A method of inhibiting biofilm calcification fouling in a hydrogen substrate biofilm reactor

Abstract

The present application relates to the technical field of water treatment membrane fouling control, and particularly relates to a method for inhibiting biological membrane calcification fouling in a hydrogen substrate biological membrane reactor. 2+ The present application obtains a Langmuir saturation index (LSI) in the biological membrane by in-situ determination of pH in the biological membrane, so as to evaluate the potential possibility of CaCO3 precipitation in the biological membrane. 2+ The in-situ LSI index in the biological membrane can effectively monitor the dynamic state of CaCO3 accumulation and calcification in the biological membrane, form a CaCO3 precipitation early warning mechanism, provide a basis for directional optimization of the reactor, delay or inhibit the generation of CaCO3 precipitation from the source, protect the mass transfer efficiency of the hollow fiber membrane, and ensure long-term stable and efficient operation of the reactor under high calcium water conditions.

Description

Technical Field

[0001] This invention relates to the field of water treatment membrane fouling control technology, and in particular to a method for inhibiting biofilm calcification fouling in hydrogen-based biofilm reactors. Background Technology

[0002] Hydrogen-based biofilm reactors (H2-MBfR) are an emerging advanced wastewater treatment technology, widely used in groundwater and drinking water treatment for nitrate (NO3) content. - ), perchlorate (ClO4) - ), bromate (BrO3) - This reactor removes oxidizing pollutants such as hydrogen (H2) and carbon dioxide (CO2) or bicarbonate. It utilizes autotrophic denitrifying microorganisms to form a biofilm on the surface of a hollow fiber membrane, achieving highly efficient pollutant reduction. Because H2 is non-toxic, produces no secondary pollution, and generates low-grade sludge, H2-MBfR is considered a green and low-carbon water treatment process, showing great promise for advanced wastewater denitrification.

[0003] However, in practical engineering applications, especially when treating groundwater in karst areas or high-hardness industrial wastewater, the influent often contains a high concentration of calcium ions (Ca). 2+ Although H2-MBfR has high NO3 efficiency - It has degradation capacity, but it continuously consumes H during its denitrification process. + and release OH - This leads to a significant increase in pH within the biofilm (the local pH easily exceeds 9.0). High pH conditions and the presence of calcium in the influent contribute to this effect. 2+ It can couple with dissolved inorganic carbon (DIC), which can easily induce the formation of CaCO3 precipitates in the biofilm and on the surface of the hollow fiber membrane, resulting in biofilm calcification pollution.

[0004] Biofilm calcification fouling can cause a series of serious operational problems: First, CaCO3 crystals on the surface of hollow fiber membranes can clog the micropores or densely cover the membrane surface, significantly reducing the transmembrane mass transfer efficiency of H2; second, biofilm calcification can severely hinder the transport of substrates (H2, CO2, NO3). - (e.g.,) diffusion within the biofilm leads to the inactivation of functional microorganisms due to substrate scarcity, resulting in biofilm structural degradation and abnormally increased thickness. Ultimately, the reactor's denitrification performance declines sharply, and the system's stable operating cycle is significantly shortened. Frequent physical rinsing or chemical acid washing may temporarily restore performance, but it easily damages the integrity of the biofilm, increasing reactor operation and maintenance costs or the risk of failure.

[0005] To address the aforementioned calcification problem, existing technologies mainly rely on overall pH adjustment of the influent or conventional CO2 supply strategies. However, these methods have significant drawbacks: (1) Directly adding acid to the influent to adjust the overall pH is difficult to precisely control the local pH gradient within the biofilm microenvironment, often only treating the symptoms and not the root cause. Furthermore, excessive acid addition can inhibit the activity of denitrifying bacteria, increasing reagent costs and the risk of water quality fluctuations; (2) Supplying CO2 through hollow fiber membranes or continuous bubbling also results in significant differences in pH and carbonate chemical equilibrium conditions at different locations within the biofilm, easily leading to local ion supersaturation and selective precipitation; (3) Existing control methods lack control over the internal Ca2+ of the biofilm. 2+ The dynamic monitoring and early warning mechanisms for accumulation and calcification status, as well as the control strategies, exhibit significant lag and blindness. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor. This invention achieves precise pH control of the biofilm microenvironment, which can delay or inhibit the formation of CaCO3 precipitate at its source, ensuring the mass transfer performance of the hollow fiber membrane and maintaining the long-term stable operation of the reactor.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor, comprising the following steps: After the hydrogen-based biofilm reactor is running stably, the pH value at different depths in the biofilm is measured in situ, and the Langerier saturation index (LSI) at each depth of the biofilm is obtained according to Equation 1. Formula 1; In Equation 1, LSI is the Langerier saturation index, pH is the pH value monitored in situ within the biofilm, and pHs is the pH value corresponding to the saturation state of calcium carbonate in the water. LSI < 0, indicating that the aqueous phase of the biofilm is unsaturated with respect to calcium carbonate. 2+ Precipitation is not likely to occur; when LSI=0, calcium carbonate is just saturated, and no precipitation is formed or dissolved; when LSI>0, calcium carbonate in the aqueous phase is supersaturated and may form calcium carbonate precipitate. If LSI > 0 occurs at any point in the biofilm, it is determined that there is a risk of calcium carbonate precipitation in the biofilm. The operating conditions of the hydrogen-based biofilm reactor are then adjusted until LSI at all depths of the biofilm is ≤ 0.

[0008] Preferably, the operating conditions of the hydrogen-based biofilm reactor are adjusted until the LSI at each depth of the biofilm is <0.

[0009] Preferably, the adjustment of the operating conditions of the hydrogen-based biofilm reactor includes: adjusting the influent pH value and / or adjusting the CO2 supply method.

[0010] Preferably, the CO2 supply method includes supplying CO2 through influent or supplying CO2 within the membrane.

[0011] Preferably, the method for in-situ determination of pH values ​​at different depths within the biofilm is as follows: using a pH microprobe, with a step size of 10~50μm, to determine pH values ​​at different depths perpendicular to the biofilm surface.

[0012] Preferably, the hydrogen-based biofilm reactor is operated stably by supplying CO2 within the membrane.

[0013] Preferably, when adjusting the operating conditions of the hydrogen-based biofilm reactor, an adjustment method with better denitrification performance is selected while ensuring that the LSI at each depth of the biofilm is ≤0 after adjustment.

[0014] This invention provides a method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor. The method involves in-situ measurement of the pH value within the biofilm to obtain the Langerile saturation index (LSI) of the biofilm, which is then used to evaluate the calcium content in the biofilm. 2+ Potential for precipitation. In-situ LSI indices within biofilms can effectively monitor Ca within biofilms. 2+ Dynamic monitoring of accumulation and calcification establishes a CaCO3 precipitation early warning mechanism, providing a basis for targeted optimization of the reactor. This delays or inhibits the formation of CaCO3 precipitation at the source, protects the mass transfer efficiency of the hollow fiber membrane, and ensures the long-term stable and efficient operation of the reactor under high-calcium influent conditions.

[0015] Traditional methods of adjusting influent pH value make it difficult to accurately control the local pH gradient within the biofilm microenvironment. This invention uses LSI to guide the directional optimization of the reactor. By measuring the pH at different depths of the biofilm in situ, the LSI at each depth of the biofilm is ≤0, ensuring that there is no risk of calcification within the entire biofilm microenvironment after adjusting the influent pH value.

[0016] Furthermore, it was verified that operating the hydrogen-based biofilm reactor using an in-membrane CO2 supply method can keep the pH of the entire biofilm area stable within the optimal denitrification range, resulting in better denitrification performance and eliminating the risk of calcium carbonate precipitation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the H2-MBfR device used in the embodiment; Figure 2 The denitrification performance and calcium residue of the reactor under CO2 influent supply mode (a), pH and LSI in the biofilm (b); Figure 3 LSI and calcium residue in biofilm under different pH conditions during CO2 supply of influent; Figure 4 The denitrification performance and calcium residue of the reactor under the in-membrane CO2 supply method (a), and pH and LSI in the biofilm (b). Detailed Implementation

[0018] This invention provides a method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor, comprising the following steps: After the hydrogen-based biofilm reactor is running stably, the pH value at different depths in the biofilm is measured in situ, and the Langerier saturation index (LSI) at each depth of the biofilm is obtained according to Equation 1. Formula 1; In Equation 1, LSI is the Langerier saturation index, pH is the pH value monitored in situ within the biofilm, and pHs is the pH value corresponding to the saturation state of calcium carbonate in the water. LSI < 0, indicating that the aqueous phase of the biofilm is unsaturated with respect to calcium carbonate. 2+ Precipitation is not likely to occur; when LSI=0, calcium carbonate is just saturated, and no precipitation is formed or dissolved; when LSI>0, calcium carbonate in the aqueous phase is supersaturated and may form calcium carbonate precipitate. If LSI > 0 occurs at any point in the biofilm, it is determined that there is a risk of calcium carbonate precipitation in the biofilm. The operating conditions of the hydrogen-based biofilm reactor are then adjusted until LSI at all depths of the biofilm is ≤ 0.

[0019] This invention does not specifically limit the hydrogen-based biofilm reactor described herein; any hydrogen-based biofilm reactor well-known in the art is acceptable. To facilitate the measurement of the biofilm's pH value and the adjustment of the CO2 supply method, the hydrogen-based biofilm reactor (H2-MBfR) device in this invention mainly consists of three parts: an H2-MBfR reaction tank, a gas supply system, and a microprobe monitoring system. The H2-MBfR reaction tank comprises a main reaction tank and a secondary reaction tank, which are connected in a single circulation loop via a reflux pump. The main reaction tank contains a membrane module composed of 32 hollow fiber membrane filaments as the main reaction zone, while the secondary reaction tank contains one hollow fiber membrane filament for mounting the microprobe monitoring system to monitor the pH gradient within the biofilm in situ.

[0020] Polluted raw water enters from the bottom of the main reaction tank through the inlet pump, exits from the top and connects to the auxiliary reaction tank, and then achieves internal circulation through the return pump. The gas supply system consists of gas cylinders, control valves and gas supply pipelines. The gas supply pipelines are connected to both ends of the hollow fiber membrane modules of the main reaction tank and the auxiliary reaction tank respectively. CO2 is supplied in two ways: water supply and membrane supply, which are achieved by opening and closing the valves on the gas supply pipeline or changing the water supply. The specific implementation methods are as follows: (1) Water supply CO2: close valve ①, keep valve ② open to pre-charge CO2 into the water until the CO2 in the water reaches the set concentration, and the gas supply system only provides H2; (2) Membrane supply CO2: open valve ① and close valve ②, and achieve the gas supply system to supply H2 / CO2 mixture by controlling the pressure divider valves on the H2 and CO2 cylinders respectively.

[0021] Before operating the hydrogen-based biofilm reactor, this invention preferably performs start-up and acclimatization. This invention does not impose specific limitations on the start-up and acclimatization process; any well-known start-up and acclimatization process in the art can be used. In an embodiment of this invention, sludge taken from the anoxic tank of a municipal wastewater treatment plant is mixed with hydrogen autotrophic denitrification sludge cultivated in the laboratory at a 1:1 ratio and inoculated into the main reaction tank. The influent pump is turned on to introduce the prepared nitrate-contaminated acclimatization raw water into the main reaction tank. Simultaneously, the reflux pump is turned on to form an internal circulation loop between the main and auxiliary reaction tanks to fully mix and reflux the mixture in the reactor. H2 is supplied to the hollow fiber membrane modules in the main and auxiliary reaction tanks, and CO2 is supplied to the influent through a gas supply system to acclimatize the reactor, causing a biofilm to form on the surface of the hollow fiber membranes in the main and auxiliary reaction tanks. The reactor start-up and acclimatization are considered complete when the nitrate concentration in the reactor effluent reaches a stable level and the biofilm thickness and morphology no longer change significantly.

[0022] After the hydrogen-based biofilm reactor has been started and acclimatized, the present invention will begin to operate under normal conditions.

[0023] In this invention, the operating conditions can be determined according to actual requirements. The inventors have discovered that operating the hydrogen-based biofilm reactor using an in-membrane CO2 supply method can stabilize the pH of the entire biofilm within the optimal denitrification range, resulting in better denitrification and eliminating the risk of calcium carbonate precipitation. Therefore, this invention preferably uses an in-membrane CO2 supply method to operate the hydrogen-based biofilm reactor.

[0024] After the hydrogen-based biofilm reactor has been running stably, the pH value at different depths within the biofilm was measured in situ.

[0025] This invention preferably employs a pH microprobe, measuring pH values ​​at different depths perpendicular to the biofilm surface with a step size of 10-50 μm. In embodiments of this invention, the step size can specifically be 10, 25, 30, 40, or 50 μm.

[0026] After measuring the pH value at different depths within the biofilm, this invention obtains the Langerilla saturation index (LSI) at each depth of the biofilm according to Equation 1. Formula 1; In Equation 1, LSI is the Langerier saturation index, pH is the pH value monitored in situ within the biofilm, and pHs is the pH value corresponding to the calcium carbonate saturation state in the water. pHs is based on Ca... 2+ Concentration and HCO3 - The concentration and the related dissociation equilibrium constant are calculated, which is common knowledge in the field of chemistry and will not be discussed further here.

[0027] LSI < 0, indicating that the aqueous phase of the biofilm is unsaturated with respect to calcium carbonate. 2+ Precipitation is not likely to occur; when LSI=0, calcium carbonate is just saturated, and no precipitation is formed or dissolved; when LSI>0, calcium carbonate in the aqueous phase is in a supersaturated state, and calcium carbonate precipitation may form.

[0028] If the LSI at all depths of the biofilm is ≤0, there is no risk of calcification, and the operation can continue as before.

[0029] If LSI > 0 occurs at any point in the biofilm, it is determined that there is a risk of calcium carbonate precipitation in the biofilm. The present invention adjusts the operating conditions of the hydrogen-based biofilm reactor until LSI at all depths of the biofilm is ≤ 0, preferably LSI at all depths of the biofilm is < 0 after adjustment.

[0030] In this invention, the preferred operating conditions of the hydrogen-based biofilm reactor include: adjusting the pH value of the influent and / or adjusting the CO2 supply method, more preferably adjusting the pH value of the influent.

[0031] Traditional methods of adjusting the influent pH value make it difficult to accurately control the local pH gradient within the biofilm microenvironment. This invention ensures that the LSI at all depths of the biofilm is ≤0 after adjusting the influent pH value, thus guaranteeing that there is no risk of calcification within the biofilm microenvironment.

[0032] This invention optimizes the denitrification performance while adjusting the operating conditions of the hydrogen-based biofilm reactor to ensure that the LSI at all depths of the biofilm is ≤0. Specifically, it aims to maintain high denitrification performance while suppressing calcium carbonate precipitation.

[0033] Through the above method, the present invention achieves precise pH control of the biofilm microenvironment, which can delay or inhibit the formation of CaCO3 precipitate from the source, ensure the mass transfer performance of hollow fiber membrane, and maintain the long-term stable operation of the reactor.

[0034] The following detailed description, in conjunction with embodiments, illustrates the method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0035] The following embodiments rely on an H2-MBfR device with switchable CO2 supply mode (see structure). Figure 1 The device mainly includes: an H2-MBfR reaction tank (forming an internal circulation loop by connecting the main reaction tank and the auxiliary reaction tank via a reflux pump), a gas supply system (including H2 cylinders, CO2 cylinders, pressure reducing valves, gas supply pipelines, and control valves ① / ②), and a microprobe monitoring system (including a pH microprobe, a signal acquisition amplifier, and a three-dimensional displacement operating stage). The main reaction tank contains a membrane module composed of 32 hollow fiber membrane filaments as the main reaction zone; the auxiliary reaction tank has a separate hollow fiber membrane filament installed to fix the microprobe for in-situ measurement of the pH gradient inside the biofilm.

[0036] The gas supply system achieves two CO2 supply modes through valve switching: (1) CO2 supply mode: close valve ①, open valve ②, CO2 is pre-charged into the water distribution tank until the set concentration is reached, and only H2 is introduced into the hollow fiber membrane; (2) Intramembrane CO2 supply mode: Open valve ① and close valve ②. H2 and CO2 are mixed in proportion through the pressure divider valve and then directly introduced into the inner cavity of the hollow fiber membrane, and diffused to the biomembrane through the membrane wall.

[0037] The operation method of the embodiment is as follows: Reactor start-up and acclimatization. Activated sludge from the anoxic tank of a municipal wastewater treatment plant and hydrogen autotrophic denitrification sludge cultured in our laboratory were mixed at a 1:1 volume ratio and inoculated into the main reactor. The influent pump was started, and NO3 was introduced. - The raw water with an -N concentration of 20 mg / L was used for acclimation, and the reflux pump was turned on to maintain the main and auxiliary tank circulation mixing. The gas system was operated in "CO2 supply mode," pre-charging CO2 into the feed water until the feed water concentration reached 50 mg / L, and H2 was introduced into the membrane. The hydraulic retention time (HRT) was controlled at 80 min, and the reaction temperature at 25±1℃. Continuous operation was continued until the effluent NO3 - When the -N concentration is stable and the biofilm thickness no longer increases significantly, the initiation process is considered complete.

[0038] After the reactor stabilized, a microprobe monitoring system was used, equipped with a pH microprobe with a tip diameter of 15 μm, a signal acquisition amplifier, and a three-dimensional displacement stage. The pH distribution inside the biofilm was measured in situ at depths of 0–950 μm, perpendicular to the membrane filament surface, with a step size of 25 μm. Real-time pH data at different membrane depths were exported and substituted into the Langerile Saturation Index (LSI) formula. (In the formula, pH is the measured pH value monitored in situ within the biofilm, and pHs is the pH value under saturation.) The calculation is performed simultaneously to quantitatively characterize the risk of calcium carbonate precipitation and establish a calcification early warning and dynamic regulation mechanism.

[0039] Example 1: CO2 supply methods and different pH adjustments for influent Maintain the CO2 supply mode for the influent (close valve ①, open valve ②), and replace the calcium-free influent wastewater with calcium-containing wastewater. 2+ =100 mg / L, NO3 - Simulated wastewater with -N=20 mg / L. Continuous monitoring of NO3 in the effluent. - -N and NO2 - -N concentration, pH of the mixture, and system Ca 2+ Retention rate (Ca in influent and effluent) 2+ (Concentration difference). After the operation stabilizes, in-situ pH profile detection of the biofilm in the 0-950 μm depth range is performed using a microprobe along the vertical direction of the membrane filaments in the sub-reaction tank, and the corresponding LSI index is calculated based on the in-situ pH at each depth.

[0040] like Figure 2 As shown in Figure (a), after the reactor reaches a stable operating state under the CO2 feedwater supply mode, the NO3 in the reactor... - -N removal flux is 1.40 g / (m 2 •d), and simultaneously measured the Ca in the reactor. 2+ The retention rate was 1.79 mg / L, indicating that calcium carbonate precipitation may have occurred to some extent within the biofilm. To further analyze the risk and specific location of calcium carbonate precipitation within the biofilm, a pH microprobe was used to monitor the pH distribution at different depths within the biofilm in situ, and the in-situ LSI index within the biofilm was calculated accordingly. The results are as follows: Figure 2 As shown in (b). From Figure 2 As shown in (b), although the CO2 supplied to the influent can control the pH of the mixed solution at 7.12, the pH gradually increases from the outer layer to the inner layer of the biofilm as the CO2 buffering effect weakens along the depth of the biofilm, reaching a maximum of 9.20 in the inner layer. This high pH environment in the inner layer of the biofilm also leads to the presence of more toxic NO2 in the effluent. - -N accumulated, reaching a concentration of 0.90 mg / L. LSI analysis results showed that in the middle and outer layers of the biofilm (250–950 μm), LSI values ​​were less than 0, indicating no risk of calcium carbonate precipitation; however, in the inner biofilm region (0–250 μm), LSI values ​​were close to 0, indicating the possibility of a small amount of calcium carbonate precipitation. This is related to the Ca in the reactor system. 2+ This is consistent with the phenomenon of interception.

[0041] The pH of the reactor influent was adjusted using dilute HCl / NaOH solution. Three control experiments were set up: the reactor was operated with the mixed liquor pH controlled at 7.6, 7.8, and 8.0. The in-situ distribution of LSI index in the biofilm under different mixed liquor pH values ​​was calculated. The results are as follows: Figure 3 As shown, when the pH of the mixed solution was controlled at 7.6, 7.8, and 8.0, the in-situ distribution of LSI within the biofilm showed significant differences. When pH ≥ 7.8, the LSI of the entire biofilm region was greater than 0, indicating the presence of varying degrees of Ca at all depths. 2+ There is a risk of precipitation, and this risk increases with increasing pH, consistent with literature reports that high pH conditions easily induce hardness ion precipitation. In contrast, when the pH is controlled at 7.6, the LSI of the entire biofilm region is less than 0, indicating that CaCO3 is in an unsaturated state and there is no risk of precipitation. Theoretically, further decreasing the pH could further inhibit CaCO3 precipitation. 2+ Precipitation occurs, but excessively low pH levels will lead to NO3 precipitation. - -N removal efficiency decreases, and there is a risk of secondary pollution due to excessive addition of pH adjusters. Therefore, under CO2 influent supply mode, to balance denitrification performance and sedimentation inhibition, it is recommended to control the reactor operating pH at around 7.6, which is the ideal control target.

[0042] Example 2: Intramembrane CO2 supply method Open valve ①, close valve ②, and switch to the in-membrane CO2 supply mode. Adjust the H2 and CO2 pressure valves to mix them at a ratio of 5.2:1 and then directly introduce the mixture into the hollow fiber membrane cavity, allowing it to diffuse through the membrane wall to the biofilm. Keep the influent conditions unchanged (Ca). 2+ =100 mg / L, NO3 - -N=20 mg / L), continuous monitoring of NO3 in effluent - -N and NO2 - -N concentration, pH of the mixture, and system Ca 2+ Retention rate (i.e., influent and effluent Ca) 2+ (Concentration difference). After the operation stabilized, the same microprobe in-situ monitoring scheme as in Example 1 was used to detect the pH profile of the biofilm and calculate the corresponding LSI in-situ distribution.

[0043] like Figure 4 As shown in (a), under the in-membrane CO2 supply mode, after the reactor reaches a stable operating state, NO3... - -N removal flux increased slightly, reaching 1.41 g / (m 2 ·d), NO2 in the water - -N cumulative concentration decreased by nearly 60%, while Ca in the reactor 2+The rejection rate decreased to 0.79 mg / L. These results suggest that the intramembrane CO2 supply mode may be more effective in controlling the pH within the biofilm.

[0044] Further analysis of the risk of calcium carbonate precipitation within the biofilm yielded the following results: Figure 4 As shown in (b): Under the intramembrane CO2 supply mode, because CO2 diffuses directly from the membrane cavity to the inner layer of the biofilm, the CO2 concentration in the inner layer is higher, and the pH control efficiency decreases from the inner layer to the outer layer. Therefore, the pH in the biofilm gradually increases from 7.06 in the inner layer to 8.13 in the outer layer. The pH of the entire biofilm region is within the range of 7.06 to 8.13, which is highly consistent with the optimal denitrification pH range reported in the literature. This is consistent with the good overall denitrification performance of the reactor and the low NO2 concentration. - This is consistent with the experimental observation of a significant decrease in -N accumulation. LSI analysis results showed that the LSI value was less than 0 throughout the entire biofilm region, indicating no risk of calcium carbonate precipitation. Approximately 0.8 mg / L of Ca still remained in the system. 2+ The amount of retention, and the possible reasons for its retention include: (1) Ca 2+ (2) Ca chelates with other trace chemicals in the reactor; 2+ Physically adsorbed by biofilms or reactor walls; (3) Ca 2+ It is absorbed and utilized by microorganisms as a nutrient.

[0045] Comparing Examples 1 and 2, both CO2 supply methods can inhibit calcium carbonate precipitation through pH regulation, but the inhibition effect and denitrification performance differ. In the in-membrane CO2 supply method, CO2 diffuses from the membrane cavity outwards from the inner layer of the biofilm, stabilizing the pH across the entire biofilm region within the optimal denitrification range, resulting in superior denitrification and eliminating the risk of calcium carbonate precipitation. In the influent CO2 supply method, the CO2 buffering capacity gradually decreases from the outside in, and the inner layer of the biofilm can still generate a higher pH, leading to NO2... - -N accumulation and the risk of calcium carbonate precipitation can be avoided by adjusting the pH of the mixture.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for inhibiting biofilm calcification fouling in a hydrogen-based biofilm reactor, characterized in that, Includes the following steps: After the hydrogen-based biofilm reactor is running stably, the pH value at different depths in the biofilm is measured in situ, and the Langerier saturation index (LSI) at each depth of the biofilm is obtained according to Equation 1. Formula 1; In Equation 1, LSI is the Langerier saturation index, pH is the pH value monitored in situ within the biofilm, and pHs is the pH value corresponding to the saturation state of calcium carbonate in the water. LSI < 0, indicating that the aqueous phase of the biofilm is unsaturated with respect to calcium carbonate. 2+ Precipitation is not likely to occur; when LSI=0, calcium carbonate is just saturated, and no precipitation is formed or dissolved; when LSI>0, calcium carbonate in the aqueous phase is supersaturated and may form calcium carbonate precipitate. If LSI > 0 occurs at any point in the biofilm, it is determined that there is a risk of calcium carbonate precipitation in the biofilm. The operating conditions of the hydrogen-based biofilm reactor are then adjusted until LSI at all depths of the biofilm is ≤ 0.

2. The method according to claim 1, characterized in that, The operating conditions of the hydrogen-based biofilm reactor were adjusted until the LSI at each depth of the biofilm was <0.

3. The method according to claim 1 or 2, characterized in that, The adjustment of the operating conditions of the hydrogen-based biofilm reactor includes: adjusting the influent pH value and / or adjusting the CO2 supply method.

4. The method according to claim 3, characterized in that, The CO2 supply methods include supplying CO2 through influent or supplying CO2 within the membrane.

5. The method according to claim 1, characterized in that, The method for in-situ determination of pH values ​​at different depths within the biofilm is as follows: pH microprobes are used to measure pH values ​​at different depths perpendicular to the biofilm surface with a step size of 10~50μm.

6. The method according to claim 1, characterized in that, The hydrogen-based biofilm reactor is operated stably by supplying CO2 within the membrane.

7. The method according to claim 1, characterized in that, When adjusting the operating conditions of the hydrogen-based biofilm reactor, while ensuring that the LSI at each depth of the biofilm is ≤0 after adjustment, an adjustment method with better denitrification performance should be selected.

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