JP2000210692A - Treatment of organic waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably treat org. waste water even if the properties of feed water are rapidly changed in the treatment of org. waste water by a two-phase activated sludge method by suppressing the variation in the concn. of org. pollutants shown by BOD in the water introduced into a treating tank. SOLUTION: Two-phase activated sludge treatment is conducted in a first bacteriological treating tank and a second treating tank for sessile protozoa treatment and activated sludge treatment. A regulation tank is provided before the first treating tank to suppress the variation in the feed water concn. of the water to be treated and to be introduced into the first treating tank. The one used in biological treatment and provided with an air or oxygen-permeable aeration pipe is used as the first treating tank, and a standard aeration tank a fixed-bed or roating-disk aeration tank or the like are used as the second treating tank. Besides, the feed rate of the waste water to the first treating tank is so selected that the treating time is longer than the maximum specific growth rate of protozoa to restrict the appearance of the protozoa.

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 containing organic pollutants (hereinafter also referred to as "organic wastewater" or "raw water") by an activated sludge method.
Furthermore, when the water to be treated containing organic substances is treated by the activated sludge method, the water quality of the treatment liquid does not deteriorate,
The present invention relates to a method for treating organic wastewater in which the treatment efficiency is remarkably improved and the excess sludge is economically and reliably reduced.

[0002]

2. Description of the Related Art The activated sludge method for treating organic wastewater with activated sludge containing aerobic microorganisms has advantages such as high purification capacity and relatively low treatment cost. Various water treatment methods have been proposed and widely used in sewage treatment and industrial wastewater treatment. In the activated sludge method, as shown in FIG. 8, various kinds of organic wastewater to be treated are led to an aeration tank (aeration tank), and in this aeration tank, organic pollutants in the wastewater indicated by BOD due to the activated sludge are introduced. Purification is performed by decomposing the components. However, certain biological loading conditions, ie, BOD
Since operation can be performed only in a state of about 0.5 to 0.8 kg / m ³ · day with a load amount, in order to perform a large amount of processing,
Equipment tends to be large, such as the need for a large aeration tank that requires a large site area.

Further, in the activated sludge treatment method, the decomposed B
50-70% of the OD is consumed as maintenance energy for the microorganisms, while the remaining 30-50% is used for the growth of cells, so that the amount of activated sludge gradually increases.
For this reason, generally, as shown in FIG. 8, the wastewater treated in the aeration tank is guided to a settling tank, and the returned activated sludge is returned from the settled activated sludge in an amount necessary for the purification treatment of the organic wastewater. To the inside of the aeration tank, and other activated sludge is removed as surplus sludge. As described above, in the water treatment method using the activated sludge method, in addition to the problem that the treatment efficiency is poor, treatment of a large amount of excess sludge is always a problem.

On the other hand, Japanese Patent Publication No. Sho 56-48235 discloses that organic wastewater (raw water) is treated with bacteria (mainly bacterial treatment with dispersing bacteria) to oxidatively decompose organic substances in the wastewater and to obtain non-coagulable substances. After conversion to bacteria, it has been further proposed to improve the biological treatment efficiency by treating the non-aggregating bacteria with a fixed protozoa and predating them.
When the above method is used, operation under a high load state becomes possible, and the treatment efficiency by the activated sludge method is remarkably improved, and furthermore, the efficiency of biological treatment can be improved and the amount of excess sludge generated can be reduced. Is described.

[0005]

Hereinafter, the present invention will be described with reference to the first embodiment.
The present invention and the second invention will be described separately. (First invention) However, as a result of the study by the present inventors, in the above-mentioned conventional method, if the processing conditions are certainly selected,
Improvement of the treatment efficiency by the activated sludge method, and furthermore, has the effect of reducing the amount of excess sludge generated, but as described above, the above-mentioned effect is obtained by successfully combining and treating a plurality of types of microorganisms having different properties. Therefore, depending on the processing conditions,
It was found that the effect was hardly obtained, and in particular, it was very easily affected by the properties of the water to be treated, which is the object of the treatment. In other words, although the above method can obtain a very high effect on the ideal water to be treated, which is modeled, the actual fluctuation in the concentration of the organic pollutant component indicated by the BOD changes every day or every moment. However, there is a practical problem that it is difficult to obtain a stable and high effect with respect to the organic wastewater.

Accordingly, an object of the present invention is to provide a method for treating organic wastewater using the activated sludge method, which is effective even when the method is applied to actual organic wastewater in which the concentration of organic pollutants represented by BOD fluctuates significantly. The method of treating organic wastewater, which can stably and reliably obtain the excellent effect of reducing the amount of excess sludge by a simple method without deteriorating the quality of treated water discharged in the final stage Is to provide. Another object of the present invention is to provide a simple and economical method for treating organic wastewater which can be applied to small-scale facilities.

(Second invention) However, as a result of investigations by the present inventors, in the above-mentioned conventional method, if the treatment conditions are selected, the treatment efficiency can be improved by the activated sludge method, and furthermore, the excess sludge can be reduced. Although there is a sufficient effect of reducing the amount of production, the above-mentioned method achieves the above-mentioned effect by using a plurality of types of microorganisms having different properties in a biological treatment in a successful combination. It was found that the effect was hardly obtained, and in particular, it was very easily affected by the properties of the water to be treated, which is the object of the treatment. That is, the above-mentioned method has a very high effect on the ideal water to be treated, which is modeled, but is not limited to the fluctuation of the organic pollutant concentration indicated by the BOD every day or every moment. In the treatment of actual organic wastewater, whose properties may fluctuate, the amount of wastewater changes, and sometimes the inflow of wastewater may stop, it is not possible to respond quickly to such fluctuations, and the quality of treated water (effluent) However, there is a practical problem that it is difficult to stably obtain a high effect, such as a temporary deterioration.

[0008] Accordingly, an object of the present invention is to provide a method in which the treatment efficiency fluctuates before and after the introduction of raw water into the treatment tank is temporarily interrupted due to a sudden change in the raw water quality or a suspension of the production line. It is possible to perform the treatment in a stable state without performing, and it is possible to reduce the amount of surplus sludge by a simple method without temporarily deteriorating the quality of the treated water discharged in the final stage. An object of the present invention is to provide a method for treating organic wastewater, which can stably obtain an effect. Another object of the present invention is to provide a simple and economical method for treating organic wastewater which can be applied to small-scale facilities.

[0009]

The above objects are achieved by the present invention described below. That is, the present invention introduces the water to be treated containing an organic pollutant component into the first treatment tank, treats the bacteria in the first treatment tank in the substantial absence of protozoa, and is contained in the water to be treated. After the organic matter is oxidatively decomposed and converted into non-aggregating bacteria, the wastewater containing the non-aggregating bacteria from the first processing tank is introduced into the second processing tank where activated sludge is present, and the second
A method of treating organic wastewater by a two-phase activated sludge method in which a fixed protozoa is treated in a treatment tank in the substantial absence of non-fixed protozoa to prey and remove non-aggregating bacteria from the fixed protozoa In the method for treating organic wastewater, the fluctuation of the concentration of the organic pollutant indicated by the BOD in the water to be treated introduced into the first treatment tank is suppressed.
The term "substantially free of protozoa" in the present invention means a state in which the growth of protozoa is suppressed, and as a result, almost no new protozoa appear during the bacterial treatment process.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to preferred embodiments of the method for treating organic wastewater of the present invention. (First Invention) The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art, and as a result, have found that actual organic wastewater
Raw water) is biologically treated by a two-phase activated sludge method consisting of a dispersible bacterial flora and a sessile protozoan flora as described in JP-B-56-48235. The fluctuation of the organic pollutant component concentration (hereinafter, simply referred to as the organic pollutant component concentration) indicated by the BOD in the water to be treated introduced into the treatment tank constituting the bacterial flora is suppressed, and the organic pollutant component concentration becomes stable. It has been found that if the treated water is configured to be treated with the bacterial phase, the purification treatment of the organic wastewater by the two-phase activated sludge method is performed stably and reliably, and the excellent effects are stably obtained. The present invention has been reached.

The method for treating organic wastewater of the present invention is characterized by suppressing the fluctuation of the concentration of organic pollutants in the water to be treated introduced into the first treatment tank. This will be described below. Examples of the organic wastewater treated in the method for treating organic wastewater of the present invention include various wastewaters containing organic substances, for example, processing plants for various fresh food products such as fish, shellfish, meat, and vegetables, dairy products, beverages, and confectionery. Industrial wastewater from various food production factories, breweries, fermentation factories, etc., or ordinary household wastewater. The concentration of organic pollutants in these organic wastewaters is not always constant because the types and production conditions of the raw materials being handled often vary from day to day or even on the same day. Specifically, several times to 30
In some cases, a density variation of 0 times or more may occur. On the other hand, according to the study of the present inventors, it has been found that when such wastewater is biologically treated by a two-phase activated sludge method described later, a stable and stable effect may not be obtained.

That is, in the ordinary activated sludge method, the parallel treatment by various microorganisms living in the same treatment tank (aeration tank) is performed for several days to perform the purification treatment. In the two-phase activated sludge method, a first treatment tank and a second treatment tank in which microorganisms having different properties inhabit, respectively, are used.
Each tank performs a unique biological treatment, and by combining these, the efficiency of the treatment is increased.
It becomes necessary to keep the balance of the processing between the two processing tanks. On the other hand, if the target water to be treated always has a certain property, it is easy to balance the two,
If the concentration of the organic pollutant component in the water to be treated fluctuates greatly, it is difficult to balance the two, and the quality of the treated water may be impaired or the treatment efficiency may not be improved. As described above, when the two-phase activated sludge method is used for actual organic wastewater that causes fluctuations in the concentration of organic pollutants as described above, there is a practical problem to be solved. .

Therefore, the method for treating organic wastewater of the present invention, in order to solve the above-mentioned problem, suppresses the fluctuation of the concentration of the organic pollutant component indicated by BOD in the water to be treated introduced into the first treatment tank. It is a mandatory requirement. Particularly preferably in the present invention, the fluctuation of the concentration of organic pollutants in the water to be treated,
It is preferable that the concentration is adjusted so as to be within 50% from the median of the average concentration of the raw water. Hereinafter, biological treatment by a two-phase activated sludge method comprising a bacterial flora and a protozoan flora employed in the present invention will be described, and further, the significance of suppressing the fluctuation of the concentration of organic pollutants in the water to be treated will be described in detail. .

In the two-phase activated sludge method used in the present invention, the biological treatment of organic wastewater with activated sludge is a process of oxidative decomposition and utilization of organic matter by bacteria and a process of producing sludge having good coagulation and settling properties. It consists of two processes, especially in view of the fact that one of these processes is the rate-limiting biological treatment of organic wastewater. That is, first,
The first treatment tank is a bacterial flora that performs bacterial treatment in the substantial absence of non-fixing protozoa for the purpose of removing only organic matter without considering the sedimentation of activated sludge. Thus, organic substances are efficiently oxidized and decomposed by bacteria, and the growth of bacteria using these organic substances as nutrients is promoted. Furthermore, at that time, the state of the bacterium is configured to be very easily predated by protozoa dispersed in individual cells. Then, the second treatment tank, which is performed subsequently to the first treatment tank, is a fixed protozoan fauna containing activated sludge for the purpose of predation of bacteria and treatment of residual organic matter, and the first treatment tank ( Bacteria that have been treated in the bacterial flora) are treated in the second treatment tank in the absence of non-fixing protozoa, in the presence of non-fixing protozoa, so that the bacteria grown in the above can be more efficiently used in protozoa. Predatory removal.

In the above, in the bacterial flora, which is the first treatment tank, it is necessary that the proliferated bacteria be in a state of being very easily eaten by protozoa dispersed in individual cells.
For this purpose, the treatment time (dilution ratio) of the water to be treated in the first treatment tank is set not to be longer than the growth rate of the protozoa. For this reason, processing in the first processing tank is usually performed within a short time of about several hours, and high-speed processing is performed. On the other hand, the treatment in the second treatment tank requires several hours to several days. However, since the above-described bacterial treatment is performed in the first treatment tank, the treatment is more difficult than in the conventional one-phase activated sludge method. Also, efficient processing can be performed.

That is, in the two-phase activated sludge method, the bacteria contained in the water to be treated which is treated in the bacterial phase (first treatment tank) and introduced into the fixed protozoan fauna (second treatment tank) Is a non-agglutinating substance and is in a state where it is very easy to be eaten by protozoa dispersed in individual cells, so that the rate of bacterial removal by protozoa in the second treatment tank becomes extremely high. Furthermore, in the second treatment tank, the treated water treated with the protozoa as described above contains, as sludge, the sticky protozoa that have proliferated in the above-described process, and the sludge has extremely excellent separability. Since it is in a state of being in a state of being separated, it can be easily separated by a conventional solid-liquid separation means such as a sedimentation tank. In addition, the final treated water discharged after the sludge has been removed is extremely clean, free of organic matter and protozoa. As a result, when the organic wastewater is treated by the two-phase activated sludge method employed in the present invention, a high load operation that is about two to three times that of a normal case can be performed, and the sludge generation amount is reduced to about 1/2. Can be reduced.

However, in the two-phase activated sludge method, the first
If the concentration of organic pollutants in the water to be treated introduced into the bacterial flora, which is the treatment tank, fluctuates greatly, the balance of the above-mentioned excellent biological treatment system may be lost, and smooth treatment may not be performed. Hereinafter, this will be described. As described above, in the first treatment tank, the oxidative decomposition of organic pollutants in the water to be treated by bacteria progresses, and the growth of bacteria using these organic substances as nutrients progresses. -It needs to be processed promptly before sedimentation occurs. That is,
As described later, if the treatment time (dilution rate) of the water to be treated in the first treatment tank is longer than the proliferative rate of the protozoa, the first
Since the appearance of protozoa in the treatment tank cannot be suppressed, and the flocculation and sedimentation of the bacterial cells occurs, the treatment time (dilution ratio) in the first treatment tank is usually set to be as short as several hours. Then, as a result of performing the treatment in the first treatment tank in this manner, the water to be treated (hereinafter, simply referred to as the first treated water) introduced from the first treatment tank to the second treatment tank becomes a cell of the bacterial cells. It contains bacteria that are not easily agglutinated or sedimented and are in a state that is very easy to be eaten by protozoa dispersed in individual cells, and as a result, predation of bacteria by protozoa in the second treatment tank progresses, Efficiency improvement can be achieved.

On the other hand, when the concentration of the organic pollutant component in the raw water fluctuates remarkably and the water to be treated having an extremely high organic pollutant component concentration is introduced into the first treatment tank, the above-mentioned treatment is carried out. As described above, since the processing time (dilution ratio) in the first processing tank is set short, the organic matter in the first processing tank is completely oxidized and decomposed by bacteria, and bacteria using the organic matter as a nutrient source grow, The first treated water may be sent to the second treatment tank before the bacteria are dispersed in individual cells that are extremely predatory to protozoa. In this case, the processing efficiency cannot be improved as much as the above case. On the other hand, in this case, if the treatment time (dilution rate) of the water to be treated in the first treatment tank is increased in order to completely perform the bacterial treatment of the water to be treated having a high concentration of organic pollutants, the protozoa in the first treatment tank In this case, the efficiency of the processing cannot be improved.

As described above, in the two-phase activated sludge method, when the concentration of the organic pollutant component in the water to be treated introduced into the bacterial flora as the first treatment tank fluctuates greatly, the biological treatment is performed in a stable state. No longer. Therefore, in the method for treating organic wastewater of the present invention, it is important to stably treat bacteria in the first treatment tank. That is, when the treatment time (dilution ratio) is as long as several days, as in the second treatment tank used in the present invention or a conventional aeration tank, even if the concentration of the organic pollutant component in the water to be treated fluctuates greatly. The effect of the variation in the concentration of the organic pollutants in the water to be treated is not so large because it can be adjusted to some extent in these tanks, but the bacterial treatment performed in the first treatment tank used in the present invention is as follows:
As mentioned earlier, because it takes place in a short time and at high speed,
The influence of the above-mentioned density fluctuation on the processing becomes great.

That is, when the treatment efficiency is improved by the two-phase activated sludge treatment as described above, the state of the microorganisms living in the first and second treatment tanks is set to an ideal state. Although it is necessary to set, especially in the first treatment tank into which the treated water containing the raw water, which is actual organic wastewater, is introduced, high-speed treatment is performed. Unless the concentration of the organic pollutant in the water to be treated is suppressed and the concentration of the organic pollutant is not stabilized, the balance in the above-mentioned treatment system is lost, and it is difficult to execute the biological treatment smoothly.

Hereinafter, a specific method for adjusting the fluctuation of the concentration of organic pollutants in the water to be treated to be introduced into the bacterial flora as the first treatment tank will be described. Even in the conventional activated sludge method,
Before the introduction of the water to be treated into the aeration tank, an adjusting tank was placed. Here, the pH of the water to be treated was adjusted, and the raw water was sometimes made uniform. It is preferable to arrange an adjustment tank beforehand and thereby to appropriately suppress the fluctuation of the concentration of the organic pollutant component in the water to be treated into the first treatment tank. For example, fluctuations in the amount of organic pollutants in raw water caused by operating conditions on one day (hereinafter, simply referred to as fluctuations in raw water concentration) do not affect the concentration of organic pollutants in the water to be treated introduced into the first treatment tank. In order to do so, an adjusting tank capable of storing 24 hours of organic wastewater (raw water) is preferably provided before the first treatment tank, and the raw water concentration is made uniform in the adjusting tank. Then, it may be configured so as to be introduced into the first processing tank. Thus, in order to eliminate the influence on the processing in the first processing tank due to the fluctuation of the raw water concentration caused by the operation status of one day, it is more preferable to eliminate the influence of 24 hours.
It is preferable to provide an adjustment tank that can store wastewater for hours. However, if only an adjustment tank for storing wastewater for 8 hours, 12 hours, or several hours can be provided due to space or the like, 1 It is necessary to configure so that the fluctuation of the raw water concentration caused by the operation status on the day does not affect the processing in the first processing tank.

The bacterial flora of the two-phase activated sludge treatment described above (first
The bacterium used in the treatment tank is not limited as long as it is aerobic, and examples thereof include genus Alcaligenes, genus Pseudomonas, genus Bacillus, genus Aerobacterium, and genus Flavobacterium. Such bacteria,
Normally, since it is alive in wastewater and multiplies using organic matter in the wastewater as a nutrient source, in the present invention in which organic wastewater is to be treated, there is no particular need to add it from the outside. However, in order to smoothly perform the purification treatment of the wastewater, an appropriate inoculum may be added from the outside at the start of the purification treatment, if necessary. Examples of the inoculum used at this time include, for example, Biocore BP, OF-10, and Serve 1
Microbial preparations such as Environmental Engineering Co., Ltd.) can be suitably used.

In the present invention, as described above, the treatment with the aerobic bacteria as described above is performed in the first treatment tank, and the wastewater discharged from the first treatment tank (first treated water).
The organic matter contained therein is oxidatively decomposed by bacteria, and the bacteria themselves grow with the organic matter as a nutrient source.
Therefore, it can be said that the organic matter in the wastewater has been converted into bacteria by looking only at the phenomenon caused by the bacterial treatment in the first treatment tank. According to the study of the present inventors, if the fluctuation of the concentration of organic pollutants in the water to be treated is suppressed and the bacterial treatment in the bacterial flora can be optimized, the removal rate of the soluble organic matter in the first treatment tank can be increased by 95 to 98. %. In terms of the conversion rate of organic matter to bacteria,
It is about 40 to 50%, and it can be said that 100 parts by weight of organic matter is converted into about 40 to 50 parts by weight of bacteria having good dispersibility. As a result, the processing efficiency in the next second processing tank is improved, and the amount of generated sludge is also reduced. But,
In this case, if the fluctuation of the concentration of the organic pollutant component in the water to be treated introduced into the first treatment tank is not suppressed, the conversion rate of organic substances into bacteria is reduced, and the above-mentioned excellent effects are impaired.

In the method for treating organic wastewater of the present invention, it is necessary to perform the bacterial treatment in the first treatment tank in the substantial absence of protozoa. As a result, the bacteria contained in the treated wastewater become non-agglomerated, effectively preventing the formation of bacterial clumps, so-called sludge, in the wastewater, and the first treatment obtained as a result of such bacterial treatment. Water is
It is substantially free of sludge and contains bacteria dispersed in fine particles converted from organic matter. Since such a dispersed bacterium is a eutrophic source of protozoa, the treatment efficiency in the next protozoa treatment in the second treatment tank composed of the activated sludge phase containing the protozoa is remarkable. Enhanced. Conversely, when the protozoa coexist in the bacterial treatment performed in the first treatment tank,
In the bacterial flora, bacteria that are easily predated by protozoa are predated, so that bacteria that are not easily predated mainly grow, and bacterial clumps are easily generated in the bacterial flora. Since these bacterial clumps are hard to be eaten by protozoa, when the first treated water containing such bacterial clumps is treated in the second treatment tank where activated sludge is present,
These may pass through the protozoa treatment process, causing a reduction in treatment efficiency in protozoa treatment. In the present invention, "substantially in the absence of protozoa" refers to a state in which the growth of protozoa is suppressed, and as a result, almost no new protozoa appear during the bacterial treatment process.

[0025] In the process of treating bacteria in the first treatment tank in the method for treating organic wastewater of the present invention, specific methods for inhibiting the growth of protozoa and for making the protozoa substantially absent include: The following methods utilizing differences in properties between bacteria and protozoa can be used. For example, there is a large difference in the growth rate between bacteria and protozoa, and the growth rate of bacteria is extremely high compared to that of protozoa. Of the protozoa can be stopped.
That is, according to this principle, the protozoa emerge from the effluent by passing the wastewater to be treated through a bacterial treatment process at a treatment time (dilution rate) equal to or higher than the maximum specific growth rate of the protozoa and equal to or lower than the maximum specific growth rate of the bacteria. Bacterial treatment can be achieved in a state in which bacteria are suppressed. In the present invention, for example, the treatment time (dilution rate) of the water to be treated in the process of treating bacteria in the first treatment tank is set to the maximum specific growth rate of the protozoa or more and the maximum specific growth rate of the bacteria or less, for example, 1 to 12 hr. . By adjusting the range, the bacterial treatment can be performed in a state where the protozoa are substantially absent.

Further, the control of the appearance of protozoa during the bacterial treatment process can also be achieved by controlling environmental conditions such as temperature and pH. That is, bacteria can grow under a wide range of environmental conditions, but the environmental conditions under which protozoa can grow are limited to a narrower range than bacteria. For example, the growth of protozoa is remarkably suppressed at a temperature of 40 ° C. or higher. Therefore, if the temperature of the bacterial treatment process is maintained at 40 ° C. or higher, the appearance of protozoa can be suppressed. In addition, protozoa are inhibited from growing at pH 4 or lower or at pH 10 or higher.
By maintaining the above range, the appearance of protozoa can be stopped.

In the method for treating organic wastewater of the present invention, as described above, 100% of organic matter contained in wastewater is reduced by efficient bacterial treatment in the first treatment tank.
It is converted into bacteria dispersed in a state of fine particles at a close ratio, and thereafter, the first treated water from the first treatment tank is treated with protozoa in the second treatment tank where activated sludge is present,
These bacteria are efficiently predated and removed by protozoa. In the present invention, furthermore, in this protozoa treatment process, in order to facilitate separation of the protozoa that have eaten the bacteria, only the fixed protozoa having good solid-liquid separation are present in the second treatment tank. The treatment is performed in a state where non-fixing protozoa having poor solid-liquid separation properties are substantially absent.

The sessile protozoa referred to in the present invention means a protozoa having a property of being easily fixed to solid particles or solid substances, or a protozoan having a property of being easily fixed and coagulated with each other. . Such a thing, for example,
Balticella, Epistealis, Opelclaria, Calcium, Zutanium, etc., include sessile-fixed ciliates, such as Aspidesca, which huffs the solid surface.
Euplotes can be used because it easily settles together with sludge. On the other hand, the non-fixed protozoan referred to in the present invention means a protozoan that does not have the above properties.

In the present invention, the second sludge containing activated sludge is used.
The sticky protozoa treatment performed in the treatment tank, as described above, must be performed in a state where the growth of non-sticky protozoa is stopped and the non-sticky protozoa are substantially absent. Such a state can be formed by utilizing the fixation and non-fixation properties of protozoa. That is, if an appropriate solid substance that can serve as a carrier for fixation is present in the treatment system, the fixative protozoa will adhere to the solid substance and grow. In contrast, non-fixing protozoa do not have such properties. Therefore, in protozoan treatment,
Non-adherent (free-swimming) protozoa can be obtained by passing the treated wastewater through the treatment process in the presence of a carrier for adherent protozoa with a treatment time (dilution rate) that is higher than the maximum specific growth rate of protozoa. While allowing them to flow out of the treatment system, the sticky protozoa can remain in the treatment system and grow. In the method for treating organic wastewater of the present invention, as described below,
In order to treat this protozoa treatment in the presence of activated sludge,
Activated sludge acts as a carrier for sessile protozoa,
A state in which non-fixing protozoa are substantially absent can be easily formed. In the present invention, an environment in which the adherent protozoa are more likely to adhere to the second treatment tank is further provided with, for example, solid particles such as sand and stone, plate-like bodies, cloth-like objects, and filter paper as carriers. It may be. In the present invention, as the second treatment tank for performing the above-mentioned sessile protozoa treatment,
What is necessary is just to use the aeration tank conventionally used for the activated sludge treatment method.

In the method for treating organic wastewater of the present invention, as described above, the first treated water after the bacterial treatment is treated with a fixed protozoa in the absence of a non-fixed protozoa, and the wastewater is treated. Bacteria are predated and removed by the protozoa, and as a result, in the second treatment tank, the fixed protozoa that grew using the bacteria as a nutrient source are present as sludge. In other words, only looking at the phenomenon that occurs in the second treatment tank, it can be said that the bacteria in the wastewater to be treated were converted into the sticky protozoa by the sticky protozoa treatment and sludge was formed. As described above, in the present invention, the organic matter in the wastewater is converted into bacteria by the bacterial treatment in the first treatment tank.
The bacterium is in the form of non-aggregated fine particles, and is present in a state of being dispersed in individual cells in wastewater, so that it is extremely easy to be eaten by protozoa. Therefore, the rate of bacterial removal by protozoa in the second treatment tank is
Extremely high values of about 95-97% are obtained. Also, from the viewpoint of conversion of bacteria to protozoa in protozoa processing, about 30 to 40% of bacteria are converted to protozoa.

In the method for treating organic wastewater of the present invention, the first
Since the fluctuation of the organic pollutant component concentration of the water to be treated introduced into the first treatment tank is suppressed so that the conversion of the organic matter into bacteria in the treatment tank is ideally performed, as described above, in this case, The conversion rate of organic matter to bacteria becomes about 40 to 50%. Therefore, taking this into consideration, the organic matter which was 100 parts by weight is converted into about 40 to 50 parts by weight of bacteria and reduced, and furthermore, about 12 to 10 parts by weight in the second treatment tank described above.
It can be said that it was converted to 20 parts by weight of protozoa (sludge) and the weight was further reduced. Therefore, according to the two-phase activated sludge treatment,
When the same amount of organic matter is treated, the amount of generated sludge can be reduced as compared with the conventional activated sludge method.

Further, the wastewater obtained by the protozoa treatment performed in the second treatment tank (hereinafter, simply referred to as the second treated water) contains the multiplied fixed protozoa as sludge as described above. . Therefore, this sludge has a property that it easily adheres to solid particles and solid substances such as activated sludge, and is very excellent in separability. It can be easily separated. As a result, the final treated water obtained is very clean without turbidity and free from organic matter and protozoa.

In the method for treating organic wastewater of the present invention,
Since the fluctuation of the concentration of the organic pollutant component in the water to be treated introduced into the first treatment tank is suppressed, the concentration of the bacteria in the first treatment water treated in the first treatment tank and introduced into the second treatment tank is suppressed. Fluctuations are also suppressed. Therefore, the processing in the second processing tank is also performed in a stable state.

Hereinafter, the method for treating organic wastewater of the present invention will be described more specifically based on the treatment flow shown in FIG. In the organic wastewater treatment method of the present invention, as is apparent from comparison with the treatment flow by the ordinary activated sludge method shown in FIG. 8, the activated sludge treatment in the ordinary activated sludge method is performed in a two-phase process. Perform separately. Further, a variation in the raw water concentration of the water to be treated introduced into the first treatment tank is suppressed by means such as always providing an adjustment tank before the first treatment tank.

In the flow shown in FIG. 1, two-phase activated sludge treatment is carried out by a first treatment tank for treating bacteria and a second treatment tank for treating fixed protozoa and activated sludge. In order to easily incorporate the organic wastewater treatment method of the present invention without greatly changing the treatment flow of the organic wastewater due to the activated sludge treatment, a conventional aeration tank is used.
The first for use as a treatment tank and for treating bacteria separately
It is preferable to provide a processing tank. Of course, as shown in FIG. 2, it may be constituted by an integrated tank.

As the first treatment tank used at this time, a vessel provided with an aeration tube for air or oxygen ventilation, which has been conventionally used in biological treatment, can be used. In addition, as the second treatment tank in which activated sludge to be provided for protozoan treatment is present, a standard type aeration tank, a fixed bed or a rotating disk type aeration tank, or the like,
Any treatment tank conventionally used for activated sludge treatment can be used.

In the present invention, the supply rate of the wastewater to be treated to the first treatment tank as described above is determined by the treatment time (dilution rate) of the maximum specific growth rate of the protozoa in order to suppress the appearance of protozoa. As described above, usually, 1 to 12 hr. It is preferable to select so that Furthermore, processing time (dilution rate)
Instead, the appearance of protozoa may be controlled by other factors such as the temperature and pH of the water to be treated. Further, in the second treatment tank following the bacterial treatment in the first treatment tank, aeration treatment is performed in the presence of sludge consisting of the sticky protozoan aggregates returned from the sedimentation tank or the like. However, in any of the above cases, the optimum treatment time (dilution ratio) and the like vary depending on the type of the water to be treated and the treatment conditions, and cannot be uniquely determined. preferable.
Furthermore, for example, when the concentration of organic matter in the wastewater to be treated is relatively high and the operation is carried out for a predetermined treatment time (dilution ratio), the load of bacteria introduced into the second treatment tank becomes too high. In order to obtain the above processing time (dilution ratio), the dilution water may be introduced from the outside into the second processing tank.

With the above-described method for treating organic wastewater of the present invention, when treating actual organic wastewater having a fluctuation in the concentration of organic pollutants indicated by BOD, it is possible to improve the treatment efficiency, The generation of sludge is suppressed, and in addition, the quality of the treated water is not inferior to that of the treated water treated by the activated sludge method generally used in the past, and is rather improved. The effect is reliably obtained in a stable state.

(Second Invention) The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art which occur when treating the actual organic wastewater whose properties and wastewater change daily or every moment. As a result, a two-phase activated sludge composed of a dispersible bacterial phase (disperse phase) and a fixed protozoan fauna as described in JP-B-56-48235 is used. It has been found that the above-mentioned phenomenon that occurs when biological treatment is carried out by the method is caused by the dispersed bacteria constituting the bacterial flora, and the present invention has been accomplished. That is, in the dispersed phase, since the operation is performed under a high load (short processing time), only about 50 kinds of bacteria (dispersed bacteria) having a high growth rate are maintained in the dispersed phase for the treatment. In addition, the activity of the dispersed bacterial species depends on the raw water condition, and when the raw water condition to be treated suddenly changes, it is not possible to cope with these changes, and as a result, the treatment is temporarily deteriorated. In addition, when the introduction of raw water to the treatment tank is temporarily stopped due to a suspension of the production line, etc., if aeration is continuously performed without introducing the raw water, the dispersed bacteria may be killed by autolysis. This leads to reduced activity and worse processing. When the treatment is deteriorated due to the above-described process, it is necessary to perform a treatment such that the treatment is temporarily stopped, a microbial preparation or activated sludge is newly added as a seed fungus, and the normal treatment is performed. . Furthermore, in order to realize economical treatment, it is necessary to accurately grasp the time when the treatment has deteriorated, to stop the treatment, or to add an appropriate amount of inoculum in an optimal state.

Therefore, in the method for treating organic wastewater of the present invention, at least the quality of water in the first treatment tank is measured over time,
When the deterioration of the water quality is detected, at least the introduction of the water to be treated into the first treatment tank is temporarily stopped to add the seed sludge or the microorganism preparation, or the introduction of the water to be treated into the first treatment tank is stopped. The operation is controlled so that the seed sludge or the microbial preparation is added without the introduction, and thereafter, the introduction of the water to be treated into the first treatment tank is restarted. Then, as a measurement method for detecting the water quality in the first treatment tank over time, any one of pH value, TOC value, turbidity, BOD value, and COD value measurement is used, and these are obtained over time. From the measured values, deterioration of the water quality in the first treatment tank is detected by any one of a decrease in pH value, a decrease in TOC removal rate, a decrease in turbidity, a decrease in BOD removal rate, and a decrease in COD removal rate.

A description will be given by taking a decrease in the pH value in the first processing tank as an example. When the treatment in the first treatment tank deteriorates, the organic acid and the like remain in the treatment tank without being treated, so that the pH value in the dispersed phase decreases. Therefore, paying attention to this, the pH value of the dispersed phase is to be constantly monitored. For example, when the pH value becomes 6 or less, the control system is activated, and the processing in the first processing tank in a normal state is performed. Will be regulated.

The method of detecting the deterioration of the water quality in the first treatment tank is not limited to the above-described decrease in the pH value, but also decreases the TOC removal rate, the turbidity, the BOD removal rate, and the COD removal rate. Can be detected by any of
In the present invention, the TOC value, turbidity value,
Either the BOD value or the COD value may be measured over time, and this value may be used to detect when the water quality has deteriorated. When measuring a decrease in the TOC removal rate, for example, the TOC value of the water quality in the first treatment tank and the quality of the treated water discharged may be measured, and the TOC removal rate may be determined from these values. Then, for example, when the TOC removal rate drops by 20% or more of the steady state, the control system may be operated to regulate the first processing tank so that the processing is performed in a normal state.

In another embodiment, when considering that stable treatment is not performed when the supply of raw water to the treatment tank is temporarily stopped due to a suspension of the production line or the like, the dispersed phase of the raw water may be considered. It is preferable to monitor the state of inflow into the tank and to operate the control system to perform processing in a normal state in the first processing tank when there is no inflow of raw water for a long time. For example, the first
When the inflow of raw water into the treatment tank is stopped for at least two hours or more, the control system is operated, and aeration is repeated at regular intervals. In this state, preparation is made for resumption of introduction of the water to be treated into the first treatment tank. do it. Furthermore, when the introduction of the water to be treated into the first treatment tank is stopped for one day or more, aeration is performed after the addition of the seed sludge or the microorganism preparation, and then the introduction of the water to be treated into the first treatment tank is restarted. What is necessary is just to comprise. This makes it possible to always perform processing in a normal state. The method for measuring the water quality in the first treatment tank over time and detecting the deterioration of the water quality, which is performed in the organic wastewater treatment method of the present invention, may be any of the above-described methods, May be selected from among them, and the control system may be designed to operate based on a comprehensive judgment from a plurality of measurement results. According to the above configuration, the purification treatment of the organic wastewater by the two-phase activated sludge method can be performed stably and reliably, and excellent effects can be stably obtained. In particular, if the control system is configured to start up automatically in response to the detection result of the deterioration of the water quality in the first processing tank, more stable processing can be realized.

Regarding the method for treating organic wastewater of the present invention,
A control system for detecting deterioration of the water quality in the first treatment tank (dispersed phase) by monitoring the pH value in the first treatment tank and performing the control on the first treatment tank in response to the detection. 3 will be described. Examples of the organic wastewater treated in the method for treating organic wastewater of the present invention include various wastewaters containing organic substances, for example, processing plants for various fresh food products such as fish, shellfish, meat, and vegetables, dairy products, beverages, and confectionery. Industrial wastewater from various food production factories, breweries, fermentation factories, etc., or ordinary household wastewater. The concentration of organic pollutants in these organic wastewaters is not always constant because the types and production conditions of the raw materials being handled often vary from day to day or even on the same day. Specifically, the density may vary several times to 300 times, or even more in some cases. Furthermore, there are cases where the amount of organic wastewater to be treated becomes extremely small or does not flow in at all because of a stop of the production line. As described above, when actual wastewater in which the properties of the raw water or the amount of wastewater changes rapidly is biologically treated by the two-phase activated sludge method described below, the treatment cannot be coped with the sudden change, and the treatment is deteriorated. In some cases, a certain effect was not obtained.

That is, in the ordinary activated sludge method, the parallel treatment with various microorganisms living in the same treatment tank (aeration tank) is performed for several days to perform the purification treatment. In the two-phase activated sludge method, a first treatment tank and a second treatment tank in which microorganisms having different properties inhabit, respectively, are used.
Biological treatment with distinctive characteristics is performed in each tank, and by combining these treatments, the efficiency of the treatment is improved. In the first treatment tank, the treatment is performed while maintaining only the disperse bacteria having a high growth rate. However, since the activity of the disperse bacteria depends on the raw water state, it cannot cope with a sudden change in the raw water state. In addition, when raw water is not introduced, if only aeration is continued, dispersed bacteria may be killed by self-digestion, and as a result, the quality of treated water may be deteriorated. In the present invention, in order to effectively prevent the occurrence of deterioration in the quality of the treated water, the fact that the treatment state has deteriorated is detected by measuring the pH value of the dispersed phase, and it is determined that the treatment state has deteriorated. In such a case, the control system is operated to temporarily stop the flow of the raw water into the first treatment tank, and further, a microbial preparation or activated sludge is added as a seed fungus to perform the restarting treatment. That is, if the treatment in the dispersed phase is insufficient, the organic acid or the like remains in an untreated state, and the pH value of the dispersed phase decreases. Used for

As a specific control system in this case, as shown in FIG. 3, first, when the pH value of the dispersed phase becomes 6 or less, the control system is activated, and the inflow of raw water is temporarily stopped. Configure to stop. The time for stopping is 1.0 time of the processing time (dilution ratio) in the first processing tank.
It may be set to about 1/5. Next, seed sludge or a microbial preparation is added to the first treatment tank as a seed fungus. In the present invention, aeration is performed for a predetermined time after the addition of the microbial preparation or activated sludge, and then normal processing is performed. It is preferable to configure. Further, in this case, if the pH value in the first treatment tank exceeds 6.0 at the time when the microbial preparation or the activated sludge is added as the inoculum, the normal treatment may be resumed in this state. When using seed sludge as the seed fungus, it is preferable to use activated sludge in the second treatment tank, which is a predatory phase provided following the dispersion phase, which is the first treatment tank, as the seed sludge. The amount of addition is 1 volume of the dispersed phase.
It is preferable to be about 程度 to 1/10. When a microbial preparation is added, it is preferable to add the microbial preparation so as to be 10 to 50 mg / l.

Next, in the method for treating organic wastewater of the present invention, a control system which is particularly effective for preventing the deterioration of the treatment caused when the introduction of raw water generated due to the suspension of the production line or the like is prevented. 4 will be described. In this case, the state of introduction of the raw water into the first treatment tank (dispersed phase) is monitored, whereby the following control is performed on the first treatment tank. As described above, if only aeration is continuously performed without raw water flowing in, disperse bacteria may die due to autolysis,
Deterioration of processing occurs. In this case, if the inflow of the raw water is in a short-term stop, for example, in a continuous state for two hours, the operation may be temporarily stopped, and then the intermittent aeration may be controlled. The intermittent aeration may vary depending on the capacity of the processing tank and the like, but may be performed, for example, at intervals of 3 to 12 hours for 5 to 20 minutes. In this way, unlike the case where the aeration is continued, it is possible to effectively prevent the germs from being killed by autolysis. Then, when the raw water is introduced as usual, if the aeration amount is immediately switched to the normal operation, it is possible to perform a stable treatment without causing any influence due to the rest state in which the raw water does not flow. .

On the other hand, when the production line is stopped for a long time, for example, when there is no inflow of raw water for one day or more,
The above-mentioned intermittent aeration of the first treatment tank alone could not cope with it, and when the treatment was restarted, satisfactory treatment could not be performed for a while, and the treatment during that time deteriorated and the quality of treated water deteriorated. It will be. Therefore, in this case, as shown in FIG. 4, raw water is added to the dispersed phase in an amount of about 1/2 to 1/6 of the dispersed phase volume, and seed sludge is further added to the dispersed phase in an amount of 1/2 to 1 of the dispersed phase volume. /
After putting in 6 and aerating for a predetermined time and restarting,
Introduce raw water and resume normal operation.

The method of treating organic wastewater according to the present invention 2
Biological treatment of organic wastewater with activated sludge is a process of oxidative decomposition and utilization of organic matter by bacteria,
The process consists of two processes of producing sludge having good coagulation and sedimentation properties. In particular, it is considered that one of these processes is a rate-limiting factor for biological treatment of organic wastewater. That is, first, the first treatment tank is used as a bacterial flora that performs bacterial treatment in the substantial absence of non-fixing protozoa for the purpose of removing only organic matter without considering the sedimentation of activated sludge. In the first treatment tank, the organic substances are efficiently oxidized and decomposed by the bacteria, and the growth of bacteria using these organic substances as a nutrient source is promoted. Furthermore, at that time, the state of the bacterium is configured to be very easily predated by protozoa dispersed in individual cells. And the 2nd processing tank performed following the above-mentioned 1st processing tank is predation of bacteria,
The sessile protozoan fauna containing activated sludge for the purpose of treating the residual organic matter is used. The wastewater containing the bacterium treated in the first treatment tank (bacterial flora) is passed through the second treatment tank to the non-adherent protozoa. By treating the fixed protozoa in the absence of the protozoa, the bacteria grown above are more efficiently predated and removed by the protozoa.

In the above, in the bacterial flora that is the first treatment tank, it is necessary to make the grown bacteria extremely susceptible to predation by protozoa dispersed in individual cells.
For this purpose, the treatment time (dilution ratio) of the water to be treated in the first treatment tank is set not to be longer than the growth rate of the protozoa. For this reason, processing in the first processing tank is usually performed within a short time of about several hours, and high-speed processing is performed. Therefore, as described above, there may be cases where it is not possible to cope with a sudden change in the raw water state that occurs in the actual operation, so that it is necessary to operate while performing the control as described above. On the other hand, the treatment in the second treatment tank requires several hours to several days. However, since the above-described bacterial treatment is performed in the first treatment tank, as described below, the conventional one treatment method is used.
More efficient treatment can be performed than in the case of the activated sludge method of the phase.

That is, in the two-phase activated sludge method, the sessile protozoan flora (second sewage sludge) is treated in the bacterial flora (first treatment tank).
Bacteria contained in the water to be treated introduced into the treatment tank) are non-aggregating and are in a state where they are extremely easily predated by protozoa dispersed in individual cells, so that the bacteria in the second treatment tank The rate of bacterial removal by protozoa is extremely high. Furthermore, in the second treatment tank, the treated water that has been treated with the protozoa as described above contains, as sludge, the fixed protozoa that have proliferated in the process described above, and the sludge is
Since the separation property is very excellent, it can be easily separated by a conventional solid-liquid separation means such as a precipitation tank. In addition, the final treated water discharged after removing the sludge is extremely clean, free of organic matter and protozoa. As a result, when the organic wastewater is treated by the two-phase activated sludge method employed in the present invention, a high load operation that is about two to three times that of a normal case can be performed, and the sludge generation amount is reduced to about 1/2. Can be reduced.

Bacteria used in the bacterial flora (first treatment tank) of the two-phase activated sludge treatment that can obtain such excellent effects are arbitrary as long as they are aerobic, and include, for example, Alcaligenes bacteria, Pseudomonas spp., Bacillus spp., Aerobacterium spp., Flavobacterium spp., And the like. Such bacteria usually live in wastewater,
Since the organic matter in the wastewater is propagated as a nutrient source, it is not particularly necessary to add the organic wastewater from the outside in the present invention in which the wastewater is treated. However, in order to smoothly perform the purification treatment of the wastewater, an appropriate inoculum may be added from the outside at the start of the purification treatment, if necessary. Examples of the inoculum used at this time include, for example, Biocore BP, OF-10, and Serve 1 (trade name, Environmental Engineering Co., Ltd.)
) Can be suitably used.

In the present invention, as described above, the treatment with the aerobic bacteria as described above is performed in the first treatment tank, and the wastewater discharged from the first treatment tank (first treated water).
The organic matter contained therein is oxidatively decomposed by bacteria, and the bacteria themselves grow with the organic matter as a nutrient source.
Therefore, it can be said that the organic matter in the wastewater has been converted into bacteria by looking only at the phenomenon caused by the bacterial treatment in the first treatment tank. According to the study of the present inventors, if the fluctuation of the concentration of organic pollutants in the water to be treated is suppressed and the bacterial treatment in the bacterial flora can be optimized, the removal rate of the soluble organic matter in the first treatment tank can be increased by 95 to 98. %. In terms of the conversion rate of organic matter to bacteria,
It is about 40 to 50%, and it can be said that 100 parts by weight of organic matter is converted into about 40 to 50 parts by weight of bacteria having good dispersibility. As a result, the processing efficiency in the next second processing tank is improved, and the amount of generated sludge is also reduced. But,
In this case, if the fluctuation of the concentration of the organic pollutant component in the water to be treated introduced into the first treatment tank is not suppressed, the conversion rate of organic substances into bacteria is reduced, and the above-mentioned excellent effects are impaired.

In the method for treating organic wastewater of the present invention, it is necessary to perform the bacterial treatment in the first treatment tank in the substantial absence of protozoa. As a result, the bacteria contained in the treated wastewater become non-agglomerated, effectively preventing the formation of bacterial clumps, so-called sludge, in the wastewater, and the first treatment obtained as a result of such bacterial treatment. Water is
It is substantially free of sludge and contains bacteria dispersed in fine particles converted from organic matter. Since such a dispersed bacterium is a eutrophic source of protozoa, the treatment efficiency in the next protozoa treatment in the second treatment tank composed of the activated sludge phase containing the protozoa is remarkable. Enhanced. Conversely, when the protozoa coexist in the bacterial treatment performed in the first treatment tank,
In the bacterial flora, bacteria that are easily predated by protozoa are predated, so that bacteria that are not easily predated mainly grow, and bacterial clumps are easily generated in the bacterial flora. Since these bacterial clumps are hard to be eaten by protozoa, when the first treated water containing such bacterial clumps is treated in the second treatment tank where activated sludge is present,
These may pass through the protozoa treatment process, causing a reduction in treatment efficiency in protozoa treatment. In the present invention, "substantially in the absence of protozoa" refers to a state in which the growth of protozoa is suppressed, and as a result, almost no new protozoa appear during the bacterial treatment process.

In the process of treating bacteria in the first treatment tank in the method for treating organic wastewater of the present invention, the specific method for inhibiting the growth of protozoa and making the protozoa substantially absent is as follows. The following methods utilizing differences in properties between bacteria and protozoa can be used. For example, there is a large difference in the growth rate between bacteria and protozoa, and the growth rate of bacteria is extremely high compared to that of protozoa. Of the protozoa can be stopped.
That is, according to this principle, the protozoa emerge from the effluent by passing the wastewater to be treated through a bacterial treatment process at a treatment time (dilution rate) equal to or higher than the maximum specific growth rate of the protozoa and equal to or lower than the maximum specific growth rate of the bacteria. Bacterial treatment can be achieved in a state in which bacteria are suppressed. In the present invention, for example, the treatment time (dilution rate) of the water to be treated in the process of treating bacteria in the first treatment tank is set to the maximum specific growth rate of the protozoa or more and the maximum specific growth rate of the bacteria or less, for example, 1 to 12 hr. . By adjusting the range, the bacterial treatment can be performed in a state where the protozoa are substantially absent.

The suppression of the appearance of protozoa during the bacterial treatment process can also be achieved by adjusting environmental conditions such as temperature and pH. That is, bacteria can grow under a wide range of environmental conditions, but the environmental conditions under which protozoa can grow are limited to a narrower range than bacteria. For example, the growth of protozoa is remarkably suppressed at a temperature of 40 ° C. or higher. Therefore, if the temperature of the bacterial treatment process is maintained at 40 ° C. or higher, the appearance of protozoa can be suppressed. In addition, protozoa are inhibited from growing at pH 4 or lower or at pH 10 or higher.
By maintaining the above range, the appearance of protozoa can be stopped.

In the method for treating organic wastewater of the present invention, as described above, the organic matter contained in wastewater is reduced to 100% by efficient bacterial treatment in the first treatment tank.
It is converted into bacteria dispersed in a state of fine particles at a close ratio, and thereafter, the first treated water from the first treatment tank is treated with protozoa in the second treatment tank where activated sludge is present,
These bacteria are efficiently predated and removed by protozoa. In the present invention, furthermore, in this protozoa treatment process, in order to facilitate separation of the protozoa that have eaten the bacteria, only the fixed protozoa having good solid-liquid separation are present in the second treatment tank. The treatment is performed in a state where non-fixing protozoa having poor solid-liquid separation properties are substantially absent.

The sessile protozoa as referred to in the present invention means a protozoa having a property of being easily fixed to solid particles or solid substances, or a protozoan having a property of being easily fixed and aggregated with each other. . Such a thing, for example,
Balticella, Epistealis, Opelclaria, Calcium, Zutanium, etc., include sessile-fixed ciliates, such as Aspidesca, which huffs the solid surface.
Euplotes can be used because it easily settles together with sludge. On the other hand, the non-fixed protozoan referred to in the present invention means a protozoan that does not have the above properties.

In the present invention, the second sludge containing activated sludge is used.
The sticky protozoa treatment performed in the treatment tank, as described above, must be performed in a state where the growth of non-sticky protozoa is stopped and the non-sticky protozoa are substantially absent. Such a state can be formed by utilizing the fixation and non-fixation properties of protozoa. That is, if an appropriate solid substance that can serve as a carrier for fixation is present in the treatment system, the fixative protozoa will adhere to the solid substance and grow. In contrast, non-fixing protozoa do not have such properties. Therefore, in protozoan treatment,
Non-adherent (free-swimming) protozoa can be obtained by passing the treated wastewater through the treatment process in the presence of a carrier for adherent protozoa with a treatment time (dilution rate) that is higher than the maximum specific growth rate of protozoa. While allowing them to flow out of the treatment system, the sticky protozoa can remain in the treatment system and grow. In the method for treating organic wastewater of the present invention, as described below,
In order to treat this protozoa treatment in the presence of activated sludge,
Activated sludge acts as a carrier for sessile protozoa,
A state in which non-fixing protozoa are substantially absent can be easily formed. In the present invention, an environment in which the adherent protozoa are more likely to adhere to the second treatment tank is further provided with, for example, solid particles such as sand and stone, plate-like bodies, cloth-like objects, and filter paper as carriers. It may be. In the present invention, as the second treatment tank for performing the above-mentioned sessile protozoa treatment,
What is necessary is just to use the aeration tank conventionally used for the activated sludge treatment method.

According to the method for treating organic wastewater of the present invention, as described above, the first treated water after the bacterial treatment is treated with a fixed protozoa in the absence of a non-fixed protozoa, and the wastewater is treated. Bacteria are predated and removed by the protozoa, and as a result, in the second treatment tank, the fixed protozoa that grew using the bacteria as a nutrient source are present as sludge. In other words, only looking at the phenomenon that occurs in the second treatment tank, it can be said that the bacteria in the wastewater to be treated were converted into the sticky protozoa by the sticky protozoa treatment and sludge was formed. As described above, in the present invention, the organic matter in the wastewater is converted into bacteria by the bacterial treatment in the first treatment tank.
The bacterium is in the form of non-aggregated fine particles, and is present in a state of being dispersed in individual cells in wastewater, so that it is extremely easy to be eaten by protozoa. Therefore, the rate of bacterial removal by protozoa in the second treatment tank is
Extremely high values of about 95-97% are obtained. Also, from the viewpoint of conversion of bacteria to protozoa in protozoa processing, about 30 to 40% of bacteria are converted to protozoa.

In the method for treating organic wastewater of the present invention, the first
Since the fluctuation of the organic pollutant component concentration of the water to be treated introduced into the first treatment tank is suppressed so that the conversion of the organic matter into bacteria in the treatment tank is ideally performed, as described above, in this case, The conversion rate of organic matter to bacteria becomes about 40 to 50%. Therefore, taking this into consideration, the organic matter which was 100 parts by weight is converted into about 40 to 50 parts by weight of bacteria and reduced, and furthermore, about 12 to 10 parts by weight in the second treatment tank described above.
It can be said that it was converted to 20 parts by weight of protozoa (sludge) and the weight was further reduced. Therefore, according to the two-phase activated sludge treatment,
When the same amount of organic matter is treated, the amount of generated sludge can be reduced as compared with the conventional activated sludge method.

Further, the wastewater obtained by the protozoa treatment performed in the second treatment tank (hereinafter, simply referred to as second treated water) contains the sessile protozoa that have multiplied as sludge as described above. . Therefore, this sludge has a property that it easily adheres to solid particles and solid substances such as activated sludge, and is very excellent in separability. It can be easily separated. As a result, the final treated water obtained is very clean without turbidity and free from organic matter and protozoa. Therefore, in the method for treating organic wastewater of the present invention,
When the pH in the first treatment tank becomes 6 or less, or when the introduction of raw water is stopped for one day or more, when adding seed sludge into the first treatment tank, It is preferred to use activated sludge.

Hereinafter, the method for treating organic wastewater of the present invention will be described more specifically based on the treatment flow shown in FIG. In the organic wastewater treatment method of the present invention, as is apparent from comparison with the treatment flow by the ordinary activated sludge method shown in FIG. 8, the activated sludge treatment in the ordinary activated sludge method is performed in a two-phase process. Perform separately. In this case, it is more preferable to provide an adjustment tank before the first treatment tank, because the fluctuation of the raw water concentration of the water to be treated introduced into the first treatment tank can be suppressed. However, in the second invention of the present invention, it is not essential to provide an adjustment tank before the first treatment tank, and the deterioration of the water quality in the first treatment tank is detected by some means. What is necessary is just to be configured to perform an operation for restoring the state in one processing tank to a good state.

In the flow shown in FIG. 3, two-phase activated sludge treatment is performed by a first treatment tank for treating bacteria and a second treatment tank for treating fixed protozoa and activated sludge. In order to easily incorporate the organic wastewater treatment method of the present invention without greatly changing the treatment flow of the organic wastewater due to the activated sludge treatment, a conventional aeration tank is used.
The first for use as a treatment tank and for treating bacteria separately
It is preferable to provide a processing tank. Of course, as shown in FIG. 5, it may be constituted by an integrated tank.

As the first treatment tank used at this time, a vessel provided with an aeration tube for air or oxygen ventilation, which has been conventionally used in biological treatment, can be used. In addition, as the second treatment tank in which activated sludge to be provided for protozoan treatment is present, a standard type aeration tank, a fixed bed or a rotating disk type aeration tank, or the like,
Any treatment tank conventionally used for activated sludge treatment can be used.

In the present invention, the supply rate of the wastewater to be treated to the first treatment tank as described above is determined by controlling the treatment time (dilution ratio) of the protozoa to the maximum specific growth rate in order to suppress the appearance of protozoa. As described above, usually, 1 to 12 hr. It is preferable to select so that Furthermore, regardless of the processing time,
The appearance of protozoa may be controlled by other factors such as the temperature and pH of the water to be treated. Further, in the second treatment tank following the bacterial treatment in the first treatment tank, aeration treatment is performed in the presence of sludge consisting of the sticky protozoan aggregates returned from the sedimentation tank or the like. However, in any of the above cases, the optimum treatment time (dilution ratio) and the like vary depending on the type of the water to be treated and the treatment conditions, and cannot be uniquely determined. preferable. Furthermore, for example, when the concentration of organic matter in the wastewater to be treated is relatively high and the operation is carried out for a predetermined treatment time (dilution ratio), the load of bacteria introduced into the second treatment tank becomes too high. In order to obtain the above processing time (dilution ratio), the dilution water may be introduced from the outside into the second processing tank.

When the actual organic wastewater is treated by the method for treating organic wastewater of the present invention as described above, the state of raw water changes abruptly, or the introduction of the water to be treated is temporarily interrupted or stopped. Even in the case where water is treated, the quality of the treated water is not deteriorated before and after the fluctuation, and is not inferior to the treated water treated by the conventional activated sludge method, but rather is improved, and the treatment efficiency is improved. In addition, the excellent effect of suppressing the generation of excess sludge and achieving remarkable weight reduction can be economically achieved in a stable state.

[0068]

Next, the present invention will be described in more detail with reference to examples of the present invention. (First Invention) Embodiment 1-1 500 liters / liter constructed according to the flow shown in FIG.
Using a day-scale pilot plant, activated sludge treatment of raw water containing organic pollutants was performed. Table 1-1 below shows the properties of the raw water, the properties in the adjustment tank, and the properties of the water to be treated adjusted in the adjustment tank and introduced into the first treatment tank. The raw water used was organic wastewater from a food factory where the concentration of organic pollutants fluctuated significantly.

[0069]

[Table 1]

As the first treatment tank for performing the bacterial treatment, a first treatment tank having an air aeration tube with a real volume of 100 liters was used, and the dissolved oxygen was adjusted to 5.0 mg / l. It was operated by aeration. The supply rate of the water to be treated to the first treatment tank was set so that the treatment time (dilution ratio) was 5 hours, and the treatment temperature at that time was 40 ° C. In this example, as the inoculum,
10 g of Biocore BP was added. In this embodiment, the concentration of the organic pollutant component indicated by the BOD in the water to be treated introduced into the first treatment tank is 1,600 to 2,400 (m
g / l). In this case, the fluctuation was introduced by adjusting within 20% from the median of the average concentration of the raw water.

The first bacteria treated in the first treatment tank described above is
The second treatment tank for introducing treated water and treating the fixed protozoa was treated using an aeration tank having a real capacity of 400 liters. In addition, 3,000 mg / liter of activated sludge was added to the second treatment tank as a support for protozoa.
After acclimation for about two weeks, the animals were subjected to the test.
With the configuration of the first and second processing tanks, the BOD load
Two-phase activated sludge treatment was performed at 0 kg / m ³ · day. Then, as shown in FIG. 1, the second treated water obtained by treating in the second treating tank was introduced into the sedimentation tank and solid-liquid separated.

With respect to the treated water after the above treatment, the amount of sludge generated per input BOD was measured and shown in Table 2-1. The amount of excess sludge generated was reduced as compared with the case of a comparative example described later. I was able to. In addition, the quality of the treated water was equal to or higher than that of Comparative Example 1 described below in which the normal treatment was performed, and it was found that the water quality was improved.

Comparative Example 1-1 The raw water shown in Table 1-1 was directly introduced without suppressing the fluctuation of the concentration of organic pollutants in the water to be treated introduced into the first treatment tank, and no adjustment tank was provided. Is 2 in the same manner as in Example 1.
A phase activated sludge treatment test was performed. As a result, as shown in Table 2-1, the BOD load (treatment efficiency) and the quality of the treated water were inferior to those of Example 1, and the amount of generated sludge was lower than that of Example 1. There were quite a lot.

[0074]

[Table 2]

(Second Invention) <Embodiment 1-2> In the test apparatus shown in FIG. 5 comprising a 200-liter adjusting tank, an 80-liter first processing tank, and a 420-liter second processing tank, A daily treatment test was performed. At that time, the amount of wastewater to be treated is 500 liters / day (introduction speed: 20.8 liters / hour),
Aeration was performed so that the dissolved oxygen was 3.0 mg / liter. As the start-up of the first treatment tank, 100 g each of Biocore BP (trade name: manufactured by Environmental Engineering Co.) and Saab I (manufactured by Environmental Engineering Co., Ltd.)
Was added. In the second treatment tank, activated sludge from the sewage treatment plant was added as seed sludge so that the MLSS became 3,000 mg / liter. In addition, sludge was discharged throughout the test period.
5 liters / day was drained from the second treatment tank.

Table 1-2 below shows properties of the wastewaters A and B used in the wastewater treatment of this example. In this embodiment,
Using these wastewaters, treatment of wastewater A was performed from the first day to the 30th day of the test, and the wastewater was treated on the 31st day of the test.
To B, and then conduct a wastewater B treatment test until the 60th day, and then perform the wastewater A treatment again from the 61st to the 100th day to confirm the change in the state of the treatment with respect to the change in the properties of the raw water. Done.

[0077]

[Table 3]

At this time, as shown in FIG. 5, a pH sensor was provided in the first treatment tank, and the pH in the tank was monitored. Then, when the pH in the first treatment tank drops to 6.0 or less, the raw water pump is stopped (3 hours), and the sludge is put into the first treatment tank by the sludge pump 2 from the second treatment tank. 10 liters were supplied. As a result, as shown in FIG. 6, it was confirmed that the quality of the treated water was not disturbed immediately after the wastewater to be treated was switched to one having a different property, and that stable treatment could be performed.

<Example 2-2> After the test of Example 1, the operation was stopped at night on Wednesday and Sunday during one week using wastewater A, and during the daytime (9:00 to 17:00). 2) Only wastewater A was supplied to the first treatment tank. Wastewater volume is 167 liters /
Performed on a day (introduction rate: 20.8 l / h). On other days of the week, wastewater is continuously supplied throughout the day, and the throughput of wastewater is 500 liters / day (introduction speed: 20.8 liters / day).
Time). After a lapse of 3 hours from the time when the inflow of the wastewater was stopped, the first treatment tank was aerated for 5 minutes at intervals of 5 hours. The other conditions were the same as in Example 1. As a result, wastewater was introduced only in the daytime, and after that, the operation was resumed after Wednesday and Sunday when the operation was stopped for a short period (night). However, as shown in FIG. It was confirmed that the treated water of good water quality was obtained stably without any change in the water quality.

<Embodiment 3-2> Using the same test apparatus as in Embodiment 1-2, the same wastewater treatment as in Embodiment 1-2 was performed, and the water quality in the first treatment tank deteriorated. To T
The change in the state of the treatment with respect to the change in the properties of the raw water was confirmed based on the degree of the decrease in the OC removal rate. That is,
In this example, the wastewater and treated water in the first treatment tank were measured at one-hour intervals by a TOC meter, and the removal rate was calculated based on the results. When the removal rate became 70% or less, the raw water pump was stopped, the state was maintained for 3 hours, and 10 liters of sludge was supplied from the second treatment tank into the first treatment tank by the sludge pump 2. As a result, as in the case of Example 1-2, it was confirmed that the quality of the treated water was not disturbed immediately after the wastewater to be treated was switched to one having a different property, and that stable treatment could be performed.

<Comparative Example 1-2> A test was performed in the same manner as in Example 1 except that the pH of the first treatment tank was measured and the operation was not controlled, but the normal continuous treatment was performed. Was. As a result, as shown in FIG. 6, immediately after switching the wastewater, it was found that the quality of the treated water deteriorated.

<Comparative Example 2-2> In Example 2-2,
The same test as in Example 2-2 was performed except that the operation was performed without stopping the aeration even during the night when the inflow of raw water was stopped. As a result, as shown in FIG. 7, it was found that the quality of the treated water deteriorated on Thursday and Monday the day after the wastewater inflow only in the daytime.

[0083]

(First invention) As described above, according to the present invention, in the method for treating organic wastewater using the activated sludge method, the actual fluctuation of the concentration of the organic pollutant component represented by BOD is remarkable. Even when organic wastewater is treated, extremely high treatment efficiency is achieved without deteriorating the quality of treated water discharged in the final stage, miniaturization of the treatment equipment is achieved, and at the same time the amount of excess sludge is reduced. Provided is a method for treating organic wastewater that can reduce the amount of organic wastewater.

(Second Invention) As described above, according to the present invention, in the method for treating the water to be treated (raw water) containing an organic substance using the activated sludge method, the raw water state changes abruptly or Even when the introduction of the water to be treated is temporarily interrupted or stopped, the quality of the treated water discharged at the final stage does not deteriorate before and after, and the improvement of the treatment efficiency can be achieved in an economical and stable state, and Provided is a method for treating organic wastewater, which achieves remarkable reduction of excess sludge.

[Brief description of the drawings]

FIG. 1 is an example of a processing flow of an organic wastewater treatment method according to the first invention of the present invention.

FIG. 2 is a schematic view showing an example of a method for treating organic wastewater of the first invention of the present invention.

FIG. 3 is an example of a processing flow of a method for treating organic wastewater according to the second invention of the present invention.

FIG. 4 is another example of the treatment flow of the method for treating organic wastewater according to the second invention of the present invention.

FIG. 5 is a schematic view showing an example of a method for treating organic wastewater according to the second invention of the present invention.

FIG. 6 is a graph for explaining the results of Examples and Comparative Examples of the second invention of the present invention.

FIG. 7 is a graph for explaining the results of Examples and Comparative Examples of the second invention of the present invention.

FIG. 8 is a schematic view showing a conventional example using an activated sludge treatment method.

 ────────────────────────────────────────────────── ─── Continued on the front page (74) The above two agents 100077698 Attorney Katsuhiro Yoshida (one outsider) (72) Inventor Kazunori Nakamura 1-3-3 Higashi, Tsukuba, Ibaraki Pref. (72) Inventor Osamu Oyama 1-9-8 Higashikanda, Chiyoda-ku, Tokyo Environmental Engineering Co., Ltd. (72) Inventor Kiyoshi Kurihara 1-9-8 Higashikanda, Chiyoda-ku, Tokyo Environmental Engineering Co., Ltd. Inside

Claims (6)

[Claims] 1. A treatment water containing an organic pollutant is introduced into a first treatment tank, and bacteria are treated in the first treatment tank in a substantially absence of protozoa. Is oxidatively decomposed and converted into non-aggregating bacteria, and then the wastewater containing the non-aggregating bacteria from the first processing tank is introduced into the second processing tank in which activated sludge is present, and non-fixed in the second processing tank. A method for treating organic wastewater by a two-phase activated sludge method in which a fixed protozoa is treated in the substantial absence of a sessile protozoa to prey and remove non-aggregating bacteria from the sessile protozoa; A method for treating organic wastewater, wherein fluctuations in the concentration of organic pollutants indicated by BOD in the water to be introduced introduced into the plant are suppressed. 2. The method according to claim 1, wherein the fluctuation of the concentration of the organic pollutant represented by the BOD in the water to be treated is within 50% of the median of the average concentration of the raw water as the actual organic wastewater. 3. The method for treating organic wastewater according to item 1. 3. A treatment water containing an organic pollutant is introduced into a first treatment tank, and bacteria are treated in the first treatment tank in a substantially absence of protozoa, and organic matter contained in the treatment water is obtained. Is oxidatively decomposed and converted into non-aggregating bacteria, and then the wastewater containing the non-aggregating bacteria from the first processing tank is introduced into the second processing tank in which activated sludge is present, and non-fixed in the second processing tank. A method of treating organic wastewater by a two-phase activated sludge method in which a non-aggregating bacterium is predated and removed by the non-agglutinating bacteria in a substantially non-existent protozoan, The water quality in the tank is measured over time, and when the deterioration of the water quality is detected, the seed sludge or the microorganism preparation is added without stopping the introduction of the water to be treated into the first treatment tank. Organic wastewater treatment method. 4. At least the water quality in the first treatment tank is measured over time by any one of pH value, TOC value, turbidity, BOD value and COD value, and the pH value decreases, the TOC removal rate decreases, and the turbidity decreases. The method for treating organic wastewater according to claim 3, wherein the deterioration of the water quality in the first treatment tank is detected by any one of a decrease in degree, a decrease in BOD removal rate, and a decrease in COD removal rate. 5. The pH value in the first treatment tank is 6 or less, or
When any of the reduction of the TOC removal rate, the reduction of the turbidity, the reduction of the BOD removal rate, and the reduction of the COD removal rate becomes more than 20% of the steady state, introduction of the water to be treated into the first treatment tank is performed. The method for treating organic wastewater according to claim 4, wherein the seed sludge or the microbial preparation is added without stopping. 6. The method for treating organic wastewater according to claim 3, wherein activated sludge in the second treatment tank is used as the seed sludge.