JP7398914B2 - Process for treating wastewater containing polyethers, wastewater treatment equipment containing polyethers, and sludge used therein - Google Patents

Description

The present invention relates to a method for treating polyether-containing wastewater, a polyether-containing wastewater treatment apparatus, and sludge used therein.

Conventionally, various studies have been made regarding the treatment of industrial wastewater, and appropriate treatment methods depending on the components of the wastewater are being adopted. Wastewater containing polyethers, which are often found in mold release agents and lubricants, is difficult to decompose and is generally incinerated, but this treatment method has a large environmental impact and is expensive. The problem is that it is easy to Therefore, a method using microorganisms can be considered as a method that can reduce environmental burden and treat at low cost. For example, Patent Document 1 describes a method for treating wastewater containing polyethylene glycol, which is a polyether, after anaerobically treating wastewater containing polyethylene glycol by passing it into an anaerobic treatment tank holding sludge containing anaerobic microorganisms. , a method of decomposing polyethylene glycol by supplying oxygen to the treated water and treating it with activated sludge is mentioned.

Japanese Patent Application Publication No. 2002-210489

However, although Patent Document 1 discloses that the sludge containing the anaerobic microorganisms is produced by methane fermentation treatment, the bacterial flora composition in the sludge is not clarified. In addition, although various studies have been conducted on treatment methods for wastewater containing polyethers, all of them remain at the academic level, and industrial-level treatment methods that have a small environmental impact, are low cost, and can be treated on a large scale. Yes, it has not been reported yet.

The present invention has been made in view of this background, and aims to provide a method for treating polyether-containing wastewater that can be treated on a large scale with low environmental impact and at low cost.

One aspect of the present invention is a method for treating polyether-containing wastewater in which the polyether-containing wastewater is anaerobically treated through sludge provided in a UASB (Upflow Anaerobic Sludge Blanket) reaction tank.
The above-mentioned sludge contains a microbial group consisting of multiple types of microorganisms, and in the microbial group, the presence ratio of one of the microorganisms belonging to the genus Geobacter and the methane bacteria is the highest, and the presence ratio of the other is the second highest. ,
The proportion of microorganisms belonging to the genus Geobacter relative to all microorganisms contained in the sludge is 20 to 65%, and the proportion of methane bacteria is 5 to 35%,
The polyether-containing wastewater contains a copolymer of ethylene glycol and propylene glycol, and the microorganism group contained in the sludge is configured to decompose the copolymer anaerobically,
The copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) in the above copolymer is in a method for treating polyether-containing wastewater, in which the molar ratio is EG:PG=1:5.0 or less .

Another aspect of the present invention is a copolymer of ethylene glycol and propylene glycol, wherein the copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) is EG:PG=1:5.0 or less in molar ratio. A sludge used for anaerobically treating wastewater containing polyethers,
Contains a microbial group consisting of multiple types of microorganisms, and in the microbial group, the presence ratio of one of the microorganisms belonging to the genus Geobacter and the methane bacteria is the highest, and the presence ratio of the other is the second highest,
Sludge used for the treatment of polyether -containing wastewater, in which the proportion of microorganisms belonging to the genus Geobacter among the above microorganisms is 20 to 65%, and the proportion of methane bacteria is 5 to 35%. It is in.

Yet another aspect of the present invention is a polyether-containing wastewater treatment apparatus that includes a UASB reaction tank in which the sludge is held.

In the microbial group consisting of multiple types of microorganisms contained in the sludge in the method for treating polyether-containing wastewater of the above embodiment, the presence ratio of either microorganisms belonging to the Geobacteraceae family (Geobacteraceae) or methane bacteria is highest, The presence ratio of the other one is the next highest. The inventors of the present application have discovered that polyether-containing wastewater can be efficiently treated by using such sludge. And, such treatment has the ability to decompose polyethers into organic acids under anaerobic conditions, among microorganisms of the Geobacteraceae family, which are known to be involved in the oxidation of metals under anaerobic conditions. They concluded that this was possible because methane bacteria exist and the methane bacteria have the ability to decompose organic acids. According to this treatment method, since the treatment is performed using sludge containing the above-mentioned microorganism group, it is possible to perform large-scale treatment with less environmental impact and at lower cost than conventional incineration treatment.

According to the sludge used for anaerobically treating polyether-containing wastewater according to the other aspect, the sludge can be actively used to treat polyether-containing wastewater, and as described above, conventional Compared to incineration treatment, large-scale treatment is possible with less environmental impact and at lower cost.

According to the polyether-containing wastewater treatment device of yet another aspect, as described above, the polyethers contained in the wastewater are efficiently decomposed under anaerobic conditions, and the polyethers-containing wastewater is efficiently purified. In addition to being processed, large-scale processing is possible at a lower cost and with less environmental impact than conventional incineration processing.

As described above, according to the present invention, it is possible to provide a method for treating polyether-containing wastewater that can be treated on a large scale with low environmental impact and at low cost.

1 is a schematic diagram showing the configuration of a polyether-containing wastewater treatment apparatus in Example 1. FIG. FIG. 3 is a diagram showing the COD concentrations of supplied wastewater, UASB-treated water, and DHS-treated water in Example 1. 3 is a diagram showing COD removal rates and OLR in UASB processing and DHS processing in Example 1. FIG. FIG. 3 is a diagram showing the amount of biogas produced in the glycol-containing wastewater treatment device in Example 1. FIG. 2 is a diagram showing the proportion of microorganisms constituting sludge at the family level in Example 1. FIG. 2 is a diagram showing the abundance ratio of microorganisms constituting sludge at the genus level in Example 1. FIG. 3 is a diagram showing test results regarding the biodegradability of polyether compounds by sludge in Example 1.

In the treatment method and the sludge, the proportion of microorganisms belonging to the Geobacteraceae family to all microorganisms contained in the sludge is 20 to 65%, and the proportion of methane bacteria is 5 to 35%. It is preferable. In this case, the decomposition of polyethers into organic acids under anaerobic conditions by microorganisms belonging to the family Geobacteraceae and the decomposition of organic acids by methane bacteria are carried out in a well-balanced manner. As a result, polyether-containing wastewater can be treated more efficiently.

In the treatment method and the sludge, the microorganisms belonging to the family Geobacteraceae preferably include microorganisms belonging to the genus Geobacter. Microorganisms belonging to the genus Geobacter have a high ability to decompose polyethers into organic acids under anaerobic conditions, so the decomposition of polyethers contained in wastewater into organic acids is further accelerated, and polyethers are Contained wastewater can be treated more efficiently.

In the treatment method and the sludge, all microorganisms contained in the sludge are preferably wild strains. In this case, since the sludge does not contain microorganisms into which mutations have been introduced by artificial manipulation, the treated water treated by the treatment method can be easily discharged into the natural world such as rivers.

The polyether-containing wastewater contains a copolymer of ethylene glycol and propylene glycol, and the microorganisms contained in the sludge are configured to decompose the copolymer anaerobically. preferable. In this case, the copolymer of ethylene glycol and propylene glycol can be efficiently decomposed by the treatment method.

The copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) in the above copolymer is preferably EG:PG=1:5.0 or less in molar ratio. In this case, by the treatment method, the polyether-containing wastewater containing the copolymer having the above copolymerization ratio can be efficiently decomposed by the microorganism group. In the above copolymerization ratio, if the copolymerization ratio of propylene glycol to ethylene glycol is greater than 5.0, the decomposition rate to organic acids by the microorganisms belonging to the Geobacteraceae family will be greatly reduced, so efficient treatment will be necessary. This becomes difficult. This is because when microorganisms decompose copolymers, they first hydrolyze between the repeating units of ethylene oxide and propylene oxide, decomposing them into polymers and monomers with a small number of repeats, and then decomposing these into organic acids. However, as the copolymerization ratio of propylene glycol increases and the number of repeats of propylene oxide increases, hydrolysis between propylene oxides tends to become difficult, resulting in a significant decrease in the decomposition rate of the copolymer. It is assumed that this is causing the

Preferably, the sludge is granule sludge. By using the sludge in the UASB reaction tank, it becomes easy to construct a polyether-containing wastewater treatment device, and the polyether-containing wastewater can be efficiently treated by the treatment device.

The polyether-containing wastewater treatment device preferably includes an aerobic treatment device to which treated water discharged from the UASB reaction tank is supplied. In this case, the organic acids contained in the treated water discharged from the UASB reaction tank can be treated under aerobic conditions by the aerobic treatment device, so the treatment of polyether-containing wastewater in the entire device Efficiency is further improved.

The aerobic treatment device is preferably a DHS (Downflow Hanging Sponge) reaction tank. In this case, the organic acids contained in the treated water discharged from the UASB reaction tank can be treated under aerobic conditions by the aerobic treatment device, so the treatment of polyether-containing wastewater in the entire device Efficiency is further improved.

(Example 1)
The method for treating polyether-containing wastewater, the polyether-containing wastewater treatment apparatus, and the sludge used therein according to this embodiment will be explained with reference to FIGS. 1 to 6.
As shown in FIG. 1, the method for treating polyether-containing wastewater of this example involves treating polyether-containing wastewater anaerobically through sludge 60 provided in a UASB reaction tank 10. It's a method. The sludge 60 includes a microbial group consisting of multiple types of microorganisms, and in the microbial group, either a microorganism belonging to the Geobacteraceae family or a methane bacteria has the highest abundance ratio, and the other has the highest abundance ratio. expensive.

The processing method of this example will be described in detail below.
First, as shown in FIG. 1, the polyether-containing wastewater treatment device (hereinafter also referred to as "treatment device") 1 used in this example includes a UASB reaction tank 10, a DHS reaction tank 20, a wastewater storage section 30, a gas It includes a recovery section 40 and a treated water recovery section 50.

The UASB reaction tank 10 includes a cylindrical reaction tank main body 11 with a bottom, ports 12a to 12d provided on the side surface of the reaction tank main body 11, and a gas-liquid-solid three-phase separation device 13 provided at the top of the reaction tank main body 11. has. The ports 12a to 12d are arranged in order from the lower side to the upper side. The port 12a is located 12 cm above the bottom end of the reaction tank main body 11, the port 12b is located 17 cm above the bottom end of the reaction tank main body 11, and the port 12c is 33 cm above the bottom end of the reaction tank main body 11. It is located on the upper side. The sludge 60 in the UASB reaction tank 10 and the supplied wastewater 32 are sampled through the ports 12a to 12d. Note that normally, the ports 12a to 12d are closed, and the inside of the UASB reaction tank 10 is kept in a sealed state. The capacity of the UASB reaction tank 10 in this example is 10L.

The reaction tank body 11 of the UASB reaction tank 10 shown in FIG. 1 is filled with sludge 60. The sludge 60 is formed by seeding the reaction tank body 11 with granule sludge collected from a medium-temperature UASB reaction tank used to treat food industry wastewater. The sludge 60 in this example is granule sludge with a particle size of approximately 0.5 to 2.0 mm.

The sludge 60 includes a microbial group consisting of a plurality of microorganisms, and the microbial group forms a predetermined bacterial flora. In the microorganism group, it is preferable that the proportion of microorganisms belonging to the Geobacteraceae family to all microorganisms contained in the sludge 60 is 20 to 65%, and the proportion of methane bacteria is 5 to 35%. Furthermore, it is preferable that the microorganisms belonging to the Geobacteriaceae family include microorganisms belonging to the Geobacter genus. In this example, all the microorganisms contained in the sludge 60 are wild strains.

As shown in FIG. 1, a wastewater supply path 31 is connected to the lower part of the UASB reaction tank 10. Supply wastewater 32 stored in the wastewater storage section 30 is supplied to the lower part of the UASB reaction tank 10 via the wastewater supply path 31 . The supply wastewater 32 is supplied to the lower part of the UASB reaction tank 10 at a predetermined flow rate via the wastewater supply path 31. The supplied wastewater 32 rises within the reaction tank main body 11 and is treated anaerobically through the sludge 60.

The gas-liquid-solid three-phase separator 13 forming the upper part of the UASB reaction tank 10 separates the biogas produced by the above treatment from the UASB-treated water and the like. A gas recovery section 40 is connected to the gas-liquid-solid three-phase separation device 13 . The gas recovery unit 40 recovers the biogas separated by the gas-liquid-solid three-phase separator 13. Furthermore, a treated water supply path 15 that supplies the supernatant (UASB treated water) of the supplied wastewater 32 that has been treated through the sludge 60 to the DHS reaction tank 20 is connected to the gas-liquid-solid three-phase separation device 13 .

In the DHS reaction tank 20, sponge carriers (not shown) holding sludge that has spontaneously grown from domestic wastewater are randomly arranged. Note that the sponge carrier is covered with a plastic net ring. The capacity of the DHS reaction tank 20 in this example is 11L, and the total volume of the sponge carrier is about 6L. The above-mentioned treated water supply path 15 is connected to the upper part of the DHS reaction tank 20.

The UASB treated water supplied to the upper part of the DHS reaction tank 20 via the treated water supply path 15 shown in FIG. 1 is dripped into the DHS reaction tank 20 and treated aerobically. The resulting DHS treated water is recovered by the treated water recovery section 50 from the treated water discharge path 21 provided at the lower part of the DHS reaction tank 20. In addition, a part of the DHS treated water may be returned to the waste water supply path 31 of the UASB reaction tank 10 via a reflux path 22 connected to the lower part of the DHS reaction tank 20 in addition to the treated water discharge path 21. . In this example, the processing device 1 is installed in a constant temperature room controlled at 37°C.

The polyether-containing wastewater to be treated in the treatment method and treatment device 1 of this example contains copolymers of ethylene glycol (EG) and propylene glycol (PG) and polyethylene glycol (PEG) as polyether compounds. ), polypropylene glycol (PPG), and polypropylene oxide (PPO). The processing method and processing apparatus 1 of this example can decompose EG/PG copolymer, PEG, PPG, and PPO. The average molecular weight Mw of the polyether compound can be 40,000 or less, preferably 20,000 or less, more preferably 10,000 or less. Note that the average molecular weight Mw indicates a weight average molecular weight, and was estimated by the GPC method in this example.

In addition, when a copolymer of ethylene glycol and propylene glycol is included as a polyether compound, the copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) in the copolymer is EG:PG=1. :5.0 or less, preferably 1:4.0 or less, more preferably 1:2.0 or less, still more preferably 1:1.3 or less.

(Evaluation test 1)
The following evaluation test was conducted regarding the processing ability of the supplied wastewater (polyether-containing wastewater) 32 by the processing apparatus 1 of this example.
First, the COD concentrations of the UASB-treated water and the DHS-treated water after a predetermined number of days had passed after the operation of the treatment apparatus 1 were measured. In addition, for comparison with these, the COD concentration of the supplied wastewater 32 was also measured. Furthermore, the amount of biogas produced by processing the supplied wastewater 32 was measured.

The COD concentration was measured using a water quality analyzer (DR-2800, manufactured by HACH) according to the potassium dichromate method. Furthermore, the amount of biogas produced was measured using a wet gas meter (WS-1, manufactured by Shinagawa) after desulfurization. The component composition of the biogas was analyzed using a TCD detector gas chromatograph (GC-8A, manufactured by Shimadzu).

In this example, as the stock solution of the supplied wastewater 32, wastewater containing a mold release agent discharged during the process of cleaning a mold in molding a rubber product was used. The mold release agent contains a copolymer of ethylene glycol (EG) and propylene glycol (PG) as a polyether compound, and the average molecular weight Mw of the copolymer is 9,000. The polymerization ratio (molar ratio) is EG:PG=1:0.12. Note that sodium bicarbonate was added to the feed wastewater 32 at a concentration of 1 g-NaHCO ₃ /g-COD. Furthermore, ammonium chloride and dipotassium hydrogen phosphate were added as nutrients such that COD:N:P=100:10:1.

The treatment apparatus 1 was started up at a supply wastewater concentration of 1000 mg-COD/L and operated for 245 days. The load was gradually increased until 101 days had passed since the start of operation, and the optimum operating conditions were investigated. After 102 days from the start of operation, the COD of the supplied wastewater 32 was adjusted to 3000 mg COD/L, the pH was adjusted to 7.9, and the hydraulic retention time (HRT) was set to 36 hours. Ta. Figure 2 shows a graph showing changes in COD concentration from 102 days after the start of operation to 245 days, and Figure 3 shows graphs showing changes in COD removal rate and OLR (Organic load rate). . Further, Table 1 shows the numerical values of the COD concentration and COD removal rate from 102 days after the start of operation to 245 days after the start of operation. Note that the COD removal rate of the UASB treatment in FIG. 3 and Table 1 is the COD concentration removed by the UASB treatment relative to the COD concentration of the supplied wastewater 32 expressed as a percentage. Further, the COD removal rate of the DHS treatment is expressed as a percentage of the COD concentration removed by both the UASB treatment and the DHS treatment with respect to the COD concentration of the supplied wastewater 32.

As shown in Figure 2 and Table 1, the COD concentration of the UASB-treated water and the COD concentration of the DHS-treated water during the entire operation from 102 days to 245 days after the start of operation compared with the COD concentration of the supplied wastewater 32. This was a significantly lower value during the period. The COD removal rate by UASB treatment was 53.5 to 77.0%, and the COD removal rate by DHS treatment was 74.1 to 94.3%, which was a very high value. As a result, it was confirmed that the treatment apparatus 1 and the treatment method described above had a very high COD removal effect, that is, a very high ethylene glycol/propylene glycol copolymer decomposition effect.

In addition, the amount of biogas produced from the 234th day of operation to the 245th day was measured, and the results are shown in FIG. 4. As shown in FIG. 4, the maximum amount of biogas produced per day during the period was a high value of 57.8 L/day. The proportion of methane gas in the biogas was 65 to 71%, and the remainder was carbon dioxide gas.

As mentioned above, according to this evaluation test, the COD concentration was sufficiently reduced by the UASB treatment, and a sufficient amount of methane gas was generated. It was strongly suggested that most of it was decomposed into organic acids during the UASB treatment and further converted into methane by methanogens.

Next, the bacterial flora of the sludge 60 provided in the treatment apparatus 1 was analyzed. First, a sample of sludge 60 was collected from port 12c of UASB reaction tank 10. The sampling was carried out 112 days after the start of operation. The collected sludge samples were washed with PBS (Phosphate buffered saline) and then separated using an ultrasonic crusher. Thereafter, DNA was extracted from the treated sludge sample using Fast DNA SPIN Kit for Soil (manufactured by MP Biomedicals). PCR was performed on the DNA extract of each sludge sample using universal primer 515F and reverse primer 806R for a predetermined number of cycles. Thereafter, the PCR amplification product was purified using MinElute PCR Purification Kit (manufactured by Qiagen). Then, all base sequences of the purified PCR amplification products were read by massively parallel 16S rRNA sequencing using next generation sequencing technology. Each read base sequence was analyzed by quantitative insights into microbial ecology (QIIME), and the abundance ratio of microorganisms in each sludge sample of sludge 60 was analyzed based on the Greengenes database.

Regarding the results of the above bacterial flora analysis, the abundance ratio of microorganisms at the family level (detection rate of 16S rRNA sequencing) is shown in Table 2 and FIG. 5, and the abundance ratio of microorganisms at the genus level is shown in Table 3 and FIG. 6.

As shown in Table 2 and FIG. 5, at the family level, it was found that in the sample of sludge 60 collected from UASB treatment equipment 1, the presence ratio of microorganisms belonging to the Geobacteraceae family to all microorganisms was highest. It was also found that microorganisms belonging to Methanobacteriaceae and Methanosaetaceae were present as methane bacteria in the microorganism group of sludge 60, and the proportion of methane bacteria present was the second highest. Specifically, as shown in Table 2, the proportion of microorganisms belonging to the family Geobacteriaceae was 35.60%, and the total proportion of methane bacteria was 12.10%. Regarding unclassified Methanomicrobiales, taxonomically it belongs to Methanobacteria, but when compared with known databases, the homology was relatively low at around 80%. Since the classification of "Microbium" may lack accuracy, it has been decided not to include it in "Methanobacterium" in this application.

Furthermore, as shown in Table 3 and Figure 6, at the genus level, it was found that in the 60 samples of sludge collected from UASB treatment equipment 1, the presence ratio of microorganisms belonging to the genus Geobacter to all microorganisms was highest. . It was also found that the microorganisms of sludge 60 contained microorganisms belonging to the genus Methanobacterium and Methanosaeta as methane bacteria, and the abundance ratio of methane bacteria was the second highest. Specifically, as shown in Table 3, the proportion of microorganisms belonging to the genus Geobacter was 35.60%, and the total proportion of methane bacteria was 11.70%.

In this bacterial flora analysis, samples of sludge 60 collected from port 12c of UASB reaction tank 10 were shown, but samples of sludge 60 collected from ports 12a and 12b of UASB reaction tank 10 were also shown in this book. Analysis results (not shown) with the same tendency as the bacterial flora analysis were obtained. In the treatment method and treatment apparatus 1 of this example, since the generation of biogas was extremely good, it was inferred that stirring of the sludge 60 was promoted inside the UASB reaction tank 10 and the bacterial flora was made uniform.

The processing method of this example, and the effects of the processing apparatus 1 and sludge 60 will be described in detail.
According to the treatment method of this example and the treatment apparatus 1, in the microbial group consisting of multiple types of microorganisms contained in the sludge 60, the abundance ratio of either microorganisms belonging to the Geobacteraceae family or methane bacteria is the highest. The presence ratio of the other is the second highest. Microorganisms belonging to the Geobacteraceae family include microorganisms that have the ability to decompose polyethers into organic acids under anaerobic conditions, and methanobacteria have the ability to decompose organic acids. Since this treatment method actively uses sludge containing microorganisms such as these, the polyethers contained in the wastewater are efficiently decomposed under anaerobic conditions, and the polyether-containing wastewater is efficiently decomposed. It will be processed accordingly. Since the treatment is performed using sludge containing the microorganisms, the environmental impact is smaller than that of conventional incineration treatment, and large-scale treatment is possible at low cost.

Furthermore, in this example, in the treatment method and sludge 60, the proportion of microorganisms belonging to the Geobacteraceae family to all microorganisms contained in the sludge 60 is within the range of 20 to 65%, and the presence of methane bacteria is in the range of 20 to 65%. The abundance ratio is within the range of 5 to 35%. As a result, the decomposition of polyethers into organic acids by microorganisms belonging to the family Geobacteraceae under anaerobic conditions and the decomposition of organic acids by methane bacteria are performed in a well-balanced manner. As a result, polyether-containing wastewater can be treated more efficiently.

Furthermore, in this example, in the treatment method and sludge 60, the microorganisms belonging to the Geobacteraceae family include the microorganisms belonging to the Geobacter genus. Microorganisms belonging to the genus Geobacter have a high ability to decompose polyethers into organic acids under anaerobic conditions, so the decomposition of polyethers contained in wastewater into organic acids is further accelerated, and polyethers are Contained wastewater can be treated more efficiently.

Furthermore, in this example, in the above treatment method and sludge 60, all the microorganisms contained in the sludge 60 are wild strains. As a result, the sludge does not contain microorganisms into which mutations have been introduced by artificial manipulation, so that the treated water treated by the treatment method can be easily discharged into the natural world such as rivers.

Furthermore, in this example, the polyether-containing wastewater contains a copolymer of ethylene glycol and propylene glycol, and the microorganisms included in the sludge 60 are configured to decompose the copolymer anaerobically. ing. Thereby, the copolymer of ethylene glycol and propylene glycol can be efficiently decomposed by the treatment method.

Further, in this example, the copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) in the above copolymer is EG:PG=1:5.0 or less in molar ratio. Thereby, by the treatment method, the polyether-containing wastewater containing the copolymer having the above-mentioned copolymerization ratio can be efficiently decomposed by the microorganism group contained in the sludge 60.

Moreover, in this example, the sludge 60 is granule sludge. By using such sludge 60 in the UASB reaction tank 10, it becomes easy to construct the polyether-containing wastewater treatment device 1 of this example, and the polyether-containing wastewater can be efficiently treated by the treatment device 1 of this example. can be processed.

Furthermore, in this example, the polyether-containing wastewater treatment apparatus 1 includes a DHS reaction tank 20 as an aerobic treatment apparatus to which treated water discharged from the UASB reaction tank 10 is supplied. As a result, the organic acids contained in the treated water discharged from the UASB reaction tank 10 can be treated under aerobic conditions by the DHS reaction tank 20 as an aerobic treatment device, so that the polyether The treatment efficiency of wastewater containing substances is further improved.

In this example, a DHS (Downflow Hanging Sponge) reaction tank 20 is employed as the aerobic treatment device. As a result, the organic acids contained in the treated water discharged from the UASB reaction tank 10 can be treated under aerobic conditions by the DHS reaction tank 20 as an aerobic treatment device, so that the polyether The treatment efficiency of wastewater containing substances is further improved.

In addition, by actively using the sludge 60 in this example for the treatment of polyether-containing wastewater, as mentioned above, compared to conventional incineration treatment, large-scale treatment is possible with less environmental impact and at lower cost. Become.

Further, according to the polyether-containing wastewater treatment device 1 in this example, as described above, the polyethers contained in the wastewater are efficiently decomposed under anaerobic conditions, and the polyether-containing wastewater is efficiently treated. At the same time, compared to conventional incineration treatment, large-scale treatment is possible with less environmental impact and at lower cost.

(Evaluation test 2)
A test was conducted to evaluate the biodegradation properties of polyether compounds. The test conditions are as follows.

1. Sludge In this evaluation test, the sludge obtained in the same manner as in Embodiment 1 was used in Test Examples 1 to 3 and Comparative Examples.

2. Substrate In this evaluation test, PEG300 (copolymerization ratio EG:PG=10:0, average molecular weight Mw=300) was used as the substrate in Test Example 1, and PPG1000 (copolymerization ratio EG:PG=0: 10, average molecular weight Mw=1000), and in Test Example 3, PPG2000 (copolymerization ratio EG:PG=5:5, average molecular weight Mw=2000) was used. In the comparative example, water was added instead of the substrate.

3. Medium In this evaluation test, a medium containing inorganic nutrients, resarin (redox indicator), and phosphate buffer was used. As inorganic nutrient salts, an inorganic salt solution I having the composition shown below (a) and an inorganic salt solution II having the composition shown below (b) were prepared in advance, and a culture medium was prepared with the composition shown in the following (c).
(a) Inorganic salt solution I
_FeCl2.4H2O : _2.0mg /L
_{CoCl2.6H2O :} 0.17mg/L
_ZnCl2 : 0.17mg/L
_H3BO3 : _0.06mg /L
_{MnCl2.2H2O :} 0.50mg/L
_{NiCl2.6H2O :} 0.04mg/L
_{CuCl2.2H2O :} 0.027mg/L
_{NaMgCl2.2H2O :} 0.025mg/L
EDTA (2Na): 5.0mg/L

(b) Inorganic salt solution II
_MgCl2.6H2O : _400mg /L
_CaCl2 : 113mg/L
_NH3Cl : 500mg/L

(c) Medium formulation Inorganic salt solution I: 2.5 mL/L
Inorganic salt solution II: 25mL/L
Phosphate buffer (1M): 62.5mL/L
Rezazurin (1g/L): 2.5mL/
Distilled water: 1L

4. Preparation of Culture Solution In this evaluation test, a culture solution having the composition shown in (d) below was prepared, and 300 mL of the culture solution was dispensed into vials each having a capacity of 720 mL. Thereafter, the pH in the vial was measured, and if necessary, 1M NaOH was added to adjust the pH in the vial to 7.0±0.2.
(d) Culture solution combination (total 300ml)
Medium: 120mL/300mL
Substrate: 6mL/300mL
Reducing agent (250mg/L _Na2.9H2O ) _: 3.0mL/300mL
Sludge: 171mL/300mL

5. Test operation In this evaluation test, the vial into which the above culture solution was dispensed was set in a 37°C bathtub, and osmotic culture was performed at 100 rpm under anaerobic conditions for 50 days, and the COD concentration was measured by sampling the aqueous solution over time. did. The COD concentration was measured by a conventional method using a permanganic acid method COD measurement reagent manufactured by HACH.

6. Measurement Results The measurement results of this evaluation test are shown in FIG. 7 and Table 4 below. As shown in FIG. 7, according to the results of measuring the COD concentration over time, in PEG300 in Test Example 1, a significant decrease in the COD concentration was observed at an early stage from the start of the measurement. On the other hand, with PPG1000 in Test Example 2, the COD concentration decreased relatively significantly from the start of the test to the 10th day, but only a slight change was observed thereafter. In addition, in PPG2000 in Test Example 3, the COD concentration decreased relatively significantly from the start of the test to the 10th day, and the COD concentration continued to decrease gradually after the 10th day. With PPG2000 in Test Example 3, the COD concentration after the 10th day was lower than that with PPG1000 in Test Example 2.

7. Evaluation From the COD concentration changes shown in FIG. 7 and Table 4, biodegradability due to sludge 60 was observed in all of Test Examples 1 to 3. The biodegradability of sludge 60 was highest for PEG300 in Test Example 1, followed by PPG2000 in Test Example 3, and lowest for PPG1000 in Test Example 2. From these results, we believe that the copolymerization ratio of EG and PG has a greater influence on the biodegradation characteristics of a copolymer of ethylene glycol (EG) and propylene glycol (PG) by Sludge 60 than the molecular weight of the copolymer. It was done.

The copolymerization ratio of EG and PG in PEG300 of Test Example 1 is EG:PG=10:0, and the copolymerization ratio of EG and PG in PPG2000 of Test Example 3 is EG:PG=5:5 ( That is, in view of the fact that 1:1), in the method for treating polyether-containing wastewater using sludge 60, the copolymerization ratio of EG and PG contained in the polyether-containing wastewater is EG:PG= It was inferred that the ratio is preferably 1:1 or less.

As described above, according to this example, it is possible to provide a method for treating polyether-containing wastewater that can be treated on a large scale with low environmental impact and at low cost.

1 Polyether-containing wastewater treatment equipment 10 UASB reaction tank 20 DHS reaction tank 21 Treated water discharge channel 22 Reflux channel 30 Wastewater storage section 32 Supply wastewater 40 Gas recovery section 50 Treated water recovery section 60 Sludge

Claims (8)

In a method for treating wastewater containing polyethers, the wastewater containing polyethers is treated anaerobically through sludge provided in a UASB (Upflow Anaerobic Sludge Blanket) reaction tank,
The above-mentioned sludge contains a microbial group consisting of multiple types of microorganisms, and in the microbial group, the presence ratio of one of the microorganisms belonging to the genus Geobacter and the methane bacteria is the highest, and the presence ratio of the other is the second highest. ,
The proportion of microorganisms belonging to the genus Geobacter relative to all microorganisms contained in the sludge is 20 to 65%, and the proportion of methane bacteria is 5 to 35%,
The polyether-containing wastewater contains a copolymer of ethylene glycol and propylene glycol, and the microorganism group contained in the sludge is configured to decompose the copolymer anaerobically,
A method for treating wastewater containing polyethers, wherein the copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) in the above copolymer is EG:PG=1:5.0 or less in molar ratio . The method for treating polyether-containing wastewater according to claim 1 , wherein all microorganisms contained in the sludge are wild strains. Anaerobic treatment of polyether-containing wastewater containing a copolymer of ethylene glycol and propylene glycol in which the copolymerization ratio of ethylene glycol (EG) and propylene glycol (PG) is less than or equal to EG:PG=1:5.0 in molar ratio. sludge used for the treatment of
Contains a microbial group consisting of multiple types of microorganisms, and in the microbial group, the presence ratio of one of the microorganisms belonging to the genus Geobacter and the methane bacteria is the highest, and the presence ratio of the other is the second highest,
Sludge used for the treatment of polyether -containing wastewater, in which the proportion of microorganisms belonging to the genus Geobacter among the above microorganisms is 20 to 65%, and the proportion of methane bacteria is 5 to 35%. . The sludge used for treating polyether-containing wastewater according to claim 3 , wherein all the microorganisms constituting the microorganism group are wild strains. The sludge used for treating polyether-containing wastewater according to claim 3 or 4 , wherein the sludge is granule sludge. A polyether-containing wastewater treatment device comprising a UASB reaction tank holding the sludge according to any one of claims 3 to 5 . The polyether-containing wastewater treatment device according to claim 6 , comprising an aerobic treatment device to which the treated water discharged from the UASB reaction tank is supplied. The polyether-containing wastewater treatment device according to claim 7 , wherein the aerobic treatment device is a DHS (Downflow Hanging Sponge) reaction tank.

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