A method for rapid formation of hydrogen / carbon dioxide matrix biofilm

Abstract

This invention belongs to the field of water treatment technology, specifically relating to a rapid method for forming a hydrogen / carbon dioxide matrix biofilm. This invention is based on utilizing Ca... 2+ When a regulated H2 / CO2 matrix biofilm purifies nitrate-containing water, the Ca2+ content is adjusted... 2+ The concentration of Ca promotes biofilm growth and biomass increase, as well as the secretion of extracellular polymers, maintaining biofilm density and thickness at a favorable state, achieving stable and rapid biofilm growth, and effectively improving the biofilm attachment efficiency of H2 / CO2 matrix biofilm systems. This invention provides the utilization of Ca... 2+ The method of regulating the rapid formation of H2 / CO2 matrix biofilm can greatly shorten the start-up and biofilm formation time of H2 / CO2 matrix biofilm system, improve the removal efficiency of H2 / CO2 matrix biofilm system for pollutants such as nitrate, and provide theoretical support for the engineering application of H2 / CO2 matrix biofilm system.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for the rapid formation of a hydrogen / carbon dioxide matrix biofilm. Background Technology

[0002] In recent years, H2 / CO2 matrix biofilm systems, as a novel water treatment process, using H2 as an electron donor and CO2 as an inorganic carbon source, have made significant progress in removing various oxidizing pollutants, especially nitrates. However, further development and engineering of H2 / CO2 matrix biofilm systems still face some challenges, one of the key technical difficulties being how to control the rapid formation of the biofilm.

[0003] As a core component of H2 / CO2-based biofilm systems, the activity of the biofilm directly affects the system's operational performance. In biofilm wastewater treatment systems, Ca... 2+ It can not only affect EPS secretion, but also directly influence biofilm formation through electrostatic interactions. Although Ca... 2+ Biofilm-based wastewater treatment processes promote biofilm growth, but most of these conclusions are based on studies involving pure bacteria. H2 / CO2 substrate biofilm systems involve a variety of mixed bacteria, and Ca... 2+ The impact on H2 / CO2-based biofilms remains unclear. Therefore, developing a method to regulate the rapid formation of H2 / CO2-based biofilms is of great significance for improving the effectiveness of biofilm treatment of nitrate-containing wastewater. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for rapid formation of hydrogen / carbon dioxide matrix biofilm, which utilizes Ca 2+ Promoting biofilm growth and extracellular polymeric substances (EPS) secretion enables stable and rapid biofilm growth, significantly shortens the start-up and biofilm formation time of H2 / CO2 matrix biofilm systems, and effectively improves the removal efficiency of H2 / CO2 matrix biofilm systems for pollutants such as nitrates.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for rapid formation of hydrogen / carbon dioxide matrix biofilms, comprising the following steps:

[0007] Anaerobic sludge was inoculated into an H2 / CO2 substrate biofilm system containing wastewater, and the Ca2+ content of the resulting mixed liquor was adjusted. 2+ When the concentration is 40–120 mg / L, H2 and CO2 are introduced to initiate biofilm formation.

[0008] In the H2 / CO2 matrix biofilm system, microorganisms utilize hydrogen as an electron donor and carbon dioxide as a carbon source.

[0009] Continue to introduce H2 and CO2, and after the H2 / CO2 substrate biofilm system has been started and biofilm formation is completed, wastewater is continuously introduced to carry out denitrification reaction and form a stable H2 / CO2 substrate biofilm.

[0010] The H2 / CO2 matrix biofilm system is equipped with a hollow fiber membrane module; the hollow fiber membrane module includes 20 to 40 hollow fiber membrane filaments;

[0011] The sign that the biofilm formation process is complete is the appearance of a visible yellowish-brown substance on the surface of the hollow fiber membrane filaments in the H2 / CO2 matrix biofilm system.

[0012] Preferably, the Ca content of the adjusted mixture is... 2+ The calcium source used for the concentration is calcium chloride.

[0013] Preferably, the inoculum amount of the anaerobic sludge is 20-25% of the effective volume of the H2 / CO2 substrate biofilm system.

[0014] Preferably, the supply pressure of H2 and CO2 is 0.02 to 0.03 MPa; the volume ratio of H2 to CO2 is 5.2:1.

[0015] Preferably, the H2 / CO2 matrix biofilm system includes a hollow fiber membrane module; the hollow fiber membrane module comprises 20 to 40 hollow fiber membrane filaments; the hollow fiber membrane filaments are made of polypropylene, and the membrane pore size of the hollow fiber membrane filaments is 0.02 to 0.2 μm, the inner diameter is 320 to 350 μm, and the outer diameter is 400 to 450 μm; the effective length of the hollow fiber membrane filaments is 300 mm.

[0016] Preferably, the DO content in the wastewater is less than 0.2 mg / L.

[0017] Preferably, the biofilm formation initiation includes a sequential water shut-off and recirculation process and an intermittent water intake process; during the water shut-off and recirculation process, water intake is stopped, the recirculation flow rate of wastewater is 80-120 mL / min, and the recirculation time is 20-30 h; during the intermittent water intake process, water intake is interrupted for 24 h and water intake is stopped for 24 h; the duration of the intermittent water intake process is 5-10 days; the inflow flow rate of the intermittent water intake process is 0.58-0.86 mL / min; and wastewater recirculation is carried out simultaneously during the intermittent water intake process, with a recirculation flow rate of 80-120 mL / min.

[0018] Preferably, the water intake method during continuous operation is simultaneous continuous water intake and recirculation; the water intake flow rate during continuous operation is 0.72–1 mL / min, and the recirculation flow rate is 80–120 mL / min; the continuous operation time is 100–120 days.

[0019] Preferably, the wastewater contains NO3 - -N concentration is 15-25 mg / L, pH value is 7.1-7.5.

[0020] Preferably, during continuous operation, the method further includes: daily water sampling for denitrification efficiency determination and periodic sampling of H2 / CO2 matrix biofilm for determination; when the H2 / CO2 matrix biofilm density reaches 0.014–0.020 g / mm³... 3 The thickness reaches 470–520 μm, the COD concentration reaches 140–220 mg / L, the protein content in the extracellular polymer reaches 360–420 mg / gVSS, the polysaccharide content in the extracellular polymer reaches 320–400 mg / gVSS, and the H2 / CO2 matrix biofilm reaches a stable state.

[0021] This invention provides a rapid method for forming a hydrogen / carbon dioxide substrate biofilm, comprising the following steps: inoculating anaerobic sludge into an H2 / CO2 substrate biofilm system containing wastewater, and adjusting the Ca2+ content of the resulting mixture. 2+ When the concentration reaches 40–120 mg / L, H2 and CO2 are introduced to initiate biofilm formation. In the H2 / CO2 substrate biofilm system, microorganisms utilize hydrogen as an electron donor and carbon dioxide as a carbon source. H2 and CO2 are continued to be introduced. After the biofilm formation is initiated, wastewater is continuously introduced into the H2 / CO2 substrate biofilm system to carry out denitrification, forming a stable H2 / CO2 substrate biofilm. The H2 / CO2 substrate biofilm system is equipped with a hollow fiber membrane module, which includes 20–40 hollow fiber membrane filaments. The completion of biofilm formation is indicated by the appearance of a visible yellowish-brown substance on the surface of the hollow fiber membrane filaments in the H2 / CO2 substrate biofilm system.

[0022] This invention adjusts Ca 2+ Concentration, using Ca 2+ It promotes biofilm growth and biomass, as well as the secretion of extracellular polymeric substances (EPS), maintains biofilm density and thickness in a good state, achieves stable and rapid biofilm growth, and greatly shortens the start-up and biofilm formation time of H2 / CO2 matrix biofilm system. This effectively improves the removal efficiency of H2 / CO2 matrix biofilm system for pollutants such as nitrate, and provides theoretical support for the engineering application of H2 / CO2 matrix biofilm system. Attached Figure Description

[0023] Figure 1 The present invention utilizes Ca 2+ A schematic diagram illustrating the principle of regulating the rapid formation of H2 / CO2 matrix biofilms;

[0024] Figure 2 This is a diagram showing the changes in the physical structure of the biofilm within the H2 / CO2 matrix biofilm system in Example 1;

[0025] Figure 3 This is a graph showing the change in COD concentration within the H2 / CO2 matrix biofilm system in Example 1;

[0026] Figure 4 This is a graph showing the changes in protein and polysaccharide content in the biofilm EPS within the H2 / CO2 matrix biofilm system in Example 1;

[0027] Figure 5 NO3 in the H2 / CO2 matrix biofilm system of Example 1 - -N removal rate variation graph;

[0028] Figure 6 NO3 in the H2 / CO2 matrix biofilm system of Example 2 - -N concentration and removal rate variation graph. Detailed Implementation

[0029] This invention provides a method for rapid formation of hydrogen / carbon dioxide matrix biofilms, comprising the following steps:

[0030] Anaerobic sludge was inoculated into an H2 / CO2 substrate biofilm system containing wastewater, and the Ca2+ content of the resulting mixed liquor was adjusted. 2+ When the concentration is 40–120 mg / L, H2 and CO2 are introduced to initiate biofilm formation.

[0031] In the H2 / CO2 matrix biofilm system, microorganisms utilize hydrogen as an electron donor and carbon dioxide as a carbon source.

[0032] Continue to introduce H2 and CO2, and after the H2 / CO2 substrate biofilm system has been started and biofilm formation is completed, wastewater is continuously introduced to carry out denitrification reaction and form a stable H2 / CO2 substrate biofilm.

[0033] The H2 / CO2 matrix biofilm system is equipped with a hollow fiber membrane module; the hollow fiber membrane module includes 20 to 40 hollow fiber membrane filaments;

[0034] The sign that the biofilm formation process is complete is the appearance of a visible yellowish-brown substance on the surface of the hollow fiber membrane filaments in the H2 / CO2 matrix biofilm system.

[0035] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0036] This invention involves inoculating anaerobic sludge into an H2 / CO2 substrate biofilm system containing wastewater, and adjusting the Ca content of the resulting mixed liquor. 2+ When the concentration is 40–120 mg / L, H2 and CO2 are introduced to initiate biofilm formation.

[0037] In the H2 / CO2 matrix biofilm system, microorganisms utilize hydrogen as an electron donor and carbon dioxide as a carbon source.

[0038] In this invention, the anaerobic sludge is preferably derived from a domestic sewage treatment plant; the inoculum amount of the anaerobic sludge is preferably 20-25% of the effective volume of the H2 / CO2 substrate biofilm system, more preferably 22-24%.

[0039] In this invention, the wastewater contains NO3 - The -N concentration is preferably 15–25 mg / L, more preferably 20 mg / L, and the pH value is preferably 7.1–7.5, more preferably 7.2–7.4. This invention does not specifically limit the wastewater used; any wastewater well-known in the art can be used. When the pH value of the wastewater is not within the above range, this invention preferably uses HCl and NaOH to adjust the pH value.

[0040] In this invention, the DO in the wastewater is <0.2 mg / L; when the DO in the wastewater is ≥0.2 mg / L, this invention preferably deoxygenates the wastewater; the preferred method for deoxygenation is nitrogen aeration.

[0041] In this invention, the Ca content of the adjusted mixture is... 2+ The preferred calcium source for the concentration is calcium chloride, more preferably CaCl2·2H2O; the Ca in the mixture... 2+ The concentration is 40–120 mg / L, preferably 80 mg / L.

[0042] In this invention, the supply pressure of H2 and CO2 is preferably 0.02–0.03 MPa, more preferably 0.025 MPa; the volume ratio of H2 to CO2 is preferably 5.2:1; and the supply method of H2 and CO2 is preferably from both ends of the hollow fiber membrane module of the H2 / CO2 matrix biofilm system. The introduced H2 and CO2 diffuse from inside the hollow fiber membrane cavity to the outside of the hollow fiber membrane to support microbial growth.

[0043] In this invention, the H2 / CO2 matrix biofilm system includes a hollow fiber membrane module; the hollow fiber membrane module comprises 20 to 40 hollow fiber membrane filaments, preferably 32 to 36 filaments; the hollow fiber membrane filaments are preferably made of polypropylene, and the membrane pore size is preferably 0.02 to 0.2 μm, more preferably 0.02 to 0.05 μm, the inner diameter is preferably 320 to 350 μm, more preferably 330 to 340 μm, and the outer diameter is preferably 400 to 450 μm, more preferably 410 to 420 μm; the effective length of the hollow fiber membrane filaments is preferably 300 mm; both ends of the hollow fiber membrane filaments are fixed and sealed with glue to form H2 / CO2 gas supply ends.

[0044] In this invention, the biofilm formation initiation preferably includes a sequential water shut-off and recirculation process and an intermittent water intake process; during the water shut-off and recirculation process, water intake is stopped, the recirculation flow rate of wastewater is preferably 80-120 mL / min, more preferably 100 mL / min, and the recirculation time is preferably 20-30 h, more preferably 24 h; the intermittent water intake process is preferably followed by a 24-hour water intake followed by a 24-hour water shut-off process; the duration of the intermittent water intake process is preferably 5-10 days, more preferably 7 days; the water intake flow rate of the intermittent water intake process is preferably 0.58-0.86 mL / min, more preferably 0.6-0.72 mL / min; and wastewater recirculation is carried out simultaneously during the intermittent water intake process, with the wastewater recirculation flow rate preferably 80-120 mL / min, more preferably 100 mL / min.

[0045] In this invention, the sign that the biofilm formation is complete is the appearance of a visible yellowish-brown substance on the surface of the hollow fiber membrane filaments in the H2 / CO2 matrix biofilm system.

[0046] After the initial biofilm formation is completed, the present invention continues to introduce H2 and CO2. Wastewater is continuously introduced into the H2 / CO2 substrate biofilm system after the initial biofilm formation is completed to carry out denitrification reaction and form a stable H2 / CO2 substrate biofilm.

[0047] In this invention, the supply pressure of H2 and CO2 is preferably 0.02–0.03 MPa, more preferably 0.025 MPa; the volume ratio of H2 to CO2 is preferably 5.2:1; and the supply method of H2 and CO2 is preferably from both ends of the hollow fiber membrane module of the H2 / CO2 matrix biofilm system. The introduced H2 and CO2 diffuse from inside the hollow fiber membrane cavity to the outside of the hollow fiber membrane to support microbial growth.

[0048] In this invention, the preferred method for continuous water intake during operation is simultaneous continuous water intake and recirculation; the preferred water intake flow rate during continuous operation is 0.72–1 mL / min, more preferably 0.76–0.86 mL / min, and the preferred recirculation flow rate is 80–120 mL / min, more preferably 100 mL / min; the preferred continuous operation time is 100–120 days, more preferably 112 days.

[0049] Figure 1 The present invention utilizes Ca 2+ A schematic diagram illustrating the principle of regulating the rapid formation of H2 / CO2 matrix biofilms. Figure 1 As shown, this invention adjusts different Ca... 2+ Concentration, using Ca 2+ It promotes biofilm growth and biomass increase, as well as promotes extracellular polymeric substances (EPS) secretion, maintains biofilm density and thickness in a good state, achieves stable and rapid biofilm growth, greatly shortens the start-up and biofilm formation time of H2 / CO2 matrix biofilm system, and thus effectively improves the removal efficiency of H2 / CO2 matrix biofilm system for pollutants such as nitrate.

[0050] During continuous operation, the present invention preferably further includes: daily water sampling for determining denitrification efficiency and periodic sampling of H2 / CO2 matrix biofilm for determination; when the density of the H2 / CO2 matrix biofilm reaches 0.014–0.020 g / mm³... 3 More preferably, it is 0.018 g / mm 3 The thickness reaches 470–520 μm, more preferably 495 ± 10 μm; the COD concentration reaches 140–220 mg / L, more preferably 200 ± 10 mg / L; the protein content in the extracellular polymeric substance (EPS) reaches 360–420 mg / gVSS, more preferably 400 ± 10 mg / gVSS; the polysaccharide content in the extracellular polymeric substance reaches 320–400 mg / gVSS, more preferably 370 ± 10 mg / gVSS; and the H2 / CO2 matrix biofilm reaches a stable state. In this invention, the frequency of periodically taking H2 / CO2 matrix biofilm samples is preferably 15–20 days / time, more preferably 15–18 days / time; NO3 is measured. - Before determining the -N concentration, the present invention preferably filters and sterilizes the water sample; the filtration is preferably performed using a 0.45 μm polyvinylidene fluoride (PVDF) filter membrane; before determining the biomass, the present invention preferably digests the H2 / CO2 matrix biofilm sample; the digestion temperature is preferably 165℃ and the time is 20 min.

[0051] In this invention, the method for determining the denitrification efficiency is preferably the determination of NO3 in the water sample. --N concentration, and combined with NO3 in wastewater - Calculation of NO3-N concentration - -N removal rate; the NO3 - The preferred method for determining the -N concentration is the national standard spectrophotometer method; the preferred method for determining the biomass is by measuring the COD concentration; the preferred method for determining the protein in the extracellular polymer (EPS) is the modified Folin-Lowry method; and the preferred method for determining the polysaccharides in the extracellular polymer (EPS) is the anthrone sulfate method.

[0052] This invention is based on the use of Ca 2+ When a regulated H2 / CO2 matrix biofilm purifies nitrate-containing water, the Ca2+ content is adjusted... 2+ The concentration of Ca promotes biofilm growth and biomass increase, as well as the secretion of extracellular polymers, maintaining biofilm density and thickness at a favorable state, achieving stable and rapid biofilm growth, and effectively improving the biofilm attachment efficiency of H2 / CO2 matrix biofilm systems. This invention provides the utilization of Ca... 2+ The method of regulating the rapid formation of H2 / CO2 matrix biofilm can greatly shorten the start-up and biofilm formation time of H2 / CO2 matrix biofilm system, improve the removal efficiency of H2 / CO2 matrix biofilm system for pollutants such as nitrate, and provide theoretical support for the engineering application of H2 / CO2 matrix biofilm system.

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] (1) Configure simulated sewage

[0056] Simulated wastewater was configured using NaNO3 as the inorganic nitrogen source and CO2 gas as the inorganic carbon source. It also included some macro- and micro-elements to maintain normal microbial growth. Ca was added to each group of systems. 2+ The concentrations were 40, 80, and 120 mg / L. The pH of the simulated wastewater was controlled at 7.3 ± 0.2. After aeration with nitrogen for 5 minutes, the simulated wastewater was placed in a 5L white plastic inlet tank. A nitrogen bag was attached to the inlet tank, which was then sealed and placed in a dark environment to maintain an anaerobic state (DO < 0.2 mg / L) and prevent the growth of green algae. The specific composition of the simulated wastewater is shown in Table 1.

[0057] Table 1 Specific components of simulated wastewater

[0058] Element Concentration (mg / L) Element Concentration (mg / L) <![CDATA[NaNO3 (calculated as N)]]> 20 <![CDATA[FeSO4·7H2O]]> 1.0 <![CDATA[Na2SO4 (calculated as SO4 - )]]> 55 <![CDATA[H3BO3]]> 0.3 <![CDATA[CaCl2·2H2O]]> 40 / 80 / 120 <![CDATA[CoCl2·6H2O]]> 0.2 <![CDATA[KH2PO4]]> 2.78 <![CDATA[CuCl2·2H2O]]> 0.01 <![CDATA[ZnSO4·7H2O]]> 0.1 <![CDATA[Na2MoO4·2H2O]]> 0.03 <![CDATA[MnCl2]]> 0.01 <![CDATA[NiCl2·6H2O]]> 0.01

[0059] (2) Operation of H2 / CO2 matrix biofilm system

[0060] In this invention, the operating conditions for the start-up film attachment stage and the continuous operation stage are shown in Table 2.

[0061] Table 2 Operating conditions of H2 / CO2 matrix biofilm system

[0062]

[0063] Biofilm initiation phase: In the H2 / CO2 substrate biofilm system, 30 mL of anaerobic sludge taken from the Qixing District Urban Wastewater Treatment Plant in Guilin City was used as the inoculum source, representing 23% of the effective volume of the H2 / CO2 substrate biofilm system. After the system was filled with simulated wastewater, the influent was stopped, and the system was run for 24 hours at a gas pressure of 0.02 MPa and a recirculation rate of 100 mL / min to ensure uniform mixing of the inoculated microorganisms. After the 24-hour water outage and recirculation period, the influent was restarted at a flow rate of 0.72 mL / min. Intermittent water influent (24 hours influent, 24 hours outfluent) was used for 7 days, with gas supplied from both ends of the hollow fiber membrane module of the H2 / CO2 substrate biofilm system, and the H2 / CO2 gas pressure remained at 0.02 MPa.

[0064] Continuous operation phase: The prepared simulated wastewater is introduced by continuous water intake, with the influent flow rate set at 0.86 mL / min, the return flow rate at 100 mL / min, and the H2 / CO2 gas pressure at 0.025 MPa, to maintain the continuous operation of the H2 / CO2 substrate biofilm system.

[0065] (3) Sampling and Analysis

[0066] Water sampling: Use a clean syringe to collect 10 mL of influent and effluent from each system daily, filter the sample through a 0.45 μm PVDF filter, store it in a sample bottle, and keep it in a 4℃ refrigerator until it is ready for testing.

[0067] Biofilm sampling: Biofilm samples were collected every 15 days. Membrane filaments and biofilms from each system were taken and cut into 3cm segments using sterile medical scissors. These segments were placed in centrifuge tubes containing ultrapure water and stored at 4°C for immediate experimentation. The growth of the biofilm was observed using a stereomicroscope. Biofilm thickness was recorded at each stage to calculate biofilm density. COD concentration was used as an indicator of biomass, reflecting the rate of biofilm formation. The protein and polysaccharide content in the biofilm EPS was measured to indicate the degree of tightness during biofilm formation, thus reflecting the rate of biofilm formation.

[0068] Example 2

[0069] Groundwater from the Huixian karst wetland in Guangxi was used as the influent for the H2 / CO2 matrix biofilm system in this embodiment. The Ca content in the groundwater... 2+ Concentration of 70–100 mg / L, NO3 - -N concentration is 20-30 mg / L, pH value is 7.3-7.5.

[0070] In the initial biofilm formation stage, 30 mL of anaerobic sludge from the Qixing District Urban Wastewater Treatment Plant in Guilin City was used as the inoculum source, accounting for 23% of the effective volume of the H2 / CO2 substrate biofilm system. The system was then filled with influent, and the influent flow was stopped. The system was operated for 24 hours at a gas pressure of 0.02 MPa and a reflux rate of 100 mL / min to ensure uniform mixing of the inoculated microorganisms. After the 24-hour water shut-off and reflux period, the influent flow was restarted at a rate of 0.72 mL / min. Intermittent influent flow (24 hours influent, 24 hours shut-off) was used for 7 days. Gas was supplied from both ends of the hollow fiber membrane module of the H2 / CO2 substrate biofilm system, with the H2 / CO2 gas pressure remaining at 0.02 MPa.

[0071] During the continuous operation phase, water is introduced continuously with an influent flow rate of 0.86 mL / min, a reflux flow rate of 100 mL / min, and an H2 / CO2 gas pressure of 0.025 MPa to maintain the continuous operation of the H2 / CO2 substrate biofilm system.

[0072] Comparative Example 1

[0073] The procedure is the same as in Example 1, except that in step (1), Ca is not added to the simulated wastewater. 2+ .

[0074] Performance testing

[0075] Figure 2 This is a diagram showing the changes in the physical structure of the biofilm within the H2 / CO2 matrix biofilm system in Example 1. As can be seen from the diagram, without the addition of Ca... 2+ At that time, the biofilm density was consistently lower than that of the other three groups, eventually stabilizing at 0.004 g / mm². 3 Add 40 mg / L Ca 2+ At that time, the biofilm density reached 0.014 g / mm³ after 120 days. 3 Add 80 mg / L Ca 2+ Compared with the addition of 120 mg / L Ca 2+ At that time, the biofilm density did not differ much, and was higher than that of the untreated biofilm. 2+ Compared with the addition of 40 mg / L Ca 2+ The biofilm density reached 0.014 g / mm³ after 45 days. 3Ultimately, it can be stabilized at 0.018 g / mm. 3 And add 80mg / L Ca 2+ The biofilm growth thickness was at a good level, reaching 495.88 μm. The results indicate that without the addition of Ca... 2+ At this time, the biofilm density is lowest, the biofilm structure is loose, and the film formation rate is slow; adding Ca 2+ At that time, the biofilm had high density and good stability. Specifically, the addition of 80 mg / L Ca... 2 + At that time, the biofilm density and thickness remained in a good state, the biofilm structure was compact, and the film formation rate was relatively fast; 40 mg / L Ca was added. 2+ Compared with the addition of 120 mg / L Ca 2+ At that time, the biofilm thickness was low, but the biofilm density was the same as that without added Ca. 2+ Approximately four times the amount of Ca added at that time, indicating that the dosage was approximately 4 times higher than usual. 2+ It can effectively promote the stability and compactness of biomembrane structures.

[0076] Figure 3 This is a graph showing the COD concentration changes within the H2 / CO2 matrix biofilm system in Example 1, used to compare the changes in biomass across different groups. Figure 3 It can be seen from this that without the addition of Ca 2+ At that time, the COD concentration was consistently the lowest among the four groups, with a final concentration of only 74.3 mg / L; 40 mg / L Ca 2+ At that time, biomass growth was slow before 60 days, then gradually increased, eventually reaching a concentration of 136.73 mg / L; 80 mg / L Ca 2+ At this time, the COD concentration in all time periods was higher than that in the other three groups, reaching 120 mg / L after 30 days and ultimately reaching 211.67 mg / L, which is higher than that in the group without Ca. 2+ The biomass reached its maximum when the dosage was 3 times that of the previous group; 120 mg / L Ca was added. 2 + At that time, the COD concentration could reach 118 mg / L after 90 days, and the COD concentration was higher than that of 40 mg / L Ca for 120 days. 2+ The COD concentration at that time was [not specified], and the final concentration reached 138.4 mg / L. The results indicate that, compared to the unadded Ca [concentration], [the concentration was lower]. 2+ In comparison, adding 80 mg / L Ca 2+ At that time, the biomass reached its maximum, and in the initial biofilm formation stage, it was better than adding 40 mg / L Ca. 2+ Compared with the addition of 120 mg / L Ca 2+ Rapid growth over time is conducive to the rapid and stable formation of biofilms.

[0077] Figure 4This is a graph showing the changes in protein and polysaccharide content in the EPS biofilm within the H2 / CO2 matrix biofilm system in Example 1. From... Figure 4 As can be seen, the EPS content of all four systems showed an increasing trend over time. Among them, the EPS content of the system without Ca... 2+ At that time, the EPS content in each stage was lower than that in the other three groups, reaching only 94.12 mg / gVSS at 120 days; 40 mg / L Ca was added. 2+ At that time, the EPS content reached 107.24 mg / gVSS after 60 days, and the EPS content growth time was longer than that without Ca. 2+ The rate of increase was twice as fast, and then stabilized at 146.09 mg / g VSS at 120 days; 80 mg / L Ca was added. 2+ At 30 days, the EPS content reached 118.37 mg / gVSS, which increased to 240 mg / gVSS at 45 days, and reached its highest level of 774.89 mg / gVSS at 120 days; 120 mg / L Ca 2+ At that time, the EPS content was lower than that of 80 mg / L Ca. 2+ The concentration decreased significantly over time, but still reached 142.22 mg / g VSS at 60 days, eventually stabilizing at 387.96 mg / g VSS. The results indicate that Ca... 2+ It will affect the EPS content; adding 40 mg / L Ca... 2+ At that time, polysaccharides were the main component of EPS; 80 mg / L Ca was added. 2+ At the time of administration, the protein and polysaccharide content in EPS was the highest. In the early and middle stages of biofilm formation, protein is the main component of EPS, playing a crucial role in biofilm formation and maturation. Adding 120 mg / L Ca... 2+ At that time, the protein and polysaccharide content in EPS decreased, but remained higher than that of EPS without added Ca. 2+ Time. Therefore, it can be seen that Ca in the biofilm water treatment process... 2+ It can significantly affect EPS secretion, and the addition of 80 mg / L Ca 2+ The effect of promoting EPS secretion is most obvious at this time, which greatly shortens the film formation time and is conducive to the stable and rapid formation of biofilm.

[0078] Figure 5 NO3 in the H2 / CO2 matrix biofilm system of Example 1 - The graph shows the change in -N removal rate. During the initial biofilm formation phase, after 7 days of intermittent operation of the H2 / CO2 substrate biofilm system, 80 mg / L Ca was added. 2+ Compared with the addition of 120 mg / L Ca 2+ At that time, NO3 - The removal efficiency of -N reached up to 100%; while the addition of 40 mg / L Ca2+ Compared with no Ca added 2+ At that time, the highest NO3 - -N removal efficiency is only 70% and 50%. During continuous operation, without the addition of Ca... 2+ At that time, NO3 - The removal efficiency of -N remained relatively stable at around 55%; the addition of Ca 2+ At that time, all systems could achieve approximately 60% NO3 concentration after 30 days. - -N removal efficiency, where 80 mg / L Ca is added 2+ At that time, NO3 - The removal efficiency of -N reaches 90% after 60 days and can then be increased to 100%; the addition of 120 mg / L Ca 2+ At that time, NO3 - The removal efficiency of -N can be stably maintained at around 85%; adding 40 mg / L Ca 2+ At that time, NO3 - The removal efficiency of -N can be stabilized at around 78.5%. The results indicate that adding 80 mg / L Ca during the intermittent operation phase... 2+ Compared with the addition of 120 mg / L Ca 2+ At that time, the amount of NO3 that can be treated per unit area of ​​biofilm - The ability of -N is far greater than that of adding 40 mg / L Ca. 2+ Compared with no Ca added 2+ The removal efficiency at that time, and during continuous operation, with an addition of 80 mg / L Ca 2+ It reached a stable state first compared to the other three groups, had the highest denitrification efficiency, and the shortest biofilm system start-up time, reflecting the stable and rapid biofilm formation efficiency of the H2 / CO2 substrate biofilm system.

[0079] Figure 6 NO3 in the H2 / CO2 matrix biofilm system of Example 2 - -N concentration and removal rate changes. During the initial biofilm formation stage, the effluent NO3... - The minimum NO3- concentration is 1.2 mg / L, and the removal efficiency can reach up to 95%; during continuous operation, after 60 days, the effluent NO3- concentration is reduced. - The NO3- concentration remained stable below 5 mg / L, and the removal rate remained stable above 90%. The results indicate that, under the condition of using actual groundwater as influent, the biofilm system has a short start-up time and effectively removes NO3-. - -N removal efficiency compared to that in Example 1 with an addition of 80 mg / L Ca 2+ The timing is similar, which shows that the actual groundwater contains Ca. 2+ A concentration of 70–100 mg / L can ensure the stable and rapid formation of H2 / CO2 matrix biofilms and maintain good NO3 levels.- -N removal efficiency.

[0080] In summary, when 80 mg / L Ca is added to an H2 / CO2 matrix biofilm system... 2+ This method can maintain good biofilm density and thickness, increase biomass, promote the secretion of extracellular polymeric substances (EPS), accelerate film formation, and achieve stable and rapid biofilm growth. It can also significantly shorten the start-up and biofilm formation time of the H2 / CO2 matrix biofilm system, thereby effectively improving the removal efficiency of H2 / CO2 matrix biofilm system for pollutants such as nitrates, and providing theoretical support for the engineering application of H2 / CO2 matrix biofilm system.

[0081] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for rapid formation of a hydrogen / carbon dioxide matrix biofilm, characterized in that, Includes the following steps: Anaerobic sludge was inoculated into an H2 / CO2 substrate biofilm system containing wastewater, and the Ca2+ content of the resulting mixed liquor was adjusted. 2+ When the concentration is 40–120 mg / L, H2 and CO2 are introduced to initiate biofilm formation. In the H2 / CO2 matrix biofilm system, microorganisms utilize hydrogen as an electron donor and carbon dioxide as a carbon source. Continue to introduce H2 and CO2, and after the H2 / CO2 substrate biofilm system has been started and biofilm formation is completed, wastewater is continuously introduced to carry out denitrification reaction and form a stable H2 / CO2 substrate biofilm. The H2 / CO2 matrix biofilm system is equipped with a hollow fiber membrane module; the hollow fiber membrane module includes 20 to 40 hollow fiber membrane filaments; The sign that the biofilm formation process is complete is the appearance of a visible yellowish-brown substance on the surface of the hollow fiber membrane filaments in the H2 / CO2 matrix biofilm system.

2. The rapid formation method according to claim 1, characterized in that, The Ca content of the adjusted mixture 2+ The calcium source used for the concentration is calcium chloride.

3. The rapid formation method according to claim 1, characterized in that, The inoculum size of the anaerobic sludge is 20-25% of the effective volume of the H2 / CO2 substrate biofilm system.

4. The rapid formation method according to claim 1, characterized in that, The supply pressure of H2 and CO2 is 0.02-0.03 MPa; the volume ratio of H2 to CO2 is 5.2:

1.

5. The rapid formation method according to claim 1, characterized in that, The hollow fiber membrane filament is made of polypropylene, and the membrane pore size of the hollow fiber membrane filament is 0.02-0.2 μm, the inner diameter is 320-350 μm, and the outer diameter is 400-450 μm; the effective length of the hollow fiber membrane filament is 300 mm.

6. The rapid formation method according to claim 1, characterized in that, The DO in the wastewater was less than 0.2 mg / L.

7. The rapid formation method according to claim 1, characterized in that, The biofilm formation initiation process includes a sequential water shut-off and recirculation process and an intermittent water intake process. During the water shut-off and recirculation process, water intake is stopped, and the recirculation flow rate is 80–120 mL / min for 20–30 hours. The intermittent water intake process involves a 24-hour water intake followed by a 24-hour water shut-off. The duration of the intermittent water intake process is 5–10 days. The recirculation flow rate during the intermittent water intake process is 0.58–0.86 mL / min. Simultaneously, wastewater recirculation occurs during the intermittent water intake process, with a recirculation flow rate of 80–120 mL / min.

8. The rapid formation method according to claim 1, characterized in that, The continuous operation involves simultaneous water intake and recirculation; the water intake flow rate during continuous operation is 0.72–1 mL / min, and the recirculation flow rate is 80–120 mL / min; the continuous operation time is 100–120 days.

9. The rapid formation method according to claim 1, characterized in that, NO3 in the wastewater - -N concentration is 15-25 mg / L, pH value is 7.1-7.

5.

10. The rapid formation method according to claim 1, characterized in that, During continuous operation, the process also includes: daily water sampling to determine denitrification efficiency and periodic sampling of H2 / CO2 matrix biofilm for measurement; when the density of the H2 / CO2 matrix biofilm reaches 0.014–0.020 g / mm³. 3 The thickness reaches 470–520 μm, the COD concentration reaches 140–220 mg / L, the protein content in the extracellular polymer reaches 360–420 mg / gVSS, the polysaccharide content in the extracellular polymer reaches 320–400 mg / gVSS, and the H2 / CO2 matrix biofilm reaches a stable state.

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