JP2013226071A - Apparatus and method for manufacturing polyhydroxyalkanoate - Google Patents

Abstract

A polyhydroxyalkanoate production apparatus and production method applicable to actual wastewater treatment are provided.
A polyhydroxyalkanoate production apparatus (1) includes a microorganism holding member (11-14) on which PHA accumulating bacteria are supported, and a microorganism that immerses and removes the microorganism holding member (11-14) from the waste water. A holding member driving device 20 and a control device 30 that controls driving of the microorganism holding member driving device 20 are provided. The control device 30 controls the microorganism holding member driving device 20, soaks the microorganism holding members 11 to 14 in the wastewater for a predetermined time, causes the organic matter in the wastewater to be ingested by the PHA-accumulating bacteria, and the PHA-accumulating bacteria converts the organic matter into the PHA. The anaerobic treatment to be converted and accumulated, and the microorganism holding members 11 to 14 are taken out from the waste water and exposed to the air for a predetermined time, and the aerobic treatment in which the PHA accumulating bacteria consume and proliferate PHA are repeatedly performed.
[Selection] Figure 1

Description

  The present invention relates to a polyhydroxyalkanoate production apparatus and production method.

  Currently, most plastics are produced from oil and natural gas. The depletion of fossil fuels in the future is also screamed, and bioplastics derived from natural resources are drawing attention.

  Bioplastics have carbon neutral properties that do not affect the increase or decrease of carbon dioxide because they are derived from biomass, and contribute to global warming countermeasures. In addition, many bioplastics are biodegradable, and even if they are landfilled or dumped, they are decomposed by microorganisms, so they are environmentally friendly.

  Bioplastics are mainly produced from corn, sugarcane, etc. with high starch and sugar content. However, since these raw materials compete with food, it is desirable to seek bioplastic production from waste other than food.

  The idea of capturing liquid biomass waste as wastewater such as sewage as a resource has become established. For example, a PHA-accumulating bacterium takes an organic substance, converts it into polyhydroxyalkanoate (hereinafter also referred to as PHA), and accumulates it. There is an idea of producing PHA that can be used as a biodegradable plastic raw material from sewage using this PHA-accumulating bacterium, but it has not yet been put into practical use.

  The reason for this is that in the activated sludge process for sewage treatment, bacteria decompose organic substances and grow to generate activated sludge (mainly an aggregate of bacteria that have grown), which contains PHA accumulating bacteria. This is because the proportion of PHA-accumulating bacteria in the activated sludge is low, and the PHA content in the activated sludge is as low as several percent. Therefore, most of the excess sludge is not effectively used and is actually disposed of as waste.

  In view of the above matters, methods for increasing the PHA content in activated sludge have been studied. In Non-Patent Document 1, the concentration of organic substances in waste water is controlled to make PHA bacteria dominant, and the PHA concentration in excess sludge is increased.

Katja Johnson, Yang Jiang, Robbert kleerebezem, Gerard Muyzer, and Mark C. M. van Loosdrecht; Enrichment of a Mixed Bacterial Culture with a High Polyhydroxyalkanoate Storage Capacity; Biomacromolecules 2009, 10, 670-676

  In the method disclosed in Non-Patent Document 1, it is necessary to control the concentration of organic matter in the discharged waste water. The wastewater contains various organic substances and its concentration is not constant, so it is not suitable for actual wastewater treatment.

  This invention is made | formed in view of the said matter, The place made into the objective is to provide the production apparatus and production method of polyhydroxyalkanoate applicable to a real wastewater treatment.

An apparatus for producing a polyhydroxyalkanoate according to the first aspect of the present invention,
A microorganism holding member on which PHA accumulating bacteria are supported;
A microorganism holding member driving device for immersing the microorganism holding member in drainage and taking out the wastewater from drainage;
A control device for controlling the driving of the microorganism holding member driving device,
The control device drives the microorganism holding member driving device to immerse the microorganism holding member in the wastewater for a predetermined time, ingest the organic matter in the wastewater into the PHA-accumulating bacteria, and the PHA-accumulating bacteria convert the organic matter to polyhydroxy Anaerobic treatment that converts to alkanoate and accumulates it,
An aerobic treatment in which the control device drives the microorganism holding member driving device to take out the microorganism holding member from the waste water and expose it to the air for a predetermined time so that the PHA-accumulating bacteria consume polyhydroxyalkanoate and proliferate; Done
The control device controls the microorganism holding member driving device and repeats the anaerobic treatment and the aerobic treatment a plurality of times to increase the proportion of the PHA-accumulating bacteria in the activated sludge formed on the microorganism holding member, Increase the content of polyhydroxyalkanoate in activated sludge,
It is characterized by that.

  Further, the control device controls the microorganism holding member so that the time of the anaerobic treatment before recovering the activated sludge is longer than the time of the anaerobic treatment so far, and the polyhydroxyalkanoate in the activated sludge is controlled. It is desirable to increase the content.

Also, comprising a plurality of the microorganism holding member,
The control device preferably controls the microorganism holding member driving device so that at least one of the other microorganism holding members is immersed in the waste water when any one of the microorganism holding members is exposed to the air. .

The method for producing a polyhydroxyalkanoate according to the second aspect of the present invention comprises:
An anaerobic structure in which a microorganism holding member carrying PHA accumulating bacteria is immersed in waste water for a predetermined time to ingest organic matter in the waste water into the PHA accumulating bacteria, and the PHA accumulating bacteria convert the organic matter to polyhydroxyalkanoate and accumulate it. Processing steps;
An aerobic treatment step in which the microorganism holding member is taken out from the waste water and exposed to the air for a predetermined time, and the PHA-accumulating bacteria consume polyhydroxyalkanoate and grow,
Repeating the anaerobic treatment step and the aerobic treatment step a plurality of times to increase the proportion of the PHA-accumulating bacteria in the activated sludge formed on the microorganism holding member, and to increase the content of polyhydroxyalkanoate in the activated sludge Increase,
It is characterized by that.

  In addition, it is desirable to increase the content of polyhydroxyalkanoate in the activated sludge by performing the anaerobic treatment step before recovering the activated sludge for a longer time than the previous anaerobic treatment step.

Further, a plurality of the microorganism holding members are used,
When any one of the microorganism holding members is exposed to the air, it is desirable to immerse at least one of the other microorganism holding members in the waste water.

  In the polyhydroxyalkanoate production apparatus and production method according to the present invention, it is possible to produce PHA as a raw material for bioplastics using organic matter in wastewater without controlling the concentration of organic matter in wastewater. The content of PHA in the activated sludge can be increased. In addition, since aeration is not necessary in the aerobic process, the production cost of PHA is also reduced. Therefore, it can be applied to actual wastewater treatment.

It is a schematic block diagram of a PHA production apparatus. It is a figure explaining operation | movement of a PHA production apparatus. It is a figure explaining operation | movement of a PHA production apparatus. It is a figure explaining operation | movement of a PHA production apparatus. It is a figure explaining operation | movement of a PHA production apparatus. It is a figure explaining operation | movement of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a figure explaining operation | movement before the activated sludge collection | recovery of a PHA production apparatus. It is a schematic block diagram of the apparatus used in Example 1, and is a figure explaining the state of anaerobic processing. It is a schematic block diagram of the apparatus used in Example 1, and is a figure explaining the state of an aerobic process. It is a graph which shows COD change of the artificial sewage inflow in Example 1, and the discharged | emitted process water. 2 is a graph showing the biomass concentration per cloth carrier in Example 1. FIG. 2 is a graph showing a biomass composition in Example 1. FIG. 6 is a graph showing a biomass composition in Example 2.

  The production apparatus and production method of polyhydroxyalkanoate (hereinafter also referred to as PHA) will be described in detail with reference to the drawings.

  As shown in the schematic configuration diagram of FIG. 1, the PHA production apparatus 1 includes microorganism holding members 11 to 14, a microorganism holding member driving device 20, and a control device 30.

  The microorganism holding members 11 to 14 carry PHA accumulating bacteria (Polyhydroxyalkanoate accumulating bacteria). The microorganism holding members 11 to 14 may be any member as long as PHA-accumulating bacteria are supported and a biofilm of the PHA-accumulating bacteria group, that is, activated sludge can be formed. In addition, in the aerobic treatment described later, when the microorganism holding members 11 to 14 are exposed to the air for a predetermined time, the microorganism holding members 11 to 14 are members having high water retention so that the microorganism holding members 11 to 14 are not dried. preferable. Examples of the microorganism holding members 11 to 14 include porous members such as cloth and sponge.

  The PHA-accumulating bacterium is not particularly limited as long as it is a microorganism capable of accumulating PHA in cells. For example, Aeromonas genus, Alcaligenes genus, Azotobacter genus, Bacillus genus, Clostridium genus, Halobacterium genus Nocardia p ) Genus, Psuedomonas genus, Ralstonia genus, Zoogloea genus and the like.

  The microorganism holding members 11 to 14 may be used after supporting the PHA accumulating bacteria. However, since the PHA accumulating bacteria are usually present in any waste water, the microorganisms can be retained without supporting the PHA accumulating bacteria. Members 11 to 14 may be used.

  The microorganism holding member driving device 20 has a function of immersing the microorganism holding members 11 to 14 in the waste water and taking out the immersed microorganism holding members 11 to 14 from the waste water. As an example, the microorganism holding member drive 20 shown in FIG. 1 is configured so that the microorganism holding members 11 to 14 suspended by a thread, a wire, or the like can be moved up and down independently by a drive source such as a built-in motor (not shown). Yes. The microorganism holding member driving device 20 may have any configuration other than the above configuration as long as the microorganism holding members 11 to 14 can be immersed in the drainage and taken out from the drainage.

  The control device 30 is a device that controls the driving of the microorganism holding member driving device 20, and controls each of the microorganism holding members 11 to 14 to be immersed in the waste water or exposed to the atmosphere for a predetermined time. The control device 30 includes a timer, and controls the microorganism holding member driving device 20 based on a preset time.

  Next, a PHA production method using the PHA production apparatus 1 will be described with reference to FIGS. Here, an example will be described in which anaerobic processing is performed for 2 hours, aerobic processing is performed for 6 hours, and anaerobic processing before PHA recovery is performed for 4 hours.

  First, the PHA production apparatus 1 is disposed in the flow path through which the drainage W flows. The PHA production apparatus 1 is disposed so as to be immersed in the waste water W flowing through the flow path when the microorganism holding members 11 to 14 are lowered, and to be taken out from the waste water W and exposed to the air when the microorganism holding members 11 to 14 are raised.

  Then, as shown in FIG. 2, the control device 30 drives the microorganism holding member driving device 20 to lower the microorganism holding member 11 and immerse it in the waste water W. Thereby, since the microorganism holding member 11 is subjected to anaerobic conditions, anaerobic treatment with PHA bacteria is performed. In the anaerobic treatment, the PHA bacteria carried on the microorganism holding member 11 ingests organic substances contained in the waste water W, converts them into PHA, and accumulates PHA in the cells.

  After 2 hours, as shown in FIG. 3, the control device 30 drives the microorganism holding member driving device 20 to raise the microorganism holding member 11 and remove it from the waste water W, and immerse the microorganism holding member 12 in the waste water W. .

  Since the microorganism holding member 11 is exposed to the atmosphere and the microorganism holding member 11 is in an aerobic condition, an aerobic treatment with PHA bacteria is performed. In the aerobic treatment, PHA bacteria respire using oxygen and accumulated PHA, and PHA bacteria grow.

  On the other hand, the microorganism holding member 12 immersed in the waste water W is subjected to anaerobic conditions and is subjected to anaerobic treatment as described above.

  After 4 hours, as shown in FIG. 4, the control device 30 drives the microorganism holding member driving device 20 to raise the microorganism holding member 12 and take it out from the waste water W, and immerse the microorganism holding member 13 in the waste water W. Let Similar to the above, the microorganism holding member 12 is subjected to an aerobic condition and is subjected to an aerobic treatment with PHA bacteria. Similarly to the above, the microorganism holding member 13 is subjected to anaerobic conditions, and anaerobic treatment is performed in the same manner as described above.

  After the elapse of 6 hours, as shown in FIG. 5, the control device 30 drives the microorganism holding member driving device 20 to raise the microorganism holding member 13 and remove it from the waste water W, and immerse the microorganism holding member 14 in the waste water W. Let Similarly to the above, the microorganism holding member 13 is subjected to an aerobic condition, and an aerobic treatment with PHA bacteria is performed. Similarly to the above, the microorganism holding member 14 is subjected to anaerobic conditions, and anaerobic treatment is performed in the same manner as described above.

  After the elapse of 8 hours, as shown in FIG. 6, the control device 30 drives the microorganism holding member driving device 20 to raise the microorganism holding member 14 and take it out from the waste water W, and again remove the microorganism holding member 11 from the waste water W. Soak in. Similarly to the above, the microorganism holding member 13 is subjected to an aerobic condition, and an aerobic treatment with PHA bacteria is performed. Further, similarly to the above, the microorganism holding member 11 is again subjected to the anaerobic condition, and the anaerobic treatment is performed in the same manner as described above.

  Then, the above steps are sequentially performed for a plurality of cycles. By repeating the anaerobic treatment and the aerobic treatment in this manner, the PHA-accumulating bacteria carried on the microorganism holding member grows. By the above cycle, other bacteria (microorganisms that can survive only under anaerobic conditions, microorganisms that can survive only under aerobic conditions) are eliminated, so the proportion of PHA accumulating bacteria in the activated sludge formed increases, and PHA accumulating bacteria Activated sludge is obtained.

  After the above cycle is performed to dominate the PHA-accumulating bacteria in the activated sludge, the activated sludge is recovered. Then, the control device 30 drives the microorganism holding member driving device 20 so that the anaerobic treatment time (for example, 4 hours) before collecting the activated sludge is longer than the previous anaerobic treatment time (for example, 2 hours). To control.

  As an example, the control device 30 controls the microorganism holding member driving device 20 as described below. FIG. 7 shows a state after X hours in which the above-described anaerobic processing and aerobic processing are repeated a plurality of times. The control device 30 drives the microorganism holding member driving device 20 so that the microorganism holding member 11 is immersed in the waste water W.

  After the elapse of X + 2 hours, as shown in FIG. 8, the control device 30 drives the microorganism holding member driving device 20 so that the microorganism holding member 12 is immersed in the waste water W. At this time, the control device 30 controls the microorganism holding member driving device 20 so that the microorganism holding member 11 is not taken out from the waste water W.

  After the elapse of X + 4 hours, as shown in FIG. 9, the control device 30 drives the microorganism holding member driving device 20 to raise the microorganism holding member 11 and remove it from the waste water W, and immerse the microorganism holding member 13 in the waste water W. Let As a result, the microorganism holding member 11 has been subjected to the anaerobic treatment for 4 hours. Thus, the activated sludge formed on the surface of the microorganism holding member 11 taken out from the waste water W is recovered, and PHA in the activated sludge is extracted.

  After the passage of X + 6 hours, the passage of X + 8 hours, and the passage of X + 10 hours, the microorganism holding members 12, 13, and 14 that have been subjected to the anaerobic treatment for 4 hours are sequentially drained, as shown in FIGS. 10, 11, and 12, respectively. W is taken out. And the activated sludge formed in the surface of the taken-out microorganisms holding member 12, 13, 14 is each collect | recovered, and PHA in activated sludge is extracted.

  As described above, by performing the anaerobic treatment before collection for a longer time than the previous anaerobic treatment, the proliferated PHA-accumulating bacteria ingest many organic substances to convert PHA, and accumulate PHA in the cells. . In this way, the content of PHA in the activated sludge to be recovered can be increased.

  In addition, collection | recovery of activated sludge can be performed by well-known methods, such as peeling of the activated sludge formed in the surface of the microorganisms holding members 11-14. In addition, the recovery of PHA in activated sludge can be performed by known methods (see Nicolas Jcquel et al., Isolation and purification of bacterial poly (3-hydroxyalkanoates), Biochemical Engineering Journnal, Vol.39 (2008) p15-27). ).

  The microorganism holding members 11 to 14 from which the activated sludge has been collected are repeatedly subjected to anaerobic treatment and aerobic treatment cycles in the same manner as described above.

  According to the present embodiment, it is possible to produce PHA as a raw material of bioplastic from organic matter in flowing wastewater without controlling the concentration of organic matter in wastewater, and PHA in the formed activated sludge The content of can be increased.

  Moreover, according to this Embodiment, aeration is unnecessary in an aerobic process. In the activated sludge method in normal wastewater treatment, aeration is performed, and the cost required for aeration is great. According to this embodiment, since aerobic treatment can be performed without performing aeration, the production cost of PHA is reduced and the wastewater treatment cost is also reduced. Therefore, it can be used as a PHA production apparatus and production method that can be applied to actual wastewater treatment.

  Moreover, since useful PHA can be produced from activated sludge, the activated sludge can be reused and the treatment cost of activated sludge can be reduced.

  In the above description, an example has been described in which the anaerobic treatment time is 2 hours, the aerobic treatment time is 6 hours, and the anaerobic treatment time before the activated sludge recovery is 4 hours. However, each treatment time is not limited to the above. As an example of each processing time in the predominance of PHA accumulation bacteria, anaerobic processing time is 1 to 6 hours, and aerobic processing time is 4 to 12 hours. Moreover, 2-12 hours are mentioned as an example of the anaerobic treatment time before activated sludge collection | recovery. What is necessary is just to comprise so that the control apparatus 30 may control the microorganisms holding member drive device 20 so that it may become said each processing time.

  Moreover, although the example using four microorganism holding members 11-14 was demonstrated above, the number of microorganism holding members is not limited and may be less than four or four or more.

  Note that at least two microorganism holding members are used, and when the aerobic treatment is performed with any one of the microorganism holding members, it is preferable to perform the anaerobic treatment by immersing at least one of the other microorganism holding members in the waste water. Since the PHA-accumulating bacteria carried on any one of the microorganism holding members constantly ingests organic matter in the wastewater, the wastewater treatment is not delayed.

  In the above description, the method for producing PHA using the PHA production apparatus 1 has been described. However, the method may be performed manually without using the microorganism holding member driving apparatus 20 and the control apparatus 30.

  The following experiment tried to increase the PHA content in the activated sludge. As shown in FIG. 13, a reactor vessel 40 having a capacity of 800 mL was prepared, and a device capable of inflowing and discharging artificial sewage with pumps 41 and 42 was constructed. A microorganism holding member was installed in the reactor vessel 40. As the microorganism holding member, a frame 43 attached with a polyester cloth (hereinafter referred to as a cloth carrier 44) was used. Three sets of two frame carriers 44 attached to one frame 43 were prepared and installed in the reactor vessel 40. That is, six cloth carriers 44 were used. The cloth carriers 44 are 2.5 cm × 6.7 cm × 0.5 cm (50 mL in total for all 6 sheets).

  In the anaerobic treatment, artificial sewage was flowed into the reactor vessel 40 at a flow rate of 5 mL / min, and as shown in FIG. 13, the reactor vessel 40 was filled with artificial sewage, and the cloth carrier 44 was immersed in the artificial sewage. Anaerobic treatment time was 4 hours. The residence time of artificial sewage in the reactor vessel 40 is 2 hours. The components of the artificial sewage that flowed are shown in Table 1.

  As shown in FIG. 14, the aerobic treatment was performed under aerobic conditions by exposing the cloth carrier 44 to the atmosphere by discharging all the artificial sewage in the reactor vessel 40. The aerobic treatment time was 8 hours.

  When the aerobic treatment is performed, all the artificial sewage in the reactor vessel 40 is transferred to the storage tank, and when the anaerobic treatment is performed, all the artificial sewage retained in the storage tank is transferred again to the reactor vessel 40. I went there.

  The above-described anaerobic treatment and aerobic treatment were repeated to form activated sludge (hereinafter referred to as biomass) on the cloth carrier 44. From 126 days after the start of operation, biomass was collected from two of the six cloth carriers 44 approximately every four days. That is, biomass was collected from the same cloth carrier 44 every 12 days.

  The amount of the collected biomass per cloth carrier and the PHA content in the biomass were measured. Biomass was obtained by measuring the PHA content in a sample using the supernatant after dipping the cloth carrier in 20 mL of pure water and kneading 10 times. The cloth carrier was then placed in the reactor vessel again and subjected to anaerobic treatment and aerobic treatment.

  In the anaerobic treatment, COD (Chemical Oxygen Demand) of artificial sewage to be introduced and discharged treated water was measured over time.

  FIG. 15 shows the measurement results of COD of artificial sewage and treated water. The COD of the artificial sewage that flows in is approximately 300 mgCOD / L, but the COD of the discharged treated water is 100 mgCOD / L, and it has been confirmed that the organic matter of the artificial sewage has been decomposed and the wastewater treatment is possible. .

  Subsequently, FIG. 16 shows the biomass concentration per collected cloth carrier. The concentration of biomass initially collected from each of the fabric carriers 44 (the biomass concentration collected on the 126th day, the 132nd day, and the 136th day) showed a high value due to the accumulation so far. Even after that, it can be seen that although there is variation, biomass is continuously formed.

  Subsequently, the collected biomass was dried to verify the composition of the biomass. The PHA and glycogen composition in the biomass was extracted by a known method, PHA was measured using an FID gas chromatogram, and glycogen was measured using a metabolic assay kit (BioVision) (Carlos DM Filipe et al., Stoichiometry and kinetics of acetate uptake). under anaerobic conditions by an enriched culture of phosphorus accumulating organisms at different pHs, Biotechnology and Bioengineering, Vol. 76 (2001), p. 32-43).

The result is shown in FIG. The content of PHA is changing at 0.15 to 0.20 g · gSS ⁻¹ , indicating that the PHA content in the biomass has been increased.

  Then, about the cloth carrier which performed the anaerobic process and the aerobic process repeatedly in Example 1, it performed by changing the time of the anaerobic process before biomass collection | recovery, and verified about the change of PHA content in the collect | recovered biomass. In the experiment, a fabric carrier that was subjected to an anaerobic and aerobic cycle for 12 days (24 cycles) in Example 1 was used.

  The same artificial sewage as Example 1 was put into a 1 L bottle, and the cloth carrier which repeated the anaerobic process and the aerobic process in Example 1 was immersed in this, and the anaerobic process was performed. The anaerobic treatment time before biomass recovery was 0 hour (no anaerobic treatment before recovery), 4 hours, 8 hours, 12 hours, 16 hours, and 20 hours. After completion of the anaerobic treatment, the biomass composition was verified in the same manner as in Example 1.

The result is shown in FIG. It can be seen that the PHA content increases as the anaerobic treatment time is increased up to 8 hours. In addition, the PHA content has exceeded 0.20 g · gSS ⁻¹ when the anaerobic treatment time is 8 hours or more. From these, it can be seen that the PHA content can be increased by performing the anaerobic treatment time before the biomass recovery for a longer time than the previous anaerobic treatment time.

  Without controlling the concentration of organic matter in the wastewater, it is possible to produce PHA as a raw material for bioplastics using the organic matter in the wastewater, and to increase the content of PHA in the formed activated sludge. In addition, since aeration is not necessary in the aerobic process, the production cost of PHA is also reduced. Therefore, it can be used for actual wastewater treatment.

DESCRIPTION OF SYMBOLS 1 PHA production apparatus 11-14 Microorganism holding member 20 Microorganism holding member drive apparatus 30 Control apparatus 40 Reactor container 41, 42 Pump 43 Frame 44 Cloth carrier W Drainage

Claims (6)

A microorganism holding member on which PHA accumulating bacteria are supported;
A microorganism holding member driving device for immersing the microorganism holding member in drainage and taking out the wastewater from drainage;
A control device for controlling the driving of the microorganism holding member driving device,
The control device drives the microorganism holding member driving device to immerse the microorganism holding member in the wastewater for a predetermined time, ingest the organic matter in the wastewater into the PHA-accumulating bacteria, and the PHA-accumulating bacteria convert the organic matter to polyhydroxy Anaerobic treatment that converts to alkanoate and accumulates it,
An aerobic treatment in which the control device drives the microorganism holding member driving device to take out the microorganism holding member from the waste water and expose it to the air for a predetermined time so that the PHA-accumulating bacteria consume polyhydroxyalkanoate and proliferate; Done
The control device controls the microorganism holding member driving device and repeats the anaerobic treatment and the aerobic treatment a plurality of times to increase the proportion of the PHA-accumulating bacteria in the activated sludge formed on the microorganism holding member, Increase the content of polyhydroxyalkanoate in activated sludge,
An apparatus for producing polyhydroxyalkanoate, characterized in that The control device controls the microorganism holding member so that the time of the anaerobic treatment before collecting the activated sludge is longer than that of the previous anaerobic treatment, and the content of polyhydroxyalkanoate in the activated sludge Enhance,
The polyhydroxyalkanoate production apparatus according to claim 1. A plurality of the microorganism holding members,
The control device controls the microorganism holding member driving device to immerse at least one of the other microorganism holding members in waste water when any one of the microorganism holding members is exposed to the air.
An apparatus for producing a polyhydroxyalkanoate according to claim 1 or 2. An anaerobic structure in which a microorganism holding member carrying PHA accumulating bacteria is immersed in waste water for a predetermined time to ingest organic matter in the waste water into the PHA accumulating bacteria, and the PHA accumulating bacteria convert the organic matter to polyhydroxyalkanoate and accumulate it. Processing steps;
An aerobic treatment step in which the microorganism holding member is taken out from the waste water and exposed to the air for a predetermined time, and the PHA-accumulating bacteria consume polyhydroxyalkanoate and grow,
Repeating the anaerobic treatment step and the aerobic treatment step a plurality of times to increase the proportion of the PHA-accumulating bacteria in the activated sludge formed on the microorganism holding member, and to increase the content of polyhydroxyalkanoate in the activated sludge Increase,
A method for producing a polyhydroxyalkanoate characterized by the above. Performing the anaerobic treatment step before recovering the activated sludge for a longer time than the previous anaerobic treatment step, and increasing the content of polyhydroxyalkanoate in the activated sludge,
The method for producing a polyhydroxyalkanoate according to claim 4. Using a plurality of the microorganism holding members,
When any one of the microorganism holding members is exposed to the air, at least one of the other microorganism holding members is immersed in the waste water.
A method for producing a polyhydroxyalkanoate according to claim 4 or 5.