JPH1080698A - Reforming method of organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compactly and efficiently reform an organic sludge in a sludge generating site of a small scale work shop or the like and to prevent the generation of problems of noise and power consumption due to the use of a deodorizing device or a large capacity blower. SOLUTION: In the reforming method of the organic sludge for treating by adding oxygen to the organic sludge, a hydrolase, a surfactant, an alkaline earth metal compound and an enzyme activity accelerating agent composed of at least one kind of an alkali metal compound are added to treat the organic sludge. At this time, 0.0002-1.0wt.% hydrolase and 0.0001-2.0wt.% enzyme activity accelerating agent per sludge dry weight are added. And simultaneously a chelating agent can be added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reforming organic sludge generated from various types of industrial wastewater treatment, sewage treatment, human waste treatment, and the like. The present invention relates to a method for modifying organic sludge which improves the properties, concentration, and peelability.

[0002]

2. Description of the Related Art In order to improve the biodegradability, volume reduction and dehydration of sludge, reforming with an enzyme agent has been conventionally studied. For example, JP-A-58-74185, JP-A-5-74185
Japanese Patent Application Laid-Open No. 0-22462 and Japanese Patent Application Laid-Open No. 50-90144 indicate that the number of treatment days is shortened by adding an enzyme when performing anaerobic digestion or aerobic digestion. In the latest technology, Japanese Patent Publication No. 7-3
No. 2920, an organic sludge is contacted with a lytic enzyme (lysozyme, zymolyase, etc.), stirred at 10 to 50 ° C. to decompose and reform the sludge, and the sludge is concentrated by stirring. A method for concentrating sludge is described, which has the advantage that it can be treated without using chemicals.

[0003] In addition, JP-A-63-116800 discloses that a hydrolytic enzyme (β-glucanase, amylase, protease, lipase, cellulase) is used alone or in a mixture of 0.01 to 0.01% per sludge dry weight (DS). 1%, and a chelating agent (ethylenediaminetetraacetic acid, sodium nitrilotriacetate / ammonium salt) alone or mixed and added in an amount of 0.001 to 0.5% based on the dry weight of sludge. At 60 ° C., pH 5 to 8, residence time 0.5 to 15 hours), the treatment is carried out by passing an oxygen-containing gas. That is, in this treatment method, a chelating agent and a hydrolytic enzyme are added to sludge containing an organic substance, and the sludge is treated by passing an oxygen-containing gas. Further, as an embodiment thereof, a wastewater containing an organic substance is added with sludge, a chelating agent, and a hydrolase from a biological treatment facility at a later stage, and is treated by passing an oxygen-containing gas, followed by dehydration treatment. A method in which the separated water is treated in the biological treatment facility, and a wastewater containing an organic substance is treated biologically, and a chelating agent and a hydrolase are added to sludge discharged from the biological treatment facility, and the enzyme is added. In this method, the treated sludge is returned by returning the treated sludge to the biological treatment facility after treating the gas containing gas.

Further, JP-A-2-191600 discloses that a single enzyme or a mixture of enzymes is added in an amount of 0.001 to 1.5% per sludge dry weight, and a chelating agent, preferably a salt of nitrilotriacetic acid, is added. The sludge dry weight per 0.00
Add 1-0.1% to decompose organic components in solids,
And intensely aerated in the aerobic treatment reactor (0.5-2
0 hours). Also, Japanese Unexamined Patent Publication No.
No. 17580 discloses that a hydrolase (lipase, amylase, cellulase, protease) is added in an amount of 0.001 to 5% (preferably 0.1 to 1%) per sludge dry weight, and the reaction is carried out at a reaction temperature of 5 to 70 ° C. It has been shown.

[0005]

As mentioned above, in the method of reforming sludge to which an enzyme is added, it is said that the use of a hydrolase as an enzyme is advantageous in sludge reforming. At that time, a method has been adopted in which an auxiliary agent such as a chelating agent is added to improve the effect. In this case, the surface of the microorganisms contained in the sludge is composed of a gel-like mucous substance and cell membrane, but the added chelating agent reduces the structural strength of the surface and promotes the autolysis of the microorganisms. As a result, the contents containing enzymes contained in the cells are eluted out of the cells, and the synergistic action of those contents and other enzymes with the added hydrolase causes sludge volume reduction and sludge reduction. It is described that the filtration property and dewatering property of the sludge are improved.

[0006] However, techniques using enzymes such as JP-A-58-74185 and JP-A-50-22462 are intended to promote conventional aerobic and anaerobic treatments. It is not intended to modify the properties of the generated sludge. In JP-A-63-116800 and JP-A-2-191600, enzymes and chelating agents are added for the purpose of improving the properties of sludge. The aerobic treatment is performed by introducing sludge into the reactor. For this reason, problems such as odor, noise due to a blower, and power consumption have not been avoided. Furthermore, sludge is generated by aerobic treatment of the enzyme decomposition product,
These newly generated sludges are considered to be inferior in properties such as dewaterability and filterability. On the other hand, Tokiko 7-32920
No. is a simple method of adding a lytic enzyme such as lysozyme to organic sludge and modifying the organic sludge only by stirring or contacting. However, lytic enzymes are enzymes intended to directly decompose the cells themselves, and lysozyme is known to mainly lyse Gram-positive bacteria, so depending on the type of sludge, does the effect of enzyme addition decrease? Alternatively, it is conceivable that microorganisms that are effective for the flocculation and concentration of sludge are lysed. Furthermore, in the case where oil or the like is attached to the sludge surface, the contact between the lytic enzyme and the sludge is hindered, so that the effect of the enzyme addition is expected to be significantly reduced. The present invention has been made to solve the above-mentioned problems of the prior art, and does not require an aeration power or a new treatment process. It is an object of the present invention to provide a method for reforming anaerobic sludge.

[0007]

The present invention has solved the above-mentioned problems by the following means. (1) An organic sludge reforming method in which an enzyme is added to an organic sludge for treatment, wherein the organic sludge is hydrolyzed with at least one of a surfactant, an alkaline earth metal compound, and an alkali metal compound. A method for reforming organic sludge, which comprises treating with an enzyme activity promoter comprising a seed. (2) The hydrolase is added in an amount of 0.00
02 to 1.0% by weight, and 0.000
The method for modifying organic sludge according to the above (1), wherein 1 to 2.0% by weight is added. (3) The method for modifying organic sludge according to the above (1) or (2), wherein a chelating agent is added to the organic sludge. (4) One of lipase, β-glucanase, protease, cellulase and amylase as the hydrolase
The method for reforming organic sludge according to any one of (1) to (3), wherein one or more kinds are used.

(5) The method for reforming organic sludge according to any one of (1) to (4), wherein calcium chloride and / or magnesium chloride is used as the alkaline earth metal compound. (6) A hydrolase and an enzyme activity promoter comprising at least one of a surfactant, an alkaline earth metal compound, and an alkali metal compound are supplied to a sludge storage tank such as a drum screen or a line system at a facility in the front part of a sludge storage tank. (1) characterized in that it is added first or added directly to the sludge storage tank.
The method for reforming organic sludge according to any one of (1) to (5). (7) Stirring an organic sludge to which a hydrolase and an enzyme activity promoter comprising at least one of a surfactant, an alkaline earth metal compound and an alkali metal compound are added in a sludge storage tank. Characteristic (1)-
The method for reforming organic sludge according to any one of (6).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the organic sludge to be treated is primary sludge generated in the treatment of sewage, human waste and various kinds of industrial wastewater, and excess sludge generated by aerobic or anaerobic treatment. Is mentioned. Examples of the hydrolase to be added thereto include protease, amylase, esterase, glucanase, and cellulase, among which esterase is particularly preferably lipase, and glucanase is β
-Glucanase is preferred. Lipase is an esterase, an enzyme that catalyzes the hydrolysis of fat, and is widely distributed in the animal and plant kingdoms, and is present in, for example, plant seeds, stems, leaves, molds, bacteria, and the like. The amount of hydrolase added
0.0002-1.0% by weight, preferably 0.0005
The amount is preferably from 0.5 to 0.5% by weight, more preferably from 0.001 to 0.1% by weight. The amount varies depending on the type of the hydrolase to be used, and an optimal amount may be used.

Further, in the present invention, an enzyme activity promoter is added together with the hydrolase, and the enzyme activity promoter is selected from a surfactant, an alkaline earth metal compound and an alkali metal compound. Is used. And a chelating agent can be added to it. This chelating agent is added mainly for the purpose of preventing the enzyme activity from being reduced by metal ions present in the sludge, and is more effective to be added prior to the enzyme addition. It is known that a chelating material reduces the strength of a viscous substance, and the same effect can be obtained in the present invention. The enzyme activity promoter in the present invention has an action as a drug that promotes the enzyme reaction or a drug that alleviates the inhibition of the enzyme reaction,
In carrying out the process, an agent such as an acid or an alkali agent for maintaining the enzyme reaction at an optimum pH value can be used together. The use of the surfactant has an effect of emulsifying fats and oils in decomposing fats and oils by lipase and promoting an enzymatic reaction, and thus is effective for reforming organic sludge having a high oil content. As the type of surfactant, a biologically-derived surfactant such as bile acid or saponin is effective, but any other surfactant having high biodegradability can be used.

As the alkali metal compound, salts and hydroxides of sodium and potassium are effective, but sodium hydroxide is sometimes used as a pH regulator. As the alkaline earth metal compound, salts of calcium, magnesium and barium are effective. Depending on the type of the enzyme used, some of them may inhibit the action thereof, so it is necessary to appropriately adjust the type and the amount added. As for the chelating agent, an enzyme reaction may be inhibited depending on the kind of metal contained in the organic sludge. Therefore, a chelating agent such as ethylenediaminetetraacetic acid (EDTA) or nitriloacetic acid (NTA) is used as an enzyme activity promoter. And blocking harmful metals is effective. However, when adding a specific metal ion to promote enzyme activity, it is necessary to adjust the type and amount of chelating agent in consideration of the affinity with harmful metals in organic sludge and the amount of blockage. There is. The chelating agent has the effect of removing the biopolymer in the activated sludge or reducing the strength thereof, in addition to the effect as the enzyme activity promoter, so that the excess sludge or the organic sludge having a high excess sludge mixing ratio is used. It is effective for reforming.

There is an optimum pH range for the enzymatic reaction,
It is well known that the enzyme activity is significantly reduced outside the pH range. Also in the present invention, depending on the type of the hydrolase, the pH condition may be changed due to the reaction product and the enzyme activity may be reduced. Therefore, an optimal pH range is maintained by adding an acid or an alkali agent. This is very effective in promoting enzyme activity. In treating with an enzyme as in the present invention, the reaction conditions must be maintained so that the enzyme reaction is performed at the highest rate. It is important that they are sufficiently mixed so that the contact between the two is maximized. For this purpose, it is necessary to stir well when the hydrolase is added to the organic sludge.

However, the reaction does not require aeration, and from this point, from the viewpoint of reforming organic sludge, it is not suitable to carry out the reaction in a conventional aerobic biological treatment tank. It is suitable to add a hydrolytic enzyme to a conventional sludge storage tank, mix and react. Thus, stirring the sludge storage tank for mixing is an important operating factor. However, since the sludge in the storage tank is generally at a high concentration, a large amount of power is required to effectively stir and mix an enzyme promoter such as a hydrolase and a surfactant with the sludge. Therefore, if these chemicals are added to the drum screen and the pipe part in the former part of the storage tank, the sludge content and the chemicals can be effectively mixed without requiring additional power. Of course, the chemical may be directly added to the sludge storage tank. In addition, it is necessary to sufficiently stir in the storage tank, but if the stirring and mixing are too vigorous, sludge floc will be reduced, the surface area will increase, and the amount of polymer added in the latter stage will increase. Is preferred. Further, as the temperature in the reaction, a temperature range that is known to be preferable when performing an enzymatic reaction may be adopted, and a certain effect can be obtained even without heating.

The chelating agent added in the present invention is conventionally considered to be effective in lowering the structural strength of the surface portion of microorganisms in organic sludge. In order to alleviate the metal ion that inhibits the action of the, it is used to block the metal ion, from this viewpoint, considering the affinity and the amount of harmful metals in organic sludge and the amount of blockage, It is necessary to adjust the type and amount of the chelating agent. The chelating agent has the effect of removing the biopolymer in the activated sludge or reducing the strength thereof, in addition to the effect as the enzyme activity promoter, so that the excess sludge or the organic sludge having a high excess sludge mixing ratio is used. It is effective for reforming.

[0015]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to only these examples. Example 1 For sludge from a sewage pretreatment plant with a large inflow of oil and fat,
The organic sludge was modified according to the present invention. Thus, the results of examining the effect of improving the sludge filterability of the modified sludge are shown. In this example, various agents were added at the addition rates shown in Table 1, and the effect of improving the filterability was examined using a CST measuring device. Tables 2 and 3 show the results of measuring the CST value, which is an index of sludge properties and sludge filterability, respectively.

In the table, TS is 5.1% and VTS is 3.0%. The sludge used here is VTS
The higher the value of / TS, the higher the organic content. In this example, a drug obtained by removing the enzyme activity promoter from the drug of the present invention was also prepared, and the effects thereof were compared. As for the order of adding the drug, first, a chelating agent was added, and after stirring for 1 hour, an enzyme agent and an enzyme activity promoter were added, followed by stirring for 11 hours. As is clear from Table 3, the filtration of the sludge is 36% by the treatment of adding the agent of the present invention.
The improvement rate was 18 points higher than that of the system without the enzyme activity promoter.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

Example 2 Sludge reforming treatment was performed on the mixed sludge of the sewage with the agent of the present invention. In this example, various chemicals were added at the addition rates shown in Table 4, and the effect of improving the dewatering property by a belt press dewatering machine was examined. Tables 5 and 6 show the results of measuring the properties of the sludge used in the experiment and the CST value, which is an index of the filterability, and the water content, respectively. In this example, a drug obtained by removing the enzyme activity promoter from the drug of the present invention was also prepared, and the effects thereof were compared. The order of adding the drugs is as follows.
After stirring for an hour, an enzyme agent and an enzyme activity promoter are added, and 1
Stir for 1 hour. In the sludge dewatering test, a polymer was added in an amount of 0.5% per sludge dry weight. Table 6 shows the results of comparing the water content of the sludge. The addition of the agent of the present invention resulted in a 4% improvement, and good results were obtained.

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

According to the present invention, organic sludge can be compactly and effectively reformed at a sludge generation site, and the filterability, sedimentation and cohesion, and dehydration of organic sludge are improved. be able to. In the present invention, since only agitation is required for the treatment and no aeration is required,
This eliminates the need for equipment for preventing odor, and can avoid the generation of noise and power consumption due to the use of a large-scale blower. In addition, the use of hydrolytic enzymes and other chemicals, which are chemicals used for the modification, is small and effective, so that the cost due to its use can be reduced.

Claims (7)

[Claims] 1. An organic sludge reforming method in which an enzyme is added to an organic sludge to treat the organic sludge with a hydrolytic enzyme, a surfactant, an alkaline earth metal compound, or an alkali metal compound. A method for reforming organic sludge, comprising adding and treating at least one enzyme activity promoter. 2. The method according to claim 1, wherein the hydrolytic enzyme is added in an amount of 0.0002 to 1.0% by weight and the enzyme activity promoter is added in an amount of 0.0001 to 2.0% by weight based on the dry weight of the sludge. The method for reforming organic sludge according to the above. 3. The method for modifying organic sludge according to claim 1, wherein a chelating agent is added to the organic sludge. 4. The lipase, β-
The method for modifying organic sludge according to any one of claims 1 to 3, wherein one or more of glucanase, protease, cellulase, and amylase are used. 5. The method for modifying organic sludge according to claim 1, wherein calcium chloride and / or magnesium chloride are used as said alkaline earth metal compound. 6. A method according to claim 6, wherein said hydrolytic enzyme and an enzyme activity promoter comprising at least one of a surfactant, an alkaline earth metal compound and an alkali metal compound are provided in a sludge storage tank such as a drum screen or a line system. The organic sludge reforming method according to any one of claims 1 to 5, wherein the organic sludge is added first in a facility or directly in a sludge storage tank. 7. An organic sludge to which a hydrolase and an enzyme activity promoter comprising at least one of a surfactant, an alkaline earth metal compound and an alkali metal compound are added is stirred in a sludge storage tank. The method for reforming organic sludge according to any one of claims 1 to 6, characterized in that: