JPH0210716B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a filtration device that captures suspended solids in raw water using a layer filled with material, and is particularly applicable to not only suspended solids but also BOD components and COD components in wastewater. , humic acid, fulvic acid, etc., at the same time.

Conventional technology Conventionally, turbidity, BOD components,
Activated sludge method is used to remove COD components etc. In this method, BOD and COD components are brought into contact with activated sludge in an aeration tank and are biologically decomposed, suspended components are adsorbed by activated sludge, and activated sludge and treated water are separated in a solid-liquid separator. be done. As a solid-liquid separator, a flotation separator and a sedimentation separator are generally used. The cross-sectional area of these devices is determined by the ratio of flotation and sinking speeds to throughput. Although flocculants or flocculant aids have been used to increase the floating speed and sinking speed, they have not achieved dramatic effects.
The cross-sectional area of these aeration tanks and solid-liquid separation devices is larger than that of other water treatment devices, and their biggest drawback is that they require a larger site area.

On the other hand, a filtration device filled with granular material such as sand or anthracite is used as a solid-liquid separator.

Problems to be Solved by the Invention However, a filtration device filled with granular material can remove suspended solids, but cannot remove BOD and COD components.

It is also possible to use sand, anthracite, etc. with microorganisms attached to the surface as a granular material, but the attached microorganisms are easy to peel off.
It is easy for detached microorganisms to be mixed into the treated water. In addition, the attached microorganisms multiply and a large amount of surplus sludge is generated.

Therefore, it is an object of the present invention to provide a filtration device that eliminates the drawbacks of the prior art described above, can remove not only suspended solids, but also BOD, COD, humic acid, etc., and does not generate excess sludge. purpose.

Means for Solving the Problems The present invention solves the above problems by using as a material immobilized microorganisms in which microorganisms, activated sludge, soil, etc. are encased and immobilized in a polymeric substance.

That is, the filtration device according to the present invention uses immobilized microorganisms obtained by entrapping and immobilizing pure cultured or mixed cultured microorganisms, activated sludge, soil, etc. in a polymeric material as a material, and has a treated water outlet on the wastewater inlet side. It is characterized by containing immobilized microorganisms with a large equivalent sphere diameter on the side.

The microorganisms to be immobilized in the present invention may be pure cultures or mixed cultures of any microorganisms such as bacteria, actinomycetes, molds, and yeasts, or activated sludge. Furthermore, for the treatment of water containing a large amount of humic acid and fulvic acid, soil that is thought to be inhabited by these degrading bacteria can be used after being immobilized.

Therefore, in the following description, the term "microorganism" refers to pure cultured or mixed cultured microorganisms,
It means microorganisms attached to activated sludge or soil.

In the present invention, it is preferable that immobilized microorganisms of different sizes are brought into contact with the wastewater in response to changes in the concentration of wastewater components in the tank. It is preferable to fill the tank with immobilized microorganisms having a larger equivalent sphere diameter than those on the side.

In the BOD removal process of wastewater using immobilized microorganisms, the possible causes of surplus sludge are (1) leakage of microorganisms from the pellets of immobilized microorganisms, and (2) growth of floating bacteria. It is thought that this is mostly due to the cause.

When microorganisms are immobilized as pellets, we investigated the size of the pellet and the growth state of the microorganisms, and found that when the diameter of the pellet is large, the microorganisms multiply near the surface of the pellet, and become sparse in the center. The activity per unit volume of pellets is low. When large-diameter pellets are used to treat wastewater, if the concentration of organic matter in the wastewater is high, the organic matter will diffuse into the interior of the pellet, and its growth will become active in the center. In the center of the pellet, which has a large diameter, there are many anaerobic bacteria, which secrete enzymes such as amylase and protease, which are unique to anaerobic bacteria.
SS is decomposed and removed. Conversely, when the concentration of organic matter in the wastewater is low, microorganisms proliferate only near the surface of the pellets, and microorganisms decrease in the center due to self-digestion, which reduces treatment performance.

On the other hand, when small-diameter pellets are used for BOD removal treatment of wastewater, microorganisms grow relatively uniformly. When the concentration of organic matter in wastewater is high, the growth of the whole pellet is active, and excess microorganisms leak out. When the concentration of organic matter is low, the activity is high and the treatment performance is good.

Therefore, in the wastewater filtration apparatus according to the present invention, the concentration of organic matter in the wastewater is high near the wastewater inlet, and the organic matter diffuses into the inside of the pellets, causing large growth of microorganisms. It is preferable to fill it with On the other hand, near the outlet of the treated water, the concentration of organic matter in the wastewater is low, so there is less proliferation of microorganisms and less leakage of microorganisms. Therefore, the outlet side of the treated water is filled with pellets of small diameter to remove soluble organic matter and to exhibit the effect as a material for SS.

In the present invention, the equivalent spherical diameter of the immobilized microorganism is
It is preferable to select within the range of 0.5 to 10 mm.

In the filtration device according to the present invention, when filling immobilized microorganisms with different equivalent sphere diameters as described above, they are filled so that they do not mix with each other, or a device for separating them so that they do not mix, such as a partitioning net, is installed. can do. By decreasing the specific gravity of pellets with large diameters and increasing the specific gravity of pellets with small diameters, they can be separated without a partition screen so that they do not mix with each other.

In the present invention, the polymer materials used for entrapping fixation include polyurethane, polyacrylamide, calcium alginate, carrageenan, methoxytetraethylene glycol methacrylate, polyethylene glycol dimethacrylate, and 2,2-bis[4-(methacryloxy-polyethoxy)phenyl]. Any known immobilization material can be used, such as propane, polyethylene glycol diacrylate, polypropylene glycol diacrylate, and the like. As a material with a low specific gravity, for example, urethane prepolymer has a specific gravity of 0.5~
By adding 20%, addition polymerizing, and molding, a product with a specific gravity of 1.02 or less can be obtained.

Function Immobilized microorganisms have the effect of removing BOD and also act as a material to adsorb SS. In addition, microorganisms proliferate inside the immobilized microorganisms and undergo self-digestion.
No excess sludge is generated as there is no leakage to the outside.

Example Next, the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic cross-sectional view of a passing device showing one embodiment of the present invention. In this embodiment, the overtank 1 includes a first chamber 2, a second chamber 3, a third chamber 4, and a fourth chamber 5.
and a fifth chamber 6, each chamber is partitioned by a strainer 7, and chambers 3, 4, and 5 contain immobilized microorganisms 10 and 5 of different diameters, respectively.
11 and 12 are filled.

When wastewater is filtered through this device, the wastewater is introduced from the wastewater inlet 8, aerated with air sent from the air pipe 9 in the first chamber 2, and then filled with a material consisting of immobilized microorganisms. While flowing down to the second chamber 3, third chamber 4, and fourth chamber 5, suspended solids are removed, and BOD, COD, etc. are also removed. The treated water flows out from the treated water outlet 13. After water has been passed for a certain period of time, backwash water is allowed to flow in from the backwash pipe 14 and discharged from the drain 15 in order to remove accumulated turbidity.

In the embodiment shown in FIG. 2, two types of immobilized microorganisms 16 and 17 having different specific gravities are filled in the overtank 1. In this case, after backwashing, the immobilized microorganisms 16 and 17 are separated and deposited without being mixed, depending on their specific gravity.

FIG. 3 shows an embodiment in which an aeration tank 18 is provided separately and aeration is carried out there.

FIG. 4 shows an embodiment in which the filtration is carried out in an upward flow.

In the filtration apparatus shown in FIGS. 2, 3 and 4, it is preferable to provide a wire gauze at the top of the tower to prevent pellets from overflowing.

As shown in Figures 1 to 4, an aeration means is provided before the material layer, that is, the aeration means is provided above the material layer in the filtration device, or a separate aeration tank is provided before the filtration tank. By aerating the wastewater before it flows into the material layer and not blowing air directly into the material layer, SS trapped in the material is effectively decomposed by immobilized microorganisms without being separated from the material. be done.

Furthermore, when using wastewater where it is difficult to separate SS and pellets, in order to adjust the specific gravity of the pellets,
When making pellets, sand, anthracite, activated carbon,
It is preferable to mix a solid agent with a high specific gravity such as garnet. For example, it is preferable that the specific gravity be 1.5 to 2.0 for small pellets with a diameter of around 1 mm, and 0.5 to 1.5 for pellets with a diameter of 1.5 mm or more.

Example 1 Production of pellets MLSS40000mg/ml of activated sludge from K sewage treatment plant
Concentrated into A solution containing 36% acrylamide and 2% triacrylic formal was prepared, and an equal amount of the above activated sludge concentrate was suspended in this solution. To this suspension were added 3-dimethylaminopropionitrile at 0.5% and potassium peroxodisulfate at 0.25%, polymerized, and formed into three spherical pellets with diameters of 4 mm, 3 mm, and 2 mm.

The first wastewater tank has a capacity of 5 with a diameter of 100 mm.
In the filter device shown in the figure, the second chamber 3 has a diameter of 4 mm.
mm pellets, 3 mm diameter pellets in the third chamber 4,
Pellets with a diameter of 2 mm are placed in the fourth chamber 5 at 10% each.
It was filled to a filling rate of .

When food wastewater with a BOD of 34 to 65 mg/and an SS of 23 to 35 mg/was treated for 20 days with a residence time of 15 minutes, treated water with a BOD of 8 to 12 mg/and an SS of 3 mg/ or less was obtained.

Example 2 Production of pellets MLSS40000mg/ml of activated sludge from K sewage treatment plant
Concentrated into Polyethylene glycol #600 diacrylate 36% and triacrylic formal 2%
A solution containing the above was prepared, and an equal amount of the above activated sludge concentrate was suspended in this solution. To this suspension, 0.5% 3-dimethylaminopropionitrile and 0.25% potassium peroxodisulfate were added, polymerized, and formed into four types of spherical pellets with diameters of 4 mm, 3 mm, 2 mm, and 1 mm. .

Wastewater filtration Using the same equipment as in Example 1, a diameter of 4 mm was placed in the first chamber 2.
mm pellets, 3 mm diameter pellets in the second chamber 3, 2 mm diameter pellets in the third chamber 4, 1 mm diameter pellets in the fourth chamber 5
mm pellets were each filled to a filling factor of 10%.

Machine factory wastewater with BOD76-140mg/SS30~45mg/was treated with the above equipment for 25 consecutive days with aeration in the first room and a residence time of 30 minutes, resulting in BOD8~16mg/SS3mg/or less. Got water.

Example 3 Production of pellets A urethane polymer with a main chain of polyethylene glycol and polypropylene glycol, a molecular weight of 4000 to 5000, and an isocyanate group at both ends.
KT water treatment plant activated sludge MLSS20000mg/5
% was added, polymerized, and formed into pellets with a diameter of 1.5 mm. The specific gravity of this pellet was 1.03 or less.

Separately, the pellets used in Example 2 with a diameter of 1 mm were prepared. The specific gravity of this pellet was 1.04-1.06.

The second wastewater tank has a capacity of 5 with a diameter of 100 mm.
Using the filter device shown in the figure, pellets with a diameter of 1 mm and pellets with a diameter of 1.5 mm were placed in the filter tank, respectively.
Filled to 15%, total filling rate of 30%.

When food water with a BOD of 25 to 42 mg/and an SS of 15 to 34 mg/was treated for 20 days with a residence time of 20 minutes using the above-mentioned apparatus, treated water with a BOD of 8 to 12 mg/and an SS of 3 mg/ or less was obtained.

Even after backwashing, due to the difference in specific gravity, pellets with a diameter of 1 mm are deposited at the bottom of the tank and pellets with a diameter of 1.5 mm are deposited at the top.

Example 4 Production of pellets 10g of surface soil of farmland in Hongo, Matsudo City, Chiba Prefecture was
After suspending in ml of tap water and homogenizing, 3% urethane prepolymer was added, polymerized, and the diameter
It was molded into 1.5 mm pellets.

Excess of Waste Water After the experiment of Example 3 was completed, everyone was filled with the soil-containing pellets described above. After backwashing, polyethylene glycol #600 diacrylate with a diameter of 1 mm
1.5 mm diameter pellets of urethane containing soil are collected in the center, and 1.5 mm diameter pellets of urethane containing activated sludge are collected in the upper part. The upper urethane pellets were fluidized by aeration.

When 5 mg/humic acid was added to the wastewater used in Example 3 and treated with the above apparatus for a residence time of 60 minutes, treated water with BOD 8 to 12 mg/, SS 3 mg/or less, and humic acid 2 to 3 mg/was obtained, It was found that humic acid can also be treated.

In each of the above examples, the sludge conversion rate, which is the amount of sludge generated from BOD removal, is calculated from the amount of SS discharged by backwashing to be 2 to 4%.
It was found that almost no surplus sludge was generated. This is thought to be because microorganisms proliferate inside the pellets and do not leak to the outside, and it is thought that self-digestion occurs inside the pellets.

Furthermore, when various wastewaters were treated using anthracite as a conventional method, BOD components, humic acid, etc. could hardly be removed.

Effects of the Invention As described above, according to the present invention, SS can be removed simultaneously with BOD removal, including the removal of persistent humic acid, and almost no surplus sludge is generated at this time.

In addition, in the conventional method of using anthracite etc. as a material, the surface layer tends to be excessive, but in the present invention, by filling the wastewater inlet side with immobilized microorganisms with a large equivalent spherical diameter, the entire material layer is effectively utilized. .

Furthermore, as shown in the figure, by providing an aeration means before the material layer and configuring the material layer so as not to aerate it, the SS trapped in the material is effectively decomposed by the immobilized microorganisms without being peeled off. It happens.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a passing device showing one embodiment of the present invention, FIG. 2 is a schematic sectional view of a passing device showing another embodiment of the present invention, and FIG. 3 is a schematic sectional view of a passing device showing another embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of an embodiment of the
The figure is a schematic cross-sectional view of a filter device showing still another embodiment of the present invention. 1... Overtank, 7... Strainer, 8... Waste water inlet, 13... Treated water outlet, 10, 11, 12,
16, 17, 19 and 20...immobilized microorganisms, 1
8...Aeration tank.

Claims (1)

[Scope of Claims] 1. In a filtration device that captures suspended matter in raw water with a layer filled with material, immobilized microorganisms in which pure cultured or mixed cultured microorganisms, activated sludge, soil, etc. are encased and immobilized in a polymeric substance are used. A wastewater filtration device using immobilized microorganisms, characterized in that the inlet side of the wastewater is filled with immobilized microorganisms having a larger equivalent spherical diameter than the outflow side of the treated water. 2. The wastewater filtration device according to claim 1, comprising a device for filling pellets with different equivalent sphere diameters in a filtration tank so that they do not mix or separating them so that they do not mix. 3. The wastewater filtration device according to claim 1 or 2, wherein the inlet side of the wastewater is filled with immobilized microorganisms that are encircled and fixed with urethane resin. 4. The wastewater filtration device according to any one of claims 1 to 3, wherein an aeration means is provided in a stage preceding the layer.