阅读说明：本技术 一种自动测定可生物降解材料好氧呼吸量的方法及系统 (Method and system for automatically measuring aerobic respiration of biodegradable material ) 是由 彭伟 何品晶 吕凡 章骅 邵立明 于 2021-08-13 设计创作，主要内容包括：本发明涉及一种自动测定可生物降解材料好氧呼吸量的方法及系统,系统包括培养装置、检测装置、换气装置和控制装置；培养装置用于进行可生物降解材料的培养；检测装置通过气体检测循环管路与培养装置连接,用于检测培养装置内气体含量；换气装置通过换气管路与培养装置连接,用于更换培养装置内部气体；控制装置与检测装置和换气装置电连接,用于接收检测装置的电信号并控制换气装置的启停。与现有技术相比,本发明具有适应多源物料、测试结果稳定可靠、测试时间短、测试结果接近实际、成本低廉、环境友好等优点,可以适用于各类可生物降解物料及其处理产物最终处置或资源化利用前评估生物稳定性等场景。(The invention relates to a method and a system for automatically measuring aerobic respiration of a biodegradable material, wherein the system comprises a culture device, a detection device, a ventilation device and a control device; the culture device is used for culturing the biodegradable material; the detection device is connected with the culture device through a gas detection circulating pipeline and is used for detecting the gas content in the culture device; the air interchanger is connected with the culture device through an air interchanging pipeline and is used for replacing the gas in the culture device; the control device is electrically connected with the detection device and the air interchanger and is used for receiving the electric signal of the detection device and controlling the air interchanger to start and stop. Compared with the prior art, the method has the advantages of adaptability to multi-source materials, stable and reliable test results, short test time, test results close to reality, low cost, environmental friendliness and the like, and can be applied to scenes of evaluating biological stability and the like before final disposal or resource utilization of various biodegradable materials and treatment products thereof.)

1. A system for automatically measuring aerobic respiration volume of biodegradable material is characterized by comprising a culture device, a detection device, a ventilation device and a control device;

the culture device is used for culturing the biodegradable material (2);

the detection device is connected with the culture device through a gas detection circulating pipeline (9) and is used for detecting the gas content in the culture device;

the air interchanger is connected with the culture device through an air interchanging pipeline (10) and is used for replacing the gas in the culture device;

the control device is electrically connected with the detection device and the air interchanger and is used for receiving the electric signal of the detection device and controlling the air interchanger to start and stop.

2. The system for automatically determining aerobic respiration rate of biodegradable material according to claim 1, wherein the culture device comprises a culture flask (1); preferably, the culture device further comprises a constant-temperature incubator, and the culture bottle (1) is placed inside the constant-temperature incubator.

3. The system for automatically measuring the aerobic respiration rate of biodegradable materials according to claim 1, wherein the gas detection circulation pipeline (9) is connected with the internal space of the culture device at the head end and the tail end to form a circulation loop; preferably, the detection device comprises a volumetric pump (3) and a gas concentration detector (4), and the volumetric pump (3) and the gas concentration detector (4) are connected to a gas detection circulating pipeline (9); preferably, the gas concentration detector (4) is an oxygen sensor or a carbon dioxide sensor.

4. The system for automatically determining the aerobic respiration rate of biodegradable materials according to claim 1, wherein the ventilation pipeline (10) comprises a gas supply section (101) and a gas exhaust section (102) connected to the culture device, and the gas outlet end of the gas supply section (101) and the gas inlet end of the gas exhaust section (102) are connected with the internal space of the culture device; preferably, the ventilation device comprises a gas supply device (6) and a water washing bottle (7) which are sequentially arranged on the gas supply section (101) along the gas flowing direction, and a water sealing bottle (8) arranged at the gas outlet end of the gas exhaust section (102); preferably, the air supply device (6) comprises an air pump, a volumetric pump or an electromagnetic valve, when the air supply device (6) is the volumetric pump, the air supply device further comprises an air bag loaded with air or oxygen and connected to the air inlet end of the volumetric pump, and when the air supply device (6) is the electromagnetic valve, the air supply device further comprises a compressed air tank loaded with compressed air or compressed oxygen and connected to the air inlet end of the electromagnetic valve.

5. The system for automatically determining the aerobic respiration rate of biodegradable materials according to claim 1, wherein the control device is a PLC (5);

the PLC (5) is electrically connected with the gas concentration detector (4) and the gas supply equipment (6) and is used for recording the gas concentration value measured by the gas concentration detector (4) in real time and controlling the operation of the gas supply equipment (6);

and the PLC (5) is also provided with a data transmission module for receiving external data and sending recorded data.

6. A method for automatically measuring aerobic respiration of a biodegradable material, wherein the system of any one of claims 1 to 5 is adopted, and comprises the following steps:

s1: collecting a sample of the biodegradable material (2), adjusting the water content, and adding the sample into a culture device;

s2: measuring the concentration of the gas to be detected in the culture device by the detection device;

s3: when the concentration of the detected gas exceeds a preset threshold value, starting the ventilation device to ventilate, restoring the concentration of the detected gas in the culture device to the concentration level of the detected gas in normal atmosphere, and simultaneously exhausting waste gas in the culture device; stopping ventilation when the concentration of the detected gas is recovered;

s4: the control device records and stores the value of the concentration of the detected gas in the culture device in real time, and the value of the aerobic respiration volume of the biodegradable material (2) in the test time is calculated according to the change of the concentration of the detected gas and the volume of the headspace of the culture device.

7. The method for automatically determining the aerobic respiration rate of biodegradable materials according to claim 6, wherein step S1 comprises any one or more of the following conditions:

(i) the biodegradable material (2) is a solid residue of biomass waste after anaerobic digestion, aerobic fermentation and/or insect cultivation of the biomass waste,

the biodegradable material (2) is food and/or plant residues in domestic garbage, livestock manure and/or crop residues in agricultural waste, sludge in municipal sewage treatment plants, degradable polymers or soil;

(ii) after a biodegradable material (2) sample is collected, adjusting the water content to 40-60 wt%;

(iii) the culture device is in a constant temperature environment of 20-70 ℃.

8. The method for automatically measuring the aerobic respiration rate of biodegradable material according to claim 6, wherein in step S2, when the detecting device measures the concentration of the gas to be detected in the culture device, the circulation rate of the gas in the culture device in the gas detection circulation line (9) is controlled to be 0.1-0.5L/min.

9. The method of claim 6, wherein in steps S2 and S3, the detected gas is oxygen or carbon dioxide;

when the detected gas is oxygen, the preset threshold value of the detected gas is 15-18% of the lower limit value of the oxygen concentration, and when the oxygen concentration is reduced to the lower limit value, the ventilation device is started to ventilate, so that the oxygen concentration in the culture device is restored to the oxygen concentration level in normal atmosphere;

when the detected gas is carbon dioxide, the preset threshold value of the detected gas is 6% of the upper limit value of the carbon dioxide concentration, and when the carbon dioxide concentration is increased to the upper limit value, the ventilation device is started to ventilate, so that the carbon dioxide concentration in the culture device is recovered to be lower than 1%.

10. The method for automatically determining the aerobic respiration rate of biodegradable material according to claim 6, wherein in step S4, the testing time is 4-7 days.

Technical Field

The invention belongs to the field of environmental protection and comprehensive utilization of resources, and particularly relates to a method and a system for automatically measuring aerobic respiration of a biodegradable material.

Background

Biodegradable materials such as kitchen waste are usually treated by anaerobic digestion, aerobic fermentation or insect breeding process. The biological stability of the biodegradable material is an important index for evaluating the biological treatment efficiency on one hand and is an important index for land utilization of the biodegradable material on the other hand. Biostability refers to the degree to which a material is stable in a particular environment, without being able to be degraded by microorganisms. The aerobic respiration of the biodegradable material can reflect the biological stability of the biodegradable material within a certain time, and in addition, the aerobic respiration of the biodegradable material can also reflect the biodegradability of the biodegradable material. For example, the final aerobic biological decomposition capability of the plastic material in the soil is measured by a method for measuring the oxygen demand in a closed respirometer or a method for measuring the released carbon dioxide in the national standard "method for measuring the final aerobic biological decomposition capability of the plastic material in the soil" (GB/T22047-2008).

At present, the index of biological stability is reflected in the national Standard "control Standard for compost contamination of Biomass waste" (promissory phase) and the local Standard "evaluation method for biological stability of Wet refuse treatment residue" (DB 31/T1208-2020). With the promulgation of these standards, there will be a large number of testing needs in the market.

Existing aerobic respiration test methods typically require the provision of an oxygen generator, which on the one hand adds significantly to the cost of the test system and on the other hand generates wastewater containing heavy metal ions such as copper ions. In the test using air as an oxygen source, the air pump is usually controlled to be opened manually, which wastes time and labor in the test process, and the accuracy of the test result is affected by manual operation. In addition, the two testing systems do not adopt humidification treatment in the process of oxygen supplementation, and the sample loses water and becomes dry in the testing process, so that the accuracy of the testing result is influenced. In recent years, some researchers have proposed methods for testing aerobic respiration rate in sewage. For example: the Chinese invention patent CN102707075A discloses an automatic biochemical oxygen consumption measuring instrument in a laboratory, which realizes automatic sample introduction and automatic cleaning of a test water sample by the cooperation of software and hardware, and reduces the workload of workers. However, the existing oxygen consumption measuring instrument is only suitable for water samples with good fluidity, and the aerobic respiration rate of solid samples has larger difference with liquid samples in the aspects of inoculation mode, sample pretreatment mode, reoxygenation mode, oxygen concentration control range, humidity maintenance and the like, so that the aerobic respiration rate of liquid samples cannot be measured.

Disclosure of Invention

The invention aims to provide a method and a system for automatically measuring the aerobic respiration of a biodegradable material, so as to realize the evaluation of biological stability before final disposal or resource utilization of various biodegradable materials and treatment products thereof. The invention has the advantages of low cost, convenient operation, small fluctuation of the water content of the material in the test process and stable and reliable test results.

The purpose of the invention is realized by the following technical scheme:

the invention provides a system for automatically measuring aerobic respiration volume of a biodegradable material, which comprises a culture device, a detection device, a ventilation device and a control device;

the culture device is used for culturing the biodegradable material;

the detection device is connected with the culture device through a gas detection circulating pipeline and is used for detecting the gas content in the culture device;

the air interchanger is connected with the culture device through an air interchanging pipeline and is used for replacing the gas in the culture device;

the control device is electrically connected with the detection device and the air interchanger and is used for receiving the electric signal of the detection device and controlling the air interchanger to start and stop.

Preferably, the culture device comprises a culture flask.

Preferably, the culture device further comprises a constant temperature incubator, and the culture bottle is placed inside the constant temperature incubator.

Preferably, the head end and the tail end of the gas detection circulation pipeline are both connected with the internal space of the culture device and form a circulation loop.

Preferably, the detection device comprises a volumetric pump and a gas concentration detector, and the volumetric pump and the gas concentration detector are connected to the gas detection circulation pipeline.

Preferably, the gas concentration detector is an oxygen sensor or a carbon dioxide sensor.

Preferably, the ventilation pipeline comprises a gas supply section and a gas exhaust section which are connected to the culture device, and the gas outlet end of the gas supply section and the gas inlet end of the gas exhaust section are connected with the inner space of the culture device.

Preferably, the ventilation device comprises a gas supply device and a water washing bottle which are sequentially arranged on the gas supply section along the gas flowing direction, and a water sealing bottle arranged at the gas outlet end of the gas exhaust section. When the air supply device is in a starting state, the air flow firstly passes through a (clear) water washing bottle and then enters the culture device, so that the humidity in the culture device is maintained. In the activated state of the gas supply device, the gas flow is discharged through a water-sealed bottle (for example, a jar using a water seal).

Preferably, the gas supply device comprises an air pump, a volumetric pump or an electromagnetic valve;

when the air supply equipment is a volumetric pump, the air supply equipment also comprises an air bag loaded with air or oxygen and connected to the air inlet end of the volumetric pump;

when the air supply equipment is an electromagnetic valve, the air supply equipment further comprises a compressed air tank loaded with compressed air or compressed oxygen and connected to the air inlet end of the electromagnetic valve.

Preferably, the control device is a PLC controller;

the PLC is electrically connected with the gas concentration detector and the gas supply equipment and is used for recording the gas concentration value measured by the gas concentration detector in real time and controlling the operation of the gas supply equipment;

the PLC is also provided with a data transmission module for receiving external data and sending recorded data.

Preferably, in the working process, the PLC is connected with a 4-20mA electric signal sent by the gas concentration detector.

Preferably, the data transmission module adopts a wireless transmission module, and can transmit the gas concentration data to the mobile terminal in real time.

Preferably, a counter can be further arranged on the PLC controller and used for recording the starting times of the pressure equipment.

Preferably, the gas detection circulation line and the ventilation line both adopt flexible pipes.

In a second aspect, the present invention provides a method for automatically determining aerobic respiration rate of biodegradable material, using the system of claim, comprising the steps of:

s1: collecting a biodegradable material sample, adjusting the water content, and adding the biodegradable material sample into a culture device;

s2: measuring the concentration of the gas to be detected in the culture device by the detection device;

s3: when the concentration of the detected gas exceeds a preset threshold value, starting the ventilation device to ventilate, restoring the concentration of the detected gas in the culture device to the concentration level of the detected gas in normal atmosphere, and simultaneously exhausting waste gas in the culture device; stopping ventilation when the concentration of the detected gas is recovered;

s4: the control device records and stores the value of the concentration of the detected gas in the culture device in real time, and the value of the aerobic respiration volume of the biodegradable material in the test time is calculated according to the change of the concentration of the detected gas and the volume of the headspace of the culture device.

Preferably, in step S1, the biodegradable material is a solid residue of the biomass waste after anaerobic digestion, aerobic fermentation and/or insect cultivation of the biomass waste;

the biodegradable material is food and/or plant residues in household garbage, livestock manure and/or crop residues in agricultural waste, sludge in municipal sewage treatment plants, degradable polymers or soil.

Preferably, in step S1, after the biodegradable material sample is collected, the water content is adjusted to 40-60 wt%;

preferably, in step S1, the culture device is in a constant temperature environment of 20-70 ℃.

Preferably, in step S2, when the detection unit detects the concentration of the gas to be detected in the culture unit, the circulation rate of the gas in the culture unit in the gas detection circulation line is controlled to be 0.1-0.5L/min.

Preferably, in steps S2 and S3, the detected gas is oxygen or carbon dioxide (the corresponding gas concentration detector is an oxygen sensor or a carbon dioxide sensor);

when the detected gas is oxygen, the preset threshold value of the detected gas refers to 15-18% (volume percentage) of the lower limit value of the oxygen concentration, and when the oxygen concentration is reduced to the lower limit value, the ventilation device is started to ventilate, so that the oxygen concentration in the culture device is restored to the oxygen concentration level in normal atmosphere;

when the detected gas is carbon dioxide, the preset threshold value of the detected gas refers to 6% (volume percentage) of the upper limit value of the carbon dioxide concentration, and when the carbon dioxide concentration is increased to the upper limit value, the ventilation device is started to ventilate, so that the carbon dioxide concentration in the culture device is restored to be lower than 1% (volume percentage).

Preferably, in step S4, the testing time is 4-7 d.

The working principle of the invention is as follows:

firstly, a biodegradable material is placed in a culture device (culture bottle) for culture, the concentration of detected gas (oxygen or carbon dioxide) in the culture device is detected in real time by a gas concentration detector, and data is transmitted to a control device (PLC), and the control device judges whether the gas concentration exceeds the range of set gas. If the oxygen concentration in the culture device is lower than the set lower limit or the carbon dioxide concentration is higher than the set upper limit, the control device automatically starts the air exchange device, air or oxygen which is wetted by a washing bottle (filled with clear water) is filled into the culture device, waste gas in the culture bottle is discharged by the water-sealed bottle, clear water is filled in the water-sealed bottle for liquid sealing, air exchange outside an exhaust stage is reduced, and the test accuracy is improved. When the gas concentration detector detects that the gas concentration in the culture bottle is recovered to a specified value (the oxygen concentration is recovered to the oxygen level in the atmosphere or the carbon dioxide concentration is lower than 1%), the control device closes the ventilation device and stops ventilation. After the culture is finished, the aerobic respiration quantity of the biodegradable material in a certain time can be calculated through the change of the gas concentration and the volume of the headspace of the culture bottle. The invention uses air as oxygen source, so that no pure oxygen or oxygen generator is introduced, thereby reducing the manufacturing cost; the automatic feedback control is utilized to realize the opening and closing of the air pump, so that the reaction rate can be improved, and the test time can be saved; setting the threshold of the oxygen concentration within a suitable range may allow for greater repeatability of the test results.

Compared with the prior art, the invention has the following beneficial effects:

1. the device can be used for evaluating the biological stability of various biodegradable materials such as organic garbage in villages and towns, feces of farm animals and landscaping garbage and the like, and provides a criterion for the final disposal mode or resource utilization way of the biodegradable materials;

2. the characteristic of high biological activity of the biodegradable material is utilized, no exogenous inoculum is required to be introduced, and the influence of the exogenous inoculum on the test accuracy is avoided;

3. the technical scheme of the invention utilizes air as an oxygen source, can reduce the manufacturing and testing cost, and can also adapt to different application scenes;

4. the oxygen concentration can be automatically recorded and stored, real-time online monitoring can be realized, and the test result has higher repeatability;

5. the invention maintains the oxygen concentration in the reactor through the gas concentration feedback control, can save the test time, reduce the test error brought by manual operation;

6. the invention realizes the opening and closing of the air pump by utilizing automatic feedback control, can improve the reaction rate of the system and save the test time;

7. the adopted aerobic respiration rate result can reflect the biological stability of the biodegradable material in the land utilization process and the influence of active organic matters on plants caused by the biodegradable material in the land utilization process.

Drawings

FIG. 1 is a schematic structural diagram of a system for automatically determining aerobic respiration of a biodegradable material according to the present invention;

FIG. 2 is a graph showing the cumulative oxygen consumption over time during the aerobic respiration test for biodegradable materials in examples 1 to 4;

FIG. 3 is a schematic diagram showing the change of the oxygen concentration with time in the aerobic respiration measurement of biogas residue in example 4;

in the figure: 1-culture flask; 2-a biodegradable material; 3-a volumetric pump; 4-a gas concentration detector; 5-a PLC controller; 6-gas supply equipment; 7-washing the bottle with water; 8-water sealed bottle.

Detailed Description

A system for automatically measuring aerobic respiration of biodegradable material, as shown in figure 1, comprises a culture device, a detection device, a ventilation device and a control device, wherein: the culture device is used for culturing the biodegradable material 2; the detection device is connected with the culture device through a gas detection circulating pipeline 9 and is used for detecting the gas content in the culture device; the air interchanger is connected with the culture device through an air interchanging pipeline 10 and is used for replacing the gas in the culture device; the control device is electrically connected with the detection device and the air interchanger and is used for receiving the electric signal of the detection device and controlling the air interchanger to start and stop.

More specifically:

the culture device comprises a culture bottle 1; further preferably, the culture apparatus further comprises a constant temperature incubator, and the culture bottle 1 is placed inside the constant temperature incubator and used for constant temperature culture. In this embodiment, preferably, a bottle cap is disposed at the mouth of the culture bottle 1, so as to prevent air from entering the culture bottle 1 and affecting the detection of aerobic respiration rate.

The head end and the tail end of a gas detection circulating pipeline 9 are both connected with the internal space of the culture device and form a circulating loop; the preferred detection device comprises a volumetric pump 3 and a gas concentration detector 4, wherein the volumetric pump 3 and the gas concentration detector 4 are connected to a gas detection circulating pipeline 9; preferably, the gas concentration detector 4 is an oxygen sensor or a carbon dioxide sensor. More specifically, the volumetric pump 3 is connected with the culture bottle 1 and the inlet end of the gas concentration detector 4 through pipes respectively, and is used for conveying the gas in the culture bottle 1 to the gas concentration detector 4 for gas concentration detection, and particularly, the pipe connected between the culture bottle 1 and the volumetric pump 3 extends into the culture bottle 1 to a depth close to the top end of the culture bottle 1. The outlet end of the gas concentration detector 4 extends into the culture bottle 1 through a pipeline to form a loop. The concentration of the gas in the culture bottle 1 is detected in a circulating loop mode, the gas components and the gas quantity in the culture bottle 1 are not changed, and the detection accuracy of the aerobic respiration quantity is improved.

In the invention, the ventilation pipeline 10 comprises a gas supply section 101 and a gas exhaust section 102 which are connected with the culture device, and the gas outlet end of the gas supply section 101 and the gas inlet end of the gas exhaust section 102 are connected with the inner space of the culture device; the air interchanger preferably comprises an air supply device 6 and a washing bottle 7 which are sequentially arranged on an air supply section 101 along the air flowing direction, and a water-sealed bottle 8 arranged at the air outlet end of an air exhaust section 102; preferably, the air supply device 6 comprises an air pump, a volumetric pump or an electromagnetic valve, and when the air supply device 6 is the air pump, the air source is air; when the air supply device 6 is a volumetric pump, the air supply device further comprises an air bag loaded with air or oxygen and connected to the air inlet end of the volumetric pump; when the gas supply device 6 is an electromagnetic valve, the device further comprises a compressed gas tank (a steel cylinder or a compressed gas storage tank) which is connected with the gas inlet end of the electromagnetic valve and is loaded with compressed air or compressed oxygen; preferably, an air pump is used as the air supply device 6 and air is used as the air source. The air supply device 6 is wetted by a water washing bottle 7 (filled with clear water) through a pipeline, then oxygen or air in an air source is conveyed into the culture bottle 1, and original waste gas in the culture bottle 1 is discharged from a water seal bottle 8 (a wide-mouth bottle adopting water seal), so that the effect of replacing the gas in the culture bottle 1 is achieved. Particularly, a pipeline connected with the gas supply device 6 extends into the lower part of the liquid level of the washing bottle 7, so that the gas fed into the culture bottle 1 is uniformly wetted, and the humidity in the culture bottle 1 is ensured; a pipeline connected with the washing bottle 7 extends into the position which is close to the upper surface of the biodegradable material 2 and below the inner part of the culture bottle 1 so as to ensure that the gas in the culture bottle 1 is completely discharged; the pipeline that connects out by blake bottle 1 stretches into 8 liquid level below of water-sealed bottle to reduce the exchange of outside air and blake bottle 1 interior gas, reduce measuring error, and the degree of depth of stretching into of blake bottle 1 end will be higher than the degree of depth of stretching into of connecting 7 pipelines of washing bottle, efficiency when improving the exhaust.

In the present invention, the control device is preferably a PLC controller 5; the PLC 5 is electrically connected with the gas concentration detector 4 (for receiving the 4-20mA electric signal sent by the gas concentration detector 4) and the gas supply device 6, and is used for recording the gas concentration value measured by the gas concentration detector 4 in real time and controlling the operation of the gas supply device 6. The PLC controller 5 is further provided with a data transmission module, preferably a wireless transmission module, which can transmit the recorded data to an external device or receive an instruction from the external device. Preferably, a counter may also be provided on the PLC controller 5 for recording the number of times the pressure device 6 is activated and storing the data in the PLC controller 5.

In the present invention, the gas detection circulation line and the ventilation line are preferably flexible tubes.

The method for automatically measuring the aerobic respiration quantity of the biodegradable material adopts the system, and comprises the following steps:

s1: collecting a biodegradable material 2 sample, adjusting the water content, and adding the sample into a culture device;

s2: measuring the concentration of the gas to be detected in the culture device by the detection device;

s3: when the concentration of the detected gas exceeds a preset threshold value, starting the ventilation device to ventilate, restoring the concentration of the detected gas in the culture device to the concentration level of the detected gas in normal atmosphere, and simultaneously exhausting waste gas in the culture device; stopping ventilation when the concentration of the detected gas is recovered;

s4: the control device records and stores the value of the concentration of the detected gas in the culture device in real time, and the value of the aerobic respiration quantity of the biodegradable material 2 in the test time is calculated according to the change of the concentration of the detected gas and the volume of the headspace of the culture device.

In step S1, the biodegradable material 2 is a solid residue of biomass waste after anaerobic digestion, aerobic fermentation and/or insect cultivation of the biomass waste, and the biodegradable material 2 is one or more of food and/or plant residue in domestic garbage, livestock manure and/or crop residue in agricultural waste, sludge in municipal sewage treatment plants, degradable polymer or soil; preferably, after a biodegradable material 2 sample is collected, adjusting the water content to 40-60 wt%; preferably, the culture device is in a constant temperature environment of 20-70 ℃.

In step S2, it is preferable that the gas circulation speed in the gas detection circulation line 9 of the gas in the culture apparatus is controlled to 0.1 to 0.5L/min when the gas concentration to be detected in the culture apparatus is measured by the detection apparatus.

In steps S2 and S3, the detected gas is preferably oxygen or carbon dioxide; when the detected gas is oxygen, the preset threshold value of the detected gas is 15-18% of the lower limit value of the oxygen concentration, and when the oxygen concentration is reduced to the lower limit value, the ventilation device is started to ventilate, so that the oxygen concentration in the culture device is restored to the oxygen concentration level in normal atmosphere; when the detected gas is carbon dioxide, the preset threshold value of the detected gas is 6% of the upper limit value of the carbon dioxide concentration, and when the carbon dioxide concentration is increased to the upper limit value, the ventilation device is started to ventilate, so that the carbon dioxide concentration in the culture device is recovered to be lower than 1%.

In the invention, when the detected gas is oxygen, the limitation of the oxygen concentration range of 15-18% on the detected gas is crucial, and the accuracy of the aerobic respiration rate test is ensured. When the value of the oxygen concentration threshold in the range is close to 18%, the method is suitable for biodegradable materials with good biological stability (low content of easily degradable organic matters, such as compost products after secondary fermentation, polylactic acid-based biodegradable plastics, peat and the like), and when the value of the oxygen concentration threshold is close to 15%, the method is suitable for materials with poor biological stability (high content of easily degradable organic matters, such as native kitchen waste, mechanical fast compost products, anaerobic digestion biogas residues and the like). When the lower limit of the oxygen concentration is set to be higher than 18%, enough oxygen is still available in the culture bottle for aerobic respiration of microorganisms, and if the air pump is started to restore the oxygen concentration to 21%, the oxygen concentration difference is too small, so that accurate determination of aerobic respiration volume is not facilitated; when the lower limit of the oxygen concentration is set to be lower than 15%, the activity of methanogenic microorganisms is enhanced due to local anaerobism in the biodegradable material, methane gas may be generated, and the result is interfered, and in conclusion, the oxygen concentration range of 15% -18% is adopted.

In the invention, when the detected gas is carbon dioxide, when the concentration of the carbon dioxide in the gas in the culture device reaches 6%, the PLC sends out an instruction, the ventilation device starts to work until the concentration of the carbon dioxide is lower than 1%, the ventilation device stops working, and the process is circulated.

The percentages of oxygen and carbon dioxide are by volume.

In step S4, the testing time is preferably 4-7 d.

The invention is described in detail below with reference to the figures and specific embodiments.

In the following examples, cumulative oxygen consumption calculations illustrate:

from the recorded oxygen concentration values, the oxygen consumption (according to the ideal gas state equation PV — nRT) can be calculated for each reoxygenation cycle (as shown in fig. 3). For example, in example 1, when the upper limit of the oxygen concentration is 20.7% and the lower limit of the oxygen concentration is 18%, the amount of oxygen consumed in each reoxygenation cycle is

Wherein, P is atmospheric pressure, 101325 Pa; v_{Head space}The difference between the volume of the flask and the sample volume, m, is the headspace volume³(ii) a R is a thermodynamic constant of 8.314J/(mol.K); t is the thermodynamic temperature in the flask, K.

The oxygen consumption in each reoxygenation period is accumulated to obtain the total accumulated oxygen consumption (unit, mg-O) in a certain time₂) Divided by the dry weight of the sample (in g-dry basis) to obtain the aerobic respiration rate in mg-O₂Per g-dry basis. Note that: the oxygen concentration in the last reoxygenation period should be calculated according to the oxygen concentration at the time of experiment stop (possibly, the lower limit of the oxygen concentration is not reached).

Example 1

Taking compost generated by the kitchen garbage mechanical composting reactor, and recording the compost as C1. Adjusting the water content of the compost to 50%, injecting 300g of the compost with the adjusted water content into a culture bottle, and culturing the culture bottle in an incubator at 20 ℃. The upper limit of the oxygen concentration was set to 20.7% and the lower limit of the oxygen concentration was set to 18%. And starting the PLC 5 to control the oxygen concentration and record data. A composting aerobic respiration rate test system is shown in figure 1. After 96 hours of culture, the oxygen consumption of the C1 reactor was 37.6mg-O₂The cumulative oxygen consumption as a function of time per g-dry basis is shown in FIG. 2. The test was repeated twice in the same operation, and the amount of oxygen consumed by the material for 96 hours was 37.9mg-O₂Per g-dry basis and 36.5mg-O₂Per g-dry basis. And the test result has high repeatability.

Example 2

Taking compost generated by a rural sunlight composting room, and recording the compost as C2. Adjusting the water content of the compost to 50%, injecting 40g of the compost with the adjusted water content into a culture bottle, and culturing the culture bottle in an incubator at 20 ℃. The upper limit of the oxygen concentration was set to 20.5% and the lower limit of the oxygen concentration was set to 18%. And starting the PLC 5 to control the oxygen concentration and record data. A composting aerobic respiration rate test system is shown in figure 1. After 96 hours of cultivation, the amount of oxygen consumed by the C2 reactor was 35.6mg-O₂The cumulative oxygen consumption as a function of time per g-dry basis is shown in FIG. 2.

Example 3

Taking the compost product which is decomposed by secondary fermentation and recording as C3. Adjusting the water content of the compost to 50%, injecting 40g of the compost with the adjusted water content into a culture bottle, and culturing the culture bottle in an incubator at 20 ℃. The upper limit of the oxygen concentration was set to 20.5% and the lower limit of the oxygen concentration was set to 18%. And starting the PLC 5 to control the oxygen concentration and record data. A composting aerobic respiration rate test system is shown in figure 1. After 96 hours of culture, the oxygen consumption of the C3 reactor was 23.0mg-O₂The cumulative oxygen consumption as a function of time per g-dry basis is shown in FIG. 2.

Example 4

The biogas residue produced by dry anaerobic digestion of municipal kitchen waste is taken and recorded as D1. Regulating the water content of the compost to 60%Then, 40g of the biogas residue with the adjusted water content was poured into a culture flask, and the flask was placed in an incubator at 20 ℃ for culture. The upper limit of the oxygen concentration was set to 20.75% and the lower limit of the oxygen concentration was set to 15%. And starting the PLC 5 to control the oxygen concentration and record data. The biogas residue aerobic respiration rate testing system is shown in figure 1. After 96 hours of culture, the oxygen consumption of the D1 reactor was 58.2mg-O₂The cumulative oxygen consumption as a function of time per g-dry basis is shown in FIG. 2. The real-time change of the oxygen concentration over time during the test is shown in FIG. 3.

As can be seen from the aerobic respiration testing processes of the compost and the biogas residue in the embodiments 1 to 4, the repeatability of the testing result can be improved by utilizing the characteristics of the oxygen concentration control system without introducing manual operation; and air is used as an oxygen source, so that the test cost can be saved, and the method can be suitable for different application scenes.

The repeatability of the test is considered, the oxygen concentration in the culture bottle is recorded in real time, and the test result has higher repeatability.

The test accuracy is considered, the adopted aerobic respiration rate result can reflect the biological stability of the biodegradable material in the land utilization process, and the aerobic respiration rate result can accurately reflect the influence of active organic matters on plants, which are brought by the biodegradable material in the land utilization process.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.