Treatment method for organic wastewater containing persistent COD components and biological treatment agent

Abstract

To provide a treatment method and biological treatment agent for organic wastewater containing persistent COD components, capable of improving a biological treatment capacity for COD components and reducing the COD value of the treated water without major modification of biological wastewater treatment facilities, including conventional activated sludge treatment facilities, even when treating wastewater containing persistent COD components.SOLUTION: A method for treating organic wastewater containing persistent COD components, which includes a biological treatment process in which organic wastewater containing persistent COD components is biologically treated in a biological treatment tank. In the biological treatment process, two or more of the following three types are added to the wastewater to provide a medicine for biological treatment: vitamin B12, pyrroloquinoline quinone, and incinerated ash of organic waste.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for treating organic wastewater in which water to be treated containing organic pollutants including persistent COD components (hereinafter referred to as organic wastewater) is biologically treated using microorganisms, and to a biological treatment agent. More specifically, the present invention relates to a technology for providing a biological treatment agent that is effective in addressing the problem of persistent COD components remaining after biological treatment, resulting in a high COD value in the resulting treated water. [Background technology]

[0002] It has been reported that in biological wastewater treatment using microorganisms, the presence or absence of mineral components other than nitrogen and phosphorus is related to the quality of the treated water, and it has been proposed to supplement mineral components in wastewater and perform biological treatment. For example, Patent Document 1 proposes that the quality of treated water after biological treatment can be improved by using incineration ash obtained by incinerating organic waste, which contains many mineral components, in biological treatment. Furthermore, Patent Document 2 proposes that adding one or more B vitamins to a biological treatment tank or to the water to be treated before biological treatment can improve the water purification ability of wastewater containing organic carbon sources, nitrogen, phosphorus, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-253437 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-141775 Summary of the Invention [Problem to be solved by the invention]

[0004] However, all of the above-mentioned conventional technologies focus on the water purification ability of the wastewater or water (hereinafter referred to as raw water) being treated, based on the BOD, which is an indicator of the biodegradability of the treated water in microbial treatment. The effectiveness of these technologies is evaluated based on the BOD of the treated water, and no sufficient consideration has been given to the less biodegradable components contained in the raw water. Therefore, when biological treatment of actual wastewater using the above-mentioned conventional technologies is performed, the effect obtained is limited depending on the raw water and environmental conditions, and satisfactory biodegradation may not occur, resulting in the need for retreatment. Specifically, for example, there are sites where persistent COD components always remain in the treated water, or where slowly biodegradable COD components remain when the water temperature drops in winter.

[0005] For example, when wastewater (raw water) containing persistent COD components such as polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) is treated using conventional biological wastewater treatment facilities, such as activated sludge treatment facilities, persistent COD remains in the treated water, resulting in a problem of high COD values, an indicator of persistent COD. This problem is thought to be caused by the insufficient treatment capacity for COD components in the biological treatment carried out in conventional treatment facilities aimed at water purification based on BOD. COD (chemical oxygen demand) is an indicator of organic pollution and is the amount of oxygen consumed when organic matter in water is oxidized with an oxidizing agent. Compared to BOD, it has the advantage of being able to measure persistent organic matter as well. Since COD is affected by measurement conditions, values ​​obtained when potassium permanganate is used as an oxidizing agent are used as COD. Mn and the value when potassium dichromate is used is COD Cr The official method for indicating water quality standards is COD. Mn The quality of treated water is usually controlled by COD Mn Potassium dichromate has a stronger oxidizing power than potassium permanganate, so it is useful as an indicator for measuring organic pollution, including more persistent organic matter, and is used as an indicator for COD when examining treatment methods. Cr is being used.

[0006] Other persistent COD components include polyethylene glycol (hereinafter sometimes abbreviated as PEG) and polyoxyethylene (50) oleyl ether (hereinafter sometimes abbreviated as POE (50)). These are water-soluble polymeric compounds that are highly versatile and widely used as industrial raw materials, and are often found in chemical factory wastewater. These components are also thought to be the cause of the high COD values ​​of treated water.

[0007] In response to this, the inventors have concluded that the insufficient COD component treatment capacity described above is due to the inability of individual microorganisms involved in biological treatment to fully utilize their capabilities. They have recognized that in order to solve this problem, it is important to develop a technology that improves the COD component treatment capacity of biological wastewater treatment facilities by fully utilizing the capabilities of the microorganisms used in biological treatment. In this case, in order to make this biological treatment technology practical, it is particularly important to reduce the COD value of treated water without requiring major modifications to the wastewater treatment facility. For example, it would be extremely useful if the above problem could be solved simply by adding chemicals to the biological treatment process in wastewater treatment facilities.

[0008] Therefore, an object of the present invention is to provide a method for treating organic wastewater containing persistent COD components, which can improve the biological treatment capacity for COD components and reduce the COD value of treated water, even when treating wastewater (raw water) containing persistent COD components, without requiring major modifications to conventional biological wastewater treatment facilities such as activated sludge treatment facilities. [Means for solving the problem]

[0009] The above object can be achieved by the present invention, which provides the following method for treating organic wastewater containing persistent COD components. [1] A method for treating organic wastewater, comprising a biological treatment step of biologically treating organic wastewater containing persistent COD components in a biological treatment tank, A method for treating organic wastewater containing persistent COD components, characterized in that in the biological treatment step, two or more selected from the following three substances are added to carry out biological treatment: vitamin B12, pyrroloquinoline quinone, and incineration ash of organic waste.

[0010] A preferred embodiment of the method for treating organic wastewater of the present invention is as follows. [2] The method for treating organic wastewater according to [1] above, wherein the persistent COD components contain polyvinyl alcohol, and the biological treatment is carried out by a microbial community consisting of multiple types of microorganisms, and the microbial community contains at least one species of bacteria from the genus Sphingomonas, Sphingopyxis, Povalibacter, Steroidobacter, and Novosphingobium that are capable of decomposing polyvinyl alcohol. [3] A method for treating organic wastewater according to [1] or [2] above, wherein in the biological treatment step, any one of a combination of vitamin B12 and incineration ash of organic waste, a combination of pyrroloquinoline quinone and incineration ash of organic waste, or a combination of vitamin B12, pyrroloquinoline quinone and incineration ash of organic waste is added for biological treatment. [4] The method for treating organic wastewater according to any one of [1] to [3] above, wherein the biological treatment step is carried out in the following cases: when persistent COD always remains in the treated water after biological treatment of the organic wastewater; when slowly degradable COD remains in the treated water after biological treatment of the organic wastewater; when biological treatment of the organic wastewater is started up; or when the COD volume load in the biological treatment tank increases.

[0011] In another embodiment, the present invention provides [5] a biological treatment agent for use in treating organic wastewater containing persistent COD components, the biological treatment agent comprising two or more components selected from the group consisting of vitamin B12, pyrroloquinoline quinone, and incineration ash from organic waste. In a preferred embodiment, the biological treatment agent contains [6] the incineration ash from organic waste as an essential component. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a useful and effective method for treating organic wastewater containing persistent COD components, which can improve the biological treatment capacity for COD components and reduce the COD value of treated water, even when treating wastewater (raw water) containing persistent COD components, without requiring major modifications to conventional biological wastewater treatment facilities such as activated sludge treatment facilities.Furthermore, according to the present invention, there is provided a biological treatment agent that can realize the excellent effects of the above-mentioned method for treating organic wastewater. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a graph showing the results of a treatment test in which the influence of the addition or absence of pyrroloquinoline quinone (PQQ) used in the treatment method of the present invention on the COD value of treated water was investigated. [Figure 2] 1 is a graph showing the results of a treatment test in which the influence of the addition or absence of vitamin B12 used in the treatment method of the present invention on the COD value of treated water was investigated. [Figure 3] FIG. 1 is a schematic diagram of a biological treatment test device used in a water flow test. [Figure 4] FIG. 1 is a schematic diagram showing an outline of an actual activated sludge treatment facility that was the subject of study in Study Example 5. [Figure 5] FIG. 1 is a graph showing the effect obtained when treatment is performed using the treatment method of the present invention, in terms of the proportion of PVA-decomposing bacteria in sludge in the aeration tank of an actual activated sludge treatment facility, obtained by genetic analysis. DETAILED DESCRIPTION OF THE INVENTION

[0014] The organic wastewater treatment method of the present invention will be described below with reference to preferred embodiments. The present inventors recognized that when organic wastewater is actually biologically treated at various sites, there are sites where persistent COD components always remain in the treated water, and sites where slowly degradable COD components remain depending on the season. It was recognized that there is a need to improve the organic wastewater treatment method so that the COD value of the treated water can be reduced and more effective biological treatment can be performed at these sites. Furthermore, if the above-mentioned effects could be achieved in such cases without requiring major modifications to biological wastewater treatment facilities, such as conventional activated sludge treatment facilities, this would be extremely useful and would realize an organic wastewater treatment method with high practical value.

[0015] In light of the current state of treatment described above, the present inventors recognized the need for the development of effective biological treatment agents to resolve the aforementioned problems of the prior art when treating wastewater containing persistent COD components without requiring major modifications to the facilities, and conducted further studies. In their studies, they used polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyoxyethylene (50) oleyl ether (POE (50)) as representative examples of persistent COD components. These components are widely used industrially and remain in biological wastewater treatment, causing the COD value of the treated water to increase. As mentioned above, these are representative examples of persistent COD components that are the subject of the present invention, but the present invention is not limited to these.

[0016] Based on the above findings, the inventors conducted water flow tests and found that by using vitamin B12 (hereinafter sometimes abbreviated as VB12), pyrroloquinoline quinone (hereinafter sometimes abbreviated as PQQ), and incineration ash from organic waste, and by using a combination of two or more of these three compounds, stable treatment can be achieved and the COD value of the treated water can be steadily reduced, even though the microorganisms such as PVA-degrading bacteria that inhabit sludge may vary depending on the biological treatment site. They confirmed that the preferred combinations for biological treatment are vitamin B12 and incineration ash from organic waste, pyrroloquinoline quinone and incineration ash from organic waste, or vitamin B12, pyrroloquinoline quinone, and incineration ash from organic waste. In other words, by adding either vitamin B12 or pyrroloquinoline quinone, or both, to the incineration ash of organic waste, it was confirmed that the concentration of PVA remaining in the treated water can be effectively and stably reduced, and the COD value of the treated water can be stably reduced, even when the PVA-degrading bacteria living in the sludge used for biological treatment differ from site to site, as will be described later.

[0017] The inventors first prepared simulated wastewater containing PVA as a representative example of a persistent COD component, and conducted a water flow test using this as raw water to investigate substances that improve the biological treatment capacity of COD components in wastewater. The test was conducted in a conventional biological treatment process using activated sludge, in which organic wastewater is biologically treated in a biological treatment tank, with the addition of the above-mentioned substances. The difference in biological treatment capacity for COD components due to the coexistence of these substances in the biological treatment process, as well as the treatability of combining these substances, were confirmed. As a result, the effectiveness of adding vitamin B12 (VB12), pyrroloquinoline quinone (PQQ), and organic waste incineration ash was first confirmed. As described below, basic studies were primarily conducted using simulated wastewater containing PVA. As described below, simulated wastewater containing PEG and POE(50) as persistent COD components was also tested and its effectiveness confirmed.

[0018] [Water flow test example] Below, we will explain the results of a water flow test in which two components of the present invention, vitamin B12 and pyrroloquinoline quinone, were added and biological treatment was carried out, and the results will be explained.

[0019] First, simulated wastewater-1 containing PVA and simulated wastewater-2 containing PVA for use in the water flow test were prepared with the properties shown in Tables 1 and 2, respectively. Specifically, two types of simulated wastewater were prepared using tap water and the chemicals shown in Tables 1 and 2, adjusting the concentrations to those shown in Tables 1 and 2. Two biological treatment test systems were also prepared: one for treatment with chemicals added and one for a blank treatment without chemicals. As shown in the schematic diagram of Figure 3, the biological treatment test system has a hollow fiber membrane in a biological treatment tank (aeration tank), biologically treats the introduced wastewater, and the supernatant is used as treated water.

[0020] 3 L of sludge was placed in each biological treatment tank. The sludge was from a treatment plant that treats PVA-containing raw water, and the initial MLSS in the biological treatment tank (aeration tank) was 3270 mg / L. Then, 3 L / day of the two types of simulated wastewater containing PVA prepared above was flowed into each biological treatment tank (aeration tank), and a water flow test was carried out while aerating. The values ​​in the lower rows of Tables 1 and 2 are the COD values ​​for each simulated wastewater. Cr , NH4-N and PO4-P measurement results.

[0021] TIFF0007735105000001.tif65170

[0022] TIFF0007735105000002.tif76170

[0023] As described above, two biological treatment tanks were prepared, and chemicals were added to one biological treatment tank, while an equal amount of tap water was added to the other. 3 L of sludge was placed in each of the two biological treatment tanks. 3 L of the two types of simulated wastewater prepared above was passed through each biological treatment tank per day, and biological treatment was carried out continuously for the period described below. The sludge was then removed using a hollow fiber membrane placed in the biological treatment tank, and 3 L of treated water was withdrawn per day. The amount of residual PVA and COD of the resulting treated water were measured. Cr A pH controller was installed in the biological treatment tank, and 0.4N NaOH was added dropwise to adjust the pH of the sludge to 7.5. The simulated wastewater was temporarily changed to increase the carbon source concentration and increase the COD volume load, and the treatability was confirmed.

[0024] In the test using PVA-containing simulated wastewater-1, two systems were tested: one with 40 μg / L of PQQ added and one without any added chemicals. In the test using PVA-containing simulated wastewater-2, two systems were tested: one with 10 μg / L of VB12 added and one without any added chemicals.

[0025] Using simulated wastewater-1 containing PVA with the properties shown in Table 1, and using the biological treatment test equipment configured as shown in Figure 3 described above, biological treatment was carried out for 24 consecutive days in two parallel systems: a non-additive system in which biological treatment was carried out without adding any chemicals to the treatment system, and a PQQ-added system in which biological treatment was carried out by adding PQQ to the treatment system. The COD Cr The values ​​were measured, and their fluctuations were confirmed. The results of the above-mentioned water flow test are shown in Figure 1. The upper part of Figure 1 shows the fluctuations in COD volume load in the biological treatment tank over the 24 days during which the water flow test was conducted.

[0026] As a result of the above water flow test, as shown in Figure 1, the biological treatment with PQQ addition system showed a significant improvement in the COD of the treated water compared to the biological treatment without PQQ addition system. CrThe concentration was lower. More specifically, the addition of PQQ resulted in a significantly lower COD concentration in the treated water compared to the untreated system when the COD volume load was high (high load). In other words, it was confirmed that the addition of PQQ was effective in improving treatment capacity, especially during high load periods.

[0027] On the other hand, when a similar test was conducted using sludge collected from another factory (not shown), the addition of PQQ did not provide a decomposition ability improvement effect that could be judged to be superior to the non-additive system. This means that depending on the type of sludge used in biological treatment, the advantageous effect of adding PQQ may not be realized. In contrast, in this case, it was confirmed that by adding either VB12 or organic waste incineration ash as specified in the present invention and using it in combination with PQQ, an improved decomposition ability effect was obtained compared to the non-additive system. This point will be discussed later.

[0028] Using simulated wastewater-2 containing PVA with the properties shown in Table 2, and using the biological treatment test equipment configured as shown in Figure 3 described above, biological treatment was carried out in two systems in parallel for 30 consecutive days: a non-additive system in which biological treatment was carried out without adding any chemicals to the treatment system, and a VB12-added system in which biological treatment was carried out by adding VB12 to the treatment system. The COD Cr The values ​​were measured, and their fluctuations were confirmed. The results of the water flow test are shown in Figure 2. The upper part of Figure 2 shows the fluctuations in COD volume load in the biological treatment tank over the 30 days of the water flow test.

[0029] As a result of the above water flow test, as shown in Figure 2, the biological treatment with VB12 added had a significantly lower COD of treated water than the biological treatment without VB12 added. CrThe concentration decreased. In other words, it was confirmed that the addition of VB12 had the effect of improving biological treatment capacity. On the other hand, when a similar test was conducted using sludge collected from another factory (not shown), the addition of VB12 did not provide a decomposition capacity improvement effect that could be judged to be superior to the no-addition system. This means that depending on the type of sludge used in biological treatment, the superior effect of adding VB12 may not be realized. In contrast, in this case, it was confirmed that by adding either pyrroloquinoline quinone as defined in the present invention or incineration ash of organic waste and using it in combination with VB12, an improvement in decomposition capacity was obtained compared to the no-addition system. This point will be discussed later.

[0030] Here, we investigated the microbial flora of sludge collected from three biological treatment facilities treating PVA-containing wastewater. The results suggested that different types of PVA-degrading bacteria were responsible for PVA degradation in raw water depending on the type of sludge. The lack of consistent results in the above-mentioned water flow tests may be due to differences in the PVA-degrading bacteria present in the sludge. The microbial flora of the sludge revealed that bacteria of the genera Sphingomonas, Sphingopyxis, Povalibacter, Steroidobacter, and Novosphingobium were sometimes responsible for PVA degradation. Based on the above findings that the activated sludge used at each biological treatment site contains different microorganisms responsible for PVA degradation, the inventors concluded that a combination of various chemicals (substances) would be necessary to improve PVA degradation in biological treatments using various types of activated sludge, and therefore conducted further studies. As a result, as mentioned above, it was found that adding a combination of two or more of vitamin B12 (VB12), pyrroloquinoline quinone (PQQ), and incineration ash from organic waste was effective. Below, we will explain the three types of chemicals (substances) specified in this invention.

[0031] <Vitamin B12 (hereinafter sometimes abbreviated as VB12)> Vitamin B12 is a water-soluble vitamin, and compounds with vitamin B12 activity include hydroxocobalamin, in which a hydroxyl group is bound to cobalt; methylcobalamin, in which a methyl group is bound; and adenosylcobalamin, in which 5'-deoxyadenosine is bound. In this invention, compounds with vitamin B12 activity are collectively referred to as vitamin B12 compounds. Vitamin B12 compounds are naturally found in various animal foods and are known to function as coenzymes for certain enzymes in the body.

[0032] <Pyrroloquinoline quinone (hereinafter sometimes abbreviated as PQQ)> PQQ is an organic molecule found in bacteria as a redox coenzyme. It is contained in small amounts in various foods and is known to have cell proliferation effects in animals and microorganisms.

[0033] <Incineration ash from organic waste> Examples of organic waste that can be used as the raw material for the incineration ash of organic waste include sewage sludge, excess sludge generated from biological treatment of industrial wastewater, kitchen waste, food waste, agricultural waste, livestock and poultry manure, livestock waste, fishery waste, and forestry waste. The effects of the present invention can be achieved with any of the incineration ash of the organic waste listed above. For example, with the development of facilities that use dried chicken manure as thermal fuel for boilers, the incineration ash of livestock and poultry manure, such as chicken manure, is obtained as a by-product. Furthermore, because this incineration ash contains a large amount of phosphorus and potassium, it is widely used as fertilizer. According to the inventors' studies, the incineration ash of the various wastes listed above, including the incineration ash of livestock and poultry manure, can be effectively used as the incineration ash of the organic waste that constitutes the present invention. Therefore, the present invention has the environmental benefit of enabling the effective utilization of the various wastes listed above in the field of wastewater treatment.

[0034] <Additional concentration> According to the inventors' investigations, it is preferable to add VB12 to raw water in a range of about 0.5 to 100 μg / L. It is preferable to add PQQ to raw water in a range of about 0.5 to 100 μg / L. It is also preferable to add organic waste incineration ash to raw water in a range of about 2 to 1000 mg / L. Furthermore, in order to achieve the objective of the present invention, which is to effectively and stably reduce the concentration of PVA remaining in treated water even when the PVA-degrading bacteria living in sludge differ depending on the site, it is necessary to select and combine two or all three of VB12, PQQ, and organic waste incineration ash. It is preferable that the amount of each added be within the range of the preferred amount for each chemical (substance) listed above. This means that the preparation of the biological treatment agent of the present invention can be achieved by using a combination of two or more agents (substances) selected from the three types of agents (substances) mentioned above, and ensuring that each agent (substance) can be used within the preferred ranges mentioned above, which has the manufacturing advantage of making it extremely easy to determine and prepare the blend of two or more agents (substances).

[0035] The above-mentioned chemicals (substances) may be added in a mixed state of two or more kinds, or each may be added separately. The location of addition is also not particularly limited, as long as the chemicals (substances) are present in the raw water biological treatment process. For example, they may be added to the raw water adjustment tank, the biological treatment tank, or supplied to the raw water inlet. [Example]

[0036] Next, the present invention will be explained in more detail by way of examples.

[0037] [Study Example 1] <Confirmation test of the effect of adding chemicals to sludge - Treatment of wastewater containing PVA> First, two types of sludge, sludge 1 and sludge 2, were used, each of which was centrifuged and washed with tap water, and then suspended in 1 mL of tap water to obtain washed sludge suspensions for biological treatment. The above sludge 1 and sludge 2 were collected from two different biological wastewater treatment facilities that treated PVA-containing wastewater.

[0038] A simulated wastewater containing PVA was prepared containing the components shown in Table 3. Specifically, reagents were added to the concentrations shown in Table 3, and the volume was adjusted to 1 L with tap water. The resulting simulated PVA wastewater and washed sludge suspensions containing the above-mentioned sludge 1 and sludge 2 were used to confirm the effect of adding chemicals (substances) in the biological treatment process as follows.

[0039] TIFF0007735105000003.tif58170

[0040] 75 mL of the PVA simulated wastewater (Table 3) prepared above was dispensed into each of 20 300 mL Erlenmeyer flasks. VB12, PQQ, and livestock and poultry manure incineration ash were added to each flask to achieve the concentrations listed in Tables 4 and 5. Next, 50 μL of the washed sludge suspensions obtained from the different sludge types, sludge 1 and sludge 2, were added to the corresponding flasks, yielding a total of 20 diluted sludge suspensions. Each diluted sludge suspension was then cultured with shaking at 30°C, and the PVA concentration in the medium was measured. The PVA concentration was measured using the Finley method described below. The measurement results are summarized in Tables 4 and 5. Specifically, the results of shaking culture using the washed sludge suspension of sludge 1 are shown in Table 4, and the results of shaking culture using the washed sludge suspension of sludge 2 are summarized in Table 5. In Tables 4 and 5, the incineration ash of livestock and poultry manure is abbreviated as "incineration ash" or "ash."

[0041] The PVA concentration was determined based on the Finley method as follows. The reaction reagents used were a 4% (w / V) boric acid solution and an iodine solution containing 25 g / L of potassium iodide and 13.7 mg / L of I2. To conduct a basic study on the biological treatment of organic wastewater containing persistent COD components, a dilution series for creating a calibration curve was prepared using the reagents, with the PVA solution concentration gradually changed from 1 mg / L to 100 mg / L.

[0042] 5 mL of boric acid solution was added to 10 mL of the measurement sample, and 1 mL of iodine solution was added. After 20 minutes, the sample was placed in a measurement cell and the absorbance at a wavelength of 690 nm was measured. A calibration curve was then prepared based on the PVA concentration and absorbance. Using the resulting calibration curve, the PVA concentration of each sample was calculated to measure the residual PVA concentration. The results are shown in Tables 4 and 5. These tables show the PVA reduction rate calculated based on the results of the shaking culture test described above without adding any chemicals (substances).

[0043] TIFF0007735105000004.tif106170

[0044] TIFF0007735105000005.tif78170

[0045] As shown in Table 4, when the washed sludge suspension of sludge 1 was used, PQQ alone provided a relatively high PVA degradation rate improvement effect. On the other hand, although VB12 alone was effective, it was found that the effect was not as high as when PQQ was added. As shown in Table 5, the PVA degradation rate improvement effect when the washed sludge suspension of sludge 2 was used showed a trend opposite to that when the washed sludge suspension of sludge 1 was used. That is, VB12 alone was confirmed to provide a relatively high PVA degradation rate improvement effect, while the addition of PQQ alone did not provide as high an effect as when VB12 was added alone. Furthermore, when livestock and poultry manure incineration ash was added alone, as shown in Table 2, the addition of livestock and poultry manure incineration ash alone did not provide much of an effect on PVA degradation when the washed sludge suspension of sludge 1 was used. On the other hand, as shown in Table 5, when the washed sludge suspension of sludge 2 was used, it was confirmed that although the effect of adding livestock and poultry manure incineration ash alone was not high, it was similar to the effect of adding PQQ alone.

[0046] The results of the shake culture test described above demonstrated that the addition of VB12, PQQ, and livestock and poultry manure incineration ash to the biological treatment process can be expected to improve PVA degradation rates, but that the effectiveness of this treatment depends on the type of sludge used in the biological treatment. Furthermore, as shown in Tables 4 and 5, a combination of two or more VB12, PQQ, and livestock and poultry manure incineration ash significantly improved PVA degradation rates compared with the addition of each agent alone. Furthermore, combining two or more agents produced a synergistic effect, and a stable improvement in PVA degradation rates could be expected, even when different sludges were used in the shake culture test.

[0047] As mentioned above, investigations of the microbial flora of sludge used in multiple treatment facilities revealed that PVA-degrading bacteria, such as Sphingomonas, Sphingopyxis, Povalibacter, Steroidobacter, and Novosphingobium, may play a key role. Based on this and the results described above, it was found that the chemicals (substances) that improve the PVA-degrading performance of PVA-degrading bacteria living in sludge differ depending on the PVA-degrading bacteria. Ideally, it would be desirable to add a different chemical (substance) suitable for each PVA-degrading bacterium. However, this method is cumbersome and not practical for biological treatment of actual raw water. Therefore, the present inventors further investigated the addition of a combination of chemicals (substances) and achieved the present invention.

[0048] As shown in Tables 4 and 5, when VB12 or PQQ was added alone, the PVA degradation rate was clearly higher when both were added in combination than when they were added in combination. This result is thought to be due to the promotion of growth of both PQQ-utilizing bacteria and VB12-utilizing bacteria in the combined addition system.

[0049] As shown in Tables 4 and 5, when livestock and poultry manure incineration ash was used, the combined addition of VB12 and / or PQQ clearly demonstrated a higher PVA degradation rate than the single-addition system. The mechanism by which livestock and poultry manure incineration ash exerts this effect is unknown. The inventors believe that livestock and poultry manure incineration ash is composed of various inorganic components, and that one of these inorganic components may have promoted the growth of PVA-degrading bacteria. However, the specific component has not been clearly identified. It is speculated that the synergistic effect of the growth promotion effect of livestock and poultry manure incineration ash on PVA-degrading bacteria due to its addition to the biological treatment process and the growth promotion effect of the added VB12 and / or PQQ on the individual PVA-degrading bacteria resulted in the higher PVA degradation ability. From the above, it was found that in order to effectively and stably improve the PVA decomposition capacity of sludge containing various types of PVA-decomposing bacteria, it is effective to add a combination of two or more of the three types of chemicals mentioned above.

[0050] [Study Example 2] <Confirmation test of the effect of adding chemicals to sludge - Treatment of wastewater containing PEG> Sludge was collected from a biological wastewater treatment facility that was treating PEG-containing wastewater, and the collected sludge was used as sludge 3. As in Example 1, the collected sludge 3 was then centrifuged and washed with tap water, and suspended in 1 mL of tap water to obtain a washed sludge suspension for use in the biological treatment of this example.

[0051] PEG-containing simulated wastewater containing the components shown in Table 6 was prepared. Specifically, reagents were added to the concentrations shown in Table 6, and the volume was adjusted to 1 L with tap water. The resulting PEG-containing simulated wastewater and the washed sludge suspension containing sludge 3 were then used to confirm the effect of adding chemicals (substances) in the biological treatment process as follows.

[0052] 75 mL of PEG-containing wastewater was dispensed into each of five 300 mL Erlenmeyer flasks. Next, VB12, PQQ, and chicken manure incineration ash were added to each flask so that the respective concentrations were as shown in Table 7. Next, 50 μL of the washed sludge suspension used in the biological treatment of this study, which was previously obtained using sludge 3, was added to each flask to obtain five dilute sludge suspensions. Each dilute sludge suspension was then cultured with shaking at 30°C for 6 days, and the resulting culture solution was centrifuged to obtain filtrate, which was used as treated water. The COD concentration of this treated water was measured using a measurement kit from HACH. Table 7 shows the COD Cr The concentration measurement results are summarized below.

[0053] TIFF0007735105000006.tif55170

[0054] TIFF0007735105000007.tif57170

[0055] [Study Example 3] <Confirmation test of the effect of adding chemicals to sludge - Treatment of wastewater containing POE(50)> Sludge was collected from a biological wastewater treatment facility treating wastewater containing POE(50), and the collected sludge was used as sludge 4. As in Example 1, the collected sludge 4 was centrifuged and washed with tap water, and then suspended in 1 mL of tap water to obtain a washed sludge suspension for use in biological treatment.

[0056] A simulated wastewater containing POE(50) containing the components shown in Table 8 was prepared. Specifically, reagents were added to the concentrations shown in Table 8, and the volume was adjusted to 1 L with tap water. The resulting simulated wastewater containing POE(50) and the washed sludge suspension containing the above-mentioned sludge 4 were used to confirm the effect of adding chemicals (substances) in the added biological treatment step. Specifically, a comparative test was conducted in the same manner as in Study Example 2, between a case where biological treatment was carried out without adding chemicals and a case where biological treatment was carried out with the addition of VB12, PQQ, and chicken manure incineration ash so that the respective concentrations were as shown in Table 9. Table 9 shows the COD of the treated water obtained by each of the above-mentioned biological treatments. Cr The concentration measurement results are summarized below.

[0057] TIFF0007735105000008.tif57170

[0058] TIFF0007735105000009.tif36170

[0059] [Study Example 4] <Confirmation test of the effect of adding chemicals on PVA-degrading bacteria present in the treatment system> Five mL of the PVA simulated wastewater shown in Table 3 was placed in each test tube, and one of three pesticides (VB12, PQQ, and chicken manure + VB12) was added. One pesticide, two pesticides, and three pesticides were added. Test tubes containing the PVA simulated wastewater without any pesticides were also prepared as controls. The VB12 pesticide, when added alone, was added at a concentration of 1 μg / L, and the PQQ pesticide, when added alone, was added at a concentration of 10 μg / L. For the combination of incineration ash and VB12, the pesticide was added at a concentration of 10 mg / L, and the VB12 pesticide was added at a concentration of 1 μg / L. For the combination of incineration ash and PQQ, the pesticide was added at a concentration of 10 mg / L, and the PQQ pesticide was added at a concentration of 10 μg / L. Furthermore, in the three combinations of incineration ash, VB12, and PQQ, the incineration ash was added at a concentration of 10 mg / L, the VB12 at a concentration of 1 μg / L, and the PQQ at a concentration of 10 μg / L.

[0060] Next, 50 μL of the washed sludge suspension containing sludge 1 used in Study Example 1 was added to each test tube, and shaking culture was initiated at 30°C. Six days after the start of shaking culture, the samples in each test tube were subjected to bacterial 16S rRNA gene analysis using NGS (next-generation sequencer). The proportion of microorganisms present in the samples (abundance ratio) was then determined.

[0061] As shown in Table 10, the results of the above tests revealed that not all PVA-degrading bacteria exhibited the same growth tendency in response to the addition of chemicals. It was found that, after shaking culture, some PVA-degrading bacteria increased in abundance compared to the untreated control, while others decreased in abundance. It is generally difficult to determine the type of PVA-degrading bacteria present in sludge without genetic analysis. However, determining the presence of degrading bacteria through genetic analysis is time-consuming and labor-intensive, making genetic analysis of sludge used in microbial wastewater treatment impractical. In contrast, the results of Table 10 suggest that, for example, the addition of a chemical containing both VB12 and PQQ can increase the abundance of PVA-degrading bacteria, regardless of the type of PVA-degrading bacteria present in the sludge. Therefore, a biological treatment method in which multiple chemicals selected from those specified in the present invention are simultaneously added can be useful for increasing the number of PVA-degrading bacteria in a treatment tank. The classification (family, genus, species) of each microorganism shown in Table 10 is based on the classification of the most homologous gene sequence group obtained by homology search using Living Tree as a database for each gene sequence obtained by NGS, among those given a genus name or a genus name and a species name.

[0062] TIFF0007735105000010.tif72170

[0063] [Study Example 5] <Confirmation test of the effectiveness of chemical addition in an actual activated sludge treatment facility> In an activated sludge treatment facility that is actually in operation, a combination of the three types of chemicals specified in this invention was added to carry out biological treatment, and a confirmation test was conducted to determine whether or not the addition of the chemicals would have any effect, similar to the simulated wastewater tested in Examples 1 to 3 above.

[0064] The facility used for the test was an activated sludge treatment facility in a textile factory that was in operation. The facility had a daily inflow of wastewater of 100 m3. 3 / day, the capacity of the activated sludge tank (aeration tank) to be treated is 150m 3The results were as follows. The test was performed by adding a combination of three chemicals to the aeration tank in the following proportions and biological treatment. Specifically, the chemicals to be added to the aeration tank were previously formulated to contain 99.98% chicken manure ash, 0.01% VB12, and 0.01% PQQ. The chicken manure ash, VB12, and PQQ were then mixed to prepare a three-chemical-containing composition. The prepared chemical-containing composition was then added intermittently at the following times to perform biological treatment. Specifically, 0 kg (no addition) of the prepared three-chemical-containing composition was added once a day during the three-chemical-free period, and 1 kg during the chemical-added period. The specific periods are described below. When the three-chemical-containing composition was added to the aeration tank as described above, the final concentrations of chicken manure ash, VB12, and PQQ in the wastewater were 10 mg / L, 1 μg / L, and 1 μg / L, respectively.

[0065] The above-mentioned chemical-free period (Period 1) during the test period was from the day the test started (Day 0) to Day 10. Treated water obtained during Period 1 was sampled at the timing described below, and the sampled treated water was evaluated. The obtained results were used as the standard. Furthermore, the chemical-added period (Period 2) was from Day 11 to Day 21 after the start of the test, after the end of the above-mentioned chemical-free period (Period 1). Treated water obtained during Period 2 was sampled at the timing described below, and each sampled treated water was evaluated. The evaluation results for each treated water obtained were used to confirm the effects obtained by the configuration of the present invention, as described below. As shown in Table 11, the number of times treated water was sampled for evaluation was four days within the period in both Period 1 and Period 2. The sampled treated water here refers to the effluent (discharged water) from the settling tank in FIG. 4. In addition, in order to confirm the efficiency of the biological treatment carried out at each point in time on the actual wastewater described above, when the treated water (discharge water) was sampled, the raw water introduced into the aeration tank for biological treatment in the aeration tank was also sampled.

[0066] The effects obtained by the configuration of the present invention were confirmed using the treated water collected as described above and the raw water at the time of collection, and the evaluation obtained for each collection, as follows. Specifically, first, the COD Mn The concentrations of COD, BOD, and PVA were measured. The COD of the treated water was compared with that of the raw water using the measured values ​​of the treated water and raw water taken at the same time. Mn The degree to which each of the measured values ​​of BOD and PVA was reduced was calculated as the removal rate. These values ​​are summarized in Table 11.

[0067] TIFF0007735105000011.tif88170

[0068] COD during drug administration period Mn The removal rates of COD, BOD, and PVA were higher than those in the period without chemical addition, and it was confirmed that the addition of chemicals improved COD decomposition performance in the actual facility.

[0069] Furthermore, sludge was collected from the aeration tank, and the bacterial 16S rRNA gene analysis using NGS was performed on each sample to evaluate the proportion of PVA-degrading bacteria present in the sludge. The sludge was collected from the aeration tank on the same day as the treated water and raw water samples were collected. The proportion of Steroidobacter bacteria, a representative example of PVA-degrading bacteria, was also examined. Figure 5 shows the results of the proportion obtained by genetic analysis in a graph. As shown in Figure 5, it was confirmed that the number of PVA-degrading bacteria clearly increased during the period when the chemical was added compared to the period when the chemical was not added.

Claims

1. A method for treating organic wastewater, comprising a biological treatment step of biologically treating organic wastewater containing persistent COD components in a biological treatment tank, comprising: the organic wastewater contains at least one persistent COD component selected from the group consisting of polyvinyl alcohol, polyethylene glycol, and polyoxyethylene oleyl ether; A method for treating organic wastewater containing persistent COD components, characterized in that in the biological treatment step, two or more selected from the group consisting of vitamin B12, pyrroloquinoline quinone, and incineration ash of organic waste are added to carry out biological treatment.

2. 2. The method for treating organic wastewater according to claim 1, wherein the persistent COD components include polyvinyl alcohol, the biological treatment is carried out by a microbial community composed of multiple types of microorganisms, and the microbial community contains at least one species of bacteria of the genus Sphingomonas, Sphingopyxis, Povalibacter, Steroidobacter, and Novosphingobium that are capable of decomposing polyvinyl alcohol.

3. 3. The method for treating organic wastewater according to claim 1 or 2, wherein the biological treatment step is carried out by adding any one of a combination of vitamin B12 and incineration ash of organic waste, a combination of pyrroloquinoline quinone and incineration ash of organic waste, or a combination of vitamin B12, pyrroloquinoline quinone and incineration ash of organic waste.

4. The method for treating organic wastewater according to any one of claims 1 to 3, wherein the biological treatment step is carried out in any of the following cases: when persistent COD always remains in treated water after biological treatment of the organic wastewater; when slowly degradable COD remains in treated water after biological treatment of the organic wastewater; when biological treatment of the organic wastewater is started up; or when the COD volume load in the biological treatment tank increases.

5. A biological treatment agent used for treating organic wastewater containing persistent COD components, comprising: the organic wastewater contains at least one persistent COD component selected from the group consisting of polyvinyl alcohol, polyethylene glycol, and polyoxyethylene oleyl ether; A biological treatment agent characterized by comprising two or more selected from the group consisting of vitamin B12, pyrroloquinoline quinone, and incineration ash of organic waste.

6. 6. The biological treatment agent according to claim 5, which contains the incineration ash of organic waste as an essential component.

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