JP4812261B2 - Method for solubilizing solid content in high-concentration organic substance, and method for treating high-concentration organic substance - Google Patents

Description

  The present invention relates to a method for solubilizing a solid content in a high-concentration organic substance. More specifically, the present invention relates to a method for treating a solid content in a high-concentration organic substance such as excess sludge or food residue under heating and pressure. The present invention relates to a method for solubilizing a solid content in a high-concentration organic substance that is solubilized with an oxidizing agent without using it, and a method for treating a high-concentration organic substance using this.

  Conventionally, in the purification treatment of organic wastewater containing organic pollutant components in wastewater shown by BOD, a satisfactory result has been obtained at a relatively low cost by a biological treatment method such as an activated sludge method. In the activated sludge method, wastewater to be treated is first guided to a settling basin, and a heavy specific gravity is precipitated and removed, and then organic matter in the liquid is biodegraded by activated sludge in an aeration tank. Therefore, food residues (shochu, sake lees, or raw garbage) etc. in wastewater discarded from households and food factories are first removed in the sedimentation basin, and some are reused, but most are landfilled or Processing such as incineration is carried out. Furthermore, in the activated sludge treatment, 50 to 70% by mass of the decomposed BOD is consumed by the living energy of microorganisms, and the remaining 30 to 50% by mass is used for the growth of bacterial cells. However, most of the excess sludge is separated in the sedimentation basin and is separately treated for landfill or incineration. However, all of these contain a large amount of moisture and are septic, and the treatment thereof is very difficult, and the treatment of organic solids such as excess sludge and food residues in waste water is as follows. It has become a big problem.

  For example, surplus sludge generated by activated sludge treatment is dehydrated as it is or by anaerobic digestion to decompose and reduce the volume to methane gas, carbon dioxide, hydrogen, hydrogen sulfide, etc., and then solid-liquid separation The anaerobic digested sludge is dehydrated and incinerated or landfilled. On the other hand, the applicant has already reduced the volume of sludge by oxidizing and decomposing surplus sludge and the above-mentioned anaerobic digested sludge in the oxidation tank with an oxidizing agent using metal ions as a catalyst. It proposes about the method of processing surplus sludge etc. by carrying out the biodegradation by returning the desorbed water etc. from the aeration tank (refer to patent documents 1).

Japanese Unexamined Patent Publication No. 7-24499

According to the above method, excess sludge generated by the activated sludge method and organic sludge such as the above-described anaerobic digested sludge can be efficiently reduced in volume, and solids that require treatment such as landfill or incineration are required. The volume of the product can be reduced. However, as a result of further studies by the present inventors, it is difficult to say that the solubilization treatment is complete in the above-described method, and furthermore, since metal ions such as iron are used as a catalyst, these remain as residues. However, although the amount of solid matter that needs to be treated such as landfill or incineration is reduced, there is a problem that treatment is necessarily required. On the other hand, the current disposal cost of sludge such as sludge is as high as 20,000-30,000 yen / m ^3, and this disposal cost tends to increase further in the future. In addition to the problem of treatment costs, landfill or incineration treatments may cause problems such as air pollution and soil elution, so it is hoped to develop a method that minimizes the treatment of solids. It is rare.

  Accordingly, the object of the present invention is to provide organic sludge such as surplus sludge and anaerobic digested sludge generated by the activated sludge system, and also in high-concentration organic substances such as shochu, sake lees, and food residues such as raw garbage. Efficiently solubilized solids to enable biodegradation such as activated sludge treatment, while at the same time greatly reducing the amount of solids that require landfill or incineration, and no risk of environmental pollution An object of the present invention is to provide an efficient and economical method for treating concentrated organic substances. Another object of the present invention is to provide a method for treating a high-concentration organic substance in which the occurrence of solid matter treatment for excess sludge is reduced.

The above object is achieved by the present invention described below. That is, the present invention is a method for solubilizing solid content in high-concentration organic material that is excess sludge or food residue, and the pressure-resistant container is filled with a high-concentration organic material having a pH adjusted to 5 or less. The container internal temperature is set to 150 to 250 ° C. , and the container internal pressure is set to 1 . When processed as a 1 ~ 2.5 MPa, temperature of the high concentration organic substances heated pressure vessel is press-fitted hydrogen peroxide as an oxidizing agent when it becomes a 0.99 ° C., under these conditions ( High concentration, characterized by oxidative decomposition and solubilization of solids in high-concentration organic substances with an oxidizing agent without using a catalyst, except at least intermittently introducing an oxygen-containing gas) It is the solubilization processing method of the solid content in an organic substance, and the processing method of a high concentration organic substance.

  According to the present invention, solids in high-concentration organic substances such as excess sludge and food residues can be efficiently solubilized to form biodegradable, and a catalyst is used for solubilization. As a result, the solid content that requires processing such as landfill or incineration can be remarkably reduced. As a result, economical processing of high-concentration organic substances is achieved. Furthermore, according to the present invention, it is possible to achieve organic wastewater treatment with reduced generation of solid matter treatment with respect to excess sludge.

  Next, the present invention will be described in more detail with reference to preferred embodiments. FIG. 1 is a diagram schematically showing an apparatus for carrying out a method for solubilizing a solid content in a high-concentration organic substance according to the present invention. The apparatus will be described with reference to FIG. First, in the present invention, the solubilization treatment of the solid content in the high-concentration organic substance is performed under the conditions of 150 to 250 ° C. heating and 0.6 to 10 MPa pressure. Reference numeral 1 in the figure denotes a pressure-resistant container that can be used in this case to be in a pressurized state. The shape or capacity of the pressure vessel 1 may be appropriately determined according to the high-concentration organic substance to be processed. Reference numeral 2 denotes a heater for heating the inside of the pressure vessel 1. By heating the inside of the container filled with a high-concentration organic substance such as activated sludge with the heater 2, the inside of the pressure-resistant container 1 is in a pressurized state. At this time, the temperature condition and the pressurizing condition are controlled by measuring the temperature in the container with the thermometer 5 provided in the pressure resistant container 1.

  In the present invention, the temperature in the pressure-resistant vessel 1 (more specifically, the temperature of the high-concentration organic substance) is treated as 150 to 250 ° C., more preferably 150 to 180 ° C. as described above. Furthermore, the pressure in the container is treated in a pressurized state in the range of 0.6 to 10 MPa, more preferably in the range of 1.1 to 2.5 MPa. Further, the oxidizing agent 3 is added to the container, and the agitation device 6 performs the treatment while stirring the high-concentration organic substance filled in the container. As an oxidizing agent to be used, an oxidizing agent used in a conventionally known chemical oxidation method such as hydrogen peroxide, calcium peroxide, ammonium persulfate, alkyl hydroperoxide, peracid ester, dialkyl peroxide or diacyl is used. it can. Hydrogen peroxide is most preferable from the viewpoint of cost and by-products. Hereinafter, hydrogen peroxide will be described as a representative example.

  The amount of hydrogen peroxide used is not particularly limited and varies depending on the content of the high-concentration organic substance, but the preferred amount is about 10 to 200 mass per 100 parts by mass (solid content) of the high-concentration organic substance. Part (as oxygen).

  The oxidizing agent 3 such as hydrogen peroxide may be press-fitted into the container using an inert gas such as nitrogen gas indicated by 4 in the figure. In the method of the present invention, it is preferable to adjust the pH of the high-concentration organic substance before the oxidation treatment to 5 or less in advance and perform the oxidation treatment with an oxidizing agent in this state. As the pH adjuster used in this case, it is preferable to use sulfuric acid, nitric acid or the like.

When the treatment temperature is lower than 150 ° C., oxidation takes time under oxidation conditions that do not use a catalyst, the efficiency is insufficient, and the utilization efficiency of hydrogen peroxide is also insufficient. Further, when the temperature exceeds 250 ° C., the heating energy consumption becomes large, and it is not an economical treatment in view of the treatment effect. The oxidation reaction time varies depending on the size, temperature and pressure of the heat-resistant container, the performance of the stirrer, etc. For example, excess sludge (solid content of about 1% by mass), which is a high-concentration organic substance, is about 10 m ³ and the temperature is 150 ° C. When sufficient agitation is performed under a pressure of 2.5 MPa, a reaction time of about 15 to 60 minutes is sufficient, and about 85 to 95% by mass of excess sludge can be decomposed.

  In the present invention, after the oxidation treatment under the heating and pressurizing conditions as described above, after stopping the heating and gradually cooling, or after cooling the container with water, the solubilized liquid is left as it is. (Or, if necessary, the filtrate obtained by filtration) is placed in an aeration tank, etc., so that high-concentration organic substances containing solids such as excess sludge are treated almost completely by biological methods. (See FIG. 2).

Next, the present invention will be described more specifically with reference to examples.
<Example 1>
Excess sludge (SS: 13,000 mg / liter, SS-type TOD 18,000 mg / liter) from a wastewater treatment facility treating wastewater from a food factory was solubilized under the following conditions. 250 ml of the above sludge was placed in a pressure resistant container made of SUS316 having an internal volume of 300 ml, and solubilized using hydrogen peroxide as an oxidizing agent. That is, using the apparatus as shown in FIG. 1, surplus sludge whose pH is adjusted to 2.5 with sulfuric acid in advance is placed in the pressure resistant container 1, and the temperature of the sludge S in the container 1 becomes 150 ° C. with the heater 2. When the temperature reached 150 ° C., the hydrogen peroxide solution 3 was pressed into the container with nitrogen gas from the nitrogen cylinder 4. The pressure in the container during the reaction was measured and found to be 2.5 MPa. The hydrogen peroxide solution 3 was added so that the amount with respect to the SS TOD was 50% (that is, a ratio of 9,000 mg / liter). It was made to react on these conditions for 30 minutes, SS amount of the liquid after reaction was measured, and SS solubilization rate (%) was calculated | required from SS amount before and behind reaction. The results are shown in Table 1. The SS solubilization rate (%) was 93%, and it was confirmed that the solid matter in the excess sludge could be almost completely solubilized by the method of this example.

<Comparative Example 1>
In Example 1, the same test as in Example 1 was performed except that a copper-based catalyst (copper ferrite) was added to the reaction vessel so that the amount of copper ions was 300 mg / liter. The results are shown in Table 1. As shown in Table 1, the solubilization rate of SS is 95%. From the comparison with Example 1, when it is heated and pressurized and oxidatively decomposed, sufficient solubilization is achieved without using a catalyst. It was confirmed that it could be processed. However, in the case of this comparative example, since the catalyst remains as a residue as it is, a filtration treatment is required when performing a biological treatment after the solubilization treatment.

<Comparative example 2>
In Example 1, the same test as in Example 1 was performed, except that hydrogen peroxide as an oxidizing agent was not used. The pressure during the reaction in this case was 0.6 MPa. The results are shown in Table 1. As shown in Table 1, the SS solubilization rate (%) is 52%. When an oxidizing agent is not used, sufficient solubilization processing cannot be performed, and biological treatment is performed after solubilization processing. It was confirmed that it was necessary to remove the solid matter.

<Comparative Example 3>
Using the sludge adjusted to pH 2.5 used in the treatment of Example 1, an iron-based catalyst (ferrous chloride) was added so that the ferrous ion was 250 mg / liter, and further, for SS-stable TOD Hydrogen peroxide was added so that the total amount was 50%, and the mixture was reacted at 50 ° C. for 1 hour while shaking at atmospheric pressure. Then, the amount of SS after the reaction was measured, and the SS solubilization rate (%) was determined in the same manner as in Example 1. Although the result was shown in Table 1, the solubilization rate was inferior to the case of Example 1 and Comparative Examples 1 and 2, and sufficient solubilization process was not performed. Further, since the catalyst remains as a residue as it is, when a biological treatment is performed after the solubilization treatment, a filtration treatment for removing them is necessary.

<Example 2>
Using shochu (SS: 35,000 mg / liter, SS-type TOD 92,000 mg / liter) from a food factory, the amount of hydrogen peroxide added is 40% with respect to the SS-type TOD. Added. Other than that, in the same manner as in Example 1, the solubilization rate (%) of SS was obtained, and the results are shown in Table 2. As shown in Table 2, the solubilization rate (%) of SS is as high as 91% even for the sample of this example with more solids than in the case of Example 1, and the shochu liquor with a high SS concentration. It was also confirmed that a good solubilization treatment can be performed.

<Comparative example 4>
In the same manner as in Comparative Example 1 except that the amount of hydrogen peroxide added to the shochu similar to that treated in Example 2 was 40% with respect to SS TOD. A solubilization test was performed. The results are shown in Table 2. As shown in Table 2, the SS solubilization rate (%) was 90%, and compared with Example 2, it was heated and pressurized to undergo oxidative decomposition. In some cases, it was confirmed that satisfactory solubilization treatment could be performed without using a catalyst. However, in the case of this comparative example, since the catalyst remains as a residue as it is, a filtration treatment is required when performing a biological treatment after the solubilization treatment.

<Comparative Example 5>
A solubilization test was performed on shochu similar to that treated in Example 2 in the same manner as in Comparative Example 2. The pressure during the reaction in this case was 0.6 MPa. The results are shown in Table 2. As shown in Table 2, the SS solubilization rate (%) was 45%. As a result, it was confirmed that when an oxidizing agent is not used, a sufficient solubilization treatment cannot be performed, and when a biological treatment is performed after the solubilization treatment, it is necessary to remove a solid matter.

  According to the present invention as described above, in an organic sludge such as surplus sludge and anaerobic digested sludge generated by the activated sludge system, or in high-concentration organic substances such as shochu, sake lees, or food residues such as raw garbage. The solubilization of the solid content of the product is possible, enabling biodegradation such as activated sludge treatment, and at the same time, the amount of solid content required for landfill or incineration is greatly reduced, with no risk of environmental pollution. An efficient and economical method for treating highly concentrated organic materials is provided. ADVANTAGE OF THE INVENTION According to this invention, the processing method of the high concentration organic substance by which generation | occurrence | production of the solid substance process with respect to excess sludge was reduced is provided.

It is the figure which showed typically the apparatus in the case of implementing this invention. It is the flow which incorporated the solubilization processing method of this invention in the processing method of organic waste_water | drain.

Explanation of symbols

1: Pressure vessel 2: Heater 3: Oxidizing agent 4: Inert gas 5: Thermometer 6: Stirrer S: High concentration organic substance

Claims (3)

In the method of solubilizing the solid content in the high-concentration organic substance that is excess sludge or food residue, the pressure-resistant container is filled with a high-concentration organic substance whose pH is adjusted to 5 or less, and the temperature in the container is 150. ˜250 ° C., and the pressure in the container is 1 . When processed as a 1 ~ 2.5 MPa, temperature of the high concentration organic substances heated pressure vessel is press-fitted hydrogen peroxide as an oxidizing agent when it becomes a 0.99 ° C., under these conditions ( High concentration, characterized by oxidative decomposition and solubilization of solids in high-concentration organic substances with an oxidizing agent without using a catalyst, except at least intermittently introducing an oxygen-containing gas) A method for solubilizing a solid content in an organic substance. The method for solubilizing a solid content in a high-concentration organic substance according to claim 1, wherein the amount of hydrogen peroxide added is such that the amount with respect to SS-type TOD is 40 to 50% .   A method for treating a high-concentration organic substance, further comprising biodegrading a solubilized product obtained by the solid-solubilization treatment method in a high-concentration organic substance according to claim 1 or 2.

Images