Device and starting method for realizing wastewater ferrous autotrophic denitrification by using bottom mud

Abstract

The present application relates to a device and a starting method for realizing wastewater ferrous autotrophic denitrification by using bottom mud, comprising an inner reaction container, an outer water bath container, a stirring mechanism, a heating module and a temperature control module, the inner reaction container is arranged in the outer water bath container, the stirring mechanism extends into the inner reaction container from outside the outer water bath container, the heating module is arranged in the water bath area between the inner reaction container and the outer water bath container, and the detection part of the temperature control module is arranged in the water bath area between the inner reaction container and the outer water bath container; the inner reaction container is used for putting black and odorous bottom mud, calcium nitrate and ferrous chloride, the black and odorous bottom mud is used as inoculum, the calcium nitrate and the ferrous chloride are put into the inner reaction container in stages, and wastewater ferrous autotrophic denitrification is realized. The device and the starting method utilize the buffer capacity of the bottom mud itself and optimize the iron-nitrogen ratio, solve the precipitation problem caused by pH adjustment in the traditional ferrous autotrophic denitrification technology, and belong to the technical field of biological denitrification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological denitrification, and particularly relates to a device and a starting method for realizing wastewater ferrous autotrophic denitrification by using bottom mud. BACKGROUND

[0002] Nitrate pollution is a key problem in current water environment management, which mainly comes from agricultural drainage, industrial wastewater and domestic sewage. Excessive nitrate not only causes water eutrophication, but also may generate carcinogens such as nitrosamine through transformation, which directly threatens drinking water safety and public health. Therefore, there is an urgent need to develop efficient and economical advanced treatment technology for nitrate wastewater.

[0003] In the biological denitrification technology, autotrophic denitrification technology is concerned because it does not need external organic carbon source and has no secondary pollution risk. Among them, the ferrous autotrophic denitrification technology uses ferrous ions as electron donors to realize the reduction of nitrate under the catalysis of specific microorganisms, and the reaction is as follows:

[0004] 5Fe 2+ +NO3 - +12H2O→5Fe(OH)3+0.5N2+9H + ;

[0005] However, the engineering application of this technology still faces major challenges. Existing research generally uses activated sludge as inoculum, and the inherent abundance of ferrous autotrophic denitrifying bacteria is very low, which leads to a long start-up period and seriously restricts its popularization and application. More importantly, a large amount of H + is produced in the reaction process, resulting in acidification of the system. In order to maintain the activity of microorganisms, existing technology must continuously add external alkalinity to neutralize the acid. This operation not only increases the operation cost, but also causes serious iron precipitation. In the process of NRFO (ferrous autotrophic denitrification), the intermediate product of nitrate reduction, nitrite, can undergo chemical denitrification with ferrous iron and generate secondary minerals in and outside the cells of microorganisms, resulting in cell crust, hindering the mass transfer process, inhibiting the activity of microorganisms, and eventually leading to serious performance degradation or even failure of the system after 2-3 months of operation. In addition, the traditional method needs to continuously add soluble ferrous salt as an electron donor, which not only increases the operation cost, but also intensifies the local precipitation risk caused by the instantaneous high concentration of ferrous iron. SUMMARY

[0006] In view of the technical problems existing in the prior art, the purpose of the present application is to provide a device and a starting method for realizing wastewater ferrous autotrophic denitrification by using bottom mud, which utilizes the buffering capacity of bottom mud itself and optimizes the iron-nitrogen ratio to solve the precipitation problem caused by pH adjustment in the traditional ferrous autotrophic denitrification technology.

[0007] In order to achieve the above object, the present application adopts the following technical solutions:

[0008] The device for realizing wastewater ferrous autotrophic denitrification by using sediment comprises an inner reaction container, an outer water bath container, a stirring mechanism, a heating module and a temperature control module, the inner reaction container is arranged in the outer water bath container, the stirring mechanism extends into the inner reaction container from outside of the outer water bath container, the heating module is arranged in a water bath area between the inner reaction container and the outer water bath container, a detection part of the temperature control module is arranged in the water bath area between the inner reaction container and the outer water bath container, and the temperature control module monitors water temperature in the outer water bath container in real time; the inner reaction container is used for placing black and odorous sediment, calcium nitrate and ferrous chloride, the black and odorous sediment is used as inoculum, the calcium nitrate and the ferrous chloride are placed in the inner reaction container in stages, and wastewater ferrous autotrophic denitrification is realized.

[0009] As a kind of preferred, the top of outer water bath container is provided with opening, opening is connected with end cap, stirring mechanism is installed on end cap, the stirring end of stirring mechanism is inserted into inner reaction container from end cap, end cap is sealedly connected with the top opening of inner reaction container, and end cap is provided with adding port and nitrogen purging interface, and adding port and nitrogen purging interface are communicated with inner reaction container;The heating end of heating module extends into the water bath area between inner reaction container and outer water bath container from outside of end cap, and the detection part of temperature control module extends into the water bath area between inner reaction container and outer water bath container from outside of end cap.

[0010] As a kind of preferred, the stirring mechanism comprises driving motor, shaft coupling and stirring shaft, driving motor is installed on end cap, the output shaft of driving motor extends into inner reaction container from end cap, shaft coupling is connected with the output shaft of motor, and stirring shaft is connected with shaft coupling;Wherein, the axial direction of stirring shaft is connected with inclined blade turbine stirring paddle.

[0011] As a kind of preferred, the bottom end of inner reaction container is bonded to the inner wall bottom of outer water bath container, the sidewall of inner reaction container is connected with three valves, the three valves are distributed at intervals between the top end and the bottom end of inner reaction container, the connection part of each valve with inner reaction container is provided with first sealing ring, and the connection part of each valve with outer water bath container is provided with second sealing ring.

[0012] As a kind of preferred, the outer wall of outer water bath container is wrapped with heat preservation layer (heat preservation layer is black sponge, which is used for light shielding and heat preservation).

[0013] A starting method for realizing wastewater ferrous autotrophic denitrification by using sediment, the starting method adopts the device, and the starting method comprises the following steps:

[0014] S1: obtaining black and odorous sediment;

[0015] S2: treating black and odorous sediment;

[0016] S3: Put the treated black and odorous sludge into the inner reaction container, add calcium nitrate, and take calcium nitrate as the water inlet matrix to perform the first-stage reaction;

[0017] S4: During the first-stage reaction, the inner reaction container is kept in constant temperature of 28-32℃ and DO<0.2 mg / L in the dark, and the black and odorous sludge and the calcium nitrate are stirred to make the black and odorous sludge and the calcium nitrate react, and the reaction time is the first time period T1;

[0018] S5: When it is detected that the sulfide reaction is complete and the ferrous content in the black and odorous sludge is unchanged, take ferrous chloride as the water inlet matrix to perform the second-stage reaction, and the reaction time is the second time period T2;

[0019] S6: Increase the nitrate concentration in the inner reaction container, and add ferrous chloride to the inner reaction container to make the black and odorous sludge denitrify.

[0020] As a kind of preferred, in step S2, the method for treating black and odorous sludge is: filtering black and odorous sludge with 10 mesh screen to make it homogeneous, and the filtered black and odorous sludge has a water content of 80%, pH of 7±0.3, ORP of-194 mv, ammonia nitrogen content of 258 mg / kg, sulfide content of 2651 mg / kg and ferrous content of 12830 mg / kg.

[0021] As a kind of preferred, in step S3, the ratio of black and odorous sludge and calcium nitrate added to the inner reaction container is 1:1.

[0022] As a kind of preferred, in step S6, the nitrate concentration is increased to 200 mg / L, and the Fe 2+ / N molar ratio in ferrous chloride is 1-5.

[0023] As a kind of preferred, the starting method further comprises the following steps: by adjusting the Fe 2+ / N molar ratio in ferrous chloride under the condition of same nitrate concentration, verifying the influence of different Fe 2+ / N molar ratio in ferrous chloride on denitrification efficiency.

[0024] Overall, the present application has the following advantages:

[0025] The apparatus and start-up method of this invention have unique advantages by utilizing black and odorous sediment as inoculum, including: providing potentially functional microorganisms adapted to high iron concentration environments, which can significantly shorten the acclimatization time; the ferrous iron and sulfides immobilized in the sediment can serve as electron donors in the initial stage of system start-up; and the sediment system possesses natural acid-base buffering capacity, which helps maintain system pH stability. By utilizing the buffering capacity of the black and odorous sediment itself and optimizing the iron-nitrogen ratio, the precipitation problem caused by pH adjustment in traditional ferrous autotrophic denitrification technology is effectively solved. The ability to maintain stable denitrification performance even under high nitrate loads demonstrates that the method of this invention has good engineering application potential and provides reliable technical support for achieving efficient and stable nitrate wastewater treatment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device.

[0027] Figure 2 This is a graph showing the change in sulfide content over reaction time.

[0028] Figure 3 This is a graph showing the change in nitrate concentration over reaction time.

[0029] Figure 4 This is a graph showing the change in ferrous iron concentration over reaction time.

[0030] Figure 5 The graph shows the changes in nitrate concentration with reaction time under Fe / N ratios of 1, 3, and 5.

[0031] Figure 6 The graph shows the nitrate removal rate as a function of reaction time under the conditions of Fe / N=1, 3, and 5.

[0032] Figure 7 The graph shows the change of ferrous concentration with reaction time under the conditions of Fe / N=1, 3, and 5.

[0033] Figure 8 The graph shows the change in ferrous iron removal rate with reaction time under the conditions of Fe / N=1, 3, and 5.

[0034] Among them, 1 is the outer water bath container, 2 is the inner reaction container, 3 is the drive motor, 4 is the nitrogen purging interface, 5 is the water outlet, 6 is the sampling port, 7 is the stirring shaft, 8 is the water bath area, 9 is the water inlet, 10 is the inclined blade turbine stirring paddle, 11 is the heating module, and 12 is the end cover. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to specific embodiments.

[0036] Example 1

[0037] like Figure 1 As shown in the figure, this embodiment provides a device for autotrophic denitrification of wastewater using bottom sludge, including an inner reaction container 2, an outer water bath container 1, a stirring mechanism, a heating module 11, and a temperature control module. The inner reaction container 2 is located inside the outer water bath container 1, and the stirring mechanism extends from the outside of the outer water bath container 1 into the inner reaction container 2. The heating module 11 is located in the water bath area 8 between the inner reaction container 2 and the outer water bath container 1. The detection part of the temperature control module is located in the water bath area 8 between the inner reaction container 2 and the outer water bath container 1, and the temperature control module monitors the water temperature in the outer water bath container 1 in real time. The inner reaction container 2 is used to put black and odorous bottom sludge, calcium nitrate, and ferrous chloride. Using the black and odorous bottom sludge as inoculum, calcium nitrate and ferrous chloride are added to the inner reaction container 2 in stages to achieve autotrophic denitrification of wastewater using ferrous chloride.

[0038] It should be noted that black and odorous sediment, as a naturally occurring anaerobic sediment, is rich in endogenous electron donors such as ferrous ions and sulfides. Using black and odorous sediment as inoculum has unique advantages, including: providing potential functional microorganisms adapted to high iron concentration environments, significantly shortening the acclimatization time; the ferrous ions and sulfides immobilized in the sediment can serve as electron donors during the initial system startup; and the sediment system possesses natural acid-base buffering capacity, helping to maintain system pH stability. By utilizing the inherent buffering capacity of black and odorous sediment and optimizing the iron-nitrogen ratio, the precipitation problem caused by pH adjustment in traditional ferrous autotrophic denitrification technology is effectively solved.

[0039] The top of the outer water bath container 1 is provided with an opening, and an end cap 12 is connected to the opening. The stirring mechanism is installed on the end cap 12, and the stirring end of the stirring mechanism extends into the inner reaction container 2 through the end cap 12. The end cap 12 is sealed to the top opening of the inner reaction container 2. The end cap 12 is provided with a dosing port and a nitrogen purging port 4, both of which are connected to the inner reaction container 2. The heating end of the heating module 11 extends from the end cap 12 into the water bath area 8 between the inner reaction container 2 and the outer water bath container 1. The detection part of the temperature control module extends from the end cap 12 into the water bath area 8 between the inner reaction container 2 and the outer water bath container 1.

[0040] It should be noted that both the inner reaction vessel 2 and the outer water bath vessel 1 are hollow cylindrical structures.

[0041] The stirring mechanism includes a drive motor 3, a coupling, and a stirring shaft 7. The drive motor 3 is mounted on the end cover 12, and its output shaft extends from the end cover 12 into the inner reaction vessel 2. The coupling connects to the motor's output shaft, and the stirring shaft 7 is connected to the coupling. A slanted blade turbine impeller 10 is axially spaced along the stirring shaft 7. Specifically, the drive motor 3 is a JX-25 model with a rotational speed of 0-500 rpm.

[0042] The bottom of the inner reaction vessel 2 is bonded to the bottom of the inner wall of the outer water bath vessel 1. Three valves are connected to the side wall of the inner reaction vessel 2, spaced apart from the top to the bottom. Each valve has a first sealing ring at its connection to the inner reaction vessel 2, and a second sealing ring at its connection to the outer water bath vessel 1. Specifically, the three valves are an outlet 5, a sampling port 6, and an inlet 9. All three valves pass through the side wall of the outer water bath vessel 1 and connect to the inner reaction vessel 2, with the sealing rings ensuring a tight seal at the connection points.

[0043] The outer wall of the external water bath container 1 is covered with an insulation layer. The insulation layer is 20mm thick black insulating sponge, which has the functions of heat preservation and light protection, providing a suitable environment for the reaction area.

[0044] It should be noted that the heating module 11 uses an existing glass heating rod, such as the readily available Risheng glass heating rod, which has a maximum heating temperature of 34 degrees Celsius. The Risheng glass heating rod integrates a temperature control module with a temperature control range of 18-32 degrees Celsius. The end cap 12 is connected to the top edge of the outer water bath container 1 via screws.

[0045] Specific application examples:

[0046] The inner reaction vessel 2 has an outer diameter of 180mm, a wall thickness of 5mm, an effective height of 550mm, and a working volume of approximately 12L. The outer water bath vessel 1 has an outer diameter of 300mm, a wall thickness of 5mm, a height of 550mm, and a jacket width of 60mm. A 25W stirring mechanism is installed on the top of the end cap 12, equipped with a double-layered inclined blade turbine impeller 10, rotating at 40rpm to ensure thorough mixing of the black and odorous sediment and liquid. A heating rod is installed in the water bath area 8, working with a temperature control module to maintain the reaction system temperature at 30±2℃. The outer water bath vessel 1 is completely wrapped with a 20mm thick black insulating sponge to achieve light protection and heat preservation. The top of the outer water bath vessel 1 is equipped with a sealed cover, and high-purity nitrogen (DO < 0.2 mg / L) is introduced through a pre-reserved dosing port and nitrogen purging interface 4 to maintain an anaerobic environment.

[0047] Example 2

[0048] This embodiment provides a start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment. The start-up method employs a device and includes the following steps:

[0049] S1: Obtain black and foul-smelling bottom sediment;

[0050] S2: Treatment of black and smelly bottom sludge;

[0051] S3: Put the treated black and odorous bottom sludge into the inner reaction vessel 2, add calcium nitrate, and use calcium nitrate as the influent substrate to carry out the first stage reaction;

[0052] S4: During the first stage of the reaction, the inner reaction vessel 2 is kept at a constant temperature of 28-32℃ in the dark, with DO < 0.2 mg / L, and the black and odorous bottom sludge and calcium nitrate are stirred to allow the black and odorous bottom sludge and calcium nitrate to react. The reaction time is the first time period T1.

[0053] S5: A sample was taken from inner reaction vessel 2, and the complete reaction of the sulfide was detected (e.g., ...). Figure 2 As shown, when the concentration of sulfide decreased from 2700 to 0 and the ferrous content in the black and odorous sediment remained unchanged, the second stage of reaction was carried out using ferrous chloride as the influent substrate, and the reaction time was the second time period T2.

[0054] S6: Increase the nitrate concentration in the inner reaction vessel 2 and add ferrous chloride to the inner reaction vessel 2 to denitrify the black and odorous bottom sludge.

[0055] In step S2, the method for treating the black and odorous sediment is as follows: filter the black and odorous sediment through a 10-mesh sieve to homogenize it. The filtered black and odorous sediment has a water content of 80%, a pH of 7±0.3, an ORP of -194mv, an ammonia nitrogen content of 258mg / kg, a sulfide content of 2651mg / kg, and a ferrous content of 12830mg / kg.

[0056] In step S3, the ratio of black and foul-smelling sludge to calcium nitrate added to the inner reaction vessel 2 is 1:1.

[0057] In step S6, Fe in ferrous chloride 2+ The / N molar ratio is 1-5.

[0058] In step S6, the nitrate concentration is increased to 200 mg / L.

[0059] This embodiment uses black and odorous bottom sludge instead of activated sludge as the carrier for ferrous autotrophic denitrification. Based on the compositional characteristics of the black and odorous bottom sludge, a strategy of phased addition of calcium nitrate and adjustment of the Fe / N ratio is adopted to achieve rapid start-up and stable operation: In the first stage, calcium nitrate oxidizes sulfides in the bottom sludge, promoting the release and oxidation of ferrous ions in the bottom sludge, and directionally acclimating the ferrous autotrophic denitrifying bacteria. In the second stage, when the available ferrous concentration in the bottom sludge decreases and the denitrification rate declines, exogenous ferrous salts are added according to a specific iron-nitrogen ratio to continuously maintain the electron donor level of the reaction system, completing the efficient acclimation of the ferrous autotrophic denitrifying bacteria. Existing technologies commonly use activated sludge from urban wastewater treatment plants or specially acclimated denitrifying sludge as inoculum. These technologies have low abundance of ferrous autotrophic denitrifying bacteria and slow start-up; the reaction produces acid, requiring continuous addition of alkali, which is costly and causes iron precipitation; nitrite reacts with ferrous iron to form secondary minerals, causing cell crusting, hindering mass transfer, and leading to short-term performance degradation of the system. Furthermore, the continued addition of ferrous salts further exacerbates precipitation and cost issues.

[0060] Specific application examples:

[0061] The black and odorous sediment used in the experiment was collected from a river in a certain town. There are numerous residential houses along the river, and large amounts of domestic sewage and garbage are discharged into the river, causing the riverbed sediment to be in a chronically anoxic or anaerobic environment, resulting in the black and odorous condition. During sampling, a large stainless steel spoon was used to scoop out the darker-colored sediment from the top 0-20cm of the riverbed. The collected black and odorous sediment was then sealed in a flange container to protect it from light before being transported back to the laboratory.

[0062] The first stage uses calcium nitrate as the sole influent substrate, with a dosage calculated based on N / (Fe+S) = 4.5, controlling the mud-to-water ratio at 1:1, and a total effective volume of 10L. The influent is added to the reactor via a peristaltic pump, and the reactor operates under strictly anaerobic conditions: constant temperature and darkness (30±2℃), mechanical stirring at 40 rpm, and continuous high-purity nitrogen to maintain DO < 0.2 mg / L. Figure 2 As shown, the first phase ends when sulfide removal is complete and ferrous concentration no longer decreases significantly (approximately 40 days).

[0063] Initiate the second stage by adding a mixed matrix of ferrous chloride (FeCl2·4H2O) and calcium nitrate at a Fe / N molar ratio of 3, and continue operation under the same environmental conditions. Figure 3 As shown, after approximately 30 days of operation in the second phase, the system's NO3... - The nitrogen (N) removal rate reached over 80%, and the simultaneous ferrous iron (Fe) removal rate reached approximately 83%. During this stage, exogenous Fe was added to stimulate the activity of functional microbial communities. In the initial stages of operation, the denitrification rate may fluctuate due to microbial community reconstruction, requiring optimization of the Fe / N ratio to achieve targeted acclimatization of the microbial community. When the system achieves efficient simultaneous removal of nitrate and Fe at a specific Fe / N ratio, it demonstrates the formation of a stable ferrous autotrophic denitrification system.

[0064] In the third stage, the influent nitrate concentration is increased to 200 mg / L (as NO3). - -N calculation), and control Fe 2+ / NO3 - The -N molar ratio is 5 when ferrous chloride is added. For example... Figure 4As shown, under these conditions, the system's denitrification efficiency reached 99% within 6 days. This result indicates that, after the first two stages of acclimatization, highly active ferrous autotrophic denitrifying bacteria have been successfully enriched, enabling the system to treat high-concentration nitrate wastewater. Simultaneously, monitoring data shows that the system's pH value remained stable within the range of 6.8-7.5 throughout the reaction process, without any sludge activity inhibition caused by ferric hydroxide precipitation. This verifies that the start-up method in this embodiment effectively solves the precipitation problem caused by pH adjustment in traditional ferrous autotrophic denitrification technology by utilizing the sediment's own buffering capacity and optimizing the iron-nitrogen ratio. Maintaining stable denitrification performance even under high nitrate loads demonstrates the method's good engineering application potential and provides reliable technical support for achieving efficient and stable nitrate wastewater treatment.

[0065] like Figures 5-8 As shown, in the fourth stage, the effect of the iron-to-nitrogen ratio (Fe / N = 1, 3, and 5) on nitrogen removal efficiency was investigated by acclimating ferrous autotrophic denitrifying microbial communities. The results showed that under a stable microbial acclimation system, the Fe / N = 5 treatment group exhibited the best nitrate removal efficiency. This confirms that the long-term acclimated microbial community can efficiently utilize ferrous iron as an electron donor to achieve a stable autotrophic denitrification process. A high Fe / N ratio not only provides sufficient reducing power but also maintains the metabolic activity of the acclimated microorganisms, thereby significantly improving nitrogen removal efficiency and stability. The method implemented in this study validates the effectiveness of the acclimation strategy for ferrous autotrophic denitrifying microorganisms and provides a reliable technical pathway for the treatment of low C / N ratio wastewater.

[0066] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment, characterized in that, The starting method employs an apparatus comprising an inner reaction vessel, an outer water bath vessel, a stirring mechanism, a heating module, and a temperature control module. The inner reaction vessel is located inside the outer water bath vessel, and the stirring mechanism extends from the outside of the outer water bath vessel into the inner reaction vessel. The heating module is located in the water bath area between the inner and outer water bath vessels, and the detection part of the temperature control module is located in the water bath area between the inner and outer water bath vessels, monitoring the water temperature inside the outer water bath vessel in real time. The inner reaction vessel is used to hold black and odorous sediment, calcium nitrate, and ferrous chloride, using the black and odorous sediment as an inoculum. The startup method includes the following steps: S1: Obtain black and foul-smelling bottom sediment; S2: Treatment of black and smelly bottom sludge; S3: The treated black and odorous bottom sludge is placed into the inner reaction vessel, calcium nitrate is added, and the first stage reaction is carried out using calcium nitrate as the influent substrate; in step S3, the ratio of black and odorous bottom sludge to calcium nitrate added to the inner reaction vessel is 1:

1. S4: During the first stage of the reaction, the inner reaction vessel is kept at a constant temperature of 28-32℃ in the dark, DO < 0.2mg / L, and the black and odorous bottom sludge and calcium nitrate are stirred to allow the black and odorous bottom sludge and calcium nitrate to react. The reaction time is the first time period T1. S5: When sampling is taken from the inner reaction vessel and the sulfide reaction is complete and the ferrous content in the black and odorous sediment remains unchanged, the second stage reaction is carried out using ferrous chloride as the influent substrate, with the reaction time being the second time period T2; in the influent substrate, ferrous chloride is added according to Fe... 2+ / NO3 - -N molar ratio is 3 for addition; S6: Increase the nitrate concentration in the influent to the internal reaction vessel to 200 mg / L, and according to Fe 2+ / NO3 - Ferrous chloride was added to the inner reaction vessel at a -N molar ratio of 5 to carry out denitrification.

2. The start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment according to claim 1, characterized in that: The top of the outer water bath container has an opening, which is connected to an end cap. The stirring mechanism is mounted on the end cap, and the stirring end of the stirring mechanism extends through the end cap into the inner reaction container. The end cap is sealed to the top opening of the inner reaction container. The end cap has a dosing port and a nitrogen purging port, both of which are connected to the inner reaction container. The heating end of the heating module extends from outside the end cap into the water bath area between the inner reaction container and the outer water bath container. The detection part of the temperature control module extends from outside the end cap into the water bath area between the inner reaction container and the outer water bath container.

3. The start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment according to claim 2, characterized in that: The stirring mechanism includes a drive motor, a coupling, and a stirring shaft. The drive motor is mounted on the end cover, and the output shaft of the drive motor passes through the end cover and extends into the inner reaction vessel. The coupling is connected to the output shaft of the motor, and the stirring shaft is connected to the coupling. The stirring shaft is axially spaced with inclined blade turbine impellers.

4. The start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment according to claim 1, characterized in that: The bottom of the inner reaction vessel is bonded to the bottom of the inner wall of the outer water bath vessel. Three valves are connected to the side wall of the inner reaction vessel. The three valves are distributed at intervals from the top to the bottom of the inner reaction vessel. Each valve is provided with a first sealing ring at the connection between it and the inner reaction vessel, and each valve is provided with a second sealing ring at the connection between it and the outer water bath vessel.

5. The start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment according to claim 1, characterized in that: The outer wall of the external water bath container is covered with an insulation layer.

6. The start-up method for achieving ferrous autotrophic denitrification of wastewater using bottom sediment according to claim 1, characterized in that, In step S2, the method for treating the black and odorous sediment is as follows: the black and odorous sediment is filtered through a 10-mesh sieve to homogenize it. The filtered black and odorous sediment has a water content of 80%, a pH of 7±0.3, an ORP of -194 mv, an ammonia nitrogen content of 258 mg / kg, a sulfide content of 2651 mg / kg, and a ferrous content of 12830 mg / kg.

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