activated carbon was treated by adding 1 to 5% of each MLSS to the denitrification tank and nitrification tank in the night soil treatment process, the familiarization period at the initial startup, which conventionally required about one month, The processing time was reduced to about three weeks, and the processability against fluctuations in the load of raw water was stabilized.

Example 6 A processing test in which pulverized coal was added as an auxiliary agent in the coagulation treatment step is shown below. (A) Aggregation treatment test Using 600 ° C. carbide (carbonization time 2 to 5 hours), treatment conditions are as follows. 30 minutes after the addition of carbide, contact with aluminum sulfate (Alum) after adjusting the pH value to 7.0, rapid stirring for 3 minutes, addition of polymer flocculant (polymer), rapid stirring for 1 minute, slow stirring for 5 minutes
Thereafter, the mixture was filtered through a 0.45 μm membrane filter. (B) Test results Table 1 shows the results of the aggregation treatment test.

[0020]

[Table 1]

(C) Alum treatment The solubility COD of raw water was 142 mg / liter,
COD with um alone at 1,000mg / liter treatment
100 mg / liter, and the addition rate is 4,000 mg.
/ Liter increased little. Here, the remaining COD is presumed to be caused by a low molecular weight organic substance that cannot be removed by the coagulation treatment. Therefore, in the case of this secondary wastewater treatment, it is considered that it is difficult to reduce the COD to 100 mg / liter or less by Alum aggregation. (D) Combined treatment with 600 ° C carbides The effect of 600 ° C carbides was not recognized up to 2,000 mg / L, but was significant when 5,000 mg / L was added, and COD65. 3mg / liter, Alum
COD 56.7 when used in combination with 4,000 mg / liter
mg / liter and chromaticity was 36 degrees.

However, the carbide at 600 ° C. is doubled to 10,000.
Even at mg / l, the effect was only marginally improved. Since the remaining COD is also caused by low molecular weight organic matter which can no longer be removed by the pores of carbide at 600 ° C., it is considered that the effect is not improved even if the added amount of carbide is increased. As described above, in a state where the carbide is not injected in the coagulation treatment step, the raw water COD 142
Even if the injection of the aluminum-based inorganic flocculant is increased with respect to mg / L, the treated water COD is about 100 mg / L, but by injecting pulverized coal at 5000 mg / L, it can be reduced to about 50 mg / L. It has become possible.

[0023]

Industrial Applicability According to the present invention, sludge generated from various wastewater treatment facilities can be effectively used, and at the same time, the processing performance in biological processing, the processing performance in physicochemical processing, and the coagulation can be improved by using the produced powdered activated carbon. It can contribute to reducing the amount of chemicals injected, improving the sedimentation and dewatering properties of the generated sludge, reducing the amount of sludge generated, and by extension, reducing the waste generated from the wastewater treatment facility to zero as much as possible. Can be.

[Brief description of the drawings]

FIG. 1 is a process diagram of a wastewater treatment system incorporating a wastewater treatment aid of the present invention in a treatment process.

FIG. 2 is a process diagram of another wastewater treatment system incorporating the wastewater treatment aid of the present invention in a treatment process.

[Explanation of symbols]

1: sewage such as human waste, 2: pretreatment step, 3: biological treatment step,
4: physicochemical treatment step, 5: treated water, 6: sewage sludge such as raw sludge, 7: gasification furnace, 8: scum, 9: excess sludge, 10:
Coagulated sludge, 11: pulverized coal, 12: generated gas, 13: carbonization furnace, 14: incinerator, 15: generated heat

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihiro Tanaka 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation

Claims (8)

[Claims] 1. Powdered coal or powdered activated carbon obtained by carbonizing and / or activating an organic sludge generated from various wastewater treatment facilities, or a mixture of the organic sludge and a component modifier comprising an organic carbon material. Wastewater treatment aid. 2. The organic sludge is at least one selected from sewage, raw sludge, surplus sludge, coagulated sludge, aquatic plants growing in waterways, or a mixed organic sludge obtained by mixing these with sludge treated with physicochemical treatment. The wastewater treatment aid according to claim 1, wherein 3. The method according to claim 1, wherein the component adjuster comprises at least one selected from tar, pitch, starch, and molasses, and is added in an amount of 0 to 20% by weight based on the organic sludge. 2. The wastewater treatment aid according to 2. 4. The carbonization treatment is performed at a carbonization temperature of 400 to 60.
The activation treatment is performed at a temperature of 600 to 900 ° C and a partial pressure of steam of 10 to 40% by volume, or at a temperature of 400 to 900 ° C and a zinc chloride content of 5 to 2%.
The wastewater treatment aid according to claim 1, 2 or 3, wherein the treatment is performed at 5% by volume. 5. The wastewater treatment aid according to claim 1, which is added to a biological treatment step for treating wastewater and used as a biological carrier, and / or used in a subsequent physicochemical treatment step. A wastewater treatment method, which is added and used as a coagulation treatment aid. 6. An organic sludge generated from a wastewater treatment facility,
The low-temperature pyrolysis treatment is performed in a gasification furnace attached to the wastewater treatment facility, the generated gas is used as a resource, and the produced pulverized coal or activated carbon obtained from the pulverized coal is used in the wastewater treatment facility as a wastewater treatment aid. Wastewater treatment system characterized by the above-mentioned. 7. An organic sludge generated from a wastewater treatment facility,
The wastewater treatment facility is introduced into a carbonization furnace attached to the wastewater treatment facility, and the generated coal or activated carbon obtained from the coal is guided as a wastewater treatment aid to the coagulation step of the wastewater treatment facility, and the coagulation including the wastewater treatment aid is performed. A wastewater treatment system wherein sludge is separated and led to a pyrolysis heat recovery step, and the generated heat is used as an external heat source of the carbonization furnace. 8. The wastewater treatment system according to claim 6, wherein the whole amount of the pulverized coal produced from the organic sludge of the wastewater treatment facility or the activated carbon obtained from the pulverized coal is used in the wastewater treatment facility.