CN111912948A - A device and method for simulating nitrogen conversion in river water-suspended particle-sediment system - Google Patents

Abstract

The invention belongs to the field of environmental science and engineering, in particular to a device and method for simulating and studying nitrogen conversion in a river water-suspended particle-sediment system. The invention first constructs an experimental device capable of simulating rivers, especially keeping suspended particles suspended in water, which is characterized by including a control cover, a container, an electric motor and its transmission device, a xenon lamp lighting device, a control panel and a stirring paddle. The control cover is connected with the container through threads to form a sealing system, and the control board is used to adjust the illumination intensity of the xenon lamp and the rotational speed of the stirring paddle to keep the particles in a suspended state. The method involved is to carry out a simulation experiment by adding samples of various phases of the river, isotope tracer substances and other reagents. During the experiment, various indicators of the water body are monitored and samples are collected at any time through auxiliary holes, and at the same time, aeration and oxygenation are used to ensure the aerobic conditions of the water phase. . Under the premise of ensuring the air tightness of the system, the method can truly restore the status of the river water-suspended particle-sediment system, reflecting the transformation characteristics of nitrogen in the river.

Description

A device for simulating nitrogen transformation in river water-suspended particle-sediment system method

technical field

The invention relates to the fields of environmental science and engineering, in particular to a device and method for simulating and studying nitrogen conversion in a river water-suspended particle-sediment system.

Background technique

With the strengthening of human intervention in nature, more and more nitrogen enters the natural environment through human activities such as farmland fertilization, fossil fuel combustion, and livestock and poultry breeding sewage, increasing the nitrogen load of the ecosystem. A considerable part of nitrogen will enter the water body through surface runoff, infiltration, atmospheric deposition, etc. Excessive nitrogen elements can easily lead to nitrogen pollution, which can lead to environmental problems such as water eutrophication. Rivers are a rich treasure house of nitrogen resources, and are also important places for nitrogen transformation, making great contributions to the rational distribution and regulation of nitrogen in the ecosystem. Previous studies have shown that river sediments are the main area where nitrogen transformation occurs; however, more and more current studies have found that suspended particles in river overlying water are also important sites for nitrogen transformation. If denitrification on suspended particles is not considered contribution to nitrogen transformation, the contribution of rivers to global nitrogen emissions will be underestimated. Therefore, the effect of suspended particles on nitrogen transformation in rivers needs to be studied in depth.

After searching, the document "Liu, Ting, et a1." , although the device uses an external stirrer to stir the water body to keep the suspended particles in suspension, but the device is too simple to solve the problem of nitrogen (N ₂ ) and nitrous oxide (N ₂ O) escape at the top of the device during the experiment. affect the experimental results. The literature does not mention the water body indicators related to the experiment during the experiment, such as dissolved oxygen (DO), oxidation-reduction potential (ORP), pH, conductivity (Conductivity), the monitoring steps of water temperature, and the collection of gas and water samples The sequence of operations is therefore unclear.

In order to truly restore the environmental conditions of water-suspended particles-sediment in natural rivers in the laboratory, solve the problem of the tightness of the device during the experiment, and at the same time facilitate the collection of nitrogen conversion products and the determination of various indicators of the water body, it is necessary to Developed a set of natural river simulation device that can form a water-suspended particle-sediment microcosm system; and after the device is constructed, it can collect samples in the device through specific operation steps, and monitor the relevant indicators of the water body to obtain more accurate the experimental results.

SUMMARY OF THE INVENTION

problem to be solved

Aiming at the problems of insufficient air tightness of the device and difficulty in collecting experimental products in the nitrogen transformation simulation experiment of the river microcosm system, the present invention proposes a device and method for simulating the nitrogen transformation of the river water-suspended particle-sediment system. First, a specific experimental device is used to simulate the movement state of natural rivers, so that microorganisms can carry out nitrogen transformation in the system, and then use certain operation steps to conduct simulation experiments, monitor various indicators in the water, and collect products in the system to achieve a more realistic The simulation effect can improve the accuracy of the experiment.

In order to solve the above problems, the present invention adopts the following technical solutions.

In a first aspect, an embodiment of the present invention provides a simulation device for studying nitrogen conversion in a river water-suspended particle-sediment system, the device is used to perform the method of the second aspect, and the device includes a top control cover (high 15.0-20.0cm, inner diameter 40.0-60.0cm, wall thickness 0.5-2.0cm, inner diameter: height = 3:1) and the bottom container (inner diameter 12.0-40.0cm, the inner diameter of the container is smaller than the inner diameter of the control cover, height 16.0-53.0cm, Inner diameter: height = 3: 4, volume 1.8-67.0L, wall thickness 0.5-2.0cm).

There are small motors on the left and right sides of the control cover, and a support body (cube, the length, width and height depends on the actual situation) under the motor to ensure the running height of the motor, the motor is connected to the transmission gear, the Connect the wires above the motor.

There is a hollow stirring paddle in the middle part of the control cover, and the upper part of the stirring paddle (inner diameter is 6.0-10.0mm, the outer diameter is 2.0-4.0mm larger than the inner diameter) has disc-shaped wings (diameter 1.8-3.0cm, the wings are relatively stirring The position of the upper part of the paddle depends on the specific situation), the wing is integrated with the upper part of the stirring paddle and is separated by a cylindrical compartment with a slightly larger volume (inner diameter 6.0-10.0cm, height 4.0-8.0cm, wall thickness 0.5-1.0cm ) surrounded, there is a small hole at the bottom of the compartment (the aperture is 1.0-2.0mm larger than the outer diameter of the upper part of the stirring paddle), so that the upper part of the stirring paddle can pass through, and the bottom of the compartment contains a circular rubber gasket (inner diameter). It is 1.0-2.0mm larger than the outer diameter of the upper part of the stirring paddle, and the outer diameter is 4.0-6.0mm larger than the wing), and the rubber gasket is coated with lubricating oil, which can reduce the friction between the wing and the bottom of the compartment. The gasket is fixed by annular fixing groove 1 (the inner diameter is the same as the outer diameter of the rubber gasket, and the outer diameter is 0.5-1.0cm larger than the inner diameter). The top of the compartment is provided with an opening (diameter 4.0-8.0cm) and a plastic cover, which can be Open and remove or put the upper part of the stirring paddle in the compartment at any time; the middle and upper part of the stirring paddle is fixed with the gear (spur bevel gear, the specific position of the gear depends on the specific situation), and the gear is connected to the motor gear (straight bevel gear). Tooth bevel gear) to achieve the effect of transmitting power (the axes of the two wheels are orthogonal to the cone vertex), the middle part of the stirring paddle is connected to the lower part of the stirring paddle with a slightly larger inner diameter (the inner diameter is 0.1- 0.6mm, the outer diameter is 3.0-6.0mm larger than the inner diameter), the number and position of the clamping holes are determined according to the actual situation, which is convenient to flexibly adjust the length of the stirring paddle.

The inner and lower side of the control cover is provided with a small hole (the diameter is 1.0-2.0mm larger than the outer diameter of the upper part of the stirring paddle), so that the upper part of the stirring paddle can pass through, and a shaft seal (the inner diameter and the outer diameter of the upper part of the stirring paddle) are provided above the small hole. The diameter is the same size, and the outer diameter is 2.0-5.0cm larger than the inner diameter), which can prevent the lower gas from escaping to the control cover. There are two annular fixing grooves around the shaft seal (the inner diameter is the same as the outer diameter of the shaft seal, and the outer diameter is larger than the inner diameter). 0.5-1.0 cm in size) is used to fix the shaft seal; there is a ring-shaped xenon lamp lighting device on the outer lower side of the control cover to simulate the lighting conditions. The outer lower side of the control cover is provided with an external thread, and the thread is connected with a container provided with an internal thread.

A control panel is provided on the outer upper left side of the control cover, and the control panel can adjust the rotational speed of the motor, the illumination intensity of the xenon lamp and connect to the external power supply.

The left and right sides of the container are respectively provided with auxiliary holes one (aperture diameter 2.0-3.0cm, the intersection of the central axis of the pipe of the hole and the inner wall of the container is located at 55%-65% of the height of the container) and auxiliary holes two (aperture diameter 0.5-1.0cm, The intersection of the central axis of the pipe of the hole and the inner wall of the container is located at 75%-85% of the height of the container), the auxiliary hole 1 is a slightly lower inward and downward inclined hole (the angle between the central axis of the pipe of the hole and the inner wall of the container) 40-50°), which is convenient for the insertion of the electrode head of the water quality measuring instrument and the insertion of the sampling tube; the second auxiliary hole is a slightly higher inward horizontal hole, which is convenient for collecting gas samples in the container. During the operation of the device, the first auxiliary hole is sealed with a rubber plug, and the second auxiliary hole is connected with a three-way valve and kept closed. After the experiment is over, samples can be taken and relevant indicators in the water can be detected.

The bottom of the container has a support base (the diameter is 70%-90% of the inner diameter of the top control cover, and the height is 1.0-5.0cm), and the support base is integrated with the container to increase the stability of the device during operation.

In a second aspect, the present invention relates to a method for simulating and studying a river water-suspended particle-sediment simulation system to study nitrogen transformation in a water body. The steps of the method are as follows:

(1) Prepare multiple devices. Before the experiment starts, open the plastic cover above the control cover, check whether the upper wing of the stirring paddle in the compartment is placed on the rubber gasket, check whether the rubber gasket is located in the fixing groove 1, and confirm that it is normal After that, open the control cover and auxiliary holes 1 and 2, and add sediment, suspended particles and river water samples (or simulated river water to reduce ¹⁴ NO ₃ ^- -N and ¹⁴ NH ₄ ⁺ -N in the actual river water samples) into different containers respectively. Effects on nitrogen isotope tracing) to construct a water-suspended particle-sediment system. In addition, it is also possible to add only suspended particles and river water samples (or simulate river water to reduce the influence of ¹⁴ NO ₃ ^- -N and ¹⁴ NH ₄ ⁺ -N on nitrogen isotope tracing in actual river water samples) to construct sediment-free water- Suspended particle system. At the same time, ensure that the water in all containers is a certain volume, the height of the water surface should not submerge the two auxiliary holes, and adjust the distance between the stirring paddle and the bottom of the container to ensure that it can evenly stir the water body;

(2) For the water-suspended particle-sediment system, quantitative ¹⁵ NH ₄ ⁺ -N ( ¹⁵ NH ₄ Cl, 99.0 atm% ¹⁵ N) was added to study the coupled nitrification and denitrification of the system, and the coupling was studied by analyzing the ³⁰ N ₂ product Nitrification and denitrification rate;

(3) For the water-suspended particle system, quantitative allyl thiourea (ATU) was added to inhibit the activity of nitrification in the system, and a quantitative amount of ¹⁴ NH ₄ ⁺ -N( ¹⁴ NH ₄ Cl, 99.0 atm was added to the system at the same time. % ¹⁴ N), ¹⁵ NO ₃ ^- -N ( ¹⁵ KNO ₃ , 99.0 atm% ¹⁵ N) and ¹⁵ NO ₂ ^- -N ( ¹⁵ KNO ₂ , 99.0 atm % ¹⁵ N) to study denitrification and anaerobicity in the system Ammoxidation, the denitrification process will generate ³⁰ N ₂ O and ³⁰ N ₂ products, while the anaerobic ammonium oxidation process will generate ²⁹ N ₂ products;

(4) After step (2) or (3) is completed, tighten the control cover, and put the pH, dissolved oxygen (DO), oxidation-reduction potential (ORP), and conductivity (Conductivity) probes into the water body through the auxiliary hole one by one. After measuring the pH, DO, ORP, conductivity and temperature in the water, seal the auxiliary hole with a rubber stopper, close the second auxiliary hole, ensure that the container is sealed, and then connect the power supply at the control board to start the motor. For the water-suspended particle system, the speed of the motor must be adjusted to keep the suspended particles in the container in a suspended state; for the water-suspended particle-sediment system, the concentration of suspended particles must be controlled by adjusting the speed. If necessary, the xenon lamp can be used to adjust different light intensities to simulate the illumination of natural light under different light levels;

(5) It is necessary to take samples from the inside of the device and oxygenate it at regular intervals. First turn off the power, open the three-way valve of the second auxiliary hole, and collect the gas in the container; after collecting the gas, keep the three-way valve open, open the auxiliary hole one to collect the water sample in the container; after the water sample is collected, put the monitoring probes in sequence Put into water through this hole, measure pH, DO, ORP, conductivity and temperature in the water; after the measurement, use a small oxygenation device to oxygenate the system through the auxiliary hole;

(6) After the completion of step (5), the first and second auxiliary holes are closed, and the motor is turned on to carry out the next stage of the experiment;

(7) After the experiment, collect the last group of gas and water samples through step (5), open the control cover, use the filter device to collect suspended particles in the water, and simultaneously collect sediment samples.

beneficial effect

Compared with the method described in the existing literature, the beneficial effects of the present invention are:

(1) The device of the present invention has good air tightness. The container and the control cover are connected by threads to form a sealed whole; during the experiment, the auxiliary hole on the container is sealed by a rubber plug, and the auxiliary hole two engages the three-way valve during the operation of the device to keep closed; the bottom of the control cover uses a shaft seal It is closely combined with the upper part of the stirring paddle, so when the device is running, the experimental products N ₂ and N ₂ O in the system are not easy to escape, so that the experimental results are more accurate.

(2) The device of the present invention is easy to collect gas and water samples inside the device during the experiment, and monitor various indicators of the water body. The inclined auxiliary hole 1 facilitates the insertion of monitoring probes and sampling pipes to monitor water environment indicators and collect water samples; the horizontal auxiliary hole 2 is used to collect gas samples.

(3) The method of the present invention can supplement dissolved oxygen at any time according to the monitoring value of the water body to ensure that the water phase is in aerobic conditions, so as to simulate the aerobic state of the actual river overlying water body. This method can monitor the dissolved oxygen (DO) concentration at any time. Once the concentration is found to be lower than the DO value of the overlying water body in the river in the sampling area, oxygen can be added to the device immediately.

(4) The present invention can also study the effect of nitrogen transformation in the water-suspended particle-sediment system under different lighting conditions. By controlling the light intensity of the xenon lamp, the river movement under different natural light illumination is simulated, and the effect of the photocatalytic phenomenon in the suspended particles on the nitrogen conversion of the river system is studied.

(5) In addition to studying the coupled nitrification and denitrification process under the river water-suspended particle-sediment system, the denitrification and anammox processes under the river water-suspended particle system, the device of the present invention can also be added to the system by adding Different components study other nitrogen conversion processes and carbon conversion processes in river water-suspended particle-sediment or water-suspended particle systems.

Description of drawings

Fig. 1 is the internal sectional view of the device of the present invention;

Figure 2 is a bottom view of the control cover;

In the figure: 1. Stirring paddle; 2. Lock; 3. Auxiliary hole 2; 4. Three-way valve; 5. Internal thread; 6. Support body; 7. Motor; 8. Compartment; 9. Plastic cover; 10 , wing; 11, rubber gasket; 12, fixing slot one; 13, control panel; 14, wire connector; 15, bevel gear; 16, external thread; 17, ring xenon lamp; 18, fixing slot two; 19, Rubber stopper; 20. Auxiliary hole one; 21. Shaft seal; 22. Support base; 23. Control cover; 24. Small hole.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In the present invention, a device for simulating a river water-suspended particle-sediment system, the device specifically includes a control cover on the top, small motors are installed on the left and right sides of the control cover, and a support body is arranged below the motor , the motor is connected to the transmission gear, the inner side of the control cover is provided with a hollow stirring paddle, the upper part of the stirring paddle has a disc-shaped wing, and the wing is integrated with the stirring paddle and is surrounded by a cylindrical shape with a slightly larger volume. The compartment is surrounded by a small hole at the bottom of the compartment to allow the upper part of the stirring paddle to pass through. The bottom of the compartment contains a circular rubber gasket, and the gasket is fixed by the annular fixing groove. The top of the room is provided with an opening and a plastic cover, the upper part of the stirring paddle is fixed with a gear, the gear is connected to the motor gear, and the middle part of the stirring paddle is connected to the lower part of the stirring paddle with a slightly larger inner diameter through a spring-type latch, There are a plurality of the card slots, the length of the stirring paddle can be adjusted, the inner and lower side of the control cover is provided with a small hole, the stirring paddle can pass through, a shaft seal is arranged above the small hole, and the shaft seal is surrounded by A second annular fixing groove is provided, the outer lower side of the control cover is provided with an annular xenon lamp lighting device, the outer lower side of the control cover is provided with an outer thread, and the lower part of the thread is connected with a container provided with an inner thread. A control panel is provided on the outer upper left side of the control cover, and the control panel can adjust the rotational speed of the motor, the illumination intensity of the xenon lamp and connect to the external power supply.

In the device for simulating nitrogen conversion in the river water-suspended particle-sediment system, the diameter of the small hole on the lower side of the control cover is 1.0-2.0 mm larger than the outer diameter of the upper part of the stirring paddle, and there is a shaft above the small hole. The inner diameter is the same as the outer diameter of the upper part of the stirring paddle, and the outer diameter is 2.0-5.0cm larger than the inner diameter. The shaft seal is fixed by the second annular fixing groove, the inner diameter is the same as the outer diameter of the shaft seal, and the outer diameter is 0.5-1.0 larger than the inner diameter. cm, the part of the top of the fixing groove that protrudes from the periphery to the center is not included.

The left and right sides of the container are respectively provided with an auxiliary hole 1 and an auxiliary hole 2, the auxiliary hole 1 is an inward and downward inclined hole with a slightly lower position, and the auxiliary hole 2 is an inward horizontal hole with a slightly higher position. The specific parameters are as follows: the first auxiliary hole has a diameter of 2.0-3.0cm, and the intersection of the central axis of the pipe of the hole and the inner wall of the container is located at 55%-65% of the height of the container; the second auxiliary hole has a diameter of 0.5-1.0cm, and the central axis of the hole and the container The intersection point of the inner wall is located at 75%-85% of the height of the container; the included angle between the central axis of the pipe of the hole of the auxiliary hole 1 and the inner wall of the container is 40-50°.

"The intersection of the central axis of the pipe of auxiliary hole 1 and the inner wall of the container is located at 55%-65% of the height of the container; the intersection of the central axis of the pipe of auxiliary hole 2 and the inner wall of the container is located at 75%-85% of the height of the container; auxiliary hole 1 The angle between the central axis of the pipe of the hole and the inner wall of the container is 40-50°”, which will affect the technical effect.

In the present invention, the height of the water surface must not submerge the two auxiliary holes, so the height set by the two auxiliary holes limits the volume of water added into the container. The volume of water is insufficient, resulting in a low content of gas, which affects the experimental results. In addition, if the included angle between the central axis of the pipeline of the auxiliary hole 1 and the inner wall of the container is too large or too small, it is inconvenient to put the monitoring probe and the sampling tube.

In the present invention, there is a shaft seal above the small hole, and the inner diameter is the same as the outer diameter of the upper part of the stirring paddle. included) is the same size as the outer diameter of the shaft seal. Therefore, the device must ensure that the "stirring paddle-shaft seal-fixing groove" fits tightly, otherwise the gas will escape to the control cover through here during the experiment, resulting in ²⁹ N ₂ and ³⁰ N ₂ collected in the sample. The content of 30 N 2 O and ³⁰ N ₂ O is lower than the actual gas content, which affects the experimental results.

In the present invention, the method for simulating and studying nitrogen transformation in river water-suspended particle-sediment system comprises the following steps:

(1) Prepare multiple devices. Before the experiment starts, open the plastic cover above the control cover, check whether the upper wing of the stirring paddle in the compartment is placed on the rubber gasket, check whether the rubber gasket is located in the fixing groove 1, and confirm that it is normal After that, open the control cover and auxiliary holes 1 and 2, and add sediment, suspended particles and river water samples (or simulated river water) to different containers to construct a water-suspended particle-sediment system.

In addition, it is also possible to add only suspended particles and river water samples (or simulated river water) to construct a water-suspended particle system without sediment. At the same time, ensure that the water in all containers is a certain volume, the height of the water surface should not submerge the two auxiliary holes, and adjust the distance between the stirring paddle and the bottom of the container to ensure that it can evenly stir the water body. The simulated river water is used to reduce the effects of ¹⁴ NO ₃ ^- -N and ¹⁴ NH ₄ ⁺ -N on nitrogen isotope tracing in actual river water samples.

(2) For the water-suspended particle-sediment system, quantitative ¹⁵ NH ₄ ⁺ -N ( ¹⁵ NH ₄ Cl, 99.0 atm% ¹⁵ N) was added to study the coupled nitrification and denitrification of the system, and the coupling was studied by analyzing the ³⁰ N ₂ product Nitrification and denitrification rate;

(3) For the water-suspended particle system, quantitative allyl thiourea (ATU) was added to inhibit the activity of nitrification in the system, and a quantitative amount of ¹⁴ NH ₄ ⁺ -N( ¹⁴ NH ₄ Cl, 99.0 atm was added to the system at the same time. % ¹⁴ N), ¹⁵ NO ₃ ^- -N ( ¹⁵ KNO ₃ , 99.0 atm% ¹⁵ N) and ¹⁵ NO ₂ ^- -N ( ¹⁵ KNO ₂ , 99.0 atm % ¹⁵ N) to study denitrification and anaerobicity in the system Ammoxidation, the denitrification process will generate ³⁰ N ₂ O and ³⁰ N ₂ products, while the anaerobic ammonium oxidation process will generate ²⁹ N ₂ products;

(4) After step (2) or (3) is completed, tighten the control cover, and put the pH, dissolved oxygen (DO), oxidation-reduction potential (ORP), and conductivity (Conductivity) probes into the water body through the auxiliary hole one by one. After measuring the pH, DO, ORP, conductivity and temperature in the water, seal the auxiliary hole with a rubber stopper, close the second auxiliary hole, ensure that the container is sealed, and then connect the power supply at the control board to start the motor. For the water-suspended particle system, the speed of the motor must be adjusted to keep the suspended particles in the container in a suspended state; for the water-suspended particle-sediment system, the concentration of suspended particles must be controlled by adjusting the speed. If necessary, the xenon lamp can be used to adjust different light intensities to simulate the illumination of natural light under different light levels;

(5) It is necessary to take samples from the inside of the device and oxygenate it at regular intervals. First turn off the power, open the three-way valve of the second auxiliary hole, and collect the gas in the container; after collecting the gas, keep the three-way valve open, open the auxiliary hole one to collect the water sample in the container; after the water sample is collected, put the monitoring probes in sequence Put into water through this hole, measure pH, DO, ORP, conductivity and temperature in the water; after the measurement, use a small oxygenation device to oxygenate the system through the auxiliary hole;

(6) After the completion of step (5), the first and second auxiliary holes are closed, and the motor is turned on to carry out the next stage of the experiment;

(7) After the experiment, collect the last group of gas and water samples through step (5), open the control cover, use the filter device to collect suspended particles in the water, and simultaneously collect sediment samples. The device and method for simulating and studying nitrogen conversion in a river water-suspended particle-sediment system according to the present invention can ensure that the system is in a closed state, and the gas generated during the nitrogen conversion process will not escape; The water phase, suspended particle phase and gas phase are continuously sampled; it can also monitor various indicators of the water body at any time, such as pH, dissolved oxygen (DO), oxidation-reduction potential (ORP), conductivity (Conductivity) and temperature; and at any time according to the monitoring value. Supplementing dissolved oxygen ensures that the water phase is in aerobic conditions to simulate the aerobic state of the actual river overlying water.

Example 1: Simulate and study the effect of suspended particle concentration on coupled nitrification and denitrification in the overlying water body of the river.

Water and sediment samples were collected from Wanzhou Hydrological Station and Tieji Road Wharf in the middle reaches of the Yangtze River; Longmen, Huayuankou and Aishan Hydrological Stations of the Yellow River. The water samples were collected at 0.2 m below the water surface, and the riverbed sediments at a depth of 0-10 cm were collected with a grab-type sampler and placed in sterile plastic bags. Simultaneously, the pH, dissolved oxygen (DO), redox potential (ORP), conductivity and temperature of the river water were measured on-site. All samples were cryopreserved and sent to the laboratory for further analysis after sampling.

The specific processing steps are as follows:

(1) Open the plastic cover 9 above the control cover 23, check whether the upper wing 10 of the stirring paddle 1 in the compartment is placed on the rubber gasket 11, and check whether the rubber gasket 11 is located in the fixing groove 1 12. After confirming that it is normal, open the control cover 23, auxiliary hole 1 20 and auxiliary hole 2 3, and add 10 cm thick sediment samples, 800 mL of simulated river water and 5 mg L ^-1 of ¹⁵ NH ₄ ⁺ -N( ¹⁵ NH ₄ to the 6 groups of containers. Cl, 99.0 atm% ¹⁵ N), each experiment was performed in triplicate. Adjust the distance between the stirring paddle and the bottom of the container through the lock 2 to ensure that the water body can be well stirred without touching the sediment.

(2) Tighten the control cover 23, put the pH, DO, ORP, and conductivity probes into the water body through the auxiliary hole 1 20 in turn to measure the pH, DO, ORP, conductivity and temperature in the water, and then plug the auxiliary hole with a rubber plug 19. The first 20 is sealed, the auxiliary hole 2 3 is kept closed, and the power supply at the control board 13 is connected to start the motor 7 after ensuring that the container is sealed. The experiments were carried out at room temperature of 25°C.

(3) In the 6 groups of systems constructed in step (1), the concentration of suspended particles generated by the disturbance of the stirring paddle is adjusted by controlling the rotational speed of the motor. Each group formed experimental systems with suspended particle concentrations of 20, 15, 8, 2.5, 1 and 0 gL ^-1 at 700, 550, 400, 200, 150 and 0 rpm, respectively, to simulate real rivers with different sediment contents.

(4) The samples in the device were collected and oxygenated every other day (collected 16 times in total). First, turn off the power supply connected to the control board 13, open the three-way valve 4 of the auxiliary hole 2 3, and collect the gas in the container through a syringe. After the gas is collected, the three-way valve 4 is kept open, and the auxiliary hole 1 20 is opened to collect the container. After collection, the water samples were filtered with a 0.45 μm pinhole filter and stored at -20°C. After the water sample is collected, the monitoring probes are put into the water through the hole in turn to measure the pH, DO, ORP, conductivity and temperature of the water. After the measurement is completed, use a small oxygen filling device to fill the container with oxygen through the auxiliary hole 1 20.

(5) After step (4) is completed, the first auxiliary hole 20 and the second auxiliary hole 3 are closed, and the motor 7 is turned on for the next stage of the experiment.

(6) After the experiment, collect the gas and water samples in the last group of systems through step (4), open the control cover 23, filter and collect the suspended particle samples in the water with a 0.45 μm filter membrane, and pour the suspended particle samples after collection. The container collects the sediment sample. Determine the content of ³⁰ N ₂ in the collected gas sample and the content of NO ₃ ^- -N, NO ₂ ^- -N and NH ₄ ⁺ -N in the water phase, then calculate the generation rate of ³⁰ N ₂ in the system, and analyze the NO in the system Changes of ₃ ^- -N, NO ₂ ^- -N and NH ₄ ⁺ -N with time. At the same time, it can also analyze the number of microorganisms in sediments and suspended particles.

Table 1 Example 1 running results (cultivation time is 31d)

Example 2: Simulate and study the effect of suspended particles of different particle sizes on denitrification and anammox in the overlying water of the river.

Water and sediment samples were collected from the Wanzhou Hydrological Station in the middle reaches of the Yangtze River. The water samples were collected at 0.2 m below the water surface, and the riverbed sediments at a depth of 0-5 cm were collected with a grab-type sampler and placed in sterile plastic bags. Simultaneously, the pH, dissolved oxygen (DO), redox potential (ORP), conductivity and temperature of the river water were measured on-site. All samples were cryopreserved and sent to the laboratory for further analysis after sampling. After investigation, it was found that the particle size of the suspended particles in the river water was less than 200μm. Therefore, a part of the sediment samples were divided into 4 groups according to the particle size of <20μm, 20-63um, 63-100μm and 100-200μm by wet sieving method. . In order to avoid interference with the experimental results due to ²⁹ N ₂ produced by ¹⁴ NO ₃ ^- in the following experiments, an ultrapure water wet sieve produced by mili-Q was used. Another part of the sediment sample was wet sieved through a 200 μm filter, and the suspended particles obtained from this part were the original suspended particles (<200 μm). The water content of the obtained 5 groups of sediment particle diameters was measured, and the wet sieved water was filtered through a 0.45 μm filter membrane. After collection, it was prepared into simulated river water with a ratio of wet sieved water: ultrapure water = 1:79. .

The specific processing steps are as follows:

(1) Open the plastic cover 9 above the control cover 23, check whether the upper wing 10 of the stirring paddle 1 in the compartment is placed on the rubber gasket 11, and check whether the rubber gasket 11 is located in the fixing groove 1 12. After confirming that it is normal, open the control cover 23, auxiliary hole 1 20 and auxiliary hole 2 3, and add 0.8g of different particle size groups (<20μm, 20-63μm, 63-100μm, 100-200μm, <200μm to 15 containers respectively. Original suspended particle samples, triplicate, a total of 5 groups) of suspended particles (dry weight) and 800 mL of simulated river water, so that the concentration of suspended particles in the system is 1.0 g L ^-1 . Since the content of dissolved organic carbon in the system is less than 0.2 mg-C L ^-1 , it is necessary to add glucose-simulating biodegradable organic carbon as an electron donor to promote the denitrification of suspended sediment in the river. According to the dissolved organic carbon concentration in the water body of the Yangtze River, a total of 5 mg-CL ^-1 glucose was added. Two groups of control groups were set up. Other conditions remained unchanged. One group only added 800 mL of simulated river water to construct a reaction system containing bacteria but no suspended particles; (sterilized at 121° C., 30 min), 800 mL of ultrapure water, and 50% w/v ZnCl ₂ to inhibit microbial activity. Adjust the distance between the stirring paddle and the bottom of the container through the lock 2 to ensure that the water body can be well stirred.

(2) 150 mg L ^-1 allyl thiourea (ATU) was added to the different systems constructed in step (1) to inhibit the activity of nitrification in the system, thereby facilitating the observation of denitrification and anammox.

(3) 2 mg L ^-1 of ¹⁴ NH ₄ ⁺ -N ( ¹⁴ NH ₄ Cl, 99.0 atm% ¹⁴ N), 2 mg L ^-1 of ¹⁵ NO ₃ ^- -N ( ¹⁵ KNO ₃ , 99.0 atm% ¹⁵ N) and 1 mg L ^-1 of ¹⁵ NO ₂ ^- -N ( ¹⁵ KNO ₂ , 99.0 atm% ¹⁵ N) to study the denitrification and anammox processes in the system, the denitrification process ³⁰ N ₂ O and ³⁰ N ₂ products are produced, while ²⁹ N ₂ products are produced during the anammox process.

(4) Tighten the control cover 23, put the pH, DO, ORP, conductivity probes into the water body through the auxiliary hole 1 20 in turn, measure the pH, DO, ORP, conductivity and temperature in the water, and use the rubber plug 19 to close the auxiliary hole. One 20 is sealed, the auxiliary hole two 3 is kept closed, and the power supply at the control panel 13 is turned on to start the motor 7 after ensuring that the container is sealed, and the speed of the motor 7 (180rpm) is adjusted to keep the suspended particles in the container suspended. The experiments were carried out at 18°C, the annual average temperature of the Yangtze River.

(5) The samples in the device were collected every 3 days and oxygenated (collected 5 times in total). First, turn off the power supply connected to the control board 13, open the three-way valve 4 of the auxiliary hole 2 3, collect the gas in the container of about 200 mL through a syringe, and keep the three-way valve 4 open after the gas is collected, and open the auxiliary hole 1 20 to collect the gas. The water samples in the 4mL container were collected and filtered with a 0.45μm pinhole filter and stored at -20°C. After the water sample is collected, the monitoring probes are put into the water through the hole in turn to measure the pH, DO, ORP, conductivity and temperature of the water. After the measurement is completed, use a small oxygen filling device to fill the container with oxygen through the auxiliary hole 1 20.

(6) After step (5) is completed, the first auxiliary hole 20 and the second auxiliary hole 3 are closed, and the motor 7 is turned on to carry out the next stage of the experiment.

(7) After the experiment, collect the gas and water samples in the last group of systems through step (5), open the control cover 23, filter and collect the suspended particle samples in the water with a 0.45 μm filter membrane. Determine the contents of ²⁹ N ₂ , ³⁰ N ₂ and ³⁰ N ₂ O in the collected gas samples and the contents of NO ₃ ^- -N, NO ₂ ^- -N and NH ₄ ⁺ -N in the water phase, and then calculate the system ²⁹ N ₂ , ³⁰ N ₂ and ³⁰ N ₂ O production rate, and analyze the variation law of NO ₃ ^- -N, NO ₂ ^- -N and NH ₄ ⁺ -N in the system with time. At the same time, it can also analyze the number of microorganisms in sediment and suspended particulate matter.

Table 2 Example 2 running results (cultivation time is 20d)

Comparative Example 1

Carry out simulation according to the method of Example 2 and study the effect of suspended particles of different particle sizes on denitrification and anammox in the overlying water body of the river, the difference is the following steps 5 and 6, otherwise the same .

(5) The samples in the device were collected every 3 days and oxygenated (collected 5 times in total). Do not turn off the power supply connected to the control board 13, open the auxiliary hole 1 20, collect the water sample in the 4 mL container, filter it with a 0.45 μm pinhole filter and store it in the environment of -20°C. After the water sample is collected, the auxiliary hole 1 20 is kept open, the three-way valve 4 of the auxiliary hole 2 3 is opened, and the gas in the container of about 200 mL is collected through a syringe. After the gas is collected, the three-way valve 4 is kept open. After the gas sample is collected, put the monitoring probe into the water through the auxiliary hole 1 20 in turn to measure the pH, dissolved oxygen (DO), redox potential (ORP), conductivity and temperature of the water. After the measurement is completed, use a small oxygen filling device to fill the container with oxygen through the auxiliary hole 1 20.

(6) After step (5) is completed, the first auxiliary hole 20 and the second auxiliary hole 3 are closed, and the experiment of the next stage is directly carried out.

According to the method of Comparative Example 1 to simulate and study the overlying water body of the river, there are the following problems:

1. In the process of collecting samples and monitoring various indicators of the water body, if the power is not turned off, the motor will drive the stirring paddle to rotate, causing inconvenience in sample collection and water quality monitoring, and may even cause safety problems. In the process of collecting water samples and aeration and oxygenation, it is necessary to extend the soft plastic sampling tube into the water through the auxiliary hole-20; after collecting the gas and water samples, the monitoring probe needs to be inserted into the water through the auxiliary hole-20. If the stirring paddle keeps rotating, the rotating stirring paddle may hit the sampling tube and monitoring probe, damage the experimental instruments or equipment, and may even cause the parts of the experimental equipment to fall off, causing a safety accident.

2. If the water sample is collected first, and then the gas sample is collected, during the collection of the water sample, since the outer diameter of the protruding sampling tube needs to be smaller than the diameter of the auxiliary hole 120, the gas in the container will be The gas exchange with the atmosphere through the auxiliary hole 1 20 leads to the escape of ²⁹ N ₂ , ³⁰ N ₂ and ³⁰ N ₂ O gas in the container, which affects the later experimental results.

Comparative Example 2

According to the method of Example 2, the simulation was carried out to study the effect of suspended particles of different particle sizes on denitrification and anammox in the overlying water body of the river. The difference is the following step 5, otherwise the same.

(5) The samples in the device were collected every 3 days and oxygenated (collected 5 times in total). First, turn off the power supply connected to the control board 13, open the three-way valve 4 of the auxiliary hole 2 3, collect the gas in the container of about 200 mL through a syringe, and keep the three-way valve 4 open after the gas is collected, and open the auxiliary hole 1 20 to collect the gas. The water samples in the 4mL container were collected and filtered with a 0.45μm pinhole filter and stored at -20°C. After the water samples are collected, oxygen is filled into the container through the auxiliary hole 1 20 by using a small oxygen filling device. Finally, the monitoring probes are put into the water through the hole in turn, and the pH, dissolved oxygen (DO), redox potential (ORP), conductivity and temperature of the water are measured.

According to the method of Comparative Example 2 to simulate and study the overlying water body of the river, there are the following problems:

1. Aeration and oxygenation will allow the gas in the container to exchange gas with the atmosphere. The purpose of monitoring the water quality is to observe whether the various indicators of the water body in the container related to the nitrogen conversion experiment are within the fluctuation range of the indicators corresponding to the river water in the sampling area. If so, you can continue the experiment, if not, you need to stop the experiment or adjust the experimental conditions to continue the experiment. If the sample is collected by aeration and oxygenation first, and then the water quality is monitored, the DO concentration in the water in the container will change during the oxygenation stage, resulting in inaccurate monitoring indicators and inability to accurately judge whether the water quality in the container is allowed. The experiment continued.

The beneficial effects of the present invention are:

(1) The device of the present invention has good air tightness. The container and the control cover are connected by threads to form a sealed whole; during the experiment, the auxiliary hole on the container is sealed by a rubber plug, and the auxiliary hole two engages the three-way valve during the operation of the device to keep closed; the bottom of the control cover uses a shaft seal It is closely combined with the upper part of the stirring paddle, so when the device is running, the experimental products N ₂ and N ₂ O in the system are not easy to escape, so that the experimental results are more accurate.

(2) The device of the present invention is easy to collect gas and water samples inside the device during the experiment, and monitor various indicators of the water body. The inclined auxiliary hole 1 facilitates the insertion of monitoring probes and sampling pipes to monitor water environment indicators and collect water samples; the horizontal auxiliary hole 2 is used to collect gas samples.

(3) The method of the present invention can supplement dissolved oxygen at any time according to the monitoring value of the water body to ensure that the water phase is in aerobic conditions, so as to simulate the aerobic state of the actual river overlying water body. This method can monitor the dissolved oxygen (DO) concentration at any time. Once the concentration is found to be lower than the DO value of the overlying water body in the river in the sampling area, oxygen can be added to the device immediately.

(4) The present invention can also study the effect of nitrogen transformation in the water-suspended particle-sediment system under different lighting conditions. By controlling the light intensity of the xenon lamp, the river movement under different natural light illumination is simulated, and the effect of the photocatalytic phenomenon in the suspended particles on the nitrogen conversion of the river system is studied.

(5) In addition to studying the coupled nitrification and denitrification process under the river water-suspended particle-sediment system, the denitrification and anammox processes under the river water-suspended particle system, the device of the present invention can also be added to the system by adding Different components study other nitrogen conversion processes and carbon conversion processes in river water-suspended particle-sediment or water-suspended particle systems.

Claims (10)

1. a device for simulating river water-suspended particles-sediment system, is characterized in that, described device specifically comprises the control cover of the top, and the left and right sides of the inside of the control cover are equipped with small motors, and there are supports below the motor. body, the motor is connected to the transmission gear, the control cover is provided with a hollow stirring paddle on the middle side, the upper part of the stirring paddle is provided with a disc-shaped wing, and the wing is integrated with the stirring paddle and is surrounded by a cylinder with a slightly larger volume. The bottom of the compartment is surrounded by a small hole, allowing the upper part of the stirring paddle to pass through. The bottom of the compartment contains a circular rubber gasket, and the gasket is fixed by the annular fixing groove. The top of the compartment is provided with an opening and a plastic cover, the middle and upper part of the stirring paddle is fixed with a gear, the gear is connected to the motor gear, and the middle part of the stirring paddle is connected to the lower part of the stirring paddle with a slightly larger inner diameter through a spring-type latch , the slot is provided with multiple, the length of the stirring paddle can be adjusted, the inner and lower side of the control cover is provided with a small hole, the stirring paddle can pass through, a shaft seal is arranged above the small hole, and the shaft seal A ring-shaped fixing groove 2 is arranged around, the outer lower side of the control cover is provided with a ring-shaped xenon lamp lighting device, the outer lower side of the control cover is provided with an external thread, and the lower part of the thread is connected with a container provided with an inner thread, and the outside of the control cover is There is a control board on the upper left side, which can adjust the speed of the motor, the illumination intensity of the xenon lamp, and connect the external power supply. 2. The device for simulating and studying the nitrogen conversion of river water-suspended particles-sediment system according to claim 1, wherein the size of the control cover is 15.0-20.0cm in height, 40.0-60.0cm in inner diameter, and 10 in wall thickness. 0.5-2.0cm, inner diameter:height=3:1. 3. The device for simulating research river water-suspended particles-sediment system nitrogen conversion according to claim 1, is characterized in that: described hollow stirring paddle is made up of upper and lower parts, and the upper part comprises disc-shaped wings, and the diameter is 1.8-3.0cm, the middle and upper part is fixed with the gear, the inner diameter of the upper part is 6.0-10.0mm, the outer diameter is 2.0-4.0mm larger than the inner diameter; the inner diameter of the lower part is 0.1-0.6mm larger than the outer diameter of the upper part of the stirring paddle, and the outer diameter is larger than the inner diameter The size is 3.0-6.0mm, the upper and lower parts are connected by a lock, and the lower part is provided with a plurality of holes to adjust the position of the lock. 4. The device for simulating nitrogen conversion in river water-suspended particle-sediment system according to claim 1, wherein the size of the compartment inside the control cover is 6.0-10.0cm in inner diameter and 4.0-8.0cm in height cm, the wall thickness is 0.5-1.0cm, there are small holes at the bottom, the hole diameter is 1.0-2.0mm larger than the outer diameter of the upper part of the stirring paddle, and the top has an opening with a diameter of 4.0-8.0cm. 5. The device for simulating and studying the nitrogen conversion of river water-suspended particles-sediment system according to claim 1, characterized in that: the inner diameter of the fixed groove one inside the compartment is the same size as the outer diameter of the rubber gasket, and the outer diameter is the same as the outer diameter of the rubber gasket. It is 0.5-1.0cm larger than the inner diameter, the inner diameter of the fixed groove-inner annular rubber gasket is 1.0-2.0mm larger than the outer diameter of the upper part of the stirring paddle, and the outer diameter is 4.0-6.0mm larger than the wing. 6. The device for simulating and studying nitrogen conversion in river water-suspended particles-sediment system according to claim 1, wherein the aperture of the small hole on the lower side inside the control cover is 1.0-2.0 larger than the outer diameter of the upper part of the stirring paddle mm, there is a shaft seal above the small hole, the inner diameter is the same as the outer diameter of the upper part of the stirring paddle, the outer diameter is 2.0-5.0cm larger than the inner diameter, the shaft seal is fixed by the second annular fixing groove, and the inner diameter is the same size as the outer diameter of the shaft seal , the outer diameter is 0.5-1.0cm larger than the inner diameter. 7. The device for simulating and studying nitrogen conversion in river water-suspended particles-sediment system according to claim 1, wherein the inner diameter of the container is 12.0-40.0cm, the inner diameter of the container is smaller than the inner diameter of the control cover, and the height is 16.0-53.0 cm cm, inner diameter:height=3:4, volume 1.8-67.0L, wall thickness 0.5-2.0cm. 8. The device for simulating and studying nitrogen conversion in river water-suspended particles-sediment system according to claim 1, wherein the left and right sides of the container are respectively provided with auxiliary holes 1 and auxiliary holes 2, and the auxiliary holes 1 It is an inward and downward inclined hole with a slightly lower position, and the second auxiliary hole is an inward horizontal hole with a slightly higher position. The intersection point is located at 55%-65% of the height of the container; the diameter of the auxiliary hole 2 is 0.5-1.0cm, and the intersection of the central axis of the pipe of the hole and the inner wall of the container is located at 75%-85% of the height of the container; auxiliary hole 1 is in the pipe of the hole. The included angle between the axis and the inner wall of the container is 40-50°. 9. The device for simulating and studying the nitrogen conversion of river water-suspended particles-sediment system according to claim 1, characterized in that: the bottom of the container has a support base, and the base is integrated with the container, and the diameter is the inner diameter of the top control cover 70%-90%, height is 1.0-5.0cm. 10. A method for simulating and studying nitrogen transformation in river water-suspended particles-sediment system, the steps of which are as follows: (1) Prepare multiple devices. Before the experiment starts, open the plastic cover above the control cover, check whether the upper wing of the stirring paddle in the compartment is placed on the rubber gasket, check whether the rubber gasket is located in the fixing groove 1, and confirm that it is normal After that, open the control cover and auxiliary holes 1 and 2, and add sediment, suspended particles and river water samples (or simulated river water) to different containers to construct a water-suspended particle-sediment system, or only add suspended particles and river water samples. (or simulated river water) to construct a water-suspended particle system, and simulated river water is used to reduce the effects of ¹⁴ NO ₃ ^- -N and ¹⁴ NH ₄ ⁺ -N on nitrogen isotope tracing in actual river water samples; (2) For the water-suspended particle-sediment system, quantitative ¹⁵ NH ₄ ⁺ -N ( ¹⁵ NH ₄ Cl, 99.0 atm% ¹⁵ N) was added to study the coupled nitrification and denitrification of the system, and the coupling was studied by analyzing the ³⁰ N ₂ product Nitrification and denitrification rate; (3) For the water-suspended particle system, quantitative allyl thiourea (ATU) was added to inhibit the activity of nitrification in the system, and a quantitative amount of ¹⁴ NH ₄ ⁺ -N( ¹⁴ NH ₄ Cl, 99.0 atm was added to the system at the same time. % ¹⁴ N), ¹⁵ NO ₃ ^- -N ( ¹⁵ KNO ₃ , 99.0 atm% ¹⁵ N) and ¹⁵ NO ₂ ^- -N ( ¹⁵ KNO ₂ , 99.0 atm % ¹⁵ N) to study denitrification and anaerobicity in the system Ammoxidation, the denitrification process will generate ³⁰ N ₂ O and ³⁰ N ₂ products, while the anaerobic ammonium oxidation process will generate ²⁹ N ₂ products; (4) After step (2) or (3) is completed, tighten the control cover, and put the pH, dissolved oxygen (DO), oxidation-reduction potential (ORP), and conductivity (Conductivity) probes into the water body through the auxiliary hole one by one. After measuring the pH, DO, ORP, conductivity and temperature in the water, seal the auxiliary hole with a rubber stopper, close the second auxiliary hole, ensure that the container is sealed and then connect the power supply at the control board to start the motor; (5) It is necessary to take samples from the inside of the device and oxygenate it at regular intervals. First turn off the power, open the three-way valve of the second auxiliary hole, and collect the gas in the container; after collecting the gas, keep the three-way valve open, open the auxiliary hole one to collect the water sample in the container; after the water sample is collected, put the monitoring probes in sequence Put into water through this hole, measure pH, DO, ORP, conductivity and temperature in the water; after the measurement, use a small oxygenation device to oxygenate the system through the auxiliary hole; (6) After the completion of step (5), the first and second auxiliary holes are closed, and the motor is turned on to carry out the next stage of the experiment; (7) After the experiment, collect the last group of gas and water samples through step (5), open the control cover, use the filter device to collect suspended particles in the water, and simultaneously collect sediment samples.

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