Device and method for measuring hydrogen utilization rate of anaerobic sludge

Abstract

The invention discloses a device and method for measuring the hydrogen utilization rate of anaerobic sludge, and the method comprises the following steps: adding pretreated anaerobic sludge into a reactor, and adding a buffer solution to adjust the pH value; the height-diameter ratio of the reactor is 2.5-3.5; introducing hydrogen into the reactor; circularly introducing hydrogen into the sludge in the reactor through a microporous aeration device, and stirring the sludge at the same time; headspace pressure is monitored through a micromanometer, and nitrogen is injected to enable the pressure in the reactor to be balanced with the atmospheric pressure; headspace gas is collected regularly, the hydrogen concentration is measured through a gas chromatograph, and the hydrogen utilization rate is calculated according to the hydrogen consumption, the sludge volume and time. By designing the constant-pressure constant-volume device and combining the height-diameter ratio reactor, the micropore aeration system and the pressure balance technology, the hydrogen utilization rate is accurately measured, and the regulation and control mechanism of the sludge concentration and the hydrogen partial pressure on the HOR is disclosed.

Description

Technical Field

[0001] The present invention relates to the technical field of anaerobic digestion for methane production, and particularly to an apparatus and method for measuring the hydrogen utilization rate of anaerobic sludge. Background Art

[0002] During the anaerobic digestion process, methanogenic archaea in the methanogenesis stage are mainly divided into two categories. One is acetate-utilizing methanogens, which can convert acetate into methane, and the other is hydrogenotrophic methanogens, which can convert H2 / CO2 into methane. Acetate-utilizing methanogens play a major role in methane production, and about 70% of methane is generated by the conversion of acetate. However, the status of hydrogenotrophic methanogens in the anaerobic digestion system cannot be ignored. It can maintain a low hydrogen partial pressure in the anaerobic digestion system, which is very beneficial to the degradation of short-chain fatty acids. Studies have found that adding hydrogenotrophic methanogens to the anaerobic digestion system can increase the degradation rates of propionate and butyrate. Therefore, in the anaerobic system, enriching hydrogenotrophic methanogens will improve the degradation efficiency of volatile fatty acids (VFAs). However, few studies have focused on developing an effective anaerobic process by enriching hydrogenotrophic methanogens. Therefore, it is very necessary to measure the activity of hydrogenotrophic methanogens to reflect their ability to regulate the hydrogen partial pressure in the reactor.

[0003] The microbial activities of different microbial groups in the anaerobic digestion process can be evaluated using a variety of indicators. However, few studies have focused on determining the activity of hydrogenotrophic methanogens. Gjizen proposed a test for hydrogenotrophic methanogenic activity using formic acid as a substrate (Gijzen J H, Bernal E, Ferrer H. Cyanide toxicity and cyanide degradation in anaerobic wastewater treatment[J]. Water Research, 2000, 34(9): 2447-2454.); however, the consumption rate of formic acid cannot directly reflect the metabolic rate of hydrogenotrophic methanogens for hydrogen. Leu et al. developed a kinetic model based on the dual-factor Monod relationship to evaluate the utilization rate of H2 / CO2 by hydrogenotrophic methanogenic archaea, and the predicted values were in good agreement with the experimental values. However, the determination and optimization of model parameters and subsequent model solution and verification were relatively difficult and time-consuming (Jyh-Yih Leu, Yen-Hui Lin, Fuh-Long. Chang Conversion of CO2 into CH4 by methane-producing bacterium FJ10 under a pressurized condition[J] Chemical Engineering Research and Design, 2011, 89(9): 1879-1890). Coates et al. developed a method for measuring the hydrogenotrophic methanogenic activity of anaerobic sludge by detecting the manometric changes in the headspace pressure (John, C.D., Coughlanb, M.F., Colleranb, E. Simple method for the measurement of the hydrogenotrophic methanogenic activity of anaerobic sludges[J]. J Microbiol Methods, 1996, 26: 237-246.). Although this manometric test is easy to perform, it cannot accurately reflect the actual activity of hydrogenotrophic methanogens because the balance between the dissolution and evacuation of CO2 cannot be controlled. Bicarbonate in the inoculum may lead to an excess of CO2 during the experiment. In addition, residual organic matter in the inoculum also produces excessive CO2. This leads to changes in the liquid-gas equilibrium of CO2 in the test bottle. Therefore, a simple and more reliable test method for the activity of hydrogenotrophic methanogens should be developed. Summary of the Invention

[0004] The present invention aims to overcome the above problems existing in the testing methods for the activity of hydrogenotrophic methanogens in the prior art, and provides a device and method for measuring the hydrogen utilization rate of anaerobic sludge. By designing a constant-pressure and constant-volume device, combining a high aspect ratio reactor, a microporous aeration system and a pressure balance technology, the above problems are solved, the accurate measurement of the hydrogen utilization rate (HUR) is achieved, and the regulation mechanism of sludge concentration and hydrogen partial pressure on HUR is revealed.

[0005] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for measuring the hydrogen utilization rate of anaerobic sludge, comprising the following steps: (A) Pretreat the anaerobic sludge; (B) Add the pretreated sludge to the reactor, and add a buffer solution to adjust the pH; the aspect ratio of the reactor is 2.5 - 3.5; (C) Introduce hydrogen into the reactor and discharge an equal volume of liquid to maintain a constant volume; (D) Circulate hydrogen into the sludge in the reactor through a microporous aeration device, and stir the sludge at the same time; (E) Monitor the headspace pressure through a micro-pressure gauge, and inject nitrogen to balance the pressure in the reactor with the atmospheric pressure; (F) Regularly collect the headspace gas, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate according to the hydrogen consumption, sludge volume and time.

[0006] The present invention uses a reactor with a relatively large aspect ratio (H / D = 2.5 - 3.5) for measurement, which can extend the residence time of hydrogen in the reactor; moreover, the present invention uses a microporous aeration device to circulate and aerate hydrogen in the reactor. The microporous aerator can disperse hydrogen into water in very fine bubbles, increasing the area of the liquid / gas interface and improving the mass transfer rate of hydrogen, thereby improving the accuracy of the detection results. At the same time, the present invention can eliminate the influence of CO2 dissolution on the measurement of the headspace gas pressure by adjusting the pressure in the reactor in real time with inert gas nitrogen and a micro-pressure gauge, improving the accuracy of the hydrogen partial pressure measurement.

[0007] The present invention reveals the regulation relationship between the activity of hydrogenotrophic methanogens and the system hydrogen partial pressure by experimentally analyzing the changes in HUR under different sludge concentrations and hydrogen partial pressure conditions, providing a theoretical basis for optimizing the anaerobic digestion process. Moreover, the present invention can quickly obtain the hydrogen utilization rate (HUR) through regular sampling and analysis using a gas chromatograph in combination with a simplified calculation formula, without the need for a complex kinetic model or long-time data processing (the traditional method requires several days of parameter optimization), and the operation is simple. It is not only applicable to the research of anaerobic sludge at the laboratory scale, but also can be extended to industrial sewage treatment plants and biogas projects, with high practical application value.

[0008] Preferably, the pretreatment method in step (A) is as follows: after washing the anaerobic sludge with anaerobic water, it is acclimated at 35 ± 2 °C for 8 - 12 h. Pretreating the anaerobic sludge can completely consume the residual substrate and improve the accuracy of the test results.

[0009] Preferably, in step (B), a buffer solution is added to adjust the pH of the sludge to 6.8 - 7.2.

[0010] Preferably, the buffer solution in step (B) contains the following components: 0.1 - 0.3 g / L NH4Cl, 0.05 - 0.1 g / L KH2PO4, 1.0 - 3.0 g / L NaHCO3.

[0011] Preferably, the sludge concentration in the reactor in step (B) is 0.5 - 1.0 gVSS / L.

[0012] Preferably, in step (D), the gas circulation ratio of the microporous aeration device is 1.5 - 2.5:1, the average bubble diameter is 50 - 100 μm; the stirring rate is 120 - 150 rpm.

[0013] Preferably, the calculation formula for the hydrogen utilization rate in step (F) is: where HUR is the hydrogen utilization rate; V H2 is the cumulative hydrogen consumption, mL; V R is the amount of sludge added to the anaerobic bottle, L; VSS is the volatile suspended solid content of the sludge used, g / L; t is the time, h.

[0014] Preferably, the gas chromatography conditions in step (F) are: Chromatographic column: TDX - 01; Carrier gas: argon, flow rate 45 - 50 mL / min; Temperature setting: injection port 75 - 85 °C, column oven 95 - 105 °C, detector 95 - 105 °C; Detector type: TCD.

[0015] In a second aspect, the present invention provides a device for measuring the hydrogen utilization rate of anaerobic sludge, comprising: A reactor; A magnetic stirring device, provided at the bottom of the reactor, for mixing the reaction solution; A microporous aeration device, connected to the reactor through a peristaltic pump, for dispersing hydrogen into the liquid phase in the form of microbubbles; A pressure balance system, including a micromanometer and a nitrogen supply device, is used to monitor and adjust the gas pressure in the reactor in real time; A gas circulation system realizes the circulating flow of the headspace gas in the reactor through a peristaltic pump.

[0016] Preferably, an airtight rubber diaphragm and a gas sampling port are provided at the top of the reactor, and the sampling port is connected to a gas chromatograph through a pressure-resistant conduit.

[0017] Therefore, the present invention has the following beneficial effects: (1) By combining the design of the reactor aspect ratio with the microporous aeration device, the mass transfer efficiency of hydrogen is significantly improved; (2) Through the pressure balance system composed of inert gas N2 and a micromanometer, the internal pressure of the reactor is adjusted in real time to maintain consistency with the atmospheric pressure, eliminating the interference of CO2 dissolution and improving the data accuracy; (3) By regularly sampling and analyzing with a gas chromatograph and combining a simplified calculation formula, the hydrogen utilization rate can be quickly obtained without a complex kinetic model or long-time data processing; (4) By controlling the hydrogen partial pressure by adjusting the hydrogen injection amount and combining with the HUR measurement, the activity change law of hydrogenotrophic methanogens is clarified, and the regulation mechanism of hydrogen partial pressure and microbial activity is revealed. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the device for measuring the hydrogen utilization rate of anaerobic sludge in the present invention.

[0019] Figure 2 It is the hydrogen utilization rate test curve of the present invention. Detailed Embodiments

[0020] The following further describes the present invention in combination with the drawings and specific embodiments.

[0021] In the present invention, unless otherwise specified, all devices and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in this field.

[0022] In order to further understand the present invention, the preferred implementation embodiments of the present invention are described below in combination with specific embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0023] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0024] Secondly, the so-called "one embodiment" or "embodiment" herein refers to specific features, structures or characteristics that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or selectively exclusive embodiments from other embodiments.

[0025] General embodiment: The device for measuring the hydrogen utilization rate of anaerobic sludge used in each embodiment of the present invention, such as Figure 1 shown, includes: Reactor 1, the reactor is made of glass, with a volume of 1.0 L and a height-to-diameter ratio of 3 (H / D = 3); a sealing plug 5 is provided at the top of the reactor. A magnetic stirring device 2 is provided at the bottom of the reactor, and a rotor 4 matching the magnetic stirring device is provided at the bottom inside the reactor. A microporous aeration device 3 is also provided at the bottom inside the reactor, and the microporous aeration device is connected to the top of the reactor through a peristaltic pump 6 and a pipeline. A U-shaped micro manometer 9 and a nitrogen gas bag 7 are provided at the top of the reactor, and the U-shaped micro manometer and the nitrogen gas bag are connected to the top of the reactor through a pipeline; a gas sampling port 10 is provided on the pipeline connecting the peristaltic pump to the top of the reactor, and control valves 8 are provided on the pipelines connecting the gas sampling port and the nitrogen gas bag to the top of the reactor.

[0026] Example 1: A method for measuring the hydrogen utilization rate of anaerobic sludge includes the following steps: (A) Pretreat the anaerobic sludge: Wash the anaerobic sludge with anaerobic water and acclimatize it at 35 °C for 10 h; (B) Add the pretreated sludge into the reactor, and add a buffer solution to adjust the pH of the sludge to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3; the sludge concentration is 0.5 gVSS / L. Seal the reactor with an airtight rubber diaphragm; (C) Introduce 400 mL of hydrogen into the reactor and discharge an equal volume of anaerobic sludge; (D) Turn on the peristaltic pump and circulate hydrogen into the sludge in the reactor through the microporous aeration device. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm; at the same time, turn on the magnetic stirring device to stir the sludge; (E) Monitor the headspace pressure through the U-shaped micro manometer and inject nitrogen through the control valve to balance the pressure inside the reactor with the atmospheric pressure; (F) Take samples of the headspace gas every 0.5 hour, use a gas chromatograph to measure the hydrogen concentration, and calculate the hydrogen utilization rate. The results are shown in Table 1 and Figure 2As shown; at the end of the HUR test, volatile suspended solids (VSS) were determined gravimetrically to calculate the biomass present in the reactor; the gas-phase volume percentage (C H2 ) of hydrogen was calculated by gas chromatography data processing software, and the hydrogen partial pressure (PH2) was calculated using the formula: PH2 = 101325 × C H2 .

[0027] A gas chromatograph from BEIFEN Corp. 3420A was used, and the gas chromatography conditions were as follows: Carrier gas: argon, flow rate 49.9 mL / min; Chromatographic column: Lanzhou Chemical Industry Company TDX-01 (3 mm × 2 m); Detector: thermal conductivity detector (TCD); Determination conditions: injection port temperature 80 °C, column oven temperature 100 °C, detector temperature 100 °C; The headspace gas in the reactor was sampled using a 500 mL pressure-lock syringe and then directly injected into the chromatographic column through a septum.

[0028] The formula for calculating the hydrogen utilization rate is: where HUR is the hydrogen utilization rate; V H2 is the cumulative hydrogen consumption, mL; V R is the amount of sludge added to the anaerobic bottle, L; VSS is the volatile suspended solid content of the sludge used, g / L; t is the time, h.

[0029] Example 2: A method for determining the hydrogen utilization rate of anaerobic sludge, comprising the following steps: (A) Pretreat the anaerobic sludge: wash the anaerobic sludge with anaerobic water and acclimatize it at 35 °C for 10 h; (B) Add the pretreated sludge to the reactor, and add a buffer solution to adjust the sludge pH to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3; the sludge concentration is 0.75 g VSS / L. Seal the reactor with an airtight rubber diaphragm; (C) Pass 400 mL of hydrogen into the reactor and displace an equal volume of anaerobic sludge; (D) Turn on the peristaltic pump and circulate hydrogen through the sludge in the reactor through a microporous aeration device. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm; at the same time, turn on the magnetic stirring device to stir the sludge; (E) Monitor the headspace pressure through a U-shaped manometer, and inject nitrogen through a control valve to balance the pressure in the reactor with the atmospheric pressure; (F) Take a sample of the headspace gas every 0.5 hours, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate. The results are shown in Table 1 and Figure 2 as shown below; The calculation method and gas chromatographic conditions are the same as those in Example 1.

[0030] Example 3: A method for measuring the hydrogen utilization rate of anaerobic sludge, comprising the following steps: (A) Pretreat the anaerobic sludge: Wash the anaerobic sludge with anaerobic water and acclimatize it at 35 °C for 10 h; (B) Add the pretreated sludge to the reactor, and add a buffer solution to adjust the sludge pH to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3; The sludge concentration is 1.0 gVSS / L. Seal the reactor with an airtight rubber diaphragm; (C) Introduce 400 mL of hydrogen into the reactor and discharge an equal volume of anaerobic sludge; (D) Turn on the peristaltic pump and circulate hydrogen through the microporous aeration device into the sludge in the reactor. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm; At the same time, turn on the magnetic stirring device to stir the sludge; (E) Monitor the headspace pressure through a U-shaped manometer, and inject nitrogen through a control valve to balance the pressure in the reactor with the atmospheric pressure; (F) Take a sample of the headspace gas every 0.5 hours, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate. The results are shown in Table 1 and Figure 2 as shown below; The calculation method and gas chromatographic conditions are the same as those in Example 1.

[0031] Example 4: A method for measuring the hydrogen utilization rate of anaerobic sludge, comprising the following steps: (A) Pretreat the anaerobic sludge: Wash the anaerobic sludge with anaerobic water and acclimatize it at 35 °C for 10 h; (B) Add the pretreated sludge to the reactor, and add a buffer solution to adjust the sludge pH to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3; The sludge concentration is 1.5 gVSS / L. Seal the reactor with an airtight rubber diaphragm; (C) Introduce 400 mL of hydrogen into the reactor and discharge an equal volume of anaerobic sludge; (D) Turn on the peristaltic pump and circulate hydrogen gas into the sludge in the reactor through the microporous aeration device. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm. At the same time, turn on the magnetic stirring device to stir the sludge. (E) Monitor the headspace pressure through a U-shaped manometer and inject nitrogen gas through the control valve to balance the pressure in the reactor with the atmospheric pressure. (F) Take samples of the headspace gas every 0.5 hours, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate. The results are shown in Table 1 and Figure 2 as shown therein; the calculation method and gas chromatographic conditions are the same as those in Example 1.

[0032] Example 5: A method for measuring the hydrogen utilization rate of anaerobic sludge, comprising the following steps: (A) Pretreat the anaerobic sludge: Wash the anaerobic sludge with anaerobic water and acclimatize it at 35 °C for 10 h. (B) Add the pretreated sludge to the reactor and add a buffer solution to adjust the pH of the sludge to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3. The sludge concentration is 2.0 gVSS / L. Seal the reactor with an airtight rubber diaphragm. (C) Introduce 400 mL of hydrogen gas into the reactor and discharge an equal volume of anaerobic sludge. (D) Turn on the peristaltic pump and circulate hydrogen gas into the sludge in the reactor through the microporous aeration device. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm. At the same time, turn on the magnetic stirring device to stir the sludge. (E) Monitor the headspace pressure through a U-shaped manometer and inject nitrogen gas through the control valve to balance the pressure in the reactor with the atmospheric pressure. (F) Take samples of the headspace gas every 0.5 hours, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate. The results are shown in Table 1 and Figure 2 as shown therein; the calculation method and gas chromatographic conditions are the same as those in Example 1.

[0033] Comparative Example 1 (the reactor has a relatively small height-to-diameter ratio): The difference between Comparative Example 1 and Example 1 is that a reactor with a height-to-diameter ratio of 2 is used, and the rest are the same as those in Example 1. The test results of the hydrogen utilization rate of Comparative Example 1 are shown in Table 1.

[0034] Comparative Example 2 (the gas circulation ratio of the microporous aeration device is not within the scope of the present invention): The difference between Comparative Example 3 and Example 1 is that the gas circulation ratio of the microporous aeration device is 4:1; the rest are the same as in Example 1; the test results of the hydrogen utilization rate of Comparative Example 2 are shown in Table 1.

[0035] Comparative Example 3 (without introducing nitrogen to maintain air pressure balance): A method for measuring the hydrogen utilization rate of anaerobic sludge includes the following steps: (A) Pretreat the anaerobic sludge: Wash the anaerobic sludge with anaerobic water and acclimatize it at 35°C for 10 h; (B) Add the pretreated sludge to the reactor, and add a buffer solution to adjust the pH of the sludge to 7.0. The buffer solution contains the following components: 0.2 g / L NH4Cl, 0.08 g / L KH2PO4, 2.0 g / L NaHCO3; the sludge concentration is 0.5 gVSS / L. Seal the reactor with an airtight rubber diaphragm; (C) Introduce 400 mL of hydrogen into the reactor and discharge an equal volume of anaerobic sludge; (D) Turn on the peristaltic pump and circulate hydrogen into the sludge in the reactor through the microporous aeration device. The gas circulation ratio of the microporous aeration device is 2:1, and the average bubble diameter is 80 μm; at the same time, turn on the magnetic stirring device to stir the sludge; (E) Take samples of the headspace gas every 0.5 h, measure the hydrogen concentration using a gas chromatograph, and calculate the hydrogen utilization rate. The results are shown in Table 1.

[0036] Hydrogen has poor solubility in water and a low mass transfer coefficient. The hydrogen concentration in the liquid phase will limit the methane production rate. To ensure the measurement of the maximum hydrogen utilization rate of methanogens, the hydrogen mass transfer rate to the liquid phase needs to ensure that the liquid phase hydrogen concentration does not limit the methane production kinetic process. The hydrogen mass transfer rate equation under steady state is: dc / dt=K La (c*-c) where, dc / dt is the hydrogen mass transfer rate; K La is the total mass transfer coefficient; c* is the equilibrium concentration of hydrogen in the bulk liquid phase; c is the hydrogen concentration in the bulk liquid phase; (c*-c) is the gas-liquid total mass transfer driving force.

[0037] Thus, it can be seen that K La is an important factor affecting the hydrogen mass transfer rate. The calculation method of K La is: ([gas] L / [gas] L* )-1=Q V / K H RTKLa K H is the Henry's law constant; R is the ideal gas constant; T is the Kelvin temperature; K La is the overall mass transfer coefficient; [gas] L is the concentration of the dissolved gas substance in the reactor; [gas] L* is the concentration of the dissolved gas substance in the reactor at thermodynamic equilibrium; Qv is the volumetric gas production rate.

[0038] The value of K proposed by Frigon and Guiot La 4.11 ± 2.62 h -1 is used to calculate the theoretical values of HUR in the above examples and comparative examples, and the results are shown in Table 1.

[0039] The calculation method of the theoretical value is: HUR* = (dc / dt) × (V / Xv); where, dc / dt is the hydrogen mass transfer rate; V is the headspace volume; Xv is the microbial biomass in the reaction flask.

[0040] Table 1: Test results of hydrogen utilization rate.

[0041] From Table 1 and Figure 2 the results, it can be seen that as the sludge concentration increases, HUR gradually decreases. When the sludge concentration is 1 g VSS / L, the HUR rate reaches the maximum value. As the sludge concentration continues to decrease, the HUR value basically remains unchanged. Through repeated experiments, it is determined that 1 g VSS / L is the critical concentration for the maximum sludge measurement, that is, when the experimental conditions have a sludge concentration lower than the critical concentration, the measured HUR is the maximum hydrogen utilization rate of anaerobic sludge. This phenomenon indicates that if the sludge concentration exceeds the threshold point, hydrogen mass transfer will be restricted, and a smaller sludge HUR value will be measured. The absorption rate of hydrogen by microorganisms is not limited by the amount of hydrogen, and the key lies in the sludge concentration.

[0042] From the comparison between the measured values of HUR and the theoretical values, it can be seen that the calculated value of HUR is greater than the experimental value. Therefore, the experimental results are reliable, and the experimental method of the HUR test is technically feasible. In Comparative Example 1, a reactor with a relatively small height-to-diameter ratio was used, resulting in a shorter residence time of hydrogen in the liquid phase, insufficient residence time for hydrogen to transfer to the liquid phase, a decrease in the mass transfer coefficient, and thus an impact on the measured value. In Comparative Example 2, the gas circulation ratio of the microporous aeration device was not within the scope of the present invention, resulting in a lower mass transfer rate of hydrogen, limited rate of hydrogen transfer from the gas phase to the liquid phase, and thus limited methane production rate. The measured value was not the maximum hydrogen utilization rate of the sludge. In Comparative Example 3, nitrogen was not introduced to maintain the pressure balance, and the influence of CO2 dissolution on the measurement of the headspace gas pressure could not be eliminated. After consuming hydrogen, the headspace pressure continuously decreased, and the pressure inside the bottle was less than the atmospheric pressure, which would cause the sludge to be sucked back and the measurement could not be carried out.

[0043] The present invention uses a reactor with a relatively large height-to-diameter ratio (H / D = 2.5 - 3.5) for measurement, which can extend the residence time of hydrogen in the reactor. Moreover, the present invention uses a microporous aeration device to circulate and aerate hydrogen in the reactor. The microporous aerator can disperse hydrogen into water in the form of very fine bubbles, increasing the area of the liquid / gas interface and improving the mass transfer rate of hydrogen, thereby improving the accuracy of the detection results. At the same time, the present invention can eliminate the influence of CO2 dissolution on the measurement of the headspace gas pressure by using the inert gas nitrogen and a micromanometer to adjust the pressure inside the reactor in real time, improving the accuracy of the hydrogen partial pressure measurement.

[0044] Test on the influence of hydrogen partial pressure on hydrogen utilization rate: The sludge samples used in the test were taken from 5 anaerobic reactors treating different wastewaters. Before the test, all sludge samples were washed with anaerobic water to remove residual organic substrates and cultured at 35°C for 8 - 12 h. The influence of hydrogen partial pressure on hydrogen utilization rate was measured, and the results are shown in Table 2.

[0045] Table 2: Test results of the influence of hydrogen partial pressure on hydrogen utilization rate. Sludge source Hydrogen partial pressure (Pa) HUR (gCOD / (gVSS·d) CSTR 89.02±1.42 0.83±0.16 UASB1 27.39±0.74 1.41±0.19 UASB2 7.54±0.12 2.73±0.35 UASB3 5.22±0.28 2.54±0.28 UASB4 2.83±0.19 1.81±0.23

[0046] As can be seen from Table 2, hydrogenotrophic methanogens play a key role in the anaerobic system. Hydrogenotrophic methanogens can utilize H2 / CO2 to produce methane, maintaining the hydrogen partial pressure in the anaerobic system at a relatively low level (P H2(<10 Pa), thereby increasing the degradation rate of intermediate products such as VFA. When the hydrogen partial pressure in the system is greater than 10 Pa, the hydrogen partial pressure in the anaerobic biological treatment system with a higher HUR is lower. As the hydrogen partial pressure in the reactor continues to decrease (<10 Pa), the sludge HUR also shows a decreasing trend, which seems to contradict the above inference. The main reason for this result is that hydrogen, as a substrate directly utilizable by methanogens, the higher its concentration, the more conducive it is to the growth and metabolism of hydrogenotrophic methanogens. On the contrary, the lower the hydrogen partial pressure, the smaller the yield of hydrogenotrophic methanogens, so that the proportion of hydrogenotrophic methanogens in anaerobic sludge is smaller, and the measured HUR of anaerobic sludge can also reflect that the proportion of hydrogenotrophic methanogens in anaerobic sludge is smaller. The experimental results show that the hydrogen partial pressure of the system can be reduced by increasing the hydrogen utilization rate of the sludge, thereby increasing the degradation rate of VFA and ensuring the efficient progress of the anaerobic biological treatment process.

[0047] As described above, only the preferred embodiments of the present invention are provided, and there is no limitation in any form and substance to the present invention. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any equivalent changes made by those skilled in the art who are familiar with this specialty without departing from the spirit and scope of the present invention by making some changes, modifications and evolutions using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for measuring the hydrogen utilization rate of anaerobic sludge, characterized in that It includes the following steps: (A)Pre-treat the anaerobic sludge; (B)Add the pre-treated sludge into the reactor, and add a buffer solution to adjust the pH; the height-diameter ratio of the reactor is 2.5 - 3.5; (C)Introduce hydrogen into the reactor, and discharge an equal volume of liquid to maintain a constant volume; (D)Circulate hydrogen into the sludge in the reactor through a microporous aeration device, and stir the sludge simultaneously; (E)Monitor the headspace pressure through a micro manometer, and inject nitrogen to balance the pressure in the reactor with the atmospheric pressure; (F)Regularly collect the headspace gas, use a gas chromatograph to measure the hydrogen concentration, and calculate the hydrogen utilization rate according to the hydrogen consumption, sludge volume and time.

2. The method for determining the hydrogen utilization rate of anaerobic sludge according to claim 1, characterized in that The pre-treatment method in step (A) is: After washing the anaerobic sludge with anaerobic water, acclimatize it at 35 ± 2 °C for 8 - 12 h.

3. The method for measuring the hydrogen utilization rate of anaerobic sludge according to claim 1, characterized in that, In step (B), add a buffer solution to adjust the pH of the sludge to 6.8 - 7.

2.

4. The method for measuring the hydrogen utilization rate of anaerobic sludge according to claim 1 or 3, characterized in that, The buffer solution in step (B) contains the following components: 0.1 - 0.3 g / L NH4Cl, 0.05 - 0.1 g / L KH2PO4, 1.0 - 3.0 g / L NaHCO3.

5. The method for measuring the hydrogen utilization rate of anaerobic sludge according to claim 1 or 3, characterized in that, In step (B), the sludge concentration in the reactor is 0.5 - 1.0 gVSS / L.

6. The method for measuring the hydrogen utilization rate of anaerobic sludge according to claim 1, characterized in that, In step (D), the gas circulation ratio of the microporous aeration device is 1.5 - 2.5:1, the average bubble diameter is 50 - 100 μm; the stirring rate is 120 - 150 rpm.

7. The method for measuring the hydrogen utilization rate of anaerobic sludge according to claim 1, characterized in that, The gas chromatographic conditions in step (F) are: Chromatographic column: TDX-01; Carrier gas: argon, flow rate 45 - 50 mL / min; Temperature setting: injection port 75 - 85 °C, column oven 95 - 105 °C, detector 95 - 105 °C; Detector type: TCD.

8. An apparatus for measuring the hydrogen utilization rate of anaerobic sludge, characterized in that, It includes: A reactor; A magnetic stirring device, arranged at the bottom of the reactor, for mixing the reaction liquid; A microporous aeration device, connected to the reactor through a peristaltic pump, for dispersing hydrogen into the liquid phase in the form of microbubbles; A pressure balancing system, including a micro manometer and a nitrogen supply device, for real-time monitoring and adjusting the gas pressure in the reactor; A gas circulation system, realizing the cyclic flow of the headspace gas in the reactor through a peristaltic pump.

9. The device for measuring the hydrogen utilization rate of anaerobic sludge according to claim 8, wherein, An airtight rubber diaphragm and a gas sampling port are provided at the top of the reactor.

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