A cascade reoxygenation dissolved oxygen control experimental device and method

Abstract

The present invention relates to a water dissolved oxygen control technology, and in particular to a cascade re-oxygenation dissolved oxygen control experimental device and method. The present invention includes a deoxygenation system, an aeration system, an oxygen stabilization system, a water replenishment system, and an experimental system. The function of the deoxygenation system is to quickly generate a sufficient amount of low-saturation dissolved oxygen water; the aeration system is responsible for achieving a continuous increase in dissolved oxygen in the low-oxygen water; the oxygen stabilization system is responsible for maintaining a stable pressure of the water entering the aeration system and a constant flow state entering the experimental system. The water replenishment system utilizes the water replenishment system to automatically and continuously input raw water into the deoxygenation system. The experimental system simulates the aquatic ecosystem in the test environment and introduces water with a constant dissolved oxygen concentration into it, comprehensively reflecting the effects of experimental water with different dissolved oxygen contents on the growth, reproduction, and behavior of aquatic organisms under different exposure times, thereby ensuring the accuracy and reliability of the experimental results.

Description

Technical Field

[0001] The present invention relates to a water body dissolved oxygen control technology, in particular to a cascade re-oxygenation dissolved oxygen control experimental device and method. Background Art

[0002] The availability of dissolved oxygen (DO) is a key factor regulating the functioning of aquatic ecosystems and an important indicator of the health of water quality ecosystems. DO plays a vital role in the survival and physiological and ecological behavior of aquatic organisms, and low DO levels are considered a key regulator of toxic effects. DO concentrations in aquatic environments are controlled by a balance between sources (i.e., environmental conditions for mixing of water with air and oxygenated advection) and sinks (including aerobic respiration and abiotic oxidation). Fluctuations in DO concentrations over time and space can trigger a series of biological, chemical, and ecological chain reactions.

[0003] Researchers have conducted in-depth studies on the effects of persistently low dissolved oxygen levels in water and sediments on aquatic organisms. These findings indicate that many aquatic organisms can tolerate short periods of hypoxic stress. However, research on the long-term effects of low dissolved oxygen on the survival, growth, and development of aquatic organisms remains relatively scarce. This is closely related to the challenge of continuously and stably controlling dissolved oxygen concentrations at multiple levels in a single laboratory environment over extended periods of time. The challenge lies in the current lack of equipment and methods that can accurately, simply, and stably control dissolved oxygen concentrations.

[0004] Increasing the amount of dissolved oxygen in water can be achieved by enhancing its mixing with air, while removing oxygen from water can be achieved through physical or chemical means. In the field of biological testing, chemical deoxygenation methods are not commonly used due to the potential for direct toxicity or increased solid content of compounds in water. Alternative physical methods include thermal degassing, vacuum degassing, and nitrogen stripping. In addition to thermal degassing, vacuum degassing and nitrogen stripping have been widely used in laboratory research due to their relative ease of operation and high efficiency. However, it should be noted that vacuum degassing technology carries higher costs and more complex maintenance and management. In contrast, nitrogen stripping degassing can show more significant cost-effectiveness in the short term.

[0005] In 2004, Irving developed a water deoxygenation system specifically designed to study the lethal and sublethal toxic effects of hypoxic conditions on invertebrates. This system operates by precisely controlling the flow of nitrogen and air into each container via flowmeters to maintain a preset dissolved oxygen (DO) level. Subsequently, in 2008, Chan developed a similar water deoxygenation system based on the same principle. This system uses sensors to automatically control the supply of air and nitrogen to ensure the desired DO level. It is worth noting that both of these methods can only produce a specific DO concentration at any given time.

[0006] Also in 2008, Mattson developed a water nitrogen deoxygenation system designed to study the toxic effects of low dissolved oxygen conditions on freshwater sediments. This system, through natural oxygenation through continuous water flow, was capable of achieving multiple desired DO levels. However, the system's mixing efficiency was relatively low, making it difficult to precisely regulate the time-dependent changes in dissolved oxygen. Furthermore, to meet the experimental water volume requirements, the device required a fractionating column of sufficient height, which was difficult to achieve in many laboratory environments.

[0007] Based on this, there is an urgent need for a device and method that can accurately, simply and stably control the dissolved oxygen concentration. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems existing in the prior art and provide a cascade reoxygenation dissolved oxygen control experimental device and method.

[0009] In order to solve the problems existing in the prior art, the present invention adopts the following technical solutions:

[0010] A cascade reoxygenation dissolved oxygen control experimental device, comprising:

[0011] A deoxygenation system, wherein the deoxygenation system is used to generate a low-saturation dissolved oxygen water body;

[0012] an oxygenation system, wherein the oxygenation system is used to gradually increase the dissolved oxygen concentration in the low-saturation dissolved oxygen water body to obtain specific saturation dissolved oxygen water bodies with different dissolved oxygen concentrations;

[0013] An oxygen stabilization system, the oxygen stabilization system is used to adjust the pressure and dissolved oxygen concentration of the water body with a specific saturation dissolved oxygen obtained by the oxygenation system;

[0014] A test system for simulating an aquatic ecosystem in a test environment, introducing water with a specific saturation dissolved oxygen concentration into the experiment, and obtaining experimental data;

[0015] The water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation system. The dissolved oxygen concentration of the low-saturation dissolved oxygen water body is adjusted by the oxygenation system according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water body, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system.

[0016] The oxygenation system includes an aerator, which is divided into a plurality of oxygenation chambers by a movable baffle, and each of the oxygenation chambers is provided with a water outlet;

[0017] The aerator is arranged on a second bracket with adjustable height and / or angle;

[0018] Along the arrangement direction of the second bracket, the plurality of oxygenation chambers are arranged from top to bottom, the water flows through the plurality of oxygenation chambers in sequence, and the dissolved oxygen concentration is gradually increased in each of the oxygenation chambers.

[0019] As an improvement to the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the cascade reoxygenation dissolved oxygen control experimental device further includes a water replenishment system; the water replenishment system is used to provide raw water for the deoxygenation system.

[0020] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the deoxygenation system includes a gas supply system for supplying nitrogen, a reactor and an ejector;

[0021] Nitrogen and reaction water are sucked in through the ejector, and the reaction water is circulated and deoxygenated through the circulating water pump.

[0022] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the ejector includes a convergent pipe, an air inlet, a diffuser, a check valve and a frequency converter;

[0023] The convergent pipe is arranged at the connection of the ejector nozzle to guide the direction of water flow. The air inlet of the ejector is a vacuum suction roller structure. The ejector sucks in the nitrogen and mixes the reaction water.

[0024] As an improvement to the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, a microporous structure unit for air and water intake is provided inside the reactor. The microporous structure unit is used to subdivide nitrogen and water into bubbles and water molecules, thereby extending the residence time of the bubbles and water molecules in the water.

[0025] As an improvement to the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the oxygen stabilization system includes a barostat and a delivery system;

[0026] The water flowing out of the oxygenation system is made to flow in the water pipe through a constant pressure device, and the flow rate is regulated by a valve.

[0027] A cascade reoxygenation dissolved oxygen control experimental method uses the above-mentioned cascade reoxygenation dissolved oxygen control experimental device; the following steps are included: after the water body passes through the deoxygenation system, it becomes a low-saturation dissolved oxygen water body; according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water body, the dissolved oxygen concentration of the low-saturation dissolved oxygen water body is adjusted by the aeration system; and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system; the experimental system obtains experimental data through the deoxygenation system, the aeration system and the oxygen stabilization system.

[0028] Beneficial effects of the present invention:

[0029] 1. This invention utilizes a compact reactor and a continuous cascade oxygenation method using natural water flow, enabling stable control and acquisition of experimental water with multiple levels of dissolved oxygen concentration in a laboratory environment. This invention significantly improves the deoxygenation efficiency during the mixing of water and nitrogen, while also meeting the need for flexible adjustment of gradient dissolved oxygen levels.

[0030] 2. The present invention is used in a laboratory environment, and has a simple structure, a convenient operation process and high oxygen enrichment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 Schematic diagram of the deoxygenation system in the present invention;

[0033] Figure 3 This is a first experimental data diagram of an embodiment of the present invention;

[0034] Figure 4 This is a second experimental data diagram of an embodiment of the present invention;

[0035] Figure 5 This is a third experimental data diagram of an embodiment of the present invention.

[0036] Explanation of the reference numerals: 1 - nitrogen; 2 - deoxygenation system; 3 - oxygenation system; 4 - experimental system; 5 - water supply system; 6 - reactor; 7 - partition; 8 - oxygenation chamber; 9 - first bracket; 10 - ejector; 11 - second bracket; 12 - diffusion tube; 13 - oxygen stabilization system. DETAILED DESCRIPTION

[0037] In order to make the purpose of the invention, technical solutions and beneficial effects of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] like Figures 1 to 4 As shown, the present invention provides a cascade reoxygenation dissolved oxygen control experimental device, which adopts the principle of continuous cascade natural oxygenation to achieve continuous control of dissolved oxygen in experimental water. The application scope of the device covers multiple disciplines such as aquatic biology, ecology, aquatic environmental toxicology, aquatic biological behavior and developmental ecology related to freshwater, seawater and sediment water bodies.

[0039] A cascade re-oxygenation dissolved oxygen control experimental device comprises: a deoxygenation system 2, an aeration system 3, an oxygen stabilization system 13, and an experimental system 4. The deoxygenation system 2 is used to generate low-saturation dissolved oxygen water; the aeration system 3 is used to gradually increase the dissolved oxygen concentration in the low-saturation dissolved oxygen water to obtain specific saturation dissolved oxygen water with different dissolved oxygen concentrations; the oxygen stabilization system 13 is used to adjust the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water obtained by the aeration system 3; and the experimental system 4 is used to simulate the aquatic ecosystem of the test environment, introduce the specific saturation dissolved oxygen water into the experiment, and obtain experimental data.

[0040] Among them, the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation system. According to the dissolved oxygen concentration of the low-saturation dissolved oxygen water body, the dissolved oxygen concentration of the low-saturation dissolved oxygen water body is adjusted through the oxygenation system 3, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained through the oxygen stabilization system 13. The experimental system 4 obtains experimental data through the deoxygenation system 2, the oxygenation system 3 and the oxygen stabilization system 13.

[0041] The specific saturated dissolved oxygen water body refers to a saturated dissolved oxygen water body that can be prepared in advance according to experiments.

[0042] In the present invention, dissolved oxygen control mainly includes two processes: oxygen separation and oxygenation. The oxygen separation effect is achieved by the deoxygenation system 2, and the oxygenation system 3 is used to achieve oxygenation. In conjunction with the oxygen stabilization system 13, the water replenishment system 5 and the experimental system 4, dissolved oxygen control is achieved together.

[0043] Nitrogen gas was introduced into the experimental water to reduce the oxygen partial pressure, thereby decreasing the solubility of oxygen in the water and causing it to continuously escape from the water until the oxygen partial pressure equilibrium was restored. After oxygen separation, the oxygen concentration in the water was gradually restored through the cascade effect of natural water flow, allowing for the stable acquisition of experimental water with multiple dissolved oxygen concentration levels.

[0044] The present invention includes a deoxygenation system 2, an oxygenation system 3 and an oxygen stabilization system 13, wherein the function of the deoxygenation system 2 is to rapidly generate a sufficient amount of low-saturation dissolved oxygen water; the oxygenation system 3 is responsible for achieving a continuous increase in dissolved oxygen in the low-oxygen water; the oxygen stabilization system 13 is responsible for maintaining a stable pressure of the water entering the oxygenation system 3 and a constant flow state entering the experimental system 4.

[0045] Furthermore, the present invention includes two components: a water replenishment system 5 and an experimental system 4. The water replenishment system 5 automatically and continuously supplies raw water to the deoxygenation system 2. The experimental system 4 simulates the aquatic ecosystem in a test environment by introducing water with a constant dissolved oxygen concentration. This comprehensively reflects the effects of experimental water with varying dissolved oxygen concentrations on the growth, reproduction, and behavior of aquatic organisms (taking into account factors such as the species, number, and growth stage of the organisms) at different exposure times, thereby ensuring the accuracy and reliability of the experimental results.

[0046] In some embodiments of the present invention, the deoxygenation system 2 includes a gas supply system for supplying nitrogen 1, a reactor 6 and an ejector 10; the nitrogen 1 and the reaction water are sucked in through the ejector 10, and the reaction water is circulated and deoxygenated by a circulating water pump.

[0047] Furthermore, the ejector 10 includes a convergent pipe, an air inlet, a diffuser 12, a check valve and a frequency converter;

[0048] Among them, the convergence pipe is set at the nozzle connection of the ejector 10 to guide the direction of water flow. The air inlet of the ejector 10 is a vacuum suction roller structure. The ejector 10 sucks in the nitrogen 1 and mixes the reaction water.

[0049] In detail, the deoxygenation system 2 in the present invention is used in conjunction with the water replenishment system 5, and the water replenishment system 5 is responsible for automatically supplying water to the system. Inside the reactor 6, the water body and the nitrogen 1 are fully mixed by the action of the water circulation pump, thereby reaching a deoxygenation partial pressure balance, and finally achieving deoxygenation. Preferably, the diffusion tube 12 is a circular pipe, with one end of the nozzle being wider as the inlet and the other end being narrow and flat as the outlet. The design of the diffusion section and the nozzle takes into account the injection angle and the uniformity of the injection, and is used to convert the high-speed jet into a circulating rising fluid, thereby further improving the efficiency of oxygen separation.

[0050] The water replenishment system 5 includes an external raw water pump, a solenoid valve switch, a liquid level sensor, and a water supply pipeline. During the experiment, the actual liquid level in the reactor 6 cavity was detected by the liquid level sensor, which controlled the solenoid valve to automatically replenish the water. The solenoid valve and liquid level sensor were connected by an electrical circuit, and the start and stop of the reactor 6 water replenishment were controlled by presetting the high and low water levels of the liquid level sensor. When the water level in reactor 6 dropped to the minimum level, the solenoid valve opened, and water from the water storage tank was introduced via the raw water pump. When the water level in reactor 6 reached the maximum level, the solenoid valve closed, and the raw water pump stopped, until the water level in reactor 6 dropped to the minimum level and then opened again.

[0051] In the deoxygenation system 2, nitrogen 1 and reaction water are sucked in through the ejector 10, and the reaction water is further circulated and deoxygenated through the circulating water pump.

[0052] As a specific embodiment of the present embodiment, the process of cyclic deoxygenation is that the circulating water pump takes water from the lower part of the reactor 6, and then it is transported to a high place through a pipeline and divided into two ways, and then processed by the ejector 10, and then enters from the bottom of the reactor 6 again. Since the convergent pipe is arranged at the nozzle connection of the ejector 10 to guide the direction of water flow, the air inlet of the ejector 10 is a vacuum suction roller structure, and the ejector 10 sucks in nitrogen 1 and mixes the reaction water body. The ejector 10 forms a negative pressure through the vacuum suction roller structure, which can suck in nitrogen 1 and make it fully mixed with the water body, thereby significantly improving the rate and efficiency of deoxygenation. Moreover, the injection angle of the diffusion pipe 12 entering the reactor 6 is designed to be tilted upward, which can make the flowing water body mediate and rise, thereby improving the mixing efficiency of the reaction water body before and after treatment.

[0053] In addition, the deoxygenation system 2 is arranged before the oxygenation system 3 and is installed on a first bracket 9. The height of the first bracket 9 is higher than that of the oxygenation system 3 to facilitate the flow of water.

[0054] As a specific example of this embodiment, reactor 6 is a transparent organic glass container with a thickness of 6 mm, which allows for easy observation of the interior of reactor 6. The main body of reactor 6 is a cylindrical structure measuring 30 cm (diameter) x 60 cm (height), with an upper portion designed as a truncated cone measuring 30 cm (lower diameter) x 20 cm (upper diameter) x 10 cm (height). The opening is equipped with a sealing cover, which is tightly secured by bolts and sealing strips to ensure the container's tightness. When necessary, the sealing cover can be opened to access the interior for cleaning.

[0055] Furthermore, two holes are provided in the center of the sealing cover: one for a water level sensor and the other for a one-way exhaust valve. This valve effectively vents excess gas from the container through an exhaust line while preventing outside air from entering. Furthermore, a manual ball valve is installed at the water outlet of reactor 6 to control the flow rate.

[0056] The gas supply system includes a pressure reducing valve, a gas cylinder, and a gas supply pipeline. The gas supply pipeline is made of PVDF. Nitrogen 1 is high-pressure pure nitrogen stored in a steel cylinder. The flow rate of nitrogen 1 entering the reactor 6 is precisely regulated by a gas pressure reducing valve. The nitrogen 1 cylinder is connected to the pressure reducing valve via a threaded connection. The pressure reducing valve and the ejector 10 are connected in a plug-in manner via a three-way valve.

[0057] In some embodiments of the present invention, the oxygenation system 3 includes an aerator, which is divided into a plurality of oxygenation chambers 8 by a movable baffle, and each oxygenation chamber 8 is provided with a water outlet;

[0058] The aerator is placed on a stand with adjustable height and / or angle;

[0059] Along the arrangement direction of the support, a plurality of oxygenation chambers 8 are arranged from top to bottom. Water flows through the plurality of oxygenation chambers 8 in sequence, and the dissolved oxygen concentration is gradually increased in each oxygenation chamber 8 .

[0060] As a specific example of this embodiment, the aerator is made of high-strength glass with a thickness of millimeters and has a size of 1350 mm × 80 mm × 80 mm. The aerator is divided into a maximum of 9 equally sized aeration chambers 8 by 8 movable glass baffles, and a water outlet is installed on the side of each aeration chamber 8. The aerator is mounted on a second bracket 11 that is adjustable in height and angle. After installation, the top-level deoxygenation chamber is located just below the outlet of the reactor 6. In addition, when the dissolved oxygen concentration falls below or exceeds a preset threshold, an alarm sounds.

[0061] In some embodiments of the present invention, the oxygen stabilization system 13 includes a constant pressure device and a delivery system; the water flowing out of the oxygenation system 3 is made to flow in the water pipe through the constant pressure device, and the flow rate is regulated by a valve.

[0062] Specifically, water entering the aerator is delivered by a constant-pressure pump, with the incoming flow rate precisely controlled by a precision valve. Water exiting the aeration chamber 8 is connected to the experimental containers via pipes. Independently controlled valves are installed in the middle of the pipes to adjust the flow rate of water entering each experimental container. In particular, a flow-through experimental system without an overhead space is used whenever possible to isolate the air.

[0063] In some embodiments of the present invention, the experimental system 4 includes an experimental container and an overflow device.

[0064] As a specific example of this embodiment, the experimental containers are several containers of uniform size, such as glass beakers or specialized experimental containers, with appropriate sealing lids configured according to the shape of the container openings. Furthermore, to prevent oxygen from the air from redissolving in the water during the experiment, no upper space is left between the overflow port and the sealing lid. The sealing lid is fitted with an overflow pipe that enters the experimental container, and a hose is used to guide the experimental water into the circulation system. Experimental conditions should be as close as possible to standard requirements, including water temperature, water quality, and lighting. For example, a temperature-controlled water bath can be used to control the experimental temperature.

[0065] The present invention also provides a cascade reoxygenation dissolved oxygen control experimental method, using the cascade reoxygenation dissolved oxygen control device as described above, including the following steps: the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation system; the dissolved oxygen concentration of the water body is adjusted by the oxygenation system 3 according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water; and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system 13; the experimental system 4 obtains experimental data through the deoxygenation system 2, the oxygenation system 3 and the oxygen stabilization system 13.

[0066] In detail, first, the power of the deoxygenation system 2 and the water supply system 5 is turned on, and the reactor 6 in the deoxygenation system 2 is replenished with raw water for the experiment from the water storage tank. When the water level in the reactor 6 reaches the highest point, the water supply is stopped.

[0067] During the initial commissioning phase, the nitrogen 1 pressure reducing valve and the deoxygenation system 2 inverter were opened to initially adjust the airflow entering the deoxygenation system 2 to initiate pre-deoxygenation, allowing the reactor 6 to reach a stable state. During the commissioning process, a handheld dissolved oxygen meter was used to measure the dissolved oxygen concentration in the reactor 6, aeration chamber 8, and experimental container every 10 minutes.

[0068] When the system runs stably, the flow rate of nitrogen 1 is adjusted through the oxygen separator and the gas pressure reducing valve so that the dissolved oxygen in the outlet water of the reactor 6 reaches a preset value.

[0069] To control the dissolved oxygen of the test system, after initial setup and deoxygenation, each experimental exposure vessel is slowly filled and continuously refreshed in the absence of test organisms. Experimental vessels ranging from 2 to 10 L can be used.

[0070] After the expected low dissolved oxygen water is obtained from the reactor 6, the slope angle, compartment distance, and compartment water level of the oxygenation device are precisely adjusted according to the difference between the dissolved oxygen concentration of the water in the experimental container and the preset level, and the flow rate of the water in and out of the compartment is controlled at the same time until the dissolved oxygen concentration in the experimental container is consistent with the preset level.

[0071] Before the experiment begins, the controller water flow rate and the flow rate of nitrogen 1 are calibrated during the test commissioning. The first compartment is designated as the lowest dissolved oxygen level, which can be set to 1 mg / L. The dissolved oxygen levels of the subsequent continuous cascades can be set to 2, 3, 4 and 5 mg / L, etc.

[0072] In this embodiment, the first compartment can serve as the first gradient, and so on, along the arrangement direction of the oxygenation chamber 8, from top to bottom, there are the first compartment, the second compartment, and so on. In the present invention, the dissolved oxygen concentration of the water body with a specific saturation of dissolved oxygen is the lowest, and the dissolved oxygen concentration of the water body with a specific saturation of dissolved oxygen in the second compartment increases in sequence.

[0073] As a specific embodiment of the present invention, the first gradient starts from a minimum of 0.5 mg / L and gradually increases to saturated dissolved oxygen 6-7 mg / L, with an increase of 0.5~1 mg / L. The number of compartments is selected according to actual needs, or the first compartment can also be 1 mg / L or other values, which are prepared according to experimental needs.

[0074] Accordingly, baffles may be repositioned, removed, or added as the temperature of the experimental system 4 changes, or when the flow rate of the compartments is altered.

[0075] In addition, the lead-out point can be selected according to actual conditions.

[0076] The following are some specific examples of using the present invention.

[0077] Example 1

[0078] Deoxygenation Rate: During the performance verification of Reactor 6, the target dissolved oxygen (DO) was achieved within the first 10 minutes of operation, with the majority (>85%) of the DO in the raw water removed. A DO concentration of 7.00 mg / L in the raw water decreased to 0.95 mg / L within 10 minutes, then to 0.62 mg / L within 20 minutes, and finally to 0.55 mg / L within the final 30 minutes of the applied deoxygenation cycle. These results formed the basis for the initial adjustment of the degassing system's equilibrium time.

[0079] Example 2

[0080] Accuracy Control: The experimental device was tested without an exposure vessel. Comparison of average DO concentrations recorded over a 48-hour period demonstrated that DO remained relatively constant across the oxygenation chamber 8 for each gradient and remained similar between data sets collected at two different times. Variations resulting from non-constant flow conditions were not considered to be a performance issue for the device. The highest DO group was used as a positive control. At nominal concentrations of 1 mg / L or higher, the system's accuracy was approximately 0.1 mg / L, corresponding to a standard error of no more than ±0.3 mg / L.

[0081] Example 3

[0082] The temperature control system consists of a water bath that controls the temperature of five to six exposure chambers. The water temperature is controlled using a temperature sensor and a water temperature controller. The water bath measures 1550 x 700 x 350 mm and is made of 5mm high-grade glass. It can accommodate five test cells. A 5cm diameter overflow pipe is installed in the middle of the water bath, maintaining an adjustable water depth of 20cm. A 1.3cm diameter drain port is located at the bottom of the water bath. Required equipment includes a circulation pump, temperature sensor, temperature regulator, and water level sensor.

[0083] Example 4

[0084] Test Unit: Each test unit consisted of a container (35 cm long, 23 cm wide, and 18 cm high) with a volume of approximately 10 L. Four test containers were placed in each test unit. The test containers consisted of 600 mL glass beakers with plexiglass lids. The lid had a 0.9 cm hole for an overflow tube extending below the liquid surface. The upper portion was covered with a 60-mesh nylon screen, the lower portion of which snapped onto the beaker. Water from each aeration chamber (8) of the aeration system flowed into the test container at a constant pressure and a steady flow rate. Approximately 600 mL of the supernatant water (containing 100 mL of sediment) in each container was exchanged with the supernatant water in the tank. During a 1-hour operation, a calibrated flow rate of 32 mL / minute flowed into each test beaker. Approximately 93% of the 150 mL test beaker volume was replaced within this 1-hour volume exchange period. Therefore, when the system was operated continuously for 24 hours per day, the overlying water replacement rate was approximately 8 volumes per day.

[0085] Example 5

[0086] In a dissolved oxygen biological effect research project, a 15-day chronic test on dissolved oxygen tolerance of aquatic organisms was carried out. In the test, the oxygenation device provided by the present invention was used to carry out chronic toxicity tests on aquatic organisms with multiple dissolved oxygen gradients.

[0087] Equipment Setup: Start the equipment. The water first passes through the deoxygenation system 2 to reach the desired low dissolved oxygen level. The water then enters the aeration system. After passing through the multi-stage aeration unit, the dissolved oxygen level is gradually increased through natural flow. The aeration device is installed on one side of the test system, and a constant pressure pump is used to transport the water to the aeration system.

[0088] Operational Procedure: Once the system is operating stably, adjust the oxygen separator's operating mode and control the flow rate of nitrogen 1 to ensure that the dissolved oxygen concentration in the water exiting reactor 6 reaches a preset value of 1 mg / L. Adjust the aeration device's slope angle, compartment spacing, and water level, while also controlling the water flow rate, to ensure that the dissolved oxygen concentration in the water of different test containers reaches six preset levels: 1.5, 2.5, 3.5, 4.5, 5.0, and 6.0 mg / L.

[0089] Effect evaluation: After debugging, the dissolved oxygen levels of the six test groups were able to stabilize within the range of ±20% of the average value and reach the preset dissolved oxygen levels: T1 = 1.46 ± 0.28 mg / L; T2 = 2.44 ± 0.31 mg / L; T3 = 3.62 ± 0.20 mg / L; T4 = 4.39 ± 0.33 mg / L; T5 = 5.10 ± 0.23 mg / L; T6 = 6.01 ± 0.21 mg / L.

[0090] Example 6

[0091] like Figures 3 to 5 Stability Demonstrated: The data presented in this example demonstrates the stability of the system at multiple solubility levels. The system has been successfully tested in a variety of aquatic toxicity tests, including goby, midge, and white shrimp, to determine its suitability for chronic toxicity testing. Since these tests, the system has been in continuous operation for nine months, with the longest continuous operation exceeding six weeks. The system operates largely automatically, requiring only routine maintenance, which takes no more than 30 minutes per day, to replace water lost through evaporation and nitrogen gas.

[0092] Among them, Figure 3 As shown, in the dissolved oxygen toxicity test on goby, the control group T0 = 5.52 ± 0.13 mg / L; T1 = 4.55 ± 0.14 mg / L; T2 = 3.55 ± 0.15 mg / L; T3 = 2.47 ± 0.09 mg / L; T4 =1.48 ± 0.11 mg / L; T5 = 1.01 ± 0.10 mg / L.

[0093] like Figure 4 As shown, in the dissolved oxygen toxicity test on chironomids, the control group T0 = 3.36 ± 0.04 mg / L; T1 = 2.94 ± 0.11 mg / L; T2 = 2.10 ± 0.10 mg / L; T3 = 1.30 ± 0.15 mg / L; T4 = 0.91 ± 0.13 mg / L.

[0094] like Figure 5 As shown, in the dissolved oxygen toxicity test of white shrimp, the control group T0 = 5.02 ± 0.09 mg / L; T1 = 4.03 ± 0.12 mg / L; T2 = 2.99 ± 0.12 mg / L; T3 = 2.03 ± 0.11 mg / L; T4 = 1.05 ± 0.09 mg / L.

[0095] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

Claims

1. A cascade reoxygenation dissolved oxygen control experimental device, characterized in that: include: A deoxygenation system, wherein the deoxygenation system is used to generate a low-saturation dissolved oxygen water body; an oxygenation system, wherein the oxygenation system is used to gradually increase the dissolved oxygen concentration in the low-saturation dissolved oxygen water body to obtain specific saturation dissolved oxygen water bodies with different dissolved oxygen concentrations; An oxygen stabilization system, the oxygen stabilization system is used to adjust the pressure and dissolved oxygen concentration of the water body with a specific saturation dissolved oxygen obtained by the oxygenation system; A test system for simulating an aquatic ecosystem in a test environment, introducing water with a specific saturation of dissolved oxygen into the experiment, and obtaining experimental data; The water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation system. The dissolved oxygen concentration of the low-saturation dissolved oxygen water body is adjusted by the oxygenation system according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water body, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system. The oxygenation system includes an aerator, which is divided into a plurality of oxygenation chambers by a movable baffle, and each of the oxygenation chambers is provided with a water outlet; The aerator is arranged on a second bracket with adjustable height and / or angle; Along the arrangement direction of the second bracket, the plurality of oxygenation chambers are arranged from top to bottom, the water flows through the plurality of oxygenation chambers in sequence, and the dissolved oxygen concentration is gradually increased in each of the oxygenation chambers.

2. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1, characterized in that: The cascade reoxygenation dissolved oxygen control experimental device also includes a water supply system; the water supply system is used to provide raw water for the deoxygenation system.

3. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1 or 2, characterized in that: The deoxygenation system includes a gas supply system for supplying nitrogen, a reactor and an ejector; Nitrogen and reaction water are sucked in through the ejector, and the reaction water is circulated and deoxygenated through the circulating water pump.

4. The cascade reoxygenation dissolved oxygen control experimental device according to claim 3, characterized in that: The ejector includes a convergent pipe, an air inlet, a diffuser, a check valve and a frequency converter; The convergent pipe is arranged at the nozzle connection of the ejector to guide the direction of water flow. The air inlet of the ejector is a vacuum suction roller structure. The ejector sucks in the nitrogen and mixes the reaction water.

5. The cascade reoxygenation dissolved oxygen control experimental device according to claim 3, characterized in that: The reactor is provided with a microporous structural unit for air and water intake. The microporous structural unit is used to subdivide nitrogen and water into bubbles and water molecules, thereby prolonging the residence time of the bubbles and water molecules in water.

6. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1 or 2, characterized in that: The oxygen stabilization system includes a barostat and a delivery system; The water flowing out of the oxygenation system is made to flow in the water pipe through a constant pressure device, and the flow rate is regulated by a valve.

7. A cascade reoxygenation dissolved oxygen control experimental method, characterized in that: Using the cascade reoxygenation dissolved oxygen control experimental device according to any one of claims 1 to 6; The following steps are included: After passing through the deoxygenation system, the water body becomes a low-saturation dissolved oxygen water body. According to the dissolved oxygen concentration of the low-saturation dissolved oxygen water body, the dissolved oxygen concentration of the low-saturation dissolved oxygen water body is adjusted by the oxygenation system, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system.

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