Reactor, reaction system and method for denitrification-coupled polyhydroxyalkanoate synthesis based on hydrogen energy

Abstract

The present application relates to a reactor, reaction system and method for denitrification-coupled polyhydroxyalkanoates based on hydrogen energy. The reactor comprises: a membrane bundle composed of a plurality of polypropylene polyurethane composite hollow fiber membranes, which is used to supply hydrogen autotrophic denitrification PHA synthesis functional bacteria to form a biofilm on the surface of the hollow fiber membrane; a liquid storage tank operatively connected to the membrane bundle, which stores an inorganic carbon denitrification culture solution for selectively enriching and culturing the functional bacteria from sludge; wherein the hydrogen autotrophic denitrification PHA synthesis functional bacteria are used to denitrify and reduce carbon in sewage and generate PHA, including one or more of hydrogen autotrophic denitrification PHA synthesis bacteria, hydrogen autotrophic denitrifying bacteria, hydrogen autotrophic acid-producing bacteria, heterotrophic denitrifying bacteria, and heterotrophic PHA synthesis bacteria. The present invention realizes for the first time the organic combination of wastewater nitrate nitrogen removal process and PHA synthesis, and utilizes CO 2 As the only carbon source, it realizes a disruptive transformation from carbon emissions to carbon fixation.

Description

Technical Field

[0001] The invention relates to the cross-field of water nitrate nitrogen treatment and PHA synthesis technology, and in particular to a reactor for denitrification coupling polyhydroxyalkanoate based on hydrogen energy, a reaction system comprising the reactor, and a method for denitrification coupling polyhydroxyalkanoate based on hydrogen energy. Background Art

[0002] Wastewater Nitrate Treatment Technology

[0003] In the traditional sewage denitrification and denitrification process, heterotrophic bacteria use organic matter in sewage as a carbon source to drive nitrate to be reduced to nitrogen (N2) to remove nitrogen from sewage. At present, the research on traditional denitrification process mainly focuses on improving denitrification efficiency and stability, reducing energy consumption and operating costs, such as improving reactor design and optimizing operating parameters. In recent years, researchers have also explored some new biological denitrification technologies, such as anaerobic ammonia oxidation (Anammox) process, short-term nitrification and denitrification (SHARON) technology and complete autotrophic denitrification (CANON) process. The development of these technologies has greatly promoted the carbon reduction goal of sewage denitrification process. Reducing energy consumption and greenhouse gas emissions in traditional denitrification processes has gradually become the focus of research, especially by optimizing process parameters and adopting new technologies to reduce greenhouse gas emissions. However, as long as the denitrification process still uses organic matter as energy, this process is always a carbon emission reaction. In contrast, the autotrophic denitrification process, including sulfur, iron and hydrogen autotrophic microorganisms, not only reduces the dependence on external organic carbon sources, but also directly promotes carbon fixation through the biological reduction of carbon dioxide, providing an effective way to achieve the goal of pollution reduction and carbon reduction.

[0004] Compared with sulfur oxides and iron oxides produced by sulfur and iron autotrophic microorganisms, hydrogen autotrophic denitrification, which oxidizes water, is a cleaner microbial metabolic process. Hydrogen autotrophic denitrification is a relatively new research direction in the field of wastewater denitrification. It uses hydrogen as an electron donor to reduce nitrate to nitrogen gas through a specific microbial community. Compared with traditional denitrification processes that rely on organic matter as electron donors, hydrogen autotrophic denitrification does not require an external organic carbon source and only uses carbon dioxide as a carbon source, which has a lower carbon footprint and energy consumption, indicating the potential for a more efficient and sustainable denitrification method. Although hydrogen autotrophic denitrification has significant environmental and economic advantages in theory, it still faces some challenges in practical applications, such as the development of an efficient and economical hydrogen supply system, as well as microbial community stability and system stable operation.

[0005] Hydrogen matrix hollow fiber membrane biofilm reactor technology

[0006] Among the existing hydrogen-based environmental microbial technologies, H2-MBfR based on the diffusion transfer of hydrogen through hollow fiber membranes is the most mature and has practical engineering applications at home and abroad. It has achieved efficient continuous removal of oxidized pollutants such as nitrate nitrogen, perchlorate and chromate in the fields of groundwater, industrial sewage and municipal sewage treatment. The hydrogen-based hollow fiber membrane biofilm reactor (H2-MBfR) is a gas-transfer membrane reactor. Hydrogen diffuses into the biofilm through the gas transfer membrane, and is then used by microorganisms to reduce pollutants. H2-MBfR is currently used in hydrogen autotrophic denitrification, biological reduction of oxidized anion pollutants and dehalogenation of organic matter. This special hollow fiber membrane gas conduction technology overcomes the problem of low hydrogen solubility. The reactor uses membranes for large-area hydrogen transfer. H2-MBfR uses multiple polymer membranes, such as polyurethane and polyethylene composite membranes, polypropylene membranes, etc. Hydrogen diffuses from the inside of the hollow fiber membrane to the outside. During the diffusion process, by controlling the hydrogen pressure, the hydrogen flux can be precisely controlled to achieve a gas utilization rate of nearly 100%. At the same time, "heterogeneous mass transfer" is also a major feature of H2-MBfR. Water-soluble pollutants and hydrogen diffuse into the biofilm in opposite directions, so that the biofilm also has a high gas concentration and maintains a high biological activity, thereby achieving efficient removal of pollutants by the entire biofilm. Relevant technical patents in my country are mainly disclosed by scientific research institutions such as Zhejiang University, Tongji University and Guilin University of Technology, including a hydrogen matrix membrane biofilm reactor (Chinese patent application publication number CN114031171A), a membrane biofilm reactor device and method for sewage treatment (Chinese patent application publication number CN111072137A), and an application of a hydrogen matrix biofilm reactor in removing bromate from drinking water (Chinese patent application publication number CN106830362A), etc.

[0007] PHA Synthesis Technology

[0008] The synthesis of PHA (polyhydroxyalkanoate) is carried out by natural or engineered microorganisms with specific functions (such as some strains of Accumulibacter, Bacillus, Cupriavidus, Pseudomonas, Halomonas and other genera) during the fermentation process. When these microorganisms are in conditions rich in carbon sources and limited in nutrients (such as nitrogen and phosphorus), they will accumulate PHA as an energy and carbon reserve material. In the production process of PHA, a variety of carbon sources including sugars, vegetable oils, glycerol and agricultural waste can be used, but the carbon source conversion in this process will lead to significant CO2 emissions. At present, the types of PHA commonly produced mainly include PHB (polyhydroxybutyrate), PHBV (3-hydroxybutyric acid-3-hydroxyvaleric acid copolyester), PHBHHX (3-hydroxybutyric acid-3-hydroxyhexanoic acid copolyester) and P34HB.

[0009] (3-hydroxybutyrate-4-hydroxybutyrate copolyester), the properties of these PHAs make them potential substitutes for petrochemical plastics. However, the uncontrollable and complex operation of PHA synthesis, which occurs within microbial cells, significantly increases production costs, and these factors currently limit the practicality of PHA as a complete substitute for petrochemical plastics.

[0010] In the past two decades, PHA synthesis technology has made significant progress, including the screening of functional microorganisms, optimization of fermentation processes, application of genetic engineering technology, development of new bioreactors, and reduction of raw material costs. By optimizing fermentation parameters (such as temperature, pH, carbon-nitrogen ratio, etc.) and using efficient bioreactor design, the production efficiency of PHA can be improved and the production cost can be reduced. Relevant PHA synthesis patents in my country include: a method for preparing high molecular weight and high performance polyhydroxyalkanoates (Chinese patent application publication number CN117209704A), a method for synthesizing polyhydroxyalkanoates by dual bacterial mixed culture (Chinese patent application publication number CN115322924A), a reaction system for synthesizing polyhydroxyalkanoates from organic waste and its use method (Chinese patent application publication number CN112961766A), etc.

[0011] Thanks to its excellent biodegradability, PHA has been widely used in packaging materials, agricultural films, biomedical materials, disposable products and other fields. Some companies have successfully established commercial-scale PHA production lines, but due to the high cost and high carbon emissions of the existing PHA production process, its output and market penetration are still low. Although PHA synthesis-related research and industrial development have been fruitful, the industry has not yet developed a model with sustainable development and low carbon emissions due to raw material limitations and process bottlenecks. Summary of the invention

[0012] In order to solve the drawbacks of existing nitrate wastewater treatment technologies such as high cost and large carbon emissions, combined with the development needs of sewage nitrate nitrogen treatment, PHA synthesis and hydrogen energy utilization industries, the purpose of this invention is to provide a new sewage denitrification coupled bioplastic production technology based on green hydrogen energy, aiming to simultaneously help solve three important environmental problems: nitrate nitrogen pollution, greenhouse gas (such as carbon dioxide) emissions and white pollution. The new technology of the present invention will promote the development of green hydrogen-driven PHA synthesis technology and help break through the technical bottlenecks of carbon emissions and sustainability.

[0013] In order to achieve the above-mentioned purpose, the first aspect of the present invention is to provide a hydrogen-based denitrification coupled polyhydroxyalkanoate reactor, which includes: a membrane bundle composed of a plurality of polypropylene polyurethane composite hollow fiber membranes, which is used to supply hydrogen autotrophic denitrification PHA synthesis functional bacteria to form a biofilm on the surface of the hollow fiber membrane; a liquid storage tank operatively connected to the membrane bundle, which stores an inorganic carbon denitrification culture solution for selectively enriching and culturing the hydrogen autotrophic denitrification PHA synthesis functional bacteria from sludge; wherein the hydrogen autotrophic denitrification PHA synthesis functional bacteria are used to denitrify and reduce carbon in sewage and generate PHA, including one or more of hydrogen autotrophic denitrification PHA synthesis bacteria, hydrogen autotrophic denitrifying bacteria, hydrogen autotrophic acid-producing bacteria, heterotrophic denitrifying bacteria, and heterotrophic PHA synthesis bacteria.

[0014] In one possible implementation of the reactor of the present invention, the hydrogen autotrophic denitrifying PHA synthesis functional bacteria include one or more of Candidatus Accumulibacter, Oryzomicrobium, Azospira, Acidovorax, Azoarcus, Siculibacillus, Azonexus, Rhodoplanes, Xanthobacter, Streptomyces, Bradyrhizobium, and Mesorhizobium.

[0015] In one possible implementation of the reactor of the present invention, the inorganic carbon denitrification culture solution includes 12.8 mg / L KH2PO4, 43.4 mg / L Na2HPO4, 202 mg / L KNO3, 2.4 mg / L Ca(NO3)2·4H2O, 2.6 mg / L Mg(NO3)2·6H2O, 2 mg / L FeCl2·4H2O, 840.1 mg / L NaHCO3 and 1 mL of trace element stock solution.

[0016] In one possible implementation of the reactor of the present invention, the trace element stock solution includes 0.136 g / L ZnCl2, 0.198 g / L MnCl2·4H2O, 0.062 g / L H3BO3, 0.476 g / L CoCl2·6H2O, 0.484 g / L Na2MoO4·2H2O, 0.0855 g / L CuCl2·2H2O, 0.119 g / L NiCl2·6H2O, 0.165 g / L Na2WO4·2H2O and 0.1315 g / L Na2SeO4·5H2O.

[0017] In a possible implementation of the reactor of the present invention, the pH of the organic carbon denitrification culture solution is between 6.8 and 7.3.

[0018] In order to achieve the above-mentioned purpose, the second aspect of the present invention is to provide a hydrogen-based denitrification-coupled polyhydroxyalkanoate reaction system, characterized in that it includes: any of the above-mentioned reactors, used to selectively enrich and cultivate the hydrogen autotrophic denitrifying PHA synthesis functional bacteria from sludge to denitrify and reduce carbon in sewage and generate a biomass product containing PHA; a water inlet device, which is configured to controllably feed sewage into the reactor; a circulation device, which is configured to fully contact the inorganic carbon denitrification culture solution in the reactor with the biofilm generated on the surface of the hollow fiber membrane by adjusting the circulation flow rate; a gas supply device, which is configured to feed gas into the reactor, wherein the gas is hydrogen or consists of hydrogen and carbon dioxide; and a control device, which is configured to control the water inlet device to feed sewage into the reactor, the circulation device to adjust the circulation flow rate, the connection between the membrane bundle in the reactor and the liquid storage tank, and the gas supply device to feed gas to the reactor based on a predetermined strategy or a determined optimal operating strategy.

[0019] In order to achieve the above-mentioned object, the third aspect of the present invention is to provide a method for denitrification coupling polyhydroxyalkanoates based on hydrogen energy, characterized in that it comprises the following steps: (1) inoculating sludge taken from an anaerobic denitrification tank of a municipal sewage treatment plant into a reactor according to any one of claims 1 to 3, and performing sequencing batch operation at a H2 partial pressure of 0.5 standard atmospheric pressure, and selectively enriching and culturing hydrogen autotrophic denitrification PHA synthesis functional bacteria using inorganic carbon denitrification culture fluid; (2) adjusting the operating state of the reactor to continuous flow, excluding non-autotrophic microorganisms through continuous flow, so as to screen the hydrogen autotrophic denitrification PHA synthesis functional bacteria; (3) waiting for The nitrate nitrogen concentration in the effluent of the reactor reaches below 0.5 mg-N / L, completing the formation of the biofilm of the hydrogen autotrophic denitrifying PHA synthesis functional bacteria; (4) based on the PHA synthesis of the biofilm under different environmental parameters, determining the optimal operation strategy for controlling the sewage feed to the reactor, adjusting the inorganic carbon denitrification culture medium feed and circulation flow rate, and the gas feed to the reactor; and (5) based on the optimal operation strategy, utilizing the hydrogen autotrophic denitrifying PHA synthesis functional bacteria to denitrify and reduce carbon in the sewage and periodically harvest the generated biomass products to extract PHA from the biomass products.

[0020] In a possible implementation of the method of the present invention, the environmental parameters in step (4) include hydraulic retention time, hydrogen pressure and nitrate concentration of the sewage.

[0021] In a possible implementation of the method of the present invention, the PHA obtained by extraction in step (5) includes PHB and PHBV.

[0022] In step (5), the mass of the biomass product periodically harvested is between 40% and 60% of the mass of the biofilm generated by the hydrogen autotrophic denitrifying PHA-synthesizing functional bacterial community.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] For the first time, the organic combination of wastewater nitrate nitrogen removal process and PHA synthesis was achieved, generating PHA while effectively denitrifying and reducing carbon in wastewater.

[0025] The H2-MBfR reactor is used as a reaction platform to achieve efficient hydrogen transfer and utilization efficiency, thereby using green hydrogen energy to replace organic substrates to provide the electron donors and energy required for denitrification and PHA synthesis.

[0026] The technical bottleneck of high reaction cost and large carbon emission caused by the use of organic substrates in existing denitrification technology and PHA microbial synthesis methods is solved, and CO2 is used as the only carbon source to achieve denitrification and PHA synthesis, thereby realizing a disruptive transformation from carbon emissions to carbon fixation.

[0027] Achieve efficient denitrification of hydrogen-autotrophic biofilm communities, directional synthesis of high-value PHA, and precise regulation of improving H2 utilization and CO2 fixation efficiency, and establish a new platform for pollution reduction and carbon reduction and the output of high-value biodegradable plastics.

[0028] The synthesized PHA can be extracted and used to produce biodegradable silk fabrics through melt spinning, wet spinning, dry spinning and electrospinning, which can be used in the production of green fabrics.

[0029] The above contents of the present invention will be more clearly understood in the following description of multiple embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings of the present invention will be provided below. These drawings are only for embodying the present invention in a more intuitive form. They are exemplary and are not intended to limit the scope of the present invention.

[0031] Figure 1 A schematic diagram showing the hydrogen autotrophic denitrification reaction and PHA accumulation principle of the present invention.

[0032] Figure 2 A schematic diagram showing a partial structure of the reaction system of the hydrogen-based denitrification coupled polyhydroxyalkanoate of the present invention.

[0033] Figure 3 The following is a photo showing an example of the reactor of the present invention coupling denitrification and PHA synthesis, wherein: Figure 3 A shows a photo of the biofilm in the reactor. Figure 3B-3D shows the electron microscope photo of the biofilm on the fiber membrane surface. Figure 3 F shows the flake-like PHA polymer obtained after separation and extraction.

[0034] Figure 4 The nitrate removal data record diagram of the reactor of the present invention during continuous flow operation is shown.

[0035] Figure 5 Demonstrates the invention Figure 3 Fourier infrared absorption spectrum of the sheet-like PHA polymer shown in F. DETAILED DESCRIPTION

[0036] To make the present invention easier to understand, the present invention is further described below in conjunction with specific examples. The experimental methods described in the present invention are conventional methods unless otherwise specified; the materials described are commercially available unless otherwise specified. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. If there is any inconsistency, the meaning described in this specification or the meaning derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0037] In order to accurately describe the technical contents of the present invention and to accurately understand the present invention, the following explanations or definitions are given for the words and terms used in this specification before describing the specific implementation methods.

[0038] The words "one embodiment" or "an embodiment" as used in this specification means that a particular feature, step, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, the particular features, steps, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0039] In view of the many problems and challenges of the prior art, the inventors of the present invention have discovered a hydrogen autotrophic denitrifying PHA synthesis functional bacterial community that can be enriched and cultivated from sludge, which can denitrify and reduce carbon in sewage and generate biomass products containing PHA, thereby realizing the organic combination of wastewater nitrate nitrogen removal process and PHA synthesis for the first time. The inventors have also explored and obtained an inorganic carbon denitrification culture solution for the effective selective enrichment and cultivation of the hydrogen autotrophic denitrifying PHA synthesis functional bacterial community, a reactor and reaction system improved for the stable growth of the hydrogen autotrophic denitrifying PHA synthesis functional bacterial community, and a method for stably operating the reaction.

[0040] In some embodiments of the present invention, the hydrogen autotrophic denitrifying PHA synthesis functional bacteria include one or more of hydrogen autotrophic denitrifying PHA synthesis bacteria, hydrogen autotrophic denitrifying bacteria, hydrogen autotrophic acid-producing bacteria, heterotrophic denitrifying bacteria, and heterotrophic PHA synthesis bacteria. In some embodiments of the present invention, the hydrogen autotrophic denitrifying PHA synthesis functional bacteria include one or more of Candidatus Accumulibacter, Oryzomicrobium, Azospira, Acidovorax, Azoarcus, Siculibacillus, Azonexus, Rhodoplanes, Xanthobacter, Streptomyces, Bradyrhizobium, and Mesorhizobium. Among the biofilms generated by the hydrogen autotrophic denitrifying PHA synthesis functional bacteria of the present invention, Figure 1 The upper part shows that there may be a single bacterial species that can achieve denitrification and PHA synthesis, or it may be Figure 1 In the lower part, there are multiple strains that cooperate to achieve: carbon dioxide is reduced to acetic acid by hydrogen autotrophic acetogenic bacteria, and acetic acid is then used by heterotrophic PHA-producing bacteria for denitrification and PHA synthesis. The inorganic carbon denitrification culture solution, reactor, reaction system and / or corresponding method of the present invention can be used to enrich functional bacteria with these two metabolic modes, namely the so-called hydrogen autotrophic denitrification PHA synthesis functional bacteria. In addition, it can be understood that since the hydrogen autotrophic denitrification PHA synthesis functional bacteria of the present invention are obtained by enrichment and culture in sludge, especially in the anaerobic denitrification tank of a municipal sewage treatment plant, there are certain changes in the composition and proportion of each component of the bacteria obtained by enrichment and culture in sludge from different regions or even different periods of time. In addition, the water quality of the treated nitrate nitrogen sewage will also change the composition and proportion of each component of the hydrogen autotrophic denitrification PHA synthesis functional bacteria that have been formed to a certain extent. However, such changes and modifications will not substantially affect the ability of the bacteria to denitrify and reduce carbon in sewage and generate biomass products containing PHA.

[0041] In some embodiments of the present invention, the inorganic carbon denitrification culture medium is prepared by the following method: accurately weigh the following chemicals: 12.8 mg / L KH2PO4, 43.4 mg / L Na2HPO4, 202 mg / L KNO3, 2.4 mg / L Ca(NO3)2·4H2O, 2.6 mg / L Mg(NO3)2·6H2O, 2 mg / L FeCl2·4H2O, 840.1 mg / L NaHCO3 and 1 mL of trace element stock solution; pour the weighed chemicals into 800 mL of water, and then stir to fully dissolve the chemicals in the water; then introduce the solution into a 1 L volumetric flask for volume adjustment, shake well and pour the adjusted solution into a solution storage bottle, and use NaOH and HCl solutions to adjust the pH of the culture solution to between 6.8 and 7.3. In some embodiments of the present invention, the trace element stock solution includes: 0.136 g / L ZnCl2, 0.198 g / L MnCl2·4H2O, 0.062 g / L H3BO3, 0.476 g / L CoCl2·6H2O, 0.484 g / L Na2MoO4·2H2O, 0.0855 g / L CuCl2·2H2O, 0.119 g / L NiCl2·6H2O, 0.165 g / L Na2WO4·2H2O and 0.1315 g / L Na2SeO4·5H2O.

[0042] The reactor of the present invention is improved from the existing hydrogen matrix hollow fiber membrane biofilm reactor (H2-MBfR), and can accurately and efficiently provide H2 for the hydrogen autotrophic denitrification PHA synthesis functional bacteria and the biofilm generated by it. In some embodiments of the present invention, the reactor includes two membrane bundles composed of 50 polypropylene polyurethane composite hollow fiber membranes, so that the hydrogen autotrophic denitrification PHA synthesis functional bacteria grow a dense biofilm on the surface of the hollow fiber membrane, thereby forming a unique "double membrane" structure of the hydrogen matrix hollow fiber membrane biofilm reactor. The reactor also includes a liquid storage tank that is controlled to be connected to the membrane bundle via a valve or pump, etc., which stores inorganic carbon denitrification culture fluid.

[0043] The reaction system of the present invention includes a reactor, a water inlet device, a circulation device, an air supply device and a control device. In some embodiments, the water inlet device feeds sewage to the reactor in a controlled manner, for example, through a valve or pump mechanism such as a peristaltic pump, and adjusts the sewage flow rate to achieve the required hydraulic retention time. In some embodiments, the circulation device, for example, adopts a circulating peristaltic pump, and the inorganic carbon denitrification culture solution is fully contacted with the biofilm by adjusting the circulation flow rate, so that the nitrate nitrogen treatment and carbon dioxide fixation are more efficient. In some embodiments, the air supply device includes a hydrogen generator and a gas steel pipe pipeline, and a pressure reducing valve is provided on the steel pipe to control the pressure of the hydrogen entering the hollow fiber membrane. The hydrogen generated by the hydrogen generator enters the hollow fiber membrane through the steel pipe pipeline at a set pressure, and then enters the biofilm through the hollow fiber membrane, so as to be used by microorganisms. Figure 2 The schematic diagram of the partial structure of the reaction system of the present invention is shown, wherein ABC respectively shows three ways of providing carbon dioxide to the reactor by the gas supply system under continuous flow state. The hydrogen autotrophic denitrification PHA synthesis functional bacteria can be supplied from the aqueous solution, an independent CO2 supply membrane and a mixture of H2 and CO2. The use of the three methods depends on the source of carbon dioxide in the nitrate nitrogen wastewater treatment application. The present invention can be used to fix CO2 (HCO 3- ,CO3 2- ), or gaseous CO2 obtained from industrial waste gas or carbon capture. The control device controls the connection of the liquid storage tank, the supply flow rate and circulation flow rate of the inorganic carbon denitrification culture solution, the sewage flow rate, and the gas supply pressure by controlling the peristaltic pump, the pressure reducing valve and other mechanisms, so as to effectively control the selective enrichment culture of the hydrogen autotrophic denitrification PHA synthesis functional bacteria and the growth of the bacteria biofilm, thereby achieving precise control of denitrification and PHA synthesis.

[0044] In some embodiments of the invention, the method for coupling denitrification with polyhydroxyalkanoates based on hydrogen energy comprises the following detailed steps:

[0045] (1) Sludge from the anaerobic denitrification tank of a municipal sewage treatment plant was inoculated into a reactor and operated in a sequencing batch mode at a H2 partial pressure of 0.5 standard atmospheric pressure. The hydrogen autotrophic denitrifying PHA-synthesizing functional bacterial community was selectively enriched and cultured using an inorganic carbon denitrification culture medium.

[0046] (2) After the functional bacteria were enriched in the sequencing batch reactor, the reactor operation state was adjusted to continuous flow, and the hydraulic retention time (HRT) started from 12 hours. Non-autotrophic microorganisms were excluded through continuous flow, and the hydrogen autotrophic denitrifying PHA-synthesizing functional bacteria were further screened.

[0047] (3) When the nitrate nitrogen concentration in the effluent of the reaction system reaches below 0.5 mg-N / L, the biofilm enrichment is completed.

[0048] (4) Based on the PHA synthesis of the biofilm under different environmental parameters, determine the optimal operation strategy for controlling the wastewater feed to the reactor, adjusting the feed and circulation flow rate of the inorganic carbon denitrification culture solution, and feeding the gas to the reactor. 3- When the rate reaches above 99% (reaching the corresponding demand index for nitrate nitrogen wastewater treatment) and the hydraulic retention time reaches below 4 hours, it can be considered that the effect of the optimal operation strategy has been achieved. At this time, the growth state of the biofilm reaches a stable state, which is also a sign that the biomass products of the biofilm have reached a harvestable state.

[0049] (5) Based on the optimal operation strategy, the biomass products generated by the hydrogen autotrophic denitrifying PHA synthesis functional bacteria for denitrification and carbon reduction of the wastewater are periodically harvested to extract PHA from the biomass products. It is recommended that the proportion of each biofilm harvest is about 40% to 60% of the total biomass on the biofilm. More can be harvested when the temperature is high in summer, while the biological growth rate is slow in winter when the temperature is low, so the biofilm can be harvested less appropriately. The monthly harvested biomass is about 10 to 20 g of biomass dry weight per square meter of membrane surface area, and the specific value depends on the nitrate concentration in the wastewater, the carbon dioxide supply and the operating water temperature. The dry weight ratio of PHA extracted from biomass is about 20% to 50%, and the specific ratio depends on the operating conditions, and the key factors are hydrogen and nitrate fluxes.

[0050] In some embodiments of the present invention, the optimal operating strategy determined in step (4) includes: a hydraulic retention time of 2 to 6 hours, a rotation speed of a circulating peristaltic pump of 50 to 150 rpm / min, a hydrogen supply pressure of 0.5 to 2.0 standard atmospheric pressures, and a nitrate concentration of the feed wastewater of 14 to 70 mg-N / L.

[0051] Example

[0052] use Figure 1 The gas supply method shown in part A of the figure, using the reaction system of the present invention, after 2 months of enrichment culture and screening of hydrogen autotrophic denitrifying PHA synthesis functional bacteria, the reactor reached a stable nitrate nitrogen continuous flow treatment state. Under the condition of hydraulic retention time of 4 hours and influent nitrate concentration of about 56 mg-N / L, this embodiment achieved >99.5 nitrate removal, and the PHA content in the biofilm reached 36% by dry weight. Figure 3 The following is a photo showing an example of the reactor of the present invention coupling denitrification and PHA synthesis, wherein: Figure 3 A shows a photo of the biofilm in the reactor. Figure 3 B-3D shows the electron microscope photo of the biofilm on the fiber membrane surface. Figure 3 F shows the flake-like PHA polymer obtained after separation and extraction.

[0053] like Figure 4 As shown in the figure, the nitrate concentration data during the continuous flow operation of the reactor for more than 250 days shows that the hydrogen autotrophic denitrifying PHA synthesis functional bacterial community of the present invention can achieve stable nitrate nitrogen removal. The data fluctuations in the figure are the fluctuations in reaction efficiency caused by biomass sampling.

[0054] The biofilm in the reactor was sampled and sent for gene sequencing. The community composition structure of the hydrogen autotrophic denitrifying PHA synthesis functional bacteria at the genus level of this embodiment is shown in the following table:

[0055] Figure 5 Shows Figure 3 The absorption spectrum of the PHA polymer shown in F is obtained by detecting it in a Fourier infrared spectrometer (FTIR). The absorption spectrum shows that the main component of the extracted microbial organic polymer is PHA, and its specific structure is speculated to be a mixture of PHB (polyhydroxybutyrate), PHBV (3-hydroxybutyric acid-3-hydroxyvaleric acid copolyester), etc. The PHA extract in this example has passed the wet spinning test and has the potential for subsequent application in the textile industry.

[0056] The above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. A hydrogen-based denitrification coupled polyhydroxyalkanoate reactor, characterized in that: include: A membrane bundle composed of a plurality of polypropylene polyurethane composite hollow fiber membranes is used for the hydrogen supply autotrophic denitrification PHA synthesis functional bacteria to form a biofilm on the surface of the hollow fiber membrane; A liquid storage tank in controlled communication with the membrane bundle, storing an inorganic carbon denitrification culture solution for selectively enriching and culturing the hydrogen autotrophic denitrification PHA synthesis functional bacteria from sludge; The hydrogen autotrophic denitrifying PHA synthesizing functional bacteria are used to denitrify and reduce carbon in sewage and generate biomass products containing PHA, including hydrogen autotrophic denitrifying PHA synthesizing bacteria, or hydrogen autotrophic denitrifying bacteria, hydrogen autotrophic acid-producing bacteria, heterotrophic denitrifying bacteria and heterotrophic PHA synthesizing bacteria; The inorganic carbon denitrification culture solution includes: 12.8 mg / L KH2PO4, 43.4 mg / L Na2HPO4, 202 mg / L KNO3, 2.4 mg / L Ca(NO3)2·4H2O, 2.6 mg / L Mg(NO3)2·6H2O, 2 mg / L FeCl2·4H2O, 840.1 mg / L NaHCO3 and 1 mL of trace element stock solution; The trace element stock solution includes: 0.136 g / L ZnCl2, 0.198 g / L MnCl2·4H2O, 0.062 g / L H3BO3, 0.476 g / L CoCl2·6H2O, 0.484 g / L Na2MoO4·2H2O, 0.0855 g / L CuCl2·2H2O, 0.119 g / L NiCl2·6H2O, 0.165 g / L Na2WO4·2H2O and 0.1315 g / L Na2SeO4·5H2O.

2. The reactor according to claim 1, characterized in that The hydrogen autotrophic denitrifying PHA synthesis functional bacteria include one or more of Candidatus Accumulibacter, Oryzomicrobium, Azospira, Acidovorax, Azoarcus, Siculibacillus, Azonexus, Rhodoplanes, Xanthobacter, Streptomyces, Bradyrhizobium, and Mesorhizobium.

3. The reactor according to claim 1, characterized in that The pH of the inorganic carbon denitrification culture solution is between 6.8 and 7.

3.

4. A hydrogen-based denitrification coupled polyhydroxyalkanoate reaction system, characterized in that: include: The reactor according to claim 1 or 2 is used to selectively enrich and cultivate the hydrogen autotrophic denitrifying PHA synthesis functional bacteria from sludge to denitrify and reduce carbon in sewage and generate a biomass product containing PHA; a water inlet device configured to controllably feed sewage into the reactor; a circulation device configured to make the inorganic carbon denitrification culture solution in the reactor fully contact with the biofilm generated on the surface of the hollow fiber membrane by adjusting the circulation flow rate; a gas supply device configured to feed gas into the reactor, wherein the gas is hydrogen or consists of hydrogen and carbon dioxide; as well as A control device is configured to control the water inlet device to feed sewage into the reactor, the circulation device to adjust the circulation flow rate, the connection between the membrane bundle in the reactor and the liquid storage tank, and the gas supply device to feed gas into the reactor based on a predetermined strategy or a determined optimal operation strategy.

5. A method for denitrification coupling of polyhydroxyalkanoates based on hydrogen energy, characterized in that: The following steps are involved: (1) Inoculating the sludge in the reactor according to claim 1 or 2, performing sequencing batch operation at a H2 partial pressure of 0.5 standard atmospheric pressure, and selectively enriching and culturing the hydrogen autotrophic denitrifying PHA synthesis functional bacteria using inorganic carbon denitrification culture solution; (2) adjusting the operation state of the reactor to continuous flow, eliminating non-autotrophic microorganisms through continuous flow, so as to screen the hydrogen autotrophic denitrifying PHA synthesis functional bacterial community; (3) When the nitrate nitrogen concentration in the effluent water of the reactor reaches below 0.5 mg-N / L, the biofilm of the hydrogenotrophic denitrifying PHA synthesis functional bacteria is formed; (4) determining an optimal operation strategy for controlling the wastewater feed to the reactor, adjusting the feed and circulation flow rate of the inorganic carbon denitrification culture solution, and feeding the gas to the reactor based on the PHA synthesis of the biofilm under different environmental parameters; as well as (5) Based on the optimal operation strategy, the hydrogen autotrophic denitrifying PHA synthesis functional bacteria are used to denitrify and reduce carbon in the sewage and the generated biomass products are periodically harvested to extract PHA from the biomass products.

6. The method according to claim 5, characterized in that The environmental parameters in step (4) include hydraulic retention time, hydrogen pressure and nitrate concentration of the wastewater.

7. The method according to claim 5, characterized in that The PHA extracted in step (5) includes PHB and PHBV.

8. The method according to claim 5, characterized in that The mass of the biomass product periodically harvested in step (5) is between 40% and 60% of the mass of the biofilm generated by the hydrogen autotrophic denitrifying PHA-synthesizing functional bacterial community.

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