JPH10337590A - Method for addition of granulated solid catalyst carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a catalyst support from flowing out into treating water when granulated solid catalyst carrier for prevention of bulking is cast into an aeration tank of activated sludge treatment by a method wherein a specific amount of a cationic or a nonionic polymer coagulant is added to a sedimentating granulated solid catalyst carrier. SOLUTION: In a method for adding a granulated solid catalyst carrier for prevention of bulking to an aeration tank of activated sludge treatment, sedimentating granulated solid catalyst carrier and 0.1 to 1 wt.% to the sedimentating solid catalyst carrier of a cationic or a nonionic polymer coagulant are added. Thereby, a sedimentation property of the catalyst carrier is raised, and surfacing is made difficult. Further the cationic or nonionic polymer coagulant is added for the purpose of accelerating adsorption of the catalyst carrier to the sludge, and not for the purpose of accelerating coagulation of the sludge. Therefore, so much amount as to accelerate coagulation of the sludge is not required to be added. A very small amount thereof suffices for the sedimentating solid catalyst carrier, and when such the loading is applied, bioremediation does not receive a bad influence therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for adding a granular solid carrier for preventing bulking to an aeration tank for treating activated sludge, and more particularly to a method for preventing the particulate solid carrier from flowing out of the aeration tank.

[0002]

2. Description of the Related Art In the activated sludge treatment of wastewater, the treatment efficiency is improved by keeping the activated sludge at a high concentration, shortening the time required for purification and reducing the capacity of the aeration tank (Japanese Patent Laid-Open No. 3-178395). ) Or by increasing the specific gravity of the activated sludge itself to prevent bulking (JP-A-48-425).
For the purpose of Japanese Patent Publication No. 70 (1999), a method of adding a granular solid carrier having a particle size of 100 μm or less, for example, clay, activated carbon, incinerated ash, granulated blast furnace slag, or the like to the aeration tank may be adopted.

[0003] In this case, a cationic polymer flocculant is added at the same time, and the sedimentation promoting effect of the granular solid carrier and the sedimentation promoting effect of the polymer flocculant due to the synergistic effect are increased to increase the sedimentation. There has also been proposed a method for obtaining a property promoting effect (JP-A-62-186997). In Japanese Patent Application Laid-Open No. 62-186997, an inorganic porous powder is used as a granular solid carrier, and in order to effectively prevent bulking of sludge, 90% by weight of such a porous carrier is used.
Both are used in combination with the following at a ratio of at least 10% by weight of the polymer flocculant (specifically, a polymer flocculant of about 1/4 of the porous carrier).

It has also been proposed to add a particulate solid carrier, a microbial preparation, an inorganic coagulant and a polymer coagulant in combination to prevent bulking (JP-A-2-24159).
No. 6). In this Japanese Patent Application Laid-Open No. 2-241596,
The granular solid carrier is preferably a porous carrier, and the polymer coagulant is preferably an anionic or nonionic polymer coagulant. Specific addition ratios are 50% by weight of the solid carrier and 1% by weight of the microorganism preparation. %, Inorganic coagulant 33% by weight, polymer coagulant 16% by weight, or ferric chloride 25kg / time for a total of 20kg / time of a solid carrier and an anionic polymer coagulant, and use of the coagulant The amount is very large.

[0005]

In order to obtain sufficient sludge sedimentation by adding a granular solid carrier, it is necessary to use MLS in an aeration tank.
It is necessary to add the granular solid carrier to the S in a dry weight ratio of 0.5 times or more, and sometimes 2 times or more in some cases. Therefore, if the capacity of the aeration tank is as large as several thousand m ³ or more, the required amount of the solid carrier is often 10 tons or more. The particulate solid carrier added in such a large amount is often negatively charged, but most of it is easily dispersed in water and physically adsorbed to activated sludge. However, part of the sludge is suspended in the treated water without being taken into the activated sludge and flows out of the aeration tank as SS. Therefore, immediately after the introduction of the carrier, there is a case where the wastewater treatment standard cannot be temporarily satisfied due to an increase in SS in the treated water.

In the method described in Japanese Patent Application Laid-Open No. 62-186997, in which a cationic polymer flocculant is used in combination, the amount of carrier added can be reduced due to the effect of accelerating the sedimentation. The coagulation effect of the molecular coagulant is temporary, and does not provide the effect of addition over a long period of time. Moreover, in order to obtain a good effect by the combined use, it is necessary to use a relatively large number of cationic polymer flocculants. However, since the cationic polymer flocculant is toxic to activated sludge, it promotes flocculation. The use of large amounts of cationic polymeric flocculants for wastewater is not preferred for biological treatment of wastewater.

In the method described in JP-A-2-241596, a relatively large amount of a coagulant is used to promote coagulation, and a bad influence on microorganisms is expected.

The methods described in JP-A-62-186997 and JP-A-2-241596 improve the sedimentation of sludge by using a coagulant in combination to prevent bulking in an aeration tank. Conventionally, no measures have been studied for preventing the carrier from flowing out into the treated water when the granular solid carrier is charged.

The present invention has been made in view of the above-mentioned conventional circumstances, and effectively prevents carrier outflow into treated water when a granular solid carrier for preventing bulking is charged into an aeration tank for activated sludge treatment. It is an object of the present invention to provide a method for adding a granular solid carrier to be prevented and an activated sludge treatment auxiliary.

[0010]

According to the present invention, there is provided a method of adding a granular solid carrier for preventing bulking to an aeration tank for treating activated sludge. 0.1 to the granular solid carrier
1% by weight of a cationic or nonionic polymer flocculant is added.

As described above, conventionally, measures have been taken to improve the sedimentation of sludge in an aeration tank, but no measures have been taken to prevent carrier outflow when granular solid carriers are charged.

The present inventors have repeatedly studied to solve the problem of deterioration of treated water quality due to the outflow of the carrier at the time of the introduction of the granular solid carrier. In addition, fine particles having a particle size of 1 μm or less are inevitably mixed, and when the fine particles are introduced into the aeration tank, they float on the water surface without being adsorbed by sludge, and this is treated water. It was found that the outflow to the side caused carrier outflow.

In the present invention, the use of a sedimentable granular solid carrier as the carrier enhances the sedimentation of the carrier and makes it difficult to float. In addition, by adding a cationic or nonionic polymer flocculant, the adsorption of the carrier to the sludge is promoted, thereby preventing the carrier from flowing into the treated water.

In the present invention, the cationic or nonionic polymer flocculant is added to promote the adsorption of the carrier to the sludge as described above, but not to promote the flocculation of the sludge. Therefore, the cationic or nonionic polymer flocculant does not need to be added in such a large amount as to promote the flocculation of sludge.
A very small amount of about 1% by weight may be used. With such an addition amount, the addition of the flocculant does not adversely affect the biological treatment.

[0015]

Embodiments of the present invention will be described below in detail.

The carrier used as the granular solid carrier in the present invention may be a porous or non-porous carrier as long as it is a sedimentable one that does not float in water. Such a sedimentable granular solid carrier has a specific gravity of about 1.5 to 7, for example, granulated slag (specific gravity 2.9), iron oxide (specific gravity 5.1), kaolin (specific gravity 2.6). , Kibushi clay (specific gravity 2.3), zeolite (specific gravity 2.6), coal ash (specific gravity 2.2) and the like.

The particle size of these carriers is preferably about 5 to 100 μm from the viewpoint of sedimentation properties, bulking prevention effect, handleability and the like.

On the other hand, the cationic or nonionic polymer flocculant is not particularly limited, but Hoffman decomposition of aminated (meth) acrylate polymer, aminated (meth) acrylamide polymer, and poly (meth) acrylamide Or a cationic polymer flocculant such as polyethyleneimine, or a nonionic polymer flocculant such as polyacrylamide.
“Acrylic” means “methacrylic or acrylic”. ).

These cationic polymer flocculants and nonionic polymer flocculants may be used in combination.

In the present invention, the amount of the cationic or nonionic polymer flocculant used is 0.1 to 1% by weight based on the settling granular solid carrier. This ratio is 0.1% by weight
If the amount is less than the above, the effect of using a cationic or nonionic polymer flocculant to prevent the carrier from flowing out of the present invention cannot be sufficiently obtained. If the amount exceeds 1% by weight, the activated sludge may be adversely affected. Cationic or nonionic polymer flocculant,
In particular, the content is preferably 0.2 to 0.8% by weight based on the settling granular solid carrier.

In the method for adding a granular solid carrier according to the present invention, when a settling granular solid carrier is added to an aeration tank to prevent bulking, a cationic or nonionic polymer flocculant is added to prevent the carrier from flowing out. In order to prevent the bulking, it is preferable that the amount of the settling granular solid carrier added for preventing bulking is 0.2 to 3 times the weight of the MLSS in the aeration tank.

[0022]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 Activated sludge having MLSS 4000 mg / L, SV30 99% with filamentous bulking was placed in a 1-L beaker, and granulated slag having an average particle size of 12 μm (specific gravity: 2.75 g) was used as a settling granular solid carrier. 9) and 5 mg / L of a cationic polymer flocculant ("Crifix CP985" manufactured by Kurita Kogyo KK) were added thereto, and the mixture was stirred at 500 rpm with a magnetic stirrer for 30 minutes. afterwards,
The solution was transferred to a 1 L measuring cylinder, and the sedimentation property was measured. The results are shown in Table 1.

The SS of the supernatant after 30 minutes was measured, and the results are shown in Table 1.

Example 2 The procedure of Example 1 was repeated, except that a nonionic polymer flocculant (“Cryfloc PN133” manufactured by Kurita Kogyo KK) was added at 10 mg / L in place of the cationic polymer flocculant. The sedimentability and SS of the supernatant were measured, and the results are shown in Table 1.

Comparative Example 1 In Example 1, the activated sludge was used alone, and the granulated slag and the flocculant were not added, and the mixture was stirred in the same manner to settle down and remove the supernatant liquid.
S was measured, and the results are shown in Table 1.

Comparative Example 2 The sedimentation property and the SS of the supernatant were measured in the same manner as in Example 1 except that no flocculant was added, and the results are shown in Table 1.

[0028]

[Table 1]

Tables 1 and 2 show that according to the present invention, an increase in SS in treated water due to the addition of a granular solid carrier can be effectively prevented.

Example 3 BO in an aeration tank capacity of 4000 m ³ and a sedimentation tank capacity of 800 m ³
D450mg / L wastewater 0.6kg-BOD
A field test was conducted with a processing apparatus of a T food factory that was processing at / m ³ · day. At this time, the activated sludge was filamentous bulking, MLSS was 4300 mg / L, SV30 was 98
%Met.

16 tons (4 g / L) of granulated slag (specific gravity: 2.9) having an average particle size of 12 μm as a granular solid carrier, and a cationic polymer flocculant (“CLIFIX CP985” manufactured by Kurita Kogyo KK) were used. 20 kg (5 mg / L) was charged.
At this time, the outflow SS in the treated water from the aeration tank was measured over time, but as shown in Table 2, no increase in SS was observed.
It was confirmed that outflow of the carrier was prevented.

[0032]

[Table 2]

[0033]

As described above in detail, according to the present invention, when a granular solid carrier for preventing bulking is introduced into an aeration tank for activated sludge treatment, the carrier is effectively prevented from flowing out into treated water. Thus, it is possible to prevent the quality of the treated water from deteriorating due to the outflow of the carrier and prevent the carrier from being wastefully consumed.

Claims (2)

[Claims] 1. A method for adding a granular solid carrier for preventing bulking to an aeration tank for treating activated sludge, comprising: a settling granular solid carrier; and 0.1 to 1% by weight based on the settling granular solid carrier. And adding a cationic or nonionic polymer flocculant as described above. 2. A method of adding a granular solid carrier for preventing bulking to an aerated layer of activated sludge treatment, comprising: a settling granular solid carrier; and 0.1 to 1% by weight based on the settling granular solid carrier. A method for adding a particulate solid carrier, characterized in that the particulate solid carrier is prevented from flowing out of the aeration tank by adding a cationic or nonionic polymer flocculant as described above.