JPH02229595A - Water treatment by biological active carbon - Google Patents

Abstract

PURPOSE:To enhance the bioregeneration effect of active carbon by passing polluted water from the layer of the active carbon having the particle density of a low specific numerical value to the layer of the active carbon of the particle density of a high specific numerical value in this order. CONSTITUTION:The polluted water, such as the secondary treated water of sewerage, is put into a treating tank 2 from above and passes through the layer of the active carbon A of the particle density as low as 0.3 to 0.6g/cc formed in the upper part thereof then through the layer of the active carbon B of the particle density as high as 0.6 to 1.0g/cc formed in the lower part in this order. Since bacteria are liable to propagate in the active carbon A, the bioeffect is sufficiently executed and the active carbon B has the large adsorption amt. of the polluting components. The bacteria which decompose the polluting materials are included in the bacteria groups sticking in a large amt. on the active carbon A and, therefore, the decomposing enzyme is secreted and while a part of the enzyme is used in the active carbon A, the other part arrives together with the polluted water at the inside of the active carbon B to make up the deficiency of the number of the bacteria in the active carbon B. The bioregeneration effect is, therefore, greatly improved. The feeding of an oxygen- contg. gas 6 from an air diffusion pipe 5 disposed in the lower part is a good practice to maintain the entire area of the active carbon packed bed in an aerobic state.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to treating contaminated water, such as secondary treated sewage water, industrial wastewater, and water source water with advanced organic contamination, using activated carbon with attached living organisms. , relates to a water treatment method that biodegrades trace organic matter, odor components, ammonia nitrogen (NH.-N), etc. in contaminated water under aerobic conditions. [Conventional technology] In the water supply field, water sources are becoming increasingly contaminated, with organic pollution becoming particularly significant. In response to this water source pollution, research and development are being carried out on purification technologies that are different from conventional ones. One of these is biological activated carbon treatment technology, and this treatment method is
When contaminated water containing dissolved oxygen is passed through an activated carbon layer, the pollutants in the contaminated water are adsorbed by the activated carbon and subjected to biological removal effects such as biological decomposition. Many pollutants are also removed. [Kurosawa et al., Water Pollution Research, Vol. 11, No. 9, pp. 590-598 (1988)].

Here, the pollutants adsorbed by the activated carbon are removed by biological removal, and it appears as if the activated carbon's adsorption capacity is restored, so this biological removal is called biological regeneration. Activated carbon is expensive, and without bioregeneration effects, it becomes a mere adsorbent and requires frequent replacement, making it uneconomical. Therefore, a biological activated carbon treatment method that requires less frequent replacement and is expected to have a biological regeneration effect is expected to be developed in the future.

[Problem to be solved by the invention]

However, with conventional biological activated carbon treatment methods, the effect of biological activated carbon was only observed by chance when an activated carbon adsorption tower was installed, and from the perspective of biological regeneration, sufficient effects have not been achieved. That's hard to say. The present invention aims to maximize the biological regeneration effect of activated carbon in a water treatment method in which contaminated water is purified in an aerobic state using activated carbon to which living organisms are attached.

[Means for solving intelligence problems]

The present invention is a water treatment method in which contaminated water is purified in an aerobic state using activated carbon to which living organisms are attached.
The above problem was fundamentally solved by a water treatment method characterized by passing through layers of activated carbon at a concentration of 6 to 1.0 g/cc in sequence. Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows one embodiment of the present invention, in which contaminated water 1 such as secondary treated sewage water enters a treatment tank 2 from the top. In the treatment tank 2, activated carbon (A) 3 and activated carbon (B) 4 are packed in a fixed bed, with the layer of activated carbon (A) 3 at the top of the treatment tank 2 and the layer of activated carbon (B) 4 at the top of the treatment tank 2. It is formed at the bottom. The most important thing in the present invention is that the contaminated water is treated with a layer of activated carbon having a particle density of 0.3 to 0.6 g/cc.
6 to 1.0 g/cc of activated carbon B is passed in this order. Conventionally, the treatment effects of biological activated carbon have focused on its micropores, particularly the amount of pores with a radius of several tens of people. This is because the size of the pollutant components dissolved in water is about a few dozen, so activated carbon, which has many micropores with a pore size of several dozen, can adsorb a large amount of these pollutants. This is based on the idea that biological regeneration effects will be enhanced. However,
Regarding the adsorption effect of activated carbon, there are not only molecular sieving effects related to the size of the adsorbed substance, but also hydrophilicity, hydrophobicity, and potential issues, so it cannot be discussed only based on the size of the adsorbed substance, but it is a significant Because of its influence, it is said to be the most influential effect. However, the inventors believed that the biological regeneration effect is largely related not only to the adsorption capacity of activated carbon itself, but also to the amount of microorganisms retained, and through experiments, they found that the amount of microorganisms retained depends on the particle density of activated carbon. I found out. In other words, activated carbon with a low particle density retains a large amount of microorganisms, but one with a high particle density retains a small amount of microorganisms.
Generally speaking, activated carbon with a low particle density is 10 μm (10
It is thought that this is because the ratio of macropores on the order of 10 μm is high, making it easy for bacteria on the order of several μm to proliferate.

Furthermore, activated carbon with a low particle density has a high ratio of macropores, which has the disadvantage that there are slightly fewer micropores on the order of tens of people that adsorb pollutants. No significant improvement can be expected in terms of effectiveness; in some cases, the bioregenerative action may actually decrease. Therefore, we investigated the relationship between the activated carbon's pore radius, pore volume, and other properties of activated carbon with different particle densities, and the relationship between these and biological regeneration effects. An example of the relationship with volume etc. is shown in Table 1.

Table 1 Properties of activated carbon As can be seen from Table 1, activated carbon with a high particle density has a
The ratio of macropores on the order of 0 μm (10′) is small, and the ratio of micropores on the order of several tens of pores is slightly high. For this reason, activated carbon has a large adsorption capacity for pollutant components, and has traditionally been used as an adsorbent for pollutant components. On the other hand, activated carbon, which has a low particle density, has many macropores of 1 μm or more, so there are fewer micropores on the order of a few dozen that adsorb pollutants. When various experiments were repeated using activated carbon with different particle densities, the particle density was 0. It was discovered that when contaminated water was passed through activated carbon A with a particle density of 3 to 0.6 g/cc and then through activated carbon B with a particle density of 0.6 to 1.0 g/cc, the biological regeneration effect was significantly increased. Specifically, activated carbon A and activated carbon B are packed and arranged in series in the direction of flow of contaminated water, and contaminated water is passed through them. For example, as shown in FIG. 1, a layer of activated carbon 8 may be formed on a layer of activated carbon B, and contaminated water may be allowed to flow down from above the activated carbon layer A.

If the particle density of activated carbon A is too small, it will easily break, so it needs to be 0.3 g/cc or more, and in practical terms it is 0.4 to 0.6 g/cc, although it varies depending on the material.
The degree is preferable. The particle density of activated carbon B is 0.6 to 1.
The range is 0g/cc, but the one with the largest number of micropores on the order of several dozen is best. If the particle density of activated carbon B is too large, the degree of activation of the activated carbon will decrease and the number of micropores will decrease, which is undesirable. Therefore, it is preferable that activated carbon B has a particle density of 0.7 to 0.9 g/cc. In addition, in the treatment of contaminated water using biological activated carbon, it is important to maintain good aerobic conditions in order to fully perform its biological effects. If the contaminated water is relatively clean, it is sufficient to add sufficient dissolved oxygen to the contaminated water before it enters the treatment tank 2, but if this is not the case, as shown in Figure 1, activated carbon As a means for maintaining the entire area of the packed bed in an aerobic state, a method may be adopted in which oxygen-containing gas 6 is introduced through a diffuser pipe 5 disposed below the activated carbon Bli. Air, oxygen, etc. are used as the oxygen-containing gas. At this time, as shown in FIG. 1, when the contaminated water is passed in a downward flow, the contact efficiency is improved due to the gas-liquid countercurrent effect, and the amount of air supplied can be saved, resulting in energy savings.

Contaminated water may flow upward. In this case, the layer of activated carbon (A) 3 becomes the lower layer. In addition, if contaminated water is passed in a downward flow and the activated carbon 80 particle size is made larger than the particle size of activated carbon B, the multi-layer filtration effect can prevent clogging of the activated carbon packed bed, resulting in coagulation and sedimentation. Pretreatment of equipment, etc. can be omitted. As described above, contaminated water 1 is purified by passing through activated carbon (A) 3 and activated carbon (B) 4 to become treated water 8, which is discharged through treated water pipe 7. Note that the layer of activated carbon A and the layer of activated carbon B may be provided separately without being directly laminated.

[Effect]

The particle density used in the present invention is 0. 3-0.6g/CC
Activated carbon (A) has a high ratio of macropores of 1 μm or more and a high ratio of macropores on the order of 10 μm, so bacteria with a size on the order of several μm can easily proliferate, so that the biological effect is sufficiently performed. In addition, the particle density is 0. 6
Activated carbon (B), which has a high concentration of ~1.0 g/cc, has a small proportion of 74 clobores of 1 μm or more, and a slightly high proportion of micropores of several tens of micropores, so it adsorbs a large amount of pollutant components. The reason why the biological regeneration effect increases markedly when contaminated water is passed through activated carbon A and activated carbon B in order is not clear, but it is likely to be as follows. As mentioned above, a large amount of bacteria adheres to activated carbon A, but since the bacterial group includes bacteria that decompose pollutants that are adsorbed substances, they secrete degrading enzymes, and some of the enzymes are attached to activated carbon A. However, it is thought that some of the activated carbon B enters the activated carbon B together with the contaminated water and compensates for the lack of bacteria in the activated carbon B.

〔Example〕

The present invention will be specifically explained below using Examples. However, the present invention is not limited to this example. EXAMPLE Secondary treated sewage water was treated according to the present invention as water to be treated. In addition, as a comparative example, the same treated water was treated using a different treatment method. The experimental equipment used was an O column with a diameter of 160 mm and a height of 5,500 mm. Table 2 shows the specifications of the activated carbon used in the experiment, and Table 3 shows the experimental conditions. As can be seen in Table 3, Comparative Example 1 is a case where activated carbon A alone was used,
Comparative Example 2 is a case where activated carbon B alone was used, and Comparative Example 3 is a case where activated carbon B and activated carbon A were filled in this order. Table 2: Activated carbon specifications When a TOC removal rate of 30% is considered as breakthrough, the usable period of activated carbon until replacement and the amount of sludge generated were determined. The results are shown in Table 4. Table 4: Treatment effect* Water quality is the value 6 months after the start of operation. ** Backwashing was performed when the filtration pressure increased by 100c11. The treated water SS does not change much from the beginning of operation, but the treated water TOC gradually increases as days pass. The present invention is based on Comparative Examples 1, 2. Compared to No. 3, treated water with the best quality was obtained. On the other hand, in the present invention, the usable period of activated carbon before replacement is approximately 1.5 to 2 times longer than in the comparative example. Further, the amount of sludge generated is almost the same as that of activated carbon A alone (Comparative Example 1), and even if activated carbon A with a low particle density is not used in its entirety, almost the same effect as when the entire amount is used can be expected.

〔Effect of the invention〕

By combining activated carbon with a low particle density and activated carbon with a high particle density in series, the present invention increases the biological regeneration effect, and accordingly, the frequency of backwashing of the activated carbon is reduced compared to conventional methods. The period of use before replacement was extended by approximately 1.5 times compared to the conventional method, which significantly extended the period during which water could pass through. Furthermore, the amount of sludge generated can be almost the same as when activated carbon with low particle density is used alone. Furthermore, by installing an aeration pipe at the bottom of the activated carbon packed bed, the entire packed bed can be maintained in an aerobic state, making it possible to effectively treat contaminated water with a high oxygen demand, such as secondary treated sewage water. can do. At this time, when the water to be treated is passed in a downward flow, a gas-liquid countercurrent effect is exhibited, so the amount of air supplied can be saved, resulting in energy savings.

In addition, if the water to be treated is passed in a downward flow and the particle size of the activated carbon with a low particle density in the upper layer is made larger than the particle size of the activated carbon with a high particle density, the clogging of the activated carbon can be prevented due to the multilayer filtration effect. Since it is possible to prevent this, pretreatment such as coagulation and sedimentation equipment can be omitted.

[Brief explanation of the drawing]

Figure 1 shows a schematic diagram of an apparatus for carrying out one embodiment of the present invention. Explanation of symbols 1... Contaminated water 2... Treatment tank 3... Activated carbon A 4... Activated carbon B5... Aeration pipe
6... Oxygen-containing gas 7... Treated water pipe 8.
...Treatment water procedure Nefli Display of official case 1999 Patent Application No. 501 62 Name of invention Person who amends water treatment method using biological activated carbon Relationship to case: Name of patent applicant: (040) Ebara Infilco Stock Company (and 1 other
given name)

Claims (1)

[Claims] In a water treatment method that purifies contaminated water in an aerobic state using activated carbon with attached organisms, the contaminated water is purified with a particle density of 0.3 to 0.
．． 6g/cc activated carbon layer, particle density 0.6-1.0g
A water treatment method characterized by passing through layers of activated carbon in order of /cc.