JPH0338289A - Biologically activated carbon water-treatment apparatus - Google Patents

Abstract

PURPOSE:To keep the high removing capacity of org. matter by providing an activated carbon fluidized bed and a biological carrier fluidized bed and providing the introducing part of water to be treated to the lower part of a biologically activated carbon tower. CONSTITUTION:Water to be treated subjected to ozone treatment is introduced into a distribution pipe 20 from inflow piping 18 and injected in the biological carrier fluidized bed 21 formed to the lower part of a biologically activated carbon tower 16 from jet orifices 19. The org. matter dissolved in the water to be treated is decomposed and removed by the action of bacteria adhered to granular carriers in the biological carrier fluidized bed 21 and the treated water is sent in an activated carbon fluidized bed 22. In the activated carbon fluidized bed 22, the org. matter in the water to be treated and sent in from the biological carrier fluidized bed 21 is mainly removed by physical adsorbing action and the water to be treated from which the org. matter is removed is sent out to a supernatant liquid stagnation part 23. By this method, the lowering of the adsorbing rate due to the adhesion of bacteria to granular activated carbon can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a biological activated carbon water treatment device that performs advanced treatment of clean water.

(Conventional technology) In recent years, water pollution in rivers, dams, lakes, etc. has progressed.
At water treatment plants that use these water sources, it is becoming necessary to review the current treatment methods that mainly involve chlorine treatment for the following two reasons.

The first reason is that carcinogenic trihalomethanes can be produced by the injected chlorine and dissolved organic matter such as humic substances contained in the intake water during pre-chlorination treatment whose main purpose is to remove ammonia nitrogen. However, some of this trihalomethane ends up being contained in purified water.

The second reason is that current treatments cannot sufficiently remove off-flavors such as algae and musty odors caused by algae, plankton, etc. that occur due to eutrophication found in dams, lakes, etc.

In order to solve these problems, water treatment plants are beginning to carry out advanced treatment of tap water. Most of the advanced water treatment currently being carried out involves the use of powdered activated carbon.

However, this treatment utilizes the adsorption of organic matter onto activated carbon, and as a breakthrough occurs in which the adsorption capacity decreases in a very short period of 3 to 6 months, it is necessary to replace or regenerate the activated carbon. However, replacing or regenerating this activated carbon requires a great deal of labor and expense.

To solve this problem, treatment plants have recently been developed that combine oxidation treatment with ozone, biological treatment using biological activated carbon, which is granular activated carbon to which microorganisms are attached and fixed, and adsorption treatment.

An example of this advanced water treatment plant is shown in FIG. To explain the configuration of this conventional advanced water treatment plant, raw water for tap water is first stored in a raw water receiving tank 1, and after separating sand etc., it enters a flocculating tank 2. Furthermore, depending on the water quality, an acidic or alkaline pH adjuster is added to coagulate suspended matter and colloids in the water.

Next, it enters the sedimentation tank 4, where the flocs are separated by sedimentation, and the settled flocs are concentrated and discharged from the lower part as slurry water 5. The supernatant liquid in the sedimentation tank 4 is sent to the advanced treatment section 6 and introduced into the ozone treatment tower 7.

In the ozone treatment tower 7, ozone 8 is injected from the lower part through a diffuser pipe, and organic substances in the water are deodorized, decolorized, or oxidized and decomposed by the ozone through gas-liquid contact. In addition, in this ozone treatment tower 7, in order to facilitate the biological treatment in the biological activated carbon water treatment device at the subsequent stage, the organic substances that are difficult to decompose are converted into biodegradable substances using ozone. Residual ozone after the reaction is discharged outside as waste ozone.

Next, the ozonated water is sent to the biological activated carbon water treatment device 10, where the biological activated carbon water treatment device 10 performs adsorption of granular activated carbon, nitrification of ammonia by microorganisms grown on the surface of activated carbon, metabolic removal of organic matter, and further treatment of granular activated carbon. Removal of organic matter adsorbed by microorganisms, that is, regeneration by living organisms, is also carried out. Therefore, the lifespan of granular activated carbon is dramatically extended compared to the case where organic matter is treated only by the adsorption effect of granular activated carbon, and the lifespan of biological activated carbon is 3 to 6 months if only the adsorption effect of granular activated carbon is used. This will extend to 2 to 3 years.

The purified water thus treated in the water supply advanced treatment unit 6 contains turbidity, and PAC is used to remove this.

Alternatively, the flocculant 11 on the pan is added to form microflocs, and a chlorine agent is added for the purpose of suppressing microscopic animals, and the mixture is introduced into the next sand filter 12. Here, the micro flocs are removed by filtration, and the purified water is sterilized! 1
Sent to 3 and sterilized! In step 13, a chlorine agent 14 such as chlorine gas or sodium hypochlorite is added to sterilize dissolved bacteria. Even if chlorine disinfection is performed here, the treated water treated in the biological activated carbon tower 7 contains only a trace amount of organic matter that produces trihalomethane, so the problem of trihalomethane production due to chlorine treatment does not occur.

The treated water that has been sterilized and becomes highly treated drinking water is sent to the treated water receiver 1.
15 is stored and supplied with water.

In such an advanced membrane water treatment plant, a conventional configuration of a biological activated carbon water treatment device 1o is shown in FIG.

In this conventional biological activated carbon water treatment device 10, granular biological activated carbon 1 with a particle size of 0.1 to several orders of magnitude is placed inside the biological activated carbon tower 16.
At the bottom thereof, there is provided an inflow pipe 18 for the water to be treated that has been ozonized in the ozone treatment tower 7, and a distribution pipe 20 connected to the inflow pipe 18 having a plurality of spout ports 19.

Then, by spouting the water to be treated from one spout of the distribution pipe 20, the granular biological activated carbon 1 becomes biological activated carbon.
Processing of organic matter and ammonia is carried out while flowing 7. At this time, the biological activated carbon tower 16 is designed to ensure a sufficient flow rate of the water to be treated (in this case, the rising speed in the tower generally refers to the air column system) to flow the biological activated carbon 17.
In addition to determining the shape of the distribution pipe 20, it is also necessary to determine the structure and installation position of the distribution pipe 20 so as to obtain a uniform flow state. Here, it is generally said that a superficial linear velocity of about 10 to 20 m/h is required to flow the granular activated carbon 17, which almost matches the flow velocity of the water to be treated.

The reason why fluidized bed treatment is used in this way is that there is no clogging near the surface layer that occurs in a fixed bed treatment in a short period of time, and there is no short-circuit flow, so the water to be treated and biologically activated carbon can be efficiently separated. This is because they can be brought into contact with each other.

In the case of a fixed-bed biological activated carbon tower, backwashing and bubble cleaning must be performed frequently to eliminate clogging near the surface layer.

(Problem to be solved by the invention) However, in such conventional biological activated carbon water treatment equipment in advanced water treatment plants, if treatment is performed only by adsorption of the activated carbon itself, the lifespan will be 3 to 6 months due to microbial adhesion. However, a detailed inspection of the quality of the treated water shows that the quality of the treated water deteriorates (in other words, the removal rate of organic matter decreases) about 3 months after the start of treatment.
was observed, and was found to remain constant thereafter.

For this reason, depending on the raw water, the trihalomethane content in the treated water after chlorination becomes high, so there are cases where the activated carbon has to be replaced or regenerated after about three months, but this activated carbon is expensive. However, there is a problem in that an expensive reprocessing device is required for regeneration, resulting in a large amount of cost.

In addition, when replacing or regenerating the granular activated carbon after 2 to 3 years of use, it takes 2 to 3 months for microorganisms to attach to the granular activated carbon, and during this time, organic matter is removed by physical adsorption, which shortens the life of the granular activated carbon. There were also some problems.

This invention was made in view of these conventional problems, and can maintain high organic matter removal performance over a long period of 2 to 3 years, and can also be used to replace activated carbon or start up after regeneration. The purpose is to provide a biological activated carbon water treatment device that can be produced quickly.

[Configuration of the Invention (Means for Solving the Problems) The biological activated carbon water treatment device of the present invention includes an activated carbon fluidized bed in which granular activated carbon is fluidized in a biological activated carbon tower, and a microorganism attached to the bottom of the activated carbon fluidized bed. A biological carrier fluidized bed for fluidizing a granular or fibrous biological carrier is provided, an inlet for water to be treated is provided at the bottom of the biological activated carbon tower, and a discharge port for treated water is provided at the top.

(Function) The biological activated carbon water treatment device of the present invention performs biological treatment of dissolved organic matter in the water to be treated using a granular carrier to which microorganisms are attached in a granular carrier fluidized bed below the biological activated carbon tower.
In the upper activated carbon fluidized bed, the organic matter in the water to be treated that is sent from this granular carrier fluidized bed is removed mainly by physical adsorption, so that much of the dissolved organic matter in the water to be treated is sent to the side of the activated carbon fluidized bed. This is to prevent this from occurring and extend the life of the granular activated carbon.

(Example) Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

FIG. 1 shows an embodiment of the biological activated carbon water treatment device of the present invention, which is generally used as the biological activated carbon water treatment device 10 in a water supply advanced treatment plant shown in FIG.

This biological activated carbon water treatment device 10 has a granular material such as metal powder sintered body, anthracite, porous ceramics, river sand, plastic, etc. in the lower half inside the biological activated carbon tower 16 that has a relatively rough surface and is easy for microorganisms to adhere to. Alternatively, a fluidized bed 21 of fibrous biological carrier is formed, and a fluidized bed 22 of granular activated carbon is formed in the upper half.

Similarly to the conventional example shown in FIG. 4, an inflow pipe 18 is connected to the lower part of the biological activated carbon tower 10 to introduce ozonated water from the ozonation tower as water to be treated, and a number of spout ports are installed at the lower part of the tower. A formed distribution pipe 20 is installed.

A supernatant liquid retention section 23 is provided in the upper part of the biological activated carbon tower 16, from which the supernatant liquid is sent out as highly treated water to a subsequent treatment tank.

Next, the operation of the biological activated carbon water treatment apparatus having the above configuration will be explained.

The ozone-treated water is transferred from the inflow pipe 18 to the distribution pipe 2.
0 and is ejected from the ejection port 19 into the biological carrier fluidized bed 21 at the bottom of the biological activated carbon column 16.

Therefore, the water to be treated decomposes and removes dissolved organic matter by the action of microorganisms attached to the surface of the granular carrier in this biological carrier fluidized bed 21, and sends it to the activated carbon fluidized bed 22.

In the activated carbon fluidized bed 22, organic matter is removed from the water to be treated sent from the biological carrier fluidized bed 21 mainly by physical adsorption, and the water to be treated from which the organic matter has been removed is sent to the supernatant liquid retention section 23.

In the supernatant liquid retention section 23, the biologically treated and purified supernatant liquid is sent to a subsequent treatment tank as treated water.

The characteristics of the biological activated carbon water treatment apparatus of this embodiment, which performs biological treatment in this manner, will be explained based on the characteristic diagram in FIG. 2.

When microorganisms adhere to the surface of granular activated carbon, they block the fine pores of the activated carbon, interfering with the original physical adsorption effect of activated carbon, and as shown by curve A in Figure 2, non-volatile matter as an indicator of organic matter is reduced. total dissolved organic carbon (NVDOC)
Judging from the remaining amount of , new activated carbon has the original 2,
It exhibits high organic matter removal ability for three months, but after that, microorganisms begin to adhere to the surface and it becomes biologically activated carbon, and the organic matter removal ability stabilizes at around 30%.

Furthermore, as shown by curve B in FIG. 2, biological activated carbon exhibits a stable removal ability from the beginning of its use, and exhibits the ability to constantly remove 20 to 30% of organic matter.

In this way, the attachment of microorganisms extends the lifespan of activated carbon, but
On the other hand, the organic matter removal rate will be reduced.

On the other hand, if microorganisms are attached to the biological carrier rather than to the activated carbon side as in the embodiment of this invention, the adhesion of microorganisms to the activated carbon side can be kept to a minute level, and the activated carbon flow can be maintained for a long period of time. Physical adsorption ability can be maintained on the layer 22 side.

Furthermore, when the granular activated carbon in the activated carbon fluidized bed 22 reaches the end of its life and needs to be replaced or regenerated, the biological carrier fluidized bed 21 can be used continuously with the microorganisms still attached to it, and the conventional This means that there is no need to wait for the bioactivated carbon to turn into biological activated carbon, and the biological activated carbon can be used for biological treatment immediately after being replaced or regenerated.

In addition, in the case of this invention, it is necessary to fluidize the biological carrier fluidized bed below and the activated carbon fluidized bed above, but for this purpose, the specific gravity of the material of the biological carrier fluidized bed is adjusted to It is necessary to select a biological carrier whose specific gravity is sufficiently larger than that of the activated carbon, and it is also necessary to avoid the particle size of the biological carrier from being smaller than the particle size of the activated carbon.

[Effects of the Invention] As described above, according to the present invention, a fluidized bed of granular activated carbon is provided in the biological activated carbon tower, and a fluidized bed of biological carrier is provided below it, so that microorganisms are attached to the biological carrier side. As a result, biological treatment of the water to be treated can be carried out on the biological carrier fluidized bed side, and physical adsorption of dissolved organic matter can be performed mainly on the granular activated carbon fluidized bed side. It is possible to minimize the adhesion of microorganisms, prevent a decrease in the adsorption rate due to the adhesion of microorganisms, and achieve high organic matter removal properties over a long period of time.

In addition, even if the granular activated carbon is replaced or regenerated, the biological carrier fluidized bed with the attached microorganisms can be used as is, so there is no need to wait for the microorganisms to adhere to the granular activated carbon as in the past, and it can be reused. It doesn't take long to start up.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of one embodiment of the present invention, Figure 2 is a comparison diagram of the organic matter removal characteristics of biological activated carbon and new activated carbon, Figure 3 is a block diagram of a general advanced water treatment plant, and Figure 4 The figure is a sectional view of a conventional biological activated carbon water treatment device. 10... Biological activated carbon water treatment device 16... Biological activated carbon tower 18... One inflow pipe...
・Spout port 20...Distribution pipe 21...Biological carrier fluidized bed 22...Activated carbon fluidized bed 23...Supernatant liquid charge Private patent attorney Hidekazu Miyoshi 20 minute piping diagram Processing period [Month I11

Claims (1)

[Claims] A biological activated carbon tower is provided with an activated carbon fluidized bed for fluidizing granular activated carbon, and a biological carrier fluidized bed for fluidizing granular or fibrous biological carriers with attached microorganisms below the activated carbon fluidized bed. A biological activated carbon water treatment device comprising an inlet for treated water at the top and a discharge section for the treated water at the top.