Rotary reactor-based biochar wetland desulfurization and denitrification system

Abstract

The present application belongs to the technical field of water treatment, and particularly relates to a biochar wetland desulfurization and denitrification system based on a rotating reactor. The system comprises a rotating sulfate-reducing unit and a biochar-based artificial wetland unit connected in series. The rotating unit is internally provided with rotatable filler devices, Ca-bacteria charcoal composite layers and granular calcium sulfide solid layers. The concentration of SO4 2‑ / is monitored in real time by an ion selective electrode, and the filler lifting and wastewater backflow are linked. 2‑ The wetland unit is provided with a biochar-sand mixed substrate layer for planting reeds. The wastewater is subjected to adsorption and reduction of SO4 2‑ by the rotating unit to generate CaSO4 precipitates and release S 2‑ into the wetland to drive sulfur autotrophic denitrification. The system can achieve a SO4 2‑ removal rate of more than 84%, a NO3 ‑ removal rate of more than 66%, and a COD effluent of less than 20 mg / L, thereby solving the problems of high water quality mineralization and inhibited denitrification.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a biochar wetland desulfurization and denitrification system based on a rotary reactor. Background Technology

[0002] Traditional biological treatment technologies have systemic defects when dealing with wastewater with high sulfate and low carbon-to-nitrogen ratio: insufficient carbon source hinders the denitrification process, and the denitrification efficiency is generally less than 50%; high concentrations of sulfate inhibit the activity of denitrifying microorganisms and produce corrosive sulfides, while the accumulation of reduction products sulfides can easily cause equipment corrosion; subsurface flow constructed wetlands suffer from flux reduction of more than 80% due to packing caking, and adding external carbon sources to improve the denitrification effect will cause the effluent COD to exceed the standard, resulting in secondary pollution.

[0003] This invention constructs a coupled system of a rotating sulfate reduction unit and a biochar-based constructed wetland unit, employing ion-selective electrode-linked packing layer control technology to enhance SO4 levels. 2- Removal rate of NO3 up to 84% or more - The removal rate exceeds 66%; the mass transfer efficiency is enhanced by a rotatable packing device, and the design of a biochar-sand mixed matrix and an open stainless steel support plate improves the system's anti-clogging ability by 80% and enables long-term stable operation; ultimately, without the need for an external carbon source, the problems of high sulfate inhibition, low denitrification efficiency due to low carbon source, and secondary pollution are solved simultaneously. Summary of the Invention

[0004] This invention provides a biochar wetland desulfurization and denitrification system based on a rotary reactor, which solves the defects of existing technologies in treating wastewater with high sulfate and low carbon-to-nitrogen ratio, such as low treatment efficiency, high carbon source requirements, easy clogging, and secondary pollution.

[0005] On the one hand, the present invention provides a biochar wetland desulfurization and denitrification system based on a rotary reactor, comprising a rotary sulfate reduction unit, a biochar-based constructed wetland unit, a data transmission device, and a remote monitoring device connected in series;

[0006] The rotating sulfate reduction unit includes: a rotatable packing device, a first peristaltic pump, a Ca-bacterial charcoal composite layer, a rotating rod, a perforated stainless steel support plate, a second peristaltic pump, a granular calcium sulfide solid layer, an ion-selective electrode, a rope chain, a heating electrode, a temperature sensor, a third peristaltic pump, a rotating sulfate reduction unit inlet, a wastewater outlet, and a rotating sulfate reduction unit outlet.

[0007] The biochar-based constructed wetland unit includes: a biochar-based constructed wetland unit inlet, a gravel support layer, a biochar-sand mixed matrix layer, a water layer, and a biochar-based constructed wetland unit outlet;

[0008] The data transmission device is used to transmit temperature and SO4. 2- S 2- The ion concentration is transmitted to a remote monitoring device in real time.

[0009] The remote monitoring device is used to monitor water quality in real time and control the rotating sulfate reduction unit.

[0010] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the rotatable packing device is driven by a rotating rod;

[0011] The Ca-bacterial char composite layer and the granular calcium sulfide solid layer are disposed within a rotatable packing device;

[0012] The granular calcium sulfide solid layer is raised and lowered by a rope chain;

[0013] The perforated stainless steel support plate has a hole diameter of 1~5mm and connects to the rotating rod to support the filler.

[0014] The ion-selective electrode is used to remove SO4 from the effluent of the rotating sulfate reduction unit. 2- S 2- Ion concentration is monitored in real time;

[0015] The heating electrode is used to heat the water.

[0016] The temperature sensor is used to detect the water temperature;

[0017] The wastewater outlet is connected to the inlet of the rotary sulfate reduction unit via a third peristaltic pump;

[0018] The first peristaltic pump and the third peristaltic pump are used to control the amount of water discharged into the rotary sulfate reduction unit;

[0019] The outlet of the rotating sulfate reduction unit is connected to the inlet of the biochar-based constructed wetland unit via a second peristaltic pump;

[0020] The second peristaltic pump is used to control the discharge of effluent from the rotating sulfate reduction unit into the biochar-based constructed wetland unit.

[0021] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the biochar-based constructed wetland unit consists of a gravel support layer, a biochar-sand mixed matrix layer, and a water layer from bottom to top.

[0022] The gravel support layer is filled with gravel with an average particle size of 2-4 cm and a height of 5 cm;

[0023] The biochar-sand mixed matrix layer is made by mixing sand with a particle size of 1-5 mm and biochar with a particle size of 1-7 mm at a volume ratio of 75-95:5-25.

[0024] The water layer height is 8-12cm, with 20-40 plants / m². 2 Plant reeds at the appropriate planting density;

[0025] The inlet of the biochar-based constructed wetland unit is located 3-8 cm above the water layer;

[0026] The outlet of the biochar-based constructed wetland unit is at the same height as the water surface.

[0027] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the Ca-bacterial biochar composite layer is composed of CaCl2 modified agricultural waste activated carbon loaded with sulfate-reducing bacteria, and three layers are filled, each layer having a height of 10~20cm, the filler particle size being 3~5mm, and the interlayer spacing being 15~25cm.

[0028] The agricultural production waste is one or more of corn cobs, rice husks, and straw, with a modification concentration of 5-10 wt% and a bacterial strain loading of 10-15%.

[0029] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the granular calcium sulfide solid layer is disposed 15-25cm above the Ca-bacterial char composite layer, the filling height is 3-7cm, and the calcium sulfide particle size is 3-5mm.

[0030] The calcium sulfide filler in the granular calcium sulfide solid layer is made of microporous organic glass material with a pore size of 0.5~1mm.

[0031] The granular calcium sulfide solid layer has a heating rod installed under the calcium sulfide filler to heat the water to 20~25℃.

[0032] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein an aeration reflux tank is also provided between the inlet and the wastewater outlet of the rotary sulfate reduction unit for oxidizing dissolved low-valence sulfur to SO4. 2- The sulfides are then adsorbed and removed, thereby reducing the corrosion of the equipment by sulfides.

[0033] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the ion-selective electrode performs the following control:

[0034] When SO4 2- When the concentration is >250 mg / L, wastewater recirculation is triggered;

[0035] When S 2- When the concentration is >33.1 mg / L, the solid layer of granular calcium sulfide is enhanced;

[0036] When S2- When the concentration is <18.3 mg / L, the particulate calcium sulfide solid layer decreases.

[0037] According to the present invention, a biochar wetland desulfurization and denitrification system based on a rotary reactor is provided, wherein the heating electrode and temperature sensor are linked to control the water temperature at 20~25℃.

[0038] On the other hand, the present invention also provides a biochar wetland desulfurization and denitrification method based on a rotary reactor, comprising the following steps:

[0039] (1) Cultivate plants and substrates in sulfate-free simulated wastewater for 30 days;

[0040] (2) Simulated wastewater enters the rotary sulfate reduction unit and runs at a speed of 250 rpm and a hydraulic retention time of 2-4 days. SO4 in the effluent is monitored in real time using an ion-selective electrode. 2- and S 2- Concentration, and adjust the rise and fall of the granular calcium sulfide solid layer and wastewater recirculation according to the concentration;

[0041] (3) The effluent from the rotating sulfate reduction unit enters the biochar-based constructed wetland unit, with a hydraulic retention time of 4 days, and the reaction takes place in the biochar-sand mixed substrate layer, including:

[0042] Aerobic zone: NH4 + →NO3 - ;

[0043] Anaerobic zone: NO3 - +Biochar / Organic Carbon → N2↑;

[0044] Sulfur-denitrification reaction: S 2- +NO3 - →SO4 2- +N2↑.

[0045] According to the present invention, a biochar wetland desulfurization and denitrification method based on a rotary reactor is provided, wherein the hydraulic retention time in step (2) is based on the influent SO4 2- Concentration adjustment:

[0046] SO4 2- When the concentration is 500 mg / L, the hydraulic retention time is 2 days.

[0047] SO4 2- When the concentration is 1000 mg / L, the hydraulic retention time is 2.5 days.

[0048] SO4 2- When the concentration is 2000 mg / L, the hydraulic retention time is 4 days.

[0049] The biochar wetland desulfurization and denitrification system based on a rotating reactor provided by this invention adsorbs and microorganisms reduce SO4 through a Ca-bacterial biochar composite layer in the rotating unit. 2- CaSO4 precipitate is formed, and S is released simultaneously. 2- The process of introducing sulfur into wetlands to drive sulfur autotrophic denitrification solves the SO4 problem in wastewater with high sulfate / low C / N ratio. 2- Overcoming the technical bottleneck of inhibiting denitrifying bacteria activity, the beneficial effect of synergistic and efficient removal of sulfate and nitrate nitrogen was achieved, including SO4. 2- Removal rate >84%, NO3 - Removal rate > 66%.

[0050] The biochar wetland desulfurization and denitrification system based on a rotating reactor provided by this invention enhances mass transfer efficiency and prevents packing caking through a rotating packing device. It combines a surface flow wetland structure with a biochar-sand mixed matrix and an open-pore stainless steel support plate to intercept flocculants, thus avoiding the clogging problem of existing subsurface flow constructed wetlands. This achieves anti-clogging and long-term stable operation, and increases throughput by 80%.

[0051] The biochar wetland desulfurization and denitrification system based on a rotary reactor provided by this invention monitors SO4 in real time using an ion-selective electrode. 2- / S 2- The concentration triggers the rise and fall of the packing layer or the recirculation of wastewater, and the heating electrode and temperature sensor work together to control the temperature, achieving dynamic and precise regulation to meet the needs of unattended operation.

[0052] The biochar wetland desulfurization and denitrification system based on a rotary reactor provided by this invention uses microporous plexiglass to encapsulate calcium sulfide to control sulfur content. 2- The slow-release rate avoids equipment damage caused by sulfide accumulation in existing technologies and extends the service life of the equipment.

[0053] The biochar wetland desulfurization and denitrification system based on a rotary reactor provided by this invention reduces raw material costs by 60% by using agricultural waste to prepare Ca-bacterial char composites, and reduces reliance on high-end materials by combining biochar-sand matrix, thus overcoming the shortcomings of traditional constructed wetlands, such as high investment and difficult maintenance.

[0054] The biochar wetland desulfurization and denitrification system based on a rotary reactor provided by this invention achieves zero external carbon source addition through sulfur autotrophic denitrification, avoiding secondary COD pollution. At the same time, it utilizes reed wetland plants to enhance the landscape effect and biodiversity, meeting the dual needs of water resource recycling and ecological restoration in arid areas, with COD effluent <20mg / L.

[0055] The biochar wetland desulfurization and denitrification system based on a rotary reactor provided by this invention dynamically adjusts the hydraulic retention time and the height of the calcium sulfide layer; and tracks water quality parameters in real time through a data transmission device and a remote monitoring device, thus solving the problem of difficult operation and maintenance and reducing manual intervention. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0057] Figure 1 This is a schematic diagram of the structure of the biochar wetland desulfurization and denitrification system based on a rotary reactor provided in an embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram of the structure of the rotating sulfate reduction unit provided in an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of the structure of a biochar-based constructed wetland unit provided in an embodiment of the present invention.

[0060] Figure label:

[0061] 1. Rotating sulfate reduction unit; 2. Rotatable packing device; 3. First peristaltic pump; 4. Ca-bacterial charcoal composite layer; 5. Rotating rod; 6. Perforated stainless steel support plate; 7. Second peristaltic pump; 8. Granular calcium sulfide solid layer; 9. Ion selective electrode; 10. Rope chain; 11. Heating electrode; 12. Temperature sensor; 13. Third peristaltic pump; 14. Rotating sulfate reduction unit inlet; 15. Wastewater outlet; 16. Rotating sulfate reduction unit outlet; 17. Biochar-based constructed wetland unit; 18. Biochar-based constructed wetland unit inlet; 19. Gravel support layer; 20. Biochar-sand mixed matrix layer; 21. Water layer; 22. Biochar-based constructed wetland unit outlet; 23. Data transmission device; 24. Remote monitoring device. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0063] The following is combined with Figures 1-3 The present invention describes a biochar wetland desulfurization and denitrification system based on a rotary reactor.

[0064] Figure 1 This is a schematic diagram of the structure of a biochar wetland desulfurization and denitrification system based on a rotary reactor provided in an embodiment of the present invention.

[0065] like Figure 1 As shown, the biochar wetland desulfurization and denitrification system based on a rotary reactor provided in this embodiment of the invention includes a rotary sulfate reduction unit 1, a biochar-based constructed wetland unit 17, a data transmission device 23, and a remote monitoring device 24 connected in series.

[0066] The rotating sulfate reduction unit 1 includes: a rotatable packing device 2, a first peristaltic pump 3, a Ca-bacterial charcoal composite layer 4, a rotating rod 5, a perforated stainless steel support plate 6, a second peristaltic pump 7, a granular calcium sulfide solid layer 8, an ion-selective electrode 9, a rope chain 10, a heating electrode 11, a temperature sensor 12, a third peristaltic pump 13, a rotating sulfate reduction unit inlet 14, a wastewater outlet 15, and a rotating sulfate reduction unit outlet 16.

[0067] The biochar-based constructed wetland unit 17 includes: a biochar-based constructed wetland unit inlet 18, a gravel support layer 19, a biochar-sand mixed matrix layer 20, a water layer 21, and a biochar-based constructed wetland unit outlet 22.

[0068] Figure 2 This is a schematic diagram of the structure of the rotating sulfate reduction unit provided in an embodiment of the present invention, wherein, Figure 2 a is a front view of the rotating sulfate reduction unit. Figure 2 b is a top view of the rotating sulfate reduction unit.

[0069] like Figure 2 a, Figure 2 As shown in b, in the rotating sulfate reduction unit provided in this embodiment of the invention, the rotatable packing device 2 is driven by a rotating rod 5; the Ca-bacterial charcoal composite layer 4 and the granular calcium sulfide solid layer 8 are disposed inside the rotatable packing device 2; the granular calcium sulfide solid layer 8 is controlled to rise and fall by a rope chain 10; the perforated stainless steel support plate 6, with a hole diameter of 1~5mm, is connected to the rotating rod 5 and supports the packing; the ion-selective electrode 9 is used to remove SO4 from the effluent of the rotating sulfate reduction unit 1. 2- S 2-Ion concentration is detected in real time; the heating electrode 11 is used to heat the water; the temperature sensor 12 is used to detect the water temperature; the wastewater outlet 15 is connected to the inlet 14 of the rotating sulfate reduction unit via a third peristaltic pump 13; the first peristaltic pump 3 and the third peristaltic pump 13 are used to control the amount of water discharged into the rotating sulfate reduction unit; the outlet 16 of the rotating sulfate reduction unit is connected to the inlet 18 of the biochar-based constructed wetland unit via a second peristaltic pump 7; the second peristaltic pump 7 is used to control the discharge of the effluent from the rotating sulfate reduction unit into the biochar-based constructed wetland unit 17.

[0070] Figure 3 This is a schematic diagram of the structure of a biochar-based constructed wetland unit provided in an embodiment of the present invention, wherein, Figure 3 a is a front view of a biochar-based constructed wetland unit. Figure 3 b is a left view of a biochar-based constructed wetland unit.

[0071] like Figure 3 a, Figure 3 As shown in b, the biochar-based constructed wetland unit provided in this embodiment of the invention consists of, from bottom to top, a gravel support layer 19, a biochar-sand mixed matrix layer 20, and a water layer 21; the inlet 18 of the biochar-based constructed wetland unit is located above the water layer 21; the outlet 22 of the biochar-based constructed wetland unit is at the same height as the water surface of the water layer 21.

[0072] In this invention, the gravel support layer 19 is filled with gravel with an average particle size of 2-4 cm and a height of 5 cm.

[0073] In this invention, the biochar-sand mixed matrix layer 20 is made by mixing sand with a particle size of 1-5 mm and biochar with a particle size of 1-7 mm at a volume ratio of 75-95:5-25, preferably sand with a particle size of 2-3 mm, biochar with a particle size of 3-5 mm, and a volume ratio of 80-90:10-20, and more preferably a volume ratio of 84-86:14-16.

[0074] In this invention, the height of the water layer 21 is 8-12 cm, preferably 9-11 cm, with 20-40 plants / m². 2 The optimal planting density for reeds is 25-35 plants / m². 2 Further optimization is to use 28-32 plants / m². 2 .

[0075] In this invention, the inlet 18 of the biochar-based constructed wetland unit is located 3-8 cm above the water layer 21, preferably 4-6 cm.

[0076] In this invention, the Ca-bacterial char composite layer 4 is composed of CaCl2 modified agricultural waste activated carbon loaded with sulfate-reducing bacteria, and is filled in three layers, each layer having a height of 10~20cm, preferably 14~16cm, the filler particle size being 3~5mm, and the interlayer spacing being 15~25cm, preferably 18~22cm.

[0077] In this invention, the agricultural waste is one or more of corn cobs, rice husks, and straw, preferably one of corn cobs, rice husks, and straw, and more preferably corn cobs. The modified concentration is 5-10 wt%, and the inoculum loading is 10-15%.

[0078] In this invention, the particulate calcium sulfide solid layer 8 is disposed 15-25cm above the Ca-bacterial charcoal composite layer 4, preferably 18-22cm, with a filling height of 3-7cm, preferably 4-6cm, and the calcium sulfide particle size is 3-5mm.

[0079] In this invention, the calcium sulfide filler in the granular calcium sulfide solid layer 8 is filled with microporous organic glass material, and the micropore diameter is 0.5~1mm.

[0080] In this invention, the granular calcium sulfide solid layer 8 is provided with a heating rod under the calcium sulfide filler to heat the water to 20~25°C.

[0081] In this invention, an aeration reflux tank is also provided between the inlet 14 and the wastewater outlet 15 of the rotating sulfate reduction unit to oxidize dissolved low-valence sulfur to SO4. 2- The sulfides are then adsorbed and removed, thereby reducing the corrosion of the equipment by sulfides.

[0082] In this invention, the ion-selective electrode 9 performs the following control:

[0083] When SO4 2- When the concentration is >250 mg / L, wastewater recirculation is triggered;

[0084] When S 2- When the concentration is >33.1 mg / L, the solid layer of particulate calcium sulfide increases by 8;

[0085] When S 2- When the concentration is <18.3 mg / L, the solid layer of particulate calcium sulfide decreases by 8%.

[0086] In this invention, the heating electrode 11 and the temperature sensor 12 are linked to control the water temperature to 20~25℃.

[0087] On the other hand, the present invention also provides a biochar wetland desulfurization and denitrification method based on a rotary reactor, comprising the following steps:

[0088] (1) Cultivate plants and substrates in sulfate-free simulated wastewater for 30 days;

[0089] (2) Simulated wastewater enters the rotary sulfate reduction unit 1 and runs at a speed of 250 rpm and a hydraulic retention time of 2-4 days. SO4 in the effluent is monitored in real time by the ion-selective electrode 9. 2- and S 2- Concentration, and adjust the rise and fall of the granular calcium sulfide solid layer 8 and wastewater recirculation according to the concentration;

[0090] (3) The effluent from the rotating sulfate reduction unit 1 enters the biochar-based constructed wetland unit 17, with a hydraulic retention time of 4 days, and the reaction takes place in the biochar-sand mixed substrate layer 20, including:

[0091] Aerobic zone: NH4 + →NO3 - ;

[0092] Anaerobic zone: NO3 - +Biochar / Organic Carbon → N2↑;

[0093] Sulfur-denitrification reaction: S 2- +NO3 - →SO4 2- +N2↑.

[0094] In this invention, the hydraulic retention time in step (2) is based on the influent SO4 2- Concentration adjustment:

[0095] SO4 2- When the concentration is 500 mg / L, the hydraulic retention time is 2 days.

[0096] SO4 2- When the concentration is 1000 mg / L, the hydraulic retention time is 2.5 days.

[0097] SO4 2- When the concentration is 2000 mg / L, the hydraulic retention time is 4 days.

[0098] In an embodiment of the present invention, the configuration of the simulated wastewater is shown in Table 1 below.

[0099] Table 1 Simulated wastewater configuration

[0100]

[0101] The wastewater treatment results were shown in Table 2 below, obtained by using wetlands alone and by using a rotating sulfate reduction unit-wetland series connection.

[0102] Table 2 Wastewater Treatment Results

[0103]

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biochar wetland desulfurization and denitrification system based on a rotary reactor, characterized in that, It includes a series of rotating sulfate reduction units (1), a biochar-based constructed wetland unit (17), a data transmission device (23), and a remote monitoring device (24). The rotating sulfate reduction unit (1) includes: a rotatable packing device (2), a first peristaltic pump (3), a Ca-bacterial charcoal composite layer (4), a rotating rod (5), an open stainless steel support plate (6), a second peristaltic pump (7), a granular calcium sulfide solid layer (8), an ion-selective electrode (9), a rope chain (10), a heating electrode (11), a temperature sensor (12), a third peristaltic pump (13), a rotating sulfate reduction unit inlet (14), a wastewater outlet (15), and a rotating sulfate reduction unit outlet (16). The biochar-based constructed wetland unit (17) includes: a biochar-based constructed wetland unit inlet (18), a gravel support layer (19), a biochar-sand mixed matrix layer (20), a water layer (21), and a biochar-based constructed wetland unit outlet (22). The data transmission device (23) is used to transmit temperature and SO4. 2- S 2- The ion concentration is transmitted to the remote monitoring device in real time (24). The remote monitoring device (24) is used to monitor water quality in real time and control the rotating sulfate reduction unit (1). The rotatable packing device (2) is driven by a rotating rod (5); The Ca-bacterial char composite layer (4) and the granular calcium sulfide solid layer (8) are disposed inside the rotatable packing device (2); The granular calcium sulfide solid layer (8) is raised and lowered by a rope chain (10); The wastewater outlet (15) is connected to the inlet (14) of the rotary sulfate reduction unit via a third peristaltic pump (13). The first peristaltic pump (3) and the third peristaltic pump (13) are used to control the amount of water discharged into the rotary sulfate reduction unit; The outlet (16) of the rotating sulfate reduction unit is connected to the inlet (18) of the biochar-based artificial wetland unit via a second peristaltic pump (7). The perforated stainless steel support plate (6) is connected to the rotating rod (5) and supports the filler. The biochar-based constructed wetland unit (17) consists of a gravel support layer (19), a biochar-sand mixed matrix layer (20), and a water layer (21) from bottom to top. The Ca-bacterial carbon composite layer (4) is composed of sulfate-reducing bacteria supported on CaCl2-modified activated carbon from agricultural production waste; The ion-selective electrode (9) is used to remove SO4 from the effluent of the rotating sulfate reduction unit (1). 2- S 2- Ion concentration is monitored in real time; The ion-selective electrode (9) performs the following control: When SO4 2- When the concentration is >250 mg / L, wastewater recirculation is triggered; When S 2- When the concentration is >33.1 mg / L, the solid layer of particulate calcium sulfide is increased (8); When S 2- When the concentration is <18.3 mg / L, the particulate calcium sulfide solid layer decreases (8).

2. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1, characterized in that, The perforated stainless steel support plate (6) has a hole diameter of 1~5mm; The heating electrode (11) is used to heat the water. The temperature sensor (12) is used to detect the water temperature.

3. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1, characterized in that, The gravel support layer (19) is filled with gravel with an average particle size of 2-4 cm and a height of 5 cm; The biochar-sand mixed matrix layer (20) is made by mixing sand with a particle size of 1-5 mm and biochar with a particle size of 1-7 mm at a volume ratio of 75-95:5-25. The water layer (21) is 8-12cm high, with 20-40 plants / m². 2 Plant reeds at the appropriate planting density; The inlet (18) of the biochar-based constructed wetland unit is located 3-8 cm above the water layer (21); The outlet (22) of the biochar-based artificial wetland unit is at the same height as the water surface of the water layer (21).

4. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1 or 2, characterized in that, The Ca-bacterial char composite layer (4) is filled with three layers, each layer having a height of 10~20cm, a filler particle size of 3~5mm, and an interlayer spacing of 15~25cm; The agricultural production waste is one or more of corn cobs, rice husks, and straw, with a modification concentration of 5-10 wt% and a bacterial strain loading of 10-15%.

5. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1 or 2, characterized in that, The granular calcium sulfide solid layer (8) is set 15-25cm above the Ca-bacterial char composite layer (4), with a filling height of 3-7cm and a calcium sulfide particle size of 3-5mm. The calcium sulfide filler in the granular calcium sulfide solid layer (8) is filled with microporous organic glass material with a pore size of 0.5~1mm; The granular calcium sulfide solid layer (8) has a heating rod installed under the calcium sulfide filler to heat the water to 20~25℃.

6. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1 or 2, characterized in that, An aeration return tank is also installed between the inlet (14) and the wastewater outlet (15) of the rotating sulfate reduction unit to oxidize dissolved low-valence sulfur into SO4. 2- The sulfides are then adsorbed and removed, thereby reducing the corrosion of the equipment by sulfides.

7. The biochar wetland desulfurization and denitrification system based on a rotary reactor according to claim 1, characterized in that, The heating electrode (11) and the temperature sensor (12) work together to control the water temperature to 20~25℃.

8. A biochar wetland desulfurization and denitrification method based on a rotary reactor, employing the system described in claim 1, characterized in that, Includes the following steps: (1) Cultivate plants and substrates in sulfate-free simulated wastewater for 30 days; (2) Simulated wastewater enters the rotating sulfate reduction unit (1) and runs at a speed of 250 rpm and a hydraulic retention time of 2-4 days. The SO4 content of the effluent is monitored in real time by an ion-selective electrode (9). 2- and S 2- Concentration, and adjust the rise and fall of the granular calcium sulfide solid layer (8) and wastewater recirculation according to the concentration; (3) The effluent from the rotating sulfate reduction unit (1) enters the biochar-based constructed wetland unit (17) with a hydraulic retention time of 4 days. The reaction takes place in the biochar-sand mixed substrate layer (20), including: Aerobic zone: NH4 + →NO3 - ; Anaerobic zone: NO3 - +Biochar / Organic Carbon → N2↑; Sulfur-denitrification reaction: S 2- +NO3 - →SO4 2- +N2↑.

9. The biochar wetland desulfurization and denitrification method based on a rotary reactor according to claim 8, characterized in that, The hydraulic retention time mentioned in step (2) is based on the influent SO4 2- Concentration adjustment: SO4 2- When the concentration is 500 mg / L, the hydraulic retention time is 2 days. SO4 2- When the concentration is 1000 mg / L, the hydraulic retention time is 2.5 days. SO4 2- When the concentration is 2000 mg / L, the hydraulic retention time is 4 days.

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