A sewage treatment system gas emission flux measuring system and measuring method

Abstract

The embodiment of the present application relates to a kind of sewage treatment system gas emission flux measurement system and measurement method.The sewage treatment system gas emission flux measurement system includes: the gas collection device of semi-closed structure and floating in the water surface of sewage carries out the gas discharged by sewage collection, control the weight of the gas collection device to offset the change of buoyancy after the gas collection device collects gas, and for the measurement device for determining the measurement of collected gas.The beneficial effects of the embodiment of the present application are that it can be simultaneously applied to the measurement of greenhouse gas emission amount emitted or released by the water surface of aeration and non-aeration sewage, and it has good applicability to the case of rapid and slow emission or release of greenhouse gas by the water surface of sewage, so that simple, rapid measurement of greenhouse gas emission amount of sewage system can be realized, and the difficulty of measurement is reduced.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a measurement system and method for measuring the gas emission flux of a wastewater treatment system. Background Technology

[0002] The wastewater treatment industry plays a decisive role in water pollution control and prevention. As an energy-intensive industry, it is also a significant carbon emitter. The greenhouse gases emitted during wastewater treatment primarily include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), making them major direct sources of greenhouse gas emissions. To promote pollution reduction, carbon reduction, and efficiency improvement in the wastewater treatment industry, a complete and accurate calculation of greenhouse gas emissions from wastewater systems is essential to lay the foundation for proposing specific implementation paths for carbon neutrality. Currently, the main methods used for measuring greenhouse gas emissions from wastewater treatment systems include gas bag sampling, floating gas flux chamber sampling, and static chamber sampling. Wastewater systems require a combination of methods such as transport, settling, mixing, stirring, aeration, and filtration to complete the treatment process. Wastewater exists in structures in two states: aerated and non-aerated. Different devices and methods are needed to measure greenhouse gas emissions under different conditions. The gas bag sampling method is only suitable for sampling and measuring greenhouse gases emitted from aerated water surfaces and cannot be used for non-aerated water surfaces. The sampling process using the gas bag method is relatively rudimentary. The installation, fixing, and sealing of the gas bag rely heavily on the operator's skill and speed, which can easily lead to inaccurate sampling time measurement, thus affecting the final results. The disadvantages of the gas flux chamber method are that it requires a stable gas source and gas collection device, resulting in a complex structure that is inconvenient to carry and operate; when the greenhouse gas emission flux within the flux chamber is too low, the difference in gas concentration between the inlet and outlet airflows cannot be detected, causing deviations in the results. The disadvantages of the static chamber method are that it is unsuitable for measuring greenhouse gas emissions from the water surface in aeration zones; it cannot monitor rapid changes in greenhouse gas rates, is prone to generating large fluctuations in gas flux at the water-gas interface, and is also unsuitable for scenarios with significant fluctuations in influent flow.

[0003] In summary, wastewater treatment systems require a combination of various methods, including pressure or gravity transport, sedimentation, mixing, flocculation, stirring, aeration, and filtration, to achieve compliant treatment. These methods result in significant differences among various wastewater treatment processes. Wastewater exists in various states within different units of the treatment system, such as aerated and non-aerated areas. Aerated areas can be further divided into areas of vigorous mechanical stirring and forced aeration; non-aerated areas can exhibit both slow dissolved gas release and vigorous gas production and release. Aerated water surfaces typically utilize the gas bag method and gas flux box method, while non-aerated water surfaces can employ the static box method. Therefore, this invention proposes a measurement system and method for the gas emission flux of wastewater treatment systems. This system is applicable to measuring the greenhouse gas emissions emitted or released from both aerated and non-aerated wastewater surfaces. It is well-suited for both vigorous and slow greenhouse gas emission from wastewater surfaces, enabling simple and rapid measurement of greenhouse gas emissions from wastewater systems and reducing the difficulty of measurement. Summary of the Invention

[0004] The technical objective of this invention is to address the significant differences in gas emission rates between aerated and non-aerated wastewater, which necessitates the use of different measuring devices for different wastewater conditions, resulting in complex and cumbersome measurement processes. By dynamically controlling the gas collection zone of the measuring device to maintain pressure equilibrium and accurately measuring the gas collection volume, this invention overcomes the problem of existing methods being susceptible to deviations in greenhouse gas detection due to factors such as gas pressure and sampling speed.

[0005] To achieve the above objectives, the present invention provides a system for measuring the gas emission flux of a wastewater treatment system, the system comprising:

[0006] The gas collection device is a semi-closed cylindrical structure with an opening at one end and a jacket. It is inverted with its opening facing downwards on the surface of the sewage to collect the gas emitted from the sewage.

[0007] The control device changes the weight of the gas collecting device by introducing gas or water into the interlayer of the gas collecting device, thereby counteracting the effect of the change in buoyancy after the gas collecting device collects gas.

[0008] A measuring device used to measure the collected gas.

[0009] Preferably, the gas collection device includes an inner shell, an outer shell is fitted over the inner shell, a sealed first cavity is formed between the outer shell and the inner shell, the interior of the inner shell is a second cavity, and an opening is provided at the bottom of the inner shell to allow the second cavity to communicate with the outside.

[0010] Preferably, the control device includes:

[0011] An inlet and outlet pipe is connected to the first cavity and one end extends to the bottom of the first cavity;

[0012] The water tank is connected to the first cavity via the inlet and outlet pipes;

[0013] The intake and exhaust pipes are connected at one end to the first cavity and at the other end to a first air pump, which pumps air into or extracts air from the first cavity.

[0014] Preferably, the measuring device includes:

[0015] The sampling tube is connected to the second cavity at one end and to the detector at the other end, and a second air pump is provided on the sampling tube to extract the sampling gas.

[0016] A level gauge is used to measure the liquid level in the second cavity;

[0017] A pressure sensor is used to measure the pressure inside the second cavity and is electrically connected to the first air pump;

[0018] A temperature sensor is used to measure the temperature inside the second cavity;

[0019] The detector mentioned is a Fourier transform infrared detector.

[0020] Preferably, the sampling tube is provided with an outlet tube, and the end of the outlet tube is detachably provided with an air collection bag.

[0021] Preferably, valve bodies are provided on the inlet / outlet pipe, the outlet / exhaust pipe, the sampling pipe, and the outlet pipe.

[0022] Preferably, a plurality of limiting rods are slidably provided on the outside of the outer shell, and a hanging ring is provided at the top of the limiting rod. In the gas collection state, the gas collection device is suspended and placed on the surface of the sewage through the hanging ring. The gas collection device can move up and down along the limiting rod under the buoyancy of the sewage.

[0023] The present invention also provides a method for measuring the gas emission flux of wastewater treatment using the above-described measurement system, the measurement method comprising:

[0024] (a) Start the first air pump to extract the gas from the first chamber, so that the clean water in the water tank enters through the inlet and outlet pipes and fills the first chamber;

[0025] (b) Then open the valve body of the inlet and outlet pipe and the valve body of the outlet pipe, and close the other valve bodies. Place the gas collection device at the surface of the sewage and let it sink slowly. The sewage enters through the opening and fills the second chamber.

[0026] (c) Start the first air pump to pump air into the first cavity, so that the clean water in the first cavity flows back to the water tank, so that the buoyancy of the gas collection device gradually increases until the gas collection device can float freely on the surface of the sewage. Stop the first air pump, close the valve of the sampling air pipe and the valve of the outlet air pipe, and start collecting the gas discharged from the sewage in the second cavity.

[0027] (d) The first air pump is started or stopped by measuring the internal pressure of the second chamber through the pressure sensor to pump or extract air, so as to adjust the weight of the air collection device so that it floats stably on the surface of the sewage.

[0028] (e) After the gas collection stops, start the second gas pump to pump the sewage discharge gas in the first chamber into the detector for testing or collect it through the gas collection bag and send it for testing.

[0029] Preferably, the following data need to be measured separately during the measurement process:

[0030] The start time of gas collection is t1;

[0031] The liquid level height H1 in the second chamber at the start of gas collection;

[0032] The end time of gas collection is t2;

[0033] The liquid level height H2 in the second chamber at the end of gas collection;

[0034] Temperature T;

[0035] The calculation method is as follows:

[0036] Calculate the rate v at which the measuring device collects the gas:

[0037] (1)

[0038] in, The gas collection rate of the measuring device is expressed in m³ / h.

[0039] This is the internal cross-sectional area of ​​the second cavity, in m2;

[0040] Furthermore, the greenhouse gas emission flux emitted or released by the wastewater unit is calculated using ν. :

[0041] (2)

[0042] in, Greenhouse gas emission flux from wastewater, expressed in g / (m³). 2 ·h);

[0043] p is the air pressure inside the second cavity, in Pa.

[0044] C represents the volume concentration of the corresponding gas, in ppm;

[0045] M is the molar mass of the gas, expressed in g / mol;

[0046] R is the ideal gas constant, with a value of 8.314 and a unit of J / (mol·K);

[0047] T represents the gas temperature inside the second chamber, in Kelvin (K).

[0048] 10 -6 This is a unit conversion constant.

[0049] Preferably, it also includes calculating the greenhouse gas emissions emitted or released by the wastewater unit. :

[0050] (3)

[0051] in, The emission of the i-th greenhouse gas that escapes or is released in the j-th measurement area of ​​the wastewater treatment unit, in g / d;

[0052] The water surface area of ​​the j-th measurement zone in the wastewater treatment unit is expressed in m². 2 .

[0053] This also includes greenhouse gas emissions from wastewater systems. :

[0054] (4)

[0055] During the measurement process, each point is sampled and measured at least three times, and the average value is taken as the wastewater greenhouse gas emission flux value of the point.

[0056] The gas emission flux measurement system for wastewater treatment systems provided by this invention has the following beneficial effects:

[0057] (1) In view of the huge difference in the amount of greenhouse gas emitted or released from the surface of sewage under different conditions in sewage system, and the difficulty in measuring it with a single device and method, the present invention provides a device and method for measuring the amount of greenhouse gas emitted from sewage that can be applied to both aerated and non-aerated surfaces. It has good applicability to both violent and slow emission of greenhouse gases from the surface of sewage, and can realize a simple and rapid measurement of the amount of greenhouse gas emitted from sewage system.

[0058] (2) By dynamically controlling the floating state of the measuring device on the sewage surface, the present invention maintains a constant pressure in the gas collection zone of the measuring device under different gas emission rates. In the aeration zone or the area where greenhouse gases are released violently, controllable and rapid collection and measurement of greenhouse gases can be achieved; in the non-aeration zone or the area where greenhouse gases are released slowly, long-term continuous collection of greenhouse gases can be achieved.

[0059] (3) The present invention solves the problem that the gas bag method is only applicable to sampling of aerated water surfaces, and the sampling process is rough and it is difficult to accurately control the sampling time. By controlling the pressure of the gas collected in the gas collection area of ​​the measuring device to be in a dynamic equilibrium state, and using a static pressure level gauge to accurately measure the volume of collected greenhouse gas, the measurement process is precise and controllable.

[0060] (4) This invention solves the problem of poor applicability of the gas flux box method in non-aerated wastewater areas with low greenhouse gas emissions. By dynamically controlling the floating state of the measuring device on the wastewater surface, continuous collection of greenhouse gases can be achieved for a long time in non-aerated areas or areas with slow greenhouse gas emissions. At the same time, the measuring device of this invention does not require a stable carrier gas source, its structure is simpler than that of the gas flux box method, and its operation is simpler, reducing the technical requirements for operators. In addition, the measuring device of this invention can use a steel wire rope to pass through the top ring of the limiting rod, which makes it convenient to be hoisted at any position in the wastewater tank, and it can be applied to sampling points in wastewater treatment tanks with large water surfaces.

[0061] (5) This invention solves the problem that static boxes are not suitable for measuring greenhouse gas emissions from the surface of water in aeration zones, and has good applicability to wastewater surfaces in various states; this invention can realize the dynamic collection of escaping or released gases, and realize the synchronous online detection of multiple greenhouse gases through Fourier transform infrared detectors. The collection and measurement process is simple and rapid, and solves the problem that static boxes require at least 5 gas samples per point to meet the linear fitting requirements of measurement data, which increases the workload and operational intensity; the gas pressure value in the gas collection area of ​​the measuring device of this invention can be dynamically controlled within a set range, avoiding the problem that the gas pressure in the static box device is prone to large deviations in the escaping performance of greenhouse gases inside and outside the static box due to the continuous change of the collected gas, thereby improving the accuracy of the final measurement results. Attached Figure Description

[0062] Figure 1 This is an overall schematic diagram of the gas emission flux measurement system for a wastewater treatment system provided in Embodiment 1 of the present invention;

[0063] Figure 2 This is a schematic diagram of the gas emission flux measurement system for a wastewater treatment system provided in Embodiment 1 of the present invention;

[0064] Figure 3This is a schematic diagram of the gas collection device of the gas emission flux measurement system for the wastewater treatment system provided in Embodiment 1 of the present invention;

[0065] Figure 4 This is a schematic diagram of the gas collection device of the gas emission flux measurement system for the wastewater treatment system provided in Embodiment 2 of the present invention;

[0066] Figure 5 This is a schematic diagram of the gas collection device of the gas emission flux measurement system for the wastewater treatment system provided in Embodiment 2 of the present invention, taken from direction A.

[0067] Figure 6 This is a schematic diagram of the gas collection device of the gas emission flux measurement system for the wastewater treatment system provided in Embodiment 3 of the present invention, taken from direction B. Detailed Implementation

[0068] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0069] First, this invention provides a system for measuring the gas emission flux of a wastewater treatment system. Figure 1 A schematic diagram of the measurement system provided for an embodiment of the present invention, such as... Figure 1 As shown, the wastewater treatment system gas emission flux measurement system provided in this embodiment of the invention includes:

[0070] The gas collection device 100 has a semi-closed cylindrical structure with an opening at one end and a jacket, and floats on the surface of the sewage to collect the gas emitted from the sewage.

[0071] The control device 200 changes the weight of the gas collecting device 100 by introducing gas or water into the interlayer of the gas collecting device 100, thereby counteracting the effect of the change in buoyancy after the gas collecting device 100 collects gas.

[0072] Measuring device 300 is used to measure the collected gas. Example 1

[0073] like Figure 2 and Figure 3 As shown, the gas collection device 100 includes an inner shell 101, an outer shell 102 is fitted over the inner shell 101, a sealed first cavity 103 is formed between the outer shell 102 and the inner shell 101, the interior of the inner shell 101 is a second cavity 104, and an opening is provided at the bottom of the inner shell 101 to allow the second cavity 104 to communicate with the outside.

[0074] There are many possible structures for the gas collection device 100. In this specific embodiment, a cylindrical inner shell 101 and outer shell 102 are preferred. The inner shell 101 and outer shell 102 are coaxially fitted together. In addition, the outer shell 102 can also be equipped with a counterweight 112 or a float to improve the stability of floating.

[0075] Furthermore, the gas collection device 100 is made of plexiglass. The inner shell 101 is a cylindrical structure with a flange 105 at its top. The flange 105 is a blind flange, integrally formed or bonded to the top face of the inner shell 101. The outer shell 102 is fitted over the inner shell 101, and its top face has a flange 106, which is bolted to the flange 105. To improve sealing, a gasket 109 can be placed between the flanges 105 and 106. The bottom of the outer shell 102 is open, with a flange 107 embedded in the opening. The bottom of the inner shell 101 has a flange 108 embedded in it. The flanges 107 and 108 are bolted together, and a gasket 109 is placed between them. Thus, the inner shell 101 and the outer shell 102 form a first cavity 103 and a second cavity 104. To ensure stable buoyancy of the gas collection device 100 during the collection process, four counterweight support bases 110 are symmetrically arranged on the outer shell 102. (See attached diagram.) Figure 3 , 5 As shown, the bottom end of the nylon limiting rod 111 passes through the counterweight support 110 and is limited by a nut. The other end of the limiting rod 111 passes through the flange 105. Furthermore, a counterweight block 112 can be mounted on the counterweight support 110 via the limiting rod 111 to increase the counterweight. Specifically, the counterweight block 112 has a cylindrical structure with a hole in the center for the limiting rod 111 to pass through. The limiting rod 111 passes through the hole and can slide freely. The counterweight block 112 is securely fixed to the counterweight support 110 using nylon straps. The counterweight blocks 112 can be installed in groups of four, requiring one block to be installed on each of the four supports 5 simultaneously. On aerated water surfaces or water surfaces with vigorous gas release, the added counterweight 112 is made of solid stainless steel to increase the weight of the measuring device and improve its stability. On non-aerated water surfaces or water surfaces with slow gas release, the counterweight 112 may not be installed, or a counterweight 112 made of polystyrene foam may be added to form a float to increase the buoyancy of the measuring device and meet the needs of the measuring device to collect gas on the sewage surface for a long time. The top of the limiting rod 111 is provided with a lifting ring 113 for lifting the gas collecting device 100. Thus, during the gas collection operation, the gas collecting device 100 is suspended at the sewage surface by the lifting ring 113. During the gas collection process, due to changes in buoyancy, the outer shell 102 can move up and down with the limiting rod 111 as the guide rod, thus preventing the opening from leaving the water surface and causing gas to overflow.

[0076] See you again Figure 1 and2 As shown, the control device 200 includes:

[0077] The inlet and outlet pipe 201 is connected to the first cavity 103 and one end extends to the bottom of the first cavity 103;

[0078] Water tank 202 is connected to the first cavity 103 through inlet and outlet pipes 201;

[0079] The intake and exhaust pipe 203 is connected at one end to the first cavity 103 and at the other end to the first air pump 204, which pumps air into or extracts air from the first cavity 103.

[0080] The measuring device 300 includes:

[0081] The sampling tube 301 is connected to the second cavity 104 at one end and to the detector 302 at the other end. A second air pump 303 is installed on the sampling tube 301 to extract the sampling gas. The first air pump 204 and the second air pump 303 are peristaltic pumps and have a control mode that can accept the switch signal output by the pressure sensor 304 to realize forward or reverse air delivery, thereby ensuring that the gas pressure value in the gas collection area of ​​the measuring device is constant.

[0082] The level gauge 305, specifically a hydrostatic level gauge, has its probe installed and fixed at the bottom of the inner wall of the second cavity 104, and is used to measure the liquid level height inside the second cavity 104.

[0083] Pressure sensor 304 is used to measure the pressure inside the second cavity 104 and is electrically connected to the first air pump 204;

[0084] Temperature sensor 306 is used to measure the temperature inside the second cavity 104.

[0085] In this embodiment, the detector 302 is a Fourier transform infrared (FTIR) detector 302. It is configured such that one end of the sampling gas tube 301 is connected to the second cavity 104, and the other end is sequentially connected to the second gas pump 303 and the detection chamber 307. The detection chamber 307 contains the sampling tube 308 of the Fourier transform infrared (FTIR) detector 302, which can perform online detection of the concentrations of greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in the gas sample, displaying the data directly on the Fourier transform infrared (FTIR) detector 302 and storing the data. The exhaust gas after detection is discharged through the detector 302 exhaust pipe 309.

[0086] To avoid testing when the detector 302 is not working, an outlet pipe 310 is provided on the sampling pipe 301. A gas collection bag 311 is detachably provided at the end of the outlet pipe 310. The gas collected by the gas collection bag 311 can be used to collect gas when the Fourier transform infrared detector 302 malfunctions or when offline testing and calibration are required.

[0087] In this embodiment, valve bodies are provided on the inlet / outlet pipe 201, the inlet / outlet pipe 203, the sampling gas pipe 301, and the outlet pipe 310. (See attached diagram.) Figure 2 As shown, one end of the inlet / outlet pipe 201 is located at the bottom inside the water tank 202, and the other end is located at the bottom of the first cavity 103, allowing water to be pumped into or discharged from the first cavity 103. One end of the inlet / outlet pipe 203 only needs to pass through the flange 105. The sensing end of the level gauge 305 extends to the bottom of the second cavity 104 to detect the liquid level within the maximum range. The sensing end of the pressure sensor 304 is located at the top of the second cavity 104 to detect the gas pressure above. Of course, all interfaces must be sealed. Example 2

[0088] Building upon the technology of Embodiment 1, a preferred technical solution of the present invention is further disclosed. For example... Figure 6 As shown, both the inner shell 101 and the outer shell 102 are hollow cylinders made of plexiglass with a wall thickness of 10mm. The inner diameter Db of the inner shell 101 is 400mm, and the inner height H is 1200mm. An plexiglass flange 108 is welded or bonded to its bottom. The inner diameter Da of the opening of the plexiglass flange 108 is 300mm. A plexiglass blind flange 105 is welded or bonded to its top. The diameter Dd of the blind flange 105 is 950mm. The inner diameter Dc of the outer shell 102 is 750mm, and the height H is 1200mm. Similarly, an plexiglass flange 107 is welded or bonded to the bottom of the outer shell 102. The inner diameter of the opening of the plexiglass flange 107 is also 300mm. An annular plexiglass flange 106 is connected to the top opening of the outer shell 102. Its outer diameter is smaller than the outer diameter Dd of the blind flange at the upper end of the inner shell 101. The plexiglass flanges 107 and 108 at the bottom of the inner shell 101 and the outer shell 102 have the same flange hole spacing, hole diameter and number of openings. A layer of annular silicone sealing gasket 109 is added between the plexiglass blind flange 105 and the annular plexiglass flange 106, and between the plexiglass flange 107 and the plexiglass flange 108, and they are tightly connected with stainless steel bolts to ensure the sealing of the bottom of the inner shell 101 and the outer shell 102.

[0089] After the inner shell 101 is connected to the outer shell 102, two independent air chambers are formed. The inner shell 101 contains a second cavity 104, which is the greenhouse gas collection area for wastewater release. The cavity 104 is open at the bottom and closed at the top, with a volume of 0.151 m³. 3 The space between the inner shell 101 and the outer shell 102 is the first cavity 103, with a total volume of 0.364 m³. 3 The first cavity 103 is closed at both ends, with interfaces for the inlet / outlet pipe 201 and the outlet / exhaust pipe 203 only at the top. Figure 4 As shown. (Attached) Figure 4 The diagram shows the locations of the pipes on the top of the gas collection device 100. Of course, this is only a preferred embodiment. In the diagram, from left to right, the flange 105 is provided with the following interfaces: inlet and outlet pipe 201 interface, inlet and outlet pipe 203 interface, level gauge 305 interface, pressure sensor 304 interface, temperature sensor 306 interface, and sampling gas pipe 301 interface. Four limiting rods 111 are provided on the edge of the flange 105. Example 3

[0090] This embodiment 3 describes a method for measuring the gas emission flux from wastewater treatment using the measurement system described in embodiment 1. The measurement method includes:

[0091] (a) Start the first air pump 204 to extract the gas in the first chamber 103, so that the clean water in the water tank 202 enters through the inlet and outlet pipes 201 and fills the first chamber 103;

[0092] (b) Then open the valve body of the inlet and outlet pipe 203 and the valve body of the outlet pipe 310, and close the other valve bodies. Place the gas collection device 100 stably at the surface of the sewage through the lifting ring 113 and slowly sink it. The sewage enters through the opening and fills the second chamber 104.

[0093] (c) Start the first air pump 204 to pump air into the first chamber 103, so that the clean water in the first chamber 103 flows back to the water tank 202, so that the buoyancy of the gas collection device 100 gradually increases until the gas collection device 100 can float freely on the surface of the sewage. Then stop the first air pump 204, close the valve of the sampling air pipe 301 and the valve of the air outlet pipe 310, and start collecting the gas discharged from the sewage in the second chamber 104.

[0094] (d) Start gas collection, record the start time, and measure the internal pressure p of the second chamber 104 by the pressure sensor 304. The threshold value is usually set with the atmospheric pressure value of the sewage system location. In this embodiment, 100±0.1KPa is used as an example. When p≥100.1KPa, the first air pump 204 is started to extract the air in the first chamber 103, and the clean water in the water tank 202 is injected. The weight of the gas collection device 100 increases to overcome the increase in buoyancy caused by the increase in gas in the second chamber 104. When p≤99.9KPa, the first air pump 204 is started to pump air into the first chamber 103, and the clean water in the first chamber 103 flows back to the water tank 202. The weight of the air collection device 100 is reduced to compensate for the reduction in buoyancy caused by the reduction of gas in the second chamber 104, thereby realizing automatic adjustment for air collection to adapt to whether the sewage is in an aerated or non-aerated state. When collecting air in sewage treatment with intense aeration, a counterweight block 112 or a float can be hung on the counterweight support 110 to improve stability.

[0095] (e) After the gas collection stops, record the stop time, open the valve of the sampling gas pipe 301, start the second gas pump 303 to pump the gas released from the sewage in the first chamber 103 into the detector 302 for detection, or open the valve of the gas outlet pipe to allow the gas to flow through the gas outlet pipe into the gas collection bag for collection and then send it for testing.

[0096] In the above method, the following data need to be measured separately during the measurement process:

[0097] The start time of gas collection is t1;

[0098] The liquid level height H1 in the second chamber 104 at the start of gas collection;

[0099] The end time of gas collection is t2;

[0100] The liquid level height H2 in the second chamber 104 at the end of gas collection;

[0101] Temperature T;

[0102] The calculation method is as follows:

[0103] Calculate the rate v at which the measuring device collects the gas:

[0104] (1)

[0105] in, The gas collection rate of the measuring device is expressed in meters per second (m). 3 / h;

[0106] This refers to the internal cross-sectional area of ​​the second cavity, expressed in m², which can be calculated by measuring the inner diameter r1 of the second cavity. =π×r1×r1 / 4, unit is m 2 ;

[0107] Furthermore, the greenhouse gas emission flux emitted or released by the wastewater unit is calculated using ν. :

[0108] (2)

[0109] in, Greenhouse gas emission flux from wastewater, expressed in g / (m³). 2 ·h);

[0110] p is the air pressure inside the second cavity 104, in Pa;

[0111] C represents the volume concentration of the corresponding gas, in ppm;

[0112] M is the molar mass of the gas, expressed in g / mol;

[0113] R is the ideal gas constant, with a value of 8.314 and a unit of J / (mol·K);

[0114] T is the gas temperature inside the second cavity 104, in K;

[0115] The area of ​​the bottom opening of the second cavity 104, i.e., the opening area of ​​the flange 108, can be calculated by measuring the inner diameter r2 of the flange 108 opening. =π×r²×r² / 4, unit is m 2 ;

[0116] 10 -6 This is a unit conversion constant.

[0117] Preferably, it also includes calculating the greenhouse gas emissions emitted or released by the wastewater unit. :

[0118] (3)

[0119] in, The emission of the i-th greenhouse gas that escapes or is released in the j-th measurement area of ​​the wastewater treatment unit, in g / d;

[0120] The average emission flux of the i-th greenhouse gas is expressed in g / (m³). 2 ·h);

[0121] The water surface area of ​​the j-th measurement zone in the wastewater treatment unit is expressed in m². 2 .

[0122] This also includes greenhouse gas emissions from wastewater systems. :

[0123] . Example 4

[0124] This embodiment 4 is a specific implementation of the method for measuring the gas emission flux of wastewater treatment using the measurement system of embodiment 2. The measurement method and the adjustment steps through the control device during the measurement process are the same as in embodiment 3, except that the formula is modified. The measurement method is as follows:

[0125] Install all components and check for airtightness. Since the measurement is performed on the surface of the aerated water, the violent release of gas can easily cause an imbalance in the forces acting on the gas collecting device 100, leading to swaying. To increase the weight of the gas collecting device 100 and improve its stability, the counterweights 112 are attached to the counterweight support seats 110 via the limiting rods 111. The counterweights 112 are solid stainless steel blocks, with four blocks in each group, installed on four counterweight support seats 110. Then, using two parallel stainless steel wire ropes threaded through the lifting ring 113 at the top of the limiting rod 111, the gas collection device 100 is hoisted upright to the selected measurement point water surface within the aeration zone of the aerobic biochemical unit. The valves of the inlet / outlet pipe 201, the inlet / outlet pipe 203, and the outlet pipe 310 are opened, while the valve of the sampling pipe 301 is closed. The first air pump 204 is started to extract the gas from the first chamber 103, allowing the clean water in the water tank 202 to enter through the inlet / outlet pipe 201 and fill the first chamber 103. At this time, the clean water in the water tank 202 enters through the inlet / outlet pipe 201 and fills the first chamber 103 under negative pressure. As the weight of the gas collection device increases, the water level slowly drops, and sewage enters through the opening and fills the second chamber 104. The first air pump 204 is stopped and switched to automatic operation. When the internal pressure p of the second chamber 104, measured by the pressure sensor 304, is greater than 100.1 kPa, a positive switching signal is output to control the first air pump 204 to pump air out of the first chamber 103 and inject clean water from the water tank 202. When p ≤ 99.9 kPa, the first air pump 204 is started to pump air into the first chamber 103, and the clean water in the first chamber 103 flows back to the water tank 202, so that the pressure value is dynamically stabilized at greater than or equal to 99.9 kPa. At this time, the valve of the air outlet pipe 310 is closed and the valve of the sampling air pipe 301 is kept closed. Simultaneously, timer t1 is started, and the liquid level height H1 in the second chamber 104 is recorded. When the gas collection is full or reaches the predetermined position, the end time t2 of the gas collection and the liquid level height H2 in the second chamber 104 are recorded. Then, the valve of the sampling gas tube 301 is opened, and the second gas pump 303 is started to pump the gas released from the sewage in the first chamber 103 into the detector 302 for detection. After 30-60 seconds, when the sampling gas has completely replaced the air in the detection box 307, the volume concentration values ​​of greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) displayed on the Fourier transform detector 302 are recorded. At the same time, the greenhouse temperature T of the gas in the gas collection area measured by the temperature sensor 306 is recorded.

[0126] The greenhouse gas emissions of this wastewater treatment unit were calculated using the following formula based on the data recorded above:

[0127] Calculate the rate at which the measuring device collects the gas:

[0128] (5)

[0129] in, The gas collection rate of the measuring device is expressed in meters per second (m). 3 / h;

[0130] Db is the inner diameter of the inner shell 101, measured in meters (m).

[0131] H1 is the liquid level value in the gas collection area of ​​the measuring device at time t1, in meters;

[0132] H2 is the liquid level value in the gas collection area of ​​the measuring device at time t2, in meters;

[0133] t1 is the time when the measuring device starts collecting gas, in minutes;

[0134] t2 is the time when the gas collection by the measuring device ends, in minutes.

[0135] Calculate and measure the greenhouse gas emission fluxes emitted or released by the wastewater unit:

[0136] (6)

[0137] in, Let be the emission flux of the i-th greenhouse gas, expressed in g / (m³). 2 ·h);

[0138] The pressure in the gas collection area of ​​the measuring device is measured in Pa, and the set value can be 100 kPa.

[0139] The gas collection rate of the measuring device is expressed in m³ / h.

[0140] C i To perform online detection of the gases collected in the gas collection area, the volume concentration of the i-th greenhouse gas is obtained, in ppm.

[0141] Let be the molar mass of the i-th greenhouse gas, expressed in g / mol.

[0142] R is the ideal gas constant, with a value of 8.314 and a unit of J / (mol·K);

[0143] T represents the gas temperature in the gas collecting zone of the measuring device, in K;

[0144] Da is the inner diameter of the flange opening at the bottom of the inner cylinder of the measuring device, in meters (m).

[0145] 10 -6 For unit conversion constants;

[0146] After the measurement is completed, open the valve of the vent pipe 310, close the valve of the sampling pipe 301, and manually stop the second air pump 303. Switch the first air pump 204 to manual operation so that it is no longer controlled by the pressure sensor 304. Manually start the first air pump 204 and run it in reverse to expel the air from the first chamber 103. Clean water enters the first chamber 103 through the inlet and outlet pipes. At this time, the gas in the second chamber 104 is discharged from the vent pipe 310 until the second chamber 104 is completely emptied of gas and filled with sewage.

[0147] A second measurement is performed at the same measurement point, following the measurement steps described above in this embodiment. A total of three measurements are required at each measurement point. Data are recorded for each measurement, and the rate at which the measuring device collects gas and the greenhouse gas emission flux value are calculated for each measurement using formulas (5) and (6). The average greenhouse gas emission flux value obtained from the three measurements is taken to obtain the average greenhouse gas emission flux emitted or released by wastewater at that measurement point.

[0148] The greenhouse gas emissions emitted or released in each measurement area of ​​a wastewater treatment unit can be calculated using the following formula. The total greenhouse gas emissions of the wastewater treatment unit can be obtained by summing the emissions from different measurement areas.

[0149] in,

[0150] The emission of the i-th greenhouse gas, expressed in g / d, is the amount released or emitted in the j-th measurement zone of the wastewater treatment unit.

[0151] The average emission flux of the i-th greenhouse gas is expressed in g / (m³). 2 ·h);

[0152] The water surface area of ​​the j-th measurement zone in the wastewater treatment unit is expressed in m². 2 .

[0153] The purpose, technical solution and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the gas emission flux of a wastewater treatment system using a gas emission flux measurement system, characterized in that, The gas emission flux of the wastewater treatment system includes: A gas collection device, a semi-closed cylindrical structure with an opening at one end, has a jacket. It is inverted with its opening facing downwards on the surface of sewage to collect the gas emitted from the sewage. Specifically, it includes: an inner shell, an outer shell fitted over the inner shell, a sealed first cavity formed between the outer shell and the inner shell, a second cavity inside the inner shell, and an opening at the bottom of the inner shell that allows the second cavity to communicate with the outside. A control device, which alters the weight of the gas collecting device by introducing gas or water into its interlayer, thereby counteracting the effect of changes in buoyancy after gas collection; includes: An inlet and outlet pipe is connected to the first cavity and one end extends to the bottom of the first cavity; The water tank is connected to the first cavity via the inlet and outlet pipes; The intake and exhaust pipes are connected at one end to the first cavity and at the other end to a first air pump, which pumps air into or extracts air from the first cavity. A measuring device for measuring the collected gas, comprising: A sampling tube is connected at one end to the second cavity, and a second air pump is provided on the sampling tube to extract the sampling gas. A level gauge is used to measure the liquid level in the second cavity; A pressure sensor is used to measure the pressure inside the second cavity and is electrically connected to the first air pump; The other end of the sampling tube is connected to the detector and / or the gas collection bag; Several limiting rods are slidably arranged on the outside of the outer shell. A hanging ring is provided at the top of the limiting rod. In the gas collection state, the gas collection device is suspended and placed on the surface of the sewage through the hanging ring. The gas collection device can move up and down along the limiting rod under the buoyancy of the sewage. The measurement method includes: (a) Start the first air pump to extract the gas from the first chamber, so that the clean water in the water tank enters through the inlet and outlet pipes and fills the first chamber; (b) Then open the valve body of the inlet and outlet pipe and the valve body of the outlet pipe, and close the other valve bodies. Place the gas collection device at the water surface of the sewage and slowly sink it. The sewage enters through the opening and fills the second chamber. (c) Start the first air pump to pump air into the first cavity, so that the clean water in the first cavity flows back to the water tank, so that the buoyancy of the gas collection device gradually increases until the gas collection device can float freely on the surface of the sewage. Stop the first air pump, close the valve of the sampling air pipe and the valve of the outlet air pipe, and start collecting the gas discharged from the sewage in the second cavity. (d) The first air pump is started or stopped by measuring the internal pressure of the second chamber through the pressure sensor to pump or extract air, so as to adjust the weight of the air collection device so that it floats stably on the surface of the sewage. (e) After the gas collection stops, start the second gas pump to pump the sewage discharge gas in the first chamber into the detector for testing or collect it through the gas collection bag and send it for testing.

2. The measurement method according to claim 1, characterized in that, The detector is a Fourier transform infrared detector, and the measuring device includes a temperature sensor for measuring the temperature inside the second cavity.

3. The measurement method according to claim 1, characterized in that, The sampling tube is equipped with an outlet tube, and the end of the outlet tube is detachably equipped with a gas collection bag.

4. The measurement method according to claim 1, characterized in that, The following data need to be measured separately during the measurement process: The start time of gas collection is t1; The liquid level height H1 in the second chamber at the start of gas collection; The end time of gas collection is t2; The liquid level height H2 in the second chamber at the end of gas collection; Temperature T; The calculation method is as follows: Calculate the rate v at which the measuring device collects the gas: (1)； in, The gas collection rate of the measuring device is expressed in m³ / h. This is the internal cross-sectional area of ​​the second cavity, in m2; Furthermore, the greenhouse gas emission flux emitted or released by the wastewater unit is calculated using ν. : (2) in, The emission flux of greenhouse gases released from wastewater is expressed in g / (m2·h). p is the air pressure inside the second cavity, in Pa. C represents the volume concentration of the corresponding gas, in ppm; M is the molar mass of the gas, expressed in g / mol; R is the ideal gas constant, with a value of 8.314 and a unit of J / (mol·K); T represents the gas temperature inside the second chamber, in Kelvin (K). 10⁻⁶ is the unit conversion constant. This represents the area of ​​the opening at the bottom of the second cavity.

5. The measurement method according to claim 1, characterized in that, It also includes, It also includes calculating the greenhouse gas emissions emitted or released by the wastewater treatment unit. : (3)； in, The emission of the i-th greenhouse gas that escapes or is released in the j-th measurement area of ​​the wastewater treatment unit, in g / d; Let be the average emission flux of the i-th greenhouse gas, expressed in g / (m²·h). Let be the water surface area of ​​the j-th measurement area in the wastewater treatment unit, in m2; This also includes the greenhouse gas emissions Q emitted or released from the wastewater system. ； During the measurement process, each point is sampled and measured at least three times, and the average value is taken as the wastewater greenhouse gas emission flux value of the point.

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