JP2000061488A - Treatment of organic wastewater and chemical agent used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of generated excess sludge without deteriorating the quality of treated water discharged from the final stage and to reduce excess sludge treatment cost in the treatment utilizing activated sludge. SOLUTION: This purification treatment utilizing activated sludge involves in any one of its treatment process stages, controlling the pH or temp. of organic wastewater, or adding at least one chemical agent selected from alkali agents, acids, waste acids and compounds each having a sterilizing or bacterolytic effect on the activated sludge to organic wastewater, or alternatively, performing a combination of plural of the above procedures, to subject a part of constituent bacteria of the activated sludge to sterilization or bacteriolysis and to inhibit growth of the activated sludge from being caused in the treatment process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating organic wastewater, and more particularly, when treating organic wastewater with activated sludge, it suppresses the growth of bacteria constituting the activated sludge and produces a surplus. The present invention relates to a method for treating organic wastewater capable of remarkably reducing the amount of sludge generated, and a chemical agent used therefor.

[0002]

2. Description of the Related Art Pollutants in water are decomposed and purified in nature such as rivers and lakes by being subjected to physicochemical and biological actions such as precipitation, aggregation, oxidation and reduction. In particular, contaminants containing organic substances are easily purified by microorganisms by a biological action. As a method for purifying organic wastewater utilizing this, there is an activated sludge method of treating organic wastewater with activated sludge containing aerobic microorganisms. Since this method has advantages such as high purification capacity and relatively low treatment cost, various methods utilizing this method have been proposed and widely used in sewage treatment and industrial wastewater treatment. There is.

In the above-mentioned activated sludge method, waste water p
After pretreatment such as H adjustment and homogenization, the organic wastewater is led to the aeration tank (aeration tank), and in this aeration tank, organic sludge components in the wastewater indicated by BOD are decomposed by activated sludge. And is purifying. At this time, 50 to 70% of the decomposed BOD is consumed as maintenance energy for microorganisms, but the remaining 30 to 50% is used for the growth of bacterial cells, so the amount of activated sludge gradually increases. . Therefore, generally, as shown in FIG. 4, the wastewater treated in the aeration tank is guided to the settling tank, and only the amount of the returned sludge necessary for the purification treatment of the organic wastewater from the precipitated activated sludge is returned. As a result, it is returned to the aeration tank and the other activated sludge is removed as excess sludge. In this way, a large amount of excess sludge is generated in the purification treatment of organic wastewater using activated sludge, but this excess sludge contains a biodegradable substance or the like,
It has drawbacks such as high viscosity and difficulty in handling, and when purifying organic wastewater by the activated sludge method, excess sludge treatment is always a problem.

On the other hand, currently used methods for treating excess sludge are the methods of dehydrating the excess sludge to separate the water content, incinerating the solid content, or landfilling it as industrial waste. Alternatively, excess sludge is subjected to anaerobic digestion, decomposed into methane gas, carbon dioxide, hydrogen, hydrogen sulfide, etc. to reduce the amount, and thereafter excess sludge and other solid matter that have not been decomposed are separated by dehydration to remove solids. There are methods such as incineration or disposal as industrial waste. Furthermore, in recent years, for the purpose of reducing excess sludge, a method of treating a part of the excess sludge with ozone and then introducing the ozone-treated sludge into an aeration tank to perform aerobic treatment is known. (See JP-A-57-19719, JP-A-7-88495, etc.).

However, the above-mentioned conventional method for treating excess sludge has various problems as described below. First, when the excess sludge is concentrated by a dehydrator without performing anaerobic digestion treatment and incinerated or disposed of as industrial waste, there is a problem that the treatment cost is significantly increased due to the large amount of excess sludge. The current sludge disposal cost is as high as 20,000 yen / m ^3, and this disposal cost tends to rise further in the future. In addition, the impact on the global environment such as the problem of securing landfill disposal sites and the problem of increased energy consumption due to sludge incineration cannot be overlooked.

The above-mentioned method for reducing excess sludge by anaerobic digestion has the advantage that energy is recovered as methane gas, but the number of days required for digestion is as long as 20 to 40 days, and excess sludge is required. Since the decomposition rate of is as low as about 60%, a large site area is required, and undecomposed excess sludge and other solids must be separated by a dehydrator and incinerated or disposed of as industrial waste. There is a problem of inefficiency and high processing cost. Further, similar to the above, there is a problem of influence on the global environment.

Further, the method of treating a part of the excess sludge with ozone can considerably reduce the volume of the excess sludge, but it is necessary to provide a special ozone generator. Therefore, it is not suitable for small-scale facilities, and there is a practical problem that the facility cost is high, the operating cost is high, the treatment cost is high, and the economy is poor.

[0008]

Therefore, an object of the present invention is to produce an excess sludge in a method for treating organic wastewater using activated sludge without deteriorating the quality of the treated water discharged at the final stage. An object of the present invention is to provide a simple and economical method for treating organic wastewater, which is capable of significantly reducing the amount of the sludge to reduce the cost required for treating excess sludge, and a chemical agent used therefor.

[0009]

The above objects can be achieved by the present invention described below. That is, the present invention, when purifying the organic wastewater using the activated sludge, by controlling the pH or temperature in any treatment process, or by alkaline agent, acid or waste acid, activated sludge Or by adding at least one selected from compounds having a bactericidal action or a bacteriolytic action to
By combining the above, a method for treating organic wastewater characterized by sterilizing or lysing a part of bacteria constituting active sludge to suppress the growth of activated sludge during the treatment process, and used for this It is a drug.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiments of the present invention will be described in more detail. As a result of earnest research to solve the above-mentioned problems of the prior art, the present inventors have conducted an aeration tank in a conventional organic wastewater treatment method using activated sludge as shown in FIG. Some of the activated sludge taken out from the inside or from the settling tank, by controlling the pH or temperature, or an alkaline agent, acid or waste acid, a compound having a bactericidal action or bacteriolytic action to the activated sludge Sterilization or bactericidal treatment by adding or by combining two or more of the above requirements (hereinafter, also simply referred to as various sterilizing or bacteriolytic treatment means) and returning the treated substance to the aeration tank again for activated sludge treatment. If you do
The present inventors have found that the amount of surplus sludge generated can be made extremely small without deteriorating the quality of the final treated water as compared with the conventional case, and arrived at the present invention.

That is, when the activated sludge is treated by the above-mentioned various sterilization or bacteriolysis treatment means, all of the above means destroy and destroy the cell wall (membrane) of the bacteria constituting the activated sludge. It has excellent functions to lyse bacteria and hydrolyze the cytoplasm that makes up the bacteria to cause functional disorders, so the bacterial cell wall is destroyed and polysaccharides and proteins in the cell wall are dissolved. (In this specification, this state is referred to as lysis), since the bacteria themselves become organic pollutants in the wastewater indicated by BOD and serve as a suitable bait for the bacteria, excessive growth of the activated sludge is suppressed, Reduction of excess sludge generation is achieved. Furthermore, the method is not limited to the method of treating a part of the activated sludge taken out from the aeration tank or the settling tank, and in the case of purifying the organic wastewater by using the activated sludge, any of the treatment steps may be performed. , A part of the bacteria constituting the activated sludge is sterilized or lysed by various sterilization or lysis treatment means, and the amount of activated sludge in the treatment process can be maintained at a necessary and sufficient amount for purification treatment, It was found that the amount of excess sludge generated can be made extremely small without impairing the quality of the final treated water.

The inventors of the present invention have controlled the pH or the temperature, or added a compound having a bactericidal action or a bactericidal action to an alkaline agent, an acid or a waste acid and activated sludge, or various combinations of these. By sterilizing or lysing the bacteria that make up the activated sludge by means, the amount of excess sludge generated can be reduced because the excessive growth of activated sludge is suppressed as follows. I believe. In the biological treatment of wastewater with activated sludge, the organic matter in the water to be treated is oxidatively decomposed by the bacteria constituting the activated sludge, and along with this, the bacteria themselves grow using the organic matter as a nutrient source. Therefore, it can be said that the organic matter in the wastewater was converted into bacteria by observing only the phenomenon caused by the bacterial treatment. According to the study by the present inventors, in terms of conversion rate of organic matter to bacteria, the conversion rate is about 40 to 50.
%, And 100 parts by weight of organic matter is converted to about 40 to 50 parts by weight of bacteria. On the other hand, when this phenomenon is viewed from the bacteria side, the amount of bacteria has increased by 40 to 50 parts by weight. Then, these bacteria are cannibalized with each other, or are predated by protozoa, and are precipitated as activated sludge having good cohesiveness and sedimentability.

Therefore, if the present inventors can promote so-called cannibalism of bacteria, the amount of bacteria (activated sludge) that gradually grows by using organic matter as food can be reduced, and the generation of excess sludge can be prevented. We considered that the problem could be resolved, and conducted various studies on conditions that could promote cannibalism of bacteria. As a result, by controlling the pH or temperature of the activated sludge treatment tank,
Alternatively, by adding an alkaline agent, an acid or a waste acid, or a compound having a bactericidal action or a bacteriolytic action to the activated sludge, and further by treating under a condition in which these means are combined, the activity is increased. Since the cell walls of the bacteria that make up the sludge can be easily destroyed and sterilized or lysed to dissolve the polysaccharides and proteins in the cell walls (see Fig. 1), the bacteria themselves are indicated by BOD. It was found to be effective because it can be efficiently converted into organic pollutants. That is, since polysaccharides and proteins that appear when bacteria are sterilized or lysed serve as suitable feeds for bacteria and protozoa, a part of the activated sludge is treated with the various sterilization or lysis treatment means described above. Then, it becomes possible to remarkably suppress the growth of bacteria (see FIG. 1).

In the method for treating organic wastewater of the present invention,
When purifying organic wastewater using activated sludge,
In any treatment process, any condition may be used as long as a part of the bacteria constituting the activated sludge is treated by the various sterilization or lysis treatment means described below. In the present invention, as a means for sterilizing or lysing part of the bacteria, by controlling the pH value or temperature in the treatment tank containing the activated sludge to be treated within a specific range,
Alternatively, a method of adding an alkaline agent, an acid or a waste acid, or a compound having a bactericidal action or a bacteriolytic action to activated sludge is used in the treatment tank. Furthermore, in order to improve the efficiency of sterilizing or lysing part of the bacteria constituting the activated sludge, it is preferable to carry out by a method in which the above means are appropriately combined. Hereinafter, these processing means will be described.

First, when the pH value is controlled,
The pH value in the treatment tank containing the activated sludge to be treated is set to 4.5 or less, preferably 2.5 to 3.5 in a strong acid state, or the pH value in the treatment tank is set to 9. It is preferable to make it a strong alkaline state of 5 or more, preferably 10 to 12. As a specific method for controlling the pH value,
An alkaline agent, an acid or a waste acid as described below may be added to the treatment tank so that the pH value in the treatment tank falls within the above range.

In the method for treating organic wastewater of the present invention,
It is also effective to control the temperature in the treatment tank containing the activated sludge to be treated to sterilize or lyse a part of the bacteria constituting the activated sludge by heat. For example, the temperature in the treatment tank containing the activated sludge to be treated is 40 to 1
If the temperature is controlled to 00 ° C, more preferably 40 to 80 ° C,
Proteins constituting the cell wall (membrane) or cytoplasm of bacteria are denatured or coagulated by heat, resulting in death or dysfunction of the bacteria, and therefore bacteria can be killed or lysed. Particularly, considering the cost of heating, it is preferable to perform the treatment at about 40 to 50 ° C. In the method for treating the organic wastewater of the present invention, either one of controlling the pH value in the treatment tank as described above or controlling the temperature in the treatment tank as described above is used. By this, a part of the bacteria constituting the activated sludge can be sterilized or lysed. Further, treatment may be carried out under conditions in which both means for controlling the pH value and temperature control are appropriately combined to sterilize or lyse a part of the bacteria constituting the activated sludge.

Further, in the method for treating organic wastewater of the present invention, the activity is obtained by adding an alkaline agent, an acid or a waste acid, and a compound having a bactericidal action or a bacteriolytic action to activated sludge in the treatment tank. A part of the bacteria that make up the sludge may be sterilized or lysed. Examples of the alkaline agent used in this case include sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and ammonia. When treated in a treatment tank with the addition of these alkaline agents, the cell wall (membrane) of the bacteria that make up the activated sludge is damaged and destroyed, and has a large function of sterilizing or lysing the bacteria. Since it is a cheap compound having a function of hydrolyzing the cytoplasm that constitutes bacteria to cause dysfunction, and yet achieving the intended purpose of the present invention described above simply and economically. obtain.

The present inventors conducted the following simulated experiments in order to find the optimum treatment conditions when treating activated sludge with an alkaline agent. As a test method, first, a plurality of 1-liter graduated cylinders were prepared, and activated sludge was adjusted to 5,000 mg / liter in each graduated cylinder. Furthermore, milk was used as artificial wastewater, and the amount of BOD in this was 1.0 kg / m ³
The solution was added once a day so that the solution was well agitated each time, and then aerated. And in the meantime, 1 a day
At a normal temperature and 40 ° C., 1000 mg of activated sludge was taken out, alkali agents were added to each of the following pHs for treatment, and the treated sludge was returned to the original activated sludge. . Further, for comparison, a system not treated with an alkaline agent was also run in parallel. The processing conditions at this time are shown in Table 1.

[0019]

[Table 1] Table 1 Alkaline treatment conditions

As a result, when the alkaline agent is added to the activated sludge at room temperature, when the pH of the activated sludge treated with the added alkaline agent is 9.5 or more, the average sludge generation amount of the average sludge. It was found that (g / day) decreased. It was also found that the amount of the alkaline agent added was smaller when the treatment was carried out at 40 ° C. than when it was at room temperature. Furthermore, as a result of the above study, even when a part of the activated sludge is sterilized or lysed in this way, there is no difference compared to the case of the conventional organic wastewater treatment method, and that the purification capacity does not decrease. It could be confirmed.

In the method for treating organic wastewater of the present invention, in the activated sludge treatment tank (aeration tank), acid or waste acid is added instead of the above-mentioned alkaline agent to remove the bacteria constituting the activated sludge. A part may be sterilized or lysed. Examples of the acid used in this case include sulfuric acid, nitric acid, hydrochloric acid and the like. Further, waste acid discharged as waste from various factories can be effectively used, but it is particularly preferable to use waste nitric acid. In the present invention, it is also possible to use waste sulfuric acid, waste hydrochloric acid, etc. which are discharged as waste from various factories. These acids or waste acids have the function of sterilizing or lysing bacteria by damaging and destroying the cell wall (membrane) of the bacteria that make up the activated sludge when the activated sludge is treated, and at a low cost. Since the compound is a compound, the intended purpose of the present invention described above can be achieved simply and economically. As a result of a detailed study by the present inventors, in this case as well, it is possible to sterilize or lyse a part of the bacteria constituting the activated sludge even at room temperature, of course, only by adding an acid. As in the case of the alkaline agent, it was found that efficient treatment can be performed by controlling the temperature in the treatment tank to around 40 to 50 ° C.

Further, in the method for treating organic wastewater of the present invention, the activated sludge is constituted by adding any one of the compounds having a bactericidal action or bacteriolytic action to the activated sludge as described below. A part of bacteria can be sterilized or lysed. That is, in an activated sludge treatment tank containing activated sludge to be treated, sorbic acid, sodium sorbate, potassium sorbate, calcium sorbate, aldehydes typified by glutaraldehyde, cationic surfactants, nonionic Surfactants, amphoteric surfactants, chlorine compounds, polyamines, aliphatic amines, phenols, nitrofurans, compounds having a trichloroalkylthio group, dithiocarbamates,
An activated sludge is formed by adding at least one compound selected from alcohols, protease, glucanase, amylase, monoperoxyphthalate magnesium, hydrogen peroxide, sodium peroxide, sodium percarbonate, and sodium carbide. Some of the bacteria present can be sterilized or lysed. These compounds are
Despite having a bactericidal action or a bacteriolytic action on the activated sludge, it does not have strong toxicity, and the drug effect does not affect the properties of the activated sludge such as pH dependency and temperature dependency, and Since it is cost effective, it can be preferably used in the method for treating organic wastewater of the present invention. The addition amount of these compounds is preferably about 0.1 to 5% by weight with respect to the activated sludge to be treated.

The compounds listed above have the function of causing damage to the cell wall (membrane) of the bacteria constituting the activated sludge and destroying them to lyse the bacteria, and the dysfunction of the bacteria due to oxidative decomposition of organic components. The function that causes it, the function that causes binding to bacterial cell proteins, the function that causes protein denaturation and coagulation, and the function that causes inactivation and destruction of the enzyme system and the occurrence of metabolic damage that causes functional failure in activated sludge. It has various functions such as making it. Therefore, if any one of these compounds is added and treated, a part of the bacteria constituting the activated sludge can be sterilized or lysed. However, in order to further improve the efficiency of sterilization or lysis treatment, it is preferable to use these compounds in combination with the above-mentioned alkaline agent, acid or waste acid. That is, if a compound having an appropriate function is selected from the above-listed compounds and used in combination with an alkali agent or an acid, depending on the properties of the organic wastewater to be treated, the treatment conditions, etc., the function different from that of the alkali agent or the acid is obtained. Since a combined synergistic effect is obtained, it becomes possible to more effectively sterilize or lyse bacteria. Therefore, a chemical agent containing an alkaline agent or an acid as a main component and the above-mentioned compounds in combination can be suitably used in the method for treating organic wastewater of the present invention. Furthermore, it is also preferable to control the temperature in the activated sludge treatment tank and perform the treatment in a heated state.

Further, as a mode in which the above-mentioned compounds are used in combination with an alkaline agent, an acid or a waste acid, for example, the following treatment methods (1) to (3) can be adopted. Therefore, when preparing a chemical agent containing an alkali agent or an acid as a main component to be used in the method for treating organic wastewater of the present invention, a form which can be conveniently used for these treatment methods is appropriately prepared. It is preferable. Prior to the alkali agent treatment (or acid treatment), the compound is treated with the combined compound, and then the alkali agent treatment (or acid treatment)
Do. When the treatment with an alkaline agent (or the treatment with an acid), a compound to be used in combination is added and the treatment is performed in combination with an alkaline agent (or an acid). After treatment with an alkaline agent (or acid treatment), a concomitant compound is added to perform treatment.

In the method for treating organic wastewater of the present invention, for example, when an acid is used for sterilizing or lysing lysis of activated sludge, sorbic acid, sodium sorbate, potassium sorbate, calcium sorbate, a peroxide and At least one selected from hydrogen oxide and sodium percarbonate
It is preferable to use two kinds of compounds in combination. As a specific combination, for example, a combination of about 0.1 to 5% by weight of hydrogen peroxide with respect to nitric acid or hydrochloric acid can be mentioned. In this case, it is also preferable to use waste nitric acid or hydrochloric acid as the acid, especially waste nitric acid, in view of economy and protection of the global environment. In the method for treating organic wastewater of the present invention, as a combination of a particularly preferred alkaline agent and a compound used in combination therewith, for example, a combination of an alkaline agent and a cationic surfactant, a combination of an alkaline agent and a chlorine compound, an alkaline agent And a combination of protease and a combination of an alkaline agent and glutaraldehyde.

Specific examples of the cationic surfactant used in combination with the alkaline agent include di- or mono-long-chain alkyl, di- or tri-lower alkyl or benzyl ammonium of a quaternary ammonium salt type cationic surfactant. Examples thereof include salts, and examples thereof include dialkyldimethylammonium salt, alkyldimethylethylammonium salt, alkyltrimethylammonium salt, alkyldimethylbenzylammonium salt, alkylamidopropyldimethylbenzylammonium salt and the like. More specifically, for example, didecyldimethylammonium chloride, dioctyldimethylammonium chloride, benzethonium chloride, trimethoxysilylpropyldimethyloctadecylammonium chloride,
Decylisononyldimethylammonium chloride can be used. Of course, other salts may be used.

Pyridinium type cationic surfactants such as alkylpyridinium salts and alkylquinolinium salts are also preferably used, and for example, alkylquinolinium chloride having 12 carbon atoms can be used. Furthermore,
Amphoteric surfactants such as alkyldi (aminoethyl) glycine hydrochloride and di (alkylaminodiethyl) glycine hydrochloride may also be used.

Further, in the present invention, as specific compounds to be used in combination with the alkaline agent, in addition to the above, polyamines such as chlorhexidine hydrochloride and chlorhexidine gluconate (these are also organic chlorine compounds), chlorine dioxide, Inorganic chlorine compounds such as sodium hypochlorite are also effective. Furthermore, proteases such as papain and various enzymes such as glucanase and amylase can be preferably used. In addition, aliphatic amines such as N-alkylenealkyldiamine, aldehydes such as glutaraldehyde, phenols such as cresol, peroxides such as hydrogen peroxide and sodium peroxide, sodium percarbonate, sodium carbide, monoperoxy. Magnesium phthalate and the like can also be used.

A suitable system diagram of the method for treating organic wastewater according to the present invention is shown in FIG. 2. As shown in FIG. 2, after introducing the organic wastewater into the treatment tank and performing aeration treatment with the activated sludge. , At least a part of the activated sludge is introduced into the sludge treatment tank from the treatment tank (aeration tank) or a settling tank provided downstream of the treatment tank, and the pH or temperature in the sludge treatment tank By appropriately controlling, or after sterilizing or lysing the activated sludge by adding an alkali agent, an acid or a waste acid, a compound having a bactericidal action or a bacteriolytic action to the activated sludge, the treated activity The sludge is introduced into the treatment tank for the organic waste water, and the aeration treatment is continued again. As a result, compared with the conventional organic wastewater purification system shown in FIG.
It is possible to reduce the amount to / 100.

In the present invention, the activated sludge to be sterilized or lysed by bacteria in the sludge treatment tank may be of any treatment stage. For example, as in the example shown in FIG. 2, a part of the returned sludge returned from the settling tank to the aeration tank is extracted and guided to a sludge treatment tank, and the activated sludge is sterilized or lysed in the tank, After that, the treated sludge may be returned to the aeration tank to continue the treatment. Further, as another embodiment, as shown in FIG. 3, when the treatment is carried out by a batch type activated sludge method without a settling tank, a part of the treated water in the aeration tank is extracted. It may be introduced into a sludge treatment tank and subjected to sterilization or lysis treatment by various sterilization or lysis treatment means. Further, although the sludge treatment tanks are separately provided in both of the examples shown in FIGS. 2 and 3, for example, in the case of a domestic septic tank, an alkaline agent,
An acid or a waste acid, or a compound having a bactericidal action or a bacteriolytic action on activated sludge, or a combination thereof may be added as an alkaline agent, an acid or a waste acid, particularly a drug having waste nitric acid as a main component, This makes it possible to reduce the amount of excess sludge generated.

[0031]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples of the present invention. <Example 1> (Acid treatment at room temperature) Using a treatment facility of 800 m ³ / day constructed according to the flow shown in FIG. 2, 0.8 kg / BOD load was used.
Activated sludge treatment of organic wastewater was performed using the organic wastewater from a food factory handling m ³ dairy products as raw water. The properties of the raw water are shown in Table 2. In this embodiment, this raw water is treated with activated sludge concentration (MLSS) of 5,000 m according to the flow shown in FIG.
Aerated with activated sludge at g / l.

[0032]

[Table 2] Table 2 Raw water condition (food factory wastewater)

In this embodiment, a part of the returned sludge is extracted from the above treatment process and introduced into the sludge treatment tank, and sulfuric acid is introduced into the sludge treatment tank to form the activated sludge. Was partially sterilized or lysed. Concentration of returned sludge is 1
It was 50,000 mg / l (about 1% concentration). The returned sludge was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr. Then, after adding 75% sulfuric acid in the sludge treatment tank to adjust the pH in the sludge treatment tank to 3.0, sterilization or bacteriolysis was performed at room temperature (20 ° C.). The treatment was terminated with a residence time of 6 hours, and the treated activated sludge was treated with 800 m ³
It returned to the inside of the aeration tank and was processed by the normal processing flow.

As a result, the amount of excess sludge generated was about 40.
It was kg / day. On the other hand, as shown in Comparative Example 1 to be described later, the amount of surplus sludge in the conventional treatment method in which a part of the returned sludge is not sterilized is 200 k.
It was g / day, and the amount of excess sludge could be obviously reduced by the method of this example. Further, the water quality of the final treated water was examined, and as shown in Table 4, there was no difference as compared with the case of treating by the conventional method described in Comparative Example 1 to be described later, and the organic matter of this example was compared. It was confirmed that the purification capacity did not deteriorate even in the wastewater treatment method. In this example, the treatment amount of the activated sludge (concentration 10,000 mg / l) subjected to the sterilization or lysis treatment was 8
It was 0 m ³ / day. In this example, the amount of activated sludge that has been sterilized or lysed in the activated sludge treatment tank is obtained as a ratio (rate) with respect to the total amount of activated sludge (4,000 kg / day) existing in the treatment process. And 20%. Table 3 collectively shows the processing conditions and the like of this example.

<Example 2> (Alkaline treatment at room temperature) In the same manner as in Example 1, a part of the returned sludge was extracted and introduced into the sludge treatment tank, and in this embodiment, the sludge treatment tank was hydrated. Sodium was added to sterilize or lyse a part of the bacteria constituting the activated sludge. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr. Then, 25% sodium hydroxide was added to adjust the pH in the sludge treatment tank to 10.0, and then sterilization or bacteriolysis was performed at room temperature (20 ° C.). 6
The treatment was terminated at the retention time of time, the treated activated sludge was returned to the inside of the aeration tank of 800 m ³ , and the treatment was carried out by the usual treatment flow.

As a result of the above treatment, the amount of excess sludge generated was about 40 kg / day, and the amount of excess sludge could be reduced as in Example 1. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also in this example, as in Example 1, the amount of activated sludge subjected to sterilization or lysis treatment was 80 m ³ / day, and the total amount of activated sludge subjected to sterilization or lysis treatment was The rate was 20% as well. Table 3 collectively shows the processing conditions of this example.

<Embodiment 3> (Heat Treatment) After returning a portion of the returned sludge to the sludge treatment tank and introducing it into the sludge treatment tank in the same manner as in Example 1, heated steam is introduced into the sludge treatment tank in this embodiment. Then, a part of the bacteria constituting the activated sludge was sterilized or lysed by heat. Introduce sludge of about 1% concentration into the sludge treatment tank at a flow rate of ³ m ³ / hr,
The temperature in the sludge treatment tank was kept at 70 ° C. for sterilization or bacteriolysis. The treatment was terminated with a residence time of 6 hours, the treated activated sludge was returned into the aeration tank of 800 m ³ , and the treatment was performed according to a normal treatment flow.

As a result of the above treatment, the amount of excess sludge generated was about 40 kg / day, and the amount of excess sludge could be reduced as in Example 1. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also in this example, as in Example 1, the amount of activated sludge subjected to sterilization or lysis treatment was 80 m ³ / day, and the total amount of activated sludge subjected to sterilization or lysis treatment was The rate was 20% as well. Table 3 collectively shows the processing conditions of this example.

<Example 4> (potassium sorbate addition treatment) [0039] In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into the sludge treatment tank, in this embodiment, it was placed in the sludge treatment tank. Potassium sorbate was added at a concentration of 0.3 g / liter to sterilize or lyse a part of the bacteria constituting the activated sludge. At this time, about 1 to the sludge treatment tank
% Active sludge was introduced at a flow rate of ³ m ³ / hr. Then, sterilization or lysis treatment was performed at room temperature (20 ° C.). 6
The treatment was terminated at the retention time of time, the treated activated sludge was returned to the inside of the aeration tank of 800 m ³ , and the treatment was carried out by the usual treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 40 kg / day, and it was possible to reduce the amount of excess sludge as in Example 1. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also in this example, as in Example 1, the amount of activated sludge subjected to sterilization or lysis treatment was 80 m ³ / day, and the total amount of activated sludge subjected to sterilization or lysis treatment was The rate was 20% as well. Table 3 collectively shows the processing conditions of this example.

<Example 5> (Glutaraldehyde addition treatment) In this example, glutaraldehyde is charged into the sludge treatment tank at 0.3 g / liter instead of potassium sorbate for treatment. In the same manner as in Example 4, a part of the bacteria constituting the activated sludge was sterilized or lysed. The activated sludge treated as above is then
Back to 800 m ³ in the aeration tank and subjected to processing by conventional process flow.

As a result of the above treatment, the amount of excess sludge generated was about 40 kg / day, and the amount of excess sludge could be reduced as in Example 1. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also in this example, as in Example 1, the amount of activated sludge subjected to sterilization or lysis treatment was 80 m ³ / day, and the total amount of activated sludge subjected to sterilization or lysis treatment was The rate was 20% as well. Table 3 collectively shows the processing conditions of this example.

<Example 6> (Addition treatment of decyl isononyl dimethyl ammonium) In this example, decyl isononyl dimethyl ammonium was added to the sludge treatment tank in place of potassium sorbate at a concentration of 0.
A part of the bacteria constituting the activated sludge was sterilized or lysed in the same manner as in Example 4 except that the treatment was carried out by adding 5 g / liter. The activated sludge treated as described above was then returned to the aeration tank of 800 m ³ and treated by the usual treatment flow.

As a result of the above treatment, the amount of excess sludge generated was about 40 kg / day, and the amount of excess sludge could be reduced as in Example 1. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also in this example, as in Example 1, the amount of activated sludge subjected to sterilization or lysis treatment was 80 m ³ / day, and the total amount of activated sludge subjected to sterilization or lysis treatment was The rate was 20% as well. Table 3 collectively shows the processing conditions of this example.

<Example 7> (Acid treatment + potassium sorbate addition treatment) In the same manner as in Example 1, a part of the returned sludge was extracted and introduced into a sludge treatment tank. Potassium sorbate was added to the tank so that it would be 0.2 g / l, and the pH of the treatment tank was adjusted to 3.0 with waste nitric acid. A part was sterilized or lysed. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr. Then, sterilization or lysis treatment was performed at room temperature (20 ° C.). The treatment was completed after a residence time of 4 hours, and the treated activated sludge was treated with 8
Back to 00m ³ in the aeration tank and subjected to processing by conventional process flow.

As a result of the above treatment, the amount of excess sludge generated was about 30 kg / day, and the amount of excess sludge could be reduced. Further, when the final treated water was examined, as shown in Table 4, the treatment of the organic wastewater of this example was comparable with that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 6
It was 0 m ³ / day, and the ratio of the activated sludge that had been sterilized or lysed to the total activated sludge was 15%. Table 3
The processing conditions of this example are shown together. Further, in the case of this example, the treatment was performed in a state where two kinds of compounds were added, but as compared with the cases of Examples 1 to 6 in which the treatment was performed under a single requirement, a more efficient treatment was obtained. Is possible,
It was found that the residence time can be shortened, moreover, efficient treatment can be performed even if the ratio of activated sludge to be treated such as sterilization is small, and an excellent effect of reducing the excess sludge amount can be obtained.

<Embodiment 8> (Alkaline agent + glutaraldehyde addition treatment) In the same manner as in Embodiment 1, after a part of the returned sludge was extracted and introduced into the sludge treatment tank, in the present embodiment, the sludge treatment tank was treated. Glutaraldehyde was added to the inside so that it would be 0.2 g / l, and the pH was adjusted to 10 with 25% sodium hydroxide.
It was adjusted to 0, and a part of the bacteria constituting the activated sludge was sterilized or lysed. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr. Then, sterilization or lysis treatment was performed at room temperature (20 ° C.). The treatment was terminated after a residence time of 3 hours, the treated activated sludge was returned to the aeration tank of 800 m ³ , and the treatment was carried out according to a usual treatment flow.

As a result of the above treatment, the amount of excess sludge generated was about 30 kg / day, and the amount of excess sludge could be reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 6
It was 0 m ³ / day, and the ratio of the activated sludge that had been sterilized or lysed to the total activated sludge was 15%. Table 3
The processing conditions of this example are shown together. Further, in the case of this example, the treatment was performed in a state where two kinds of compounds were added, but as compared with the cases of Examples 1 to 6 in which the treatment was performed under a single requirement, a more efficient treatment was obtained. Is possible,
It was found that the residence time can be shortened, moreover, efficient treatment can be performed even if the ratio of activated sludge to be treated such as sterilization is small, and an excellent effect of reducing the amount of excess sludge can be obtained.

<Example 9> (Alkaline agent + decylisononyldimethylammonium addition treatment) In the same manner as in Example 1, one part of the returned sludge was extracted and introduced into a sludge treatment tank. Decylisononyldimethylammonium was added to the sludge treatment tank at 0.3 / liter, and the pH was adjusted to 9.0 with 25% sodium hydroxide to form active sludge. A part of the bacteria that are sterilized or lysed.
At this time, 3m of activated sludge with a concentration of about 1% was added to the sludge treatment tank.
^It was introduced at a flow rate of ³ / hr. Then, sterilization or lysis treatment was performed at room temperature (20 ° C.). The treatment was terminated with a residence time of 4 hours, the treated activated sludge was returned to the 800 m ³ aeration tank, and treatment was carried out according to a normal treatment flow.

As a result of the above treatment, the amount of excess sludge generated was about 30 kg / day, and the amount of excess sludge could be reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 6
It was 0 m ³ / day, and the ratio of the activated sludge that had been sterilized or lysed to the total activated sludge was 15%. Table 3
The processing conditions of this example are shown together. Further, in the case of this example, the treatment was performed in a state where two kinds of compounds were added, but as compared with the cases of Examples 1 to 6 in which the treatment was performed under a single requirement, a more efficient treatment was obtained. Is possible,
It was found that the residence time can be shortened, moreover, efficient treatment can be performed even if the ratio of activated sludge to be treated such as sterilization is small, and an excellent effect of reducing the excess sludge amount can be obtained.

<Example 10> (Heat treatment + acid treatment) After a part of the returned sludge was extracted and introduced into the sludge treatment tank in the same manner as in Example 1, in this embodiment, the sludge treatment tank was heated. Steam was introduced and heated, and further, the pH was adjusted to 3.0 with 75% sulfuric acid to sterilize or lyse a part of the bacteria constituting the activated sludge. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr, and sterilized or lysed at 50 ° C. Four
The treatment was terminated at the retention time of time, the treated activated sludge was returned to the inside of the aeration tank of 800 m ³ , and the treatment was carried out by the usual treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be significantly reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Further, in this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of sterilized or lysis treatment to total activated sludge was 12.5%. Met. Table 3 collectively shows the processing conditions of this example. Further, in the case of the present example, the treatment was carried out in a state where two kinds of requirements including heat treatment were added, but as compared with the case of Examples 1 to 6 in which the treatment was carried out under the single requirement, the residence time was changed. It has been found that the same effect can be obtained even when the ratio of activated sludge to be treated is small, as well as being able to shorten. Moreover, Example 7 in which two kinds of compounds were added for treatment
It was found that even if the ratio of the activated sludge to be sterilized or lysed was smaller than that in Example 9, the same effect was obtained and the efficiency was good.

<Example 11> (Heat treatment + Alkali agent treatment) In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into the sludge treatment tank, in this embodiment, it was placed in the sludge treatment tank. A heating steam was introduced and heated, and further, the pH was adjusted to 10.0 with 25% sodium hydroxide, and a part of bacteria constituting the activated sludge was sterilized or lysed. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr, and sterilized or lysed at 50 ° C. The treatment was terminated with a residence time of 4 hours, the treated activated sludge was returned to the 800 m ³ aeration tank, and treatment was carried out according to a normal treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be significantly reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Further, in this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of sterilized or lysis treatment to total activated sludge was 12.5%. Met. Table 3 collectively shows the processing conditions of this example. Further, in the case of the present example, the treatment was carried out in a state where two kinds of requirements including heat treatment were added, but as compared with the case of Examples 1 to 6 in which the treatment was carried out under the single requirement, the residence time was changed. It has been found that the same effect can be obtained even when the ratio of activated sludge to be treated is small, as well as being able to shorten. Moreover, Example 7 in which two kinds of compounds were added for treatment
It was found that even if the ratio of the activated sludge to be sterilized or lysed was smaller than that in Example 9, the same effect was obtained and the efficiency was good.

<Example 12> (Heat treatment + potassium sorbate addition treatment) In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into the sludge treatment tank, the sludge treatment tank was used in this embodiment. A heating steam was introduced thereinto to heat the mixture, and then potassium sorbate was added at a concentration of 0.2 g / liter to sterilize or lyse some of the bacteria constituting the activated sludge.
At this time, 3m of activated sludge with a concentration of about 1% was added to the sludge treatment tank.
^It was introduced at a flow rate of ³ / hr and sterilized or lysed at 50 ° C. The treatment was terminated with a residence time of 4 hours, the treated activated sludge was returned to the 800 m ³ aeration tank, and treatment was carried out according to a normal treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be greatly reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Further, in this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of sterilized or lysis treatment to total activated sludge was 12.5%. Met. Table 3 collectively shows the processing conditions of this example. Further, in the case of the present example, the treatment was carried out in a state where two kinds of requirements including heat treatment were added, but as compared with the case of Examples 1 to 6 in which the treatment was carried out under the single requirement, the residence time was changed. It has been found that the same effect can be obtained even when the ratio of activated sludge to be treated is small, as well as being able to shorten. Moreover, Example 7 in which two kinds of compounds were added for treatment
It was found that even if the ratio of the activated sludge to be sterilized or lysed was smaller than that in Example 9, the same effect was obtained and the efficiency was good.

<Example 13> (Heat Treatment + Glutaraldehyde Addition Treatment) In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into the sludge treatment tank, in the present embodiment, the sludge treatment tank A heating steam was introduced into the mixture to heat it, and then glutaraldehyde was added at a concentration of 0.2 g / liter to sterilize or lyse a part of the bacteria constituting the activated sludge.
At this time, 3m of activated sludge with a concentration of about 1% was added to the sludge treatment tank.
^It was introduced at a flow rate of ³ / hr and sterilized or lysed at 50 ° C. The treatment was terminated with a residence time of 4 hours, the treated activated sludge was returned to the 800 m ³ aeration tank, and treatment was carried out according to a normal treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be significantly reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Further, in this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of sterilized or lysis treatment to total activated sludge was 12.5%. Met. Table 3 collectively shows the processing conditions of this example. Further, in the case of the present example, the treatment was carried out in a state where two kinds of requirements including heat treatment were added, but as compared with the case of Examples 1 to 6 in which the treatment was carried out under the single requirement, the residence time was changed. It has been found that the same effect can be obtained even when the ratio of activated sludge to be treated is small, as well as being able to shorten. Moreover, Example 7 in which two kinds of compounds were added for treatment
It was found that even if the ratio of the activated sludge to be sterilized or lysed was smaller than that in Example 9, the same effect was obtained and the efficiency was good.

<Example 14> (Heat treatment + decylisononyldimethylammonium addition treatment) In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into a sludge treatment tank, the sludge was treated in this example. Introduce heating steam into the treatment tank to heat it, and then add decylisononyldimethylammonium at 0.3 g / liter to sterilize or lyse some of the bacteria that make up the activated sludge. did. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr, and sterilized or lysed at 50 ° C. The treatment was terminated with a residence time of 4 hours, the treated activated sludge was returned to the 800 m ³ aeration tank, and treatment was carried out according to a normal treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be significantly reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Further, in this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of sterilized or lysis treatment to total activated sludge was 12.5%. Met. Table 3 collectively shows the processing conditions of this example. Further, in the case of the present example, the treatment was carried out in a state where two kinds of requirements including heat treatment were added, but as compared with the case of Examples 1 to 6 in which the treatment was carried out under the single requirement, the residence time was changed. It has been found that the same effect can be obtained even when the ratio of activated sludge to be treated is small, as well as being able to shorten. Moreover, Example 7 in which two kinds of compounds were added for treatment
It was found that the same effect can be obtained even when the ratio of the activated sludge to be sterilized or lysed is smaller than in the case of Example 9.

<Example 15> (Heat treatment + acid treatment + addition of potassium sorbate) In the same manner as in Example 1, a part of the returned sludge was extracted and introduced into a sludge treatment tank. Heated steam is introduced into the treatment tank to heat it, potassium sorbate is added to 0.1 g / liter, and the pH is adjusted to 75 with 75% sulfuric acid to remove activated sludge. A part of the constituting bacteria was sterilized or lysed. At this time, the activated sludge with a concentration of about 1% was added to the sludge treatment tank at 3 m ³ /
It was introduced at a flow rate of hr and sterilized or lysed at 50 ° C. The treatment was terminated after a residence time of 3 hours, the treated activated sludge was returned to the aeration tank of 800 m ³ , and the treatment was carried out according to a usual treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was almost 0 kg / day, and the amount of excess sludge could be further reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. or,
In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of activated sludge subjected to sterilization or lysis treatment to the total activated sludge was 12.5%. It was Table 3 collectively shows the processing conditions of this example.
Further, in the case of this example, the treatment was performed in the state where three kinds of requirements including the heat treatment were added, but the treatment was performed alone or in the state where two kinds of requirements were added. Examples 1 to 14
It was found that the residence time can be shortened as compared with the case. Moreover, it was found that the amount of excess sludge can be reduced to almost zero, and the effect of reducing the amount is great.

<Example 16> (heat treatment + alkali agent + glutaraldehyde addition) In the same manner as in Example 1, a part of the returned sludge was extracted and introduced into a sludge treatment tank. Introduce heated steam into the tank to heat it, add glutaraldehyde to 0.1 g / liter, and adjust the pH to 10.0 with 25% sodium hydroxide to remove activated sludge. A part of the constituting bacteria was sterilized or lysed. At this time, activated sludge having a concentration of about 1% was introduced into the sludge treatment tank at a flow rate of ³ m ³ / hr, and sterilized or lysed at 50 ° C. The treatment was terminated after a residence time of 3 hours, the treated activated sludge was returned to the aeration tank of 800 m ³ , and the treatment was carried out according to a usual treatment flow.

As a result of the above-mentioned treatment, the amount of excess sludge generated was approximately 0 kg / day, and the amount of excess sludge could be further reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. or,
In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of activated sludge subjected to sterilization or lysis treatment to the total activated sludge was 12.5%. It was Table 3 collectively shows the processing conditions of this example.
Further, in the case of this example, the treatment was performed in the state where three kinds of requirements including the heat treatment were added, but the treatment was performed alone or in the state where two kinds of requirements were added. Examples 1 to 14
It was found that the residence time can be shortened as compared with the case. Moreover, it was found that the amount of excess sludge can be reduced to almost zero, and the effect of reducing the amount is great.

<Example 17> (Heat treatment + alkali agent + decylisononyldimethylammonium addition) In the same manner as in Example 1, after a part of the returned sludge was extracted and introduced into a sludge treatment tank, Heating steam was introduced into the sludge treatment tank to heat it, and decylisononyldimethylammonium was added so as to be 0.1 g / liter, and the pH was adjusted to 9.0 with 25% sodium hydroxide. The bacterium was prepared and part of the bacteria constituting the activated sludge was sterilized or lysed. At this time, about 1 to the sludge treatment tank
50% of activated sludge was introduced at a flow rate of ³ m ³ / hr,
Sterilization or bacteriolysis was performed at ℃. The treatment was terminated after a residence time of 3 hours, the treated activated sludge was returned to the aeration tank of 800 m ³ , and the treatment was carried out according to a usual treatment flow.

As a result of performing the above-mentioned treatment, the amount of excess sludge generated was approximately 0 kg / day, and the amount of excess sludge could be further reduced significantly. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. or,
In this example, the amount of activated sludge subjected to sterilization or lysis treatment was 50 m ³ / day, and the ratio of activated sludge subjected to sterilization or lysis treatment to the total activated sludge was 12.5%. It was Table 3 collectively shows the processing conditions of this example.
Further, in the case of this example, the treatment was performed in the state where three kinds of requirements including the heat treatment were added, but the treatment was performed alone or in the state where two kinds of requirements were added. Examples 1 to 14
It was found that the residence time can be shortened as compared with the case. Moreover, it was found that the amount of excess sludge can be reduced to almost zero, and the effect of reducing the amount is great.

<Example 18> Without providing the settling tank shown in FIG. 3, a predetermined amount of activated sludge was extracted from the aeration tank and put into the sludge treatment tank for treatment, and then the treated sludge was returned to the aeration tank. In the batch type activated sludge treatment system, the activated sludge treatment of the organic wastewater was performed in the same manner as in Example 1 except that the activated sludge was introduced into the sludge treatment tank at a time of 80 m ^{3 at the} time of the wastewater process. . As a result of performing the above treatment, the amount of excess sludge generated was about 40 kg / day, and as shown in Table 3, it was confirmed that the excess sludge amount can be reduced even in the batch type activated sludge treatment system. did it.
In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method.

Comparative Example 1 Organic sludge was treated with activated sludge in the same manner as in Example 18 except that a portion of the activated sludge from the aeration tank was not treated with an alkaline agent. As a result, the amount of excess sludge generated as shown in Table 4 was 20
It was 0 kg / day, and at least 5 times or more of excess sludge was generated as compared with the case of the example.

<Example 19> Activated sludge treatment of organic wastewater was carried out by using organic wastewater from a food factory handling dairy products similar to that used in Example 1 as raw water. In this example, a part of the returned sludge or the like is extracted and introduced into a sludge treatment tank, and waste nitric acid and hydrogen peroxide water are put into the sludge treatment tank to solubilize the activated sludge. Lysis treatment was performed. At this time, the amount of hydrogen peroxide solution added was 5 kg, which was equivalent to about 1.3% by weight with respect to the activated sludge to be treated. 12 m ³ of activated sludge was introduced into the sludge treatment tank at one time, waste nitric acid was added until the pH reached 3, and the mixture was stirred at 20 ° C. for 4 hours. Then, the treated activated sludge was returned to the aeration treatment tank having a capacity of 800 m ³ .

As a result of the above-mentioned treatment, the amount of excess sludge generated was about 30 kg / day, and the amount of excess sludge could be reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also, the amount of activated sludge subjected to sterilization or lysis treatment is 60 m ³ / day,
The ratio of the activated sludge that had been sterilized or lysed to the total activated sludge was 15%. Table 3 collectively shows the processing conditions of this example. Further, in the case of this example, the treatment was carried out in a state where two kinds of compounds containing waste nitric acid were added, and in this case also, in the case of Examples 1 to 6 in which the treatment was carried out under a single condition. It was found that similar effects can be obtained even when the ratio of the activated sludge to be sterilized or lysed is small as compared with. If configured as in this example, more economical treatment can be achieved by using waste nitric acid.

Example 20 The activated sludge treatment of the organic wastewater was carried out by using the organic wastewater from a food factory handling dairy products similar to that used in Example 1 as raw water. In this example, a part of the returned sludge or the like is extracted and introduced into a sludge treatment tank, and waste nitric acid and hydrogen peroxide water are put into the sludge treatment tank to solubilize the activated sludge. Lysis treatment was performed. At this time, the amount of hydrogen peroxide solution added was 5 kg, which was equivalent to about 1.3% by weight with respect to the activated sludge to be treated. An amount of 12 m ³ of activated sludge was introduced into the sludge treatment tank at one time, waste nitric acid was added until the pH reached 3, and sterilization or bacteriolysis was performed at 40 ° C. The treatment was terminated after a residence time of 3 hours, and the treated activated sludge was returned to the aeration treatment tank having a capacity of 800 m ³ .

As a result of the above treatment, the amount of excess sludge generated was about 20 kg / day, and the amount of excess sludge could be reduced. In addition, when the final treated water was investigated, as shown in Table 4, the treatment of the organic wastewater of this example was comparable to that of the conventional method described in Comparative Example 1 described later. It was confirmed that the purification ability did not decrease even in the method. Also, the amount of activated sludge subjected to sterilization or lysis treatment is 50 m ³ / day,
The ratio of the activated sludge that had been sterilized or lysed to the total activated sludge was 12.5%. Table 3 collectively shows the processing conditions of this example. Furthermore, in the case of this example, the treatment was performed in a state where three kinds of requirements including heat treatment were added, but Examples 1 to 14 in which the treatment was performed alone or in a state where two kinds of requirements were added It was found that the residence time can be shortened as compared with the case of Example 19. Moreover, it was found that the amount of excess sludge can be reduced to almost zero, and the effect of reducing the amount is great. Further, with the configuration as in this example, more economical treatment can be performed by using waste nitric acid.

[0073]

[Table 3] Table 3 Conditions for sterilization or lysis treatment of activated sludge

[0074]

[Table 4] Table 4 Result of organic wastewater treatment

[0075]

As described above, according to the present invention, in the treatment of organic wastewater using the activated sludge method, the amount of excess sludge generated without deteriorating the quality of the treated water discharged at the final stage. It is possible to significantly reduce the amount, and the purification treatment of organic wastewater can be performed easily and economically.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an action of a factor having a bactericidal action or a bacteriolytic action on activated sludge used in the present invention.

FIG. 2 is a schematic system diagram showing an example of a method for treating organic wastewater according to the present invention.

FIG. 3 is a schematic system diagram showing another example of the method for treating organic wastewater of the present invention.

FIG. 4 is an example of a processing flow of a conventional method for treating organic wastewater.

Claims (6)

[Claims] 1. When purifying an organic wastewater using activated sludge, pH or temperature is controlled in any treatment process, or an alkaline agent, an acid or a waste acid, and activated sludge are added. On the other hand, by adding at least one selected from compounds having a bactericidal action or a bacteriolytic action, or by combining two or more of the above requirements, a part of bacteria constituting the activated sludge is sterilized or lysed. A method for treating organic wastewater, which comprises suppressing the growth of activated sludge during the treatment process. 2. An organic wastewater is introduced into a treatment tank to aerate at least one additive selected from an alkaline agent, an acid or a waste acid, and a compound having a bactericidal action or a bacteriolytic action on activated sludge together with the activated sludge. After the treatment, the treatment is carried out in the activated sludge treatment tank into which the activated sludge extracted from the treatment tank (aeration tank) or the settling tank provided on the downstream side of the treatment tank is introduced. The method for treating organic wastewater according to claim 1, wherein the treated activated sludge is introduced into the treatment tank after sterilizing or lysing the activated sludge in the tank. 3. The compound is sorbic acid, sodium sorbate, potassium sorbate, calcium sorbate,
It has aldehydes represented by glutaraldehyde, cationic surfactants, nonionic surfactants, amphoteric surfactants, chlorine compounds, polyamines, aliphatic amines, phenols, nitrofurans, and trichloroalkylthio groups. The organic wastewater according to claim 1, which is any one of a compound, dithiocarbamate, alcohol, protease, glucanase, amylase, magnesium monoperoxyphthalate, hydrogen peroxide, sodium peroxide, sodium percarbonate, and sodium carbide. Processing method. 4. At least the activated sludge is introduced from the inside of the treatment tank (aeration tank) or from the settling tank provided downstream of the treatment tank after introducing the organic wastewater into the treatment tank and performing aeration treatment with the activated sludge. A part is extracted and introduced into an activated sludge treatment tank, and the temperature in the treatment tank is controlled within a range of 40 to 100 ° C to sterilize or lyse the activated sludge, and the treated activated sludge is then treated in the above treatment tank. The method for treating organic wastewater according to claim 1, which is introduced into 5. After introducing organic wastewater into the treatment tank and subjecting it to aeration treatment together with the activated sludge, at least a part of the activated sludge is extracted from the treatment tank or from a settling tank provided downstream of the treatment tank. The activated sludge is sterilized or lysed by introducing it into an activated sludge treatment tank and controlling the pH value in the treatment tank to be 4.5 or less, or 9.5 or more, and then treating the treated activated sludge. The method for treating organic wastewater according to claim 1, which is introduced into the treatment tank. 6. A chemical for sterilizing or lysing a part of bacteria constituting activated sludge, which is characterized by mainly containing an alkaline agent, an acid or a waste acid.