A method and device for combining in-situ and ex-situ repair of black and odorous water body sediment

Abstract

A method and device for combining in-situ and ex-situ remediation of black and odorous water body sediments belongs to the field of sludge treatment technology. The device consists of an interconnected sludge suction pump, a sludge concentration tank, a sludge fermentation tank, a tailwater treatment tank, a clear water tank, a plate and frame filter press, a tailwater storage tank, and a chemical injector. The sediment is salvaged from the river channel, gravity concentrated, and fermented in an alkaline environment to fully release the pollutants in the sediment. After fermentation, the sediment is conditioned and dehydrated to complete the ex-situ remediation of the sediment. The tailwater generated by sediment concentration and dehydration is aerobically treated, and the purified tailwater is injected into the sediment. The nitrates, calcium ions, and iron ions in the purified tailwater are used to achieve in-situ remediation of the sediment. The deficiencies of each technology can be compensated for, reducing secondary pollution from ex-situ remediation of sediment, while also reducing the cost of chemicals for in-situ remediation.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, and in particular to a method and device for repairing black and odorous water body sludge by combining in-situ and ex-situ repair. Background Art

[0002] Bottom sediment is a component of natural water bodies, serving as both a reservoir for surface water pollutants and a source of release. Once external pollution is effectively controlled, bottom sediment becomes a significant source of surface water pollutants. Therefore, remediation of bottom sediment is crucial for treating black and odorous water bodies.

[0003] Currently, there are two main types of sediment remediation technologies: ex situ and in situ. Ex situ remediation primarily involves treating sediment dredged by sediment dredgers. While sediment dredging can quickly displace pollutants, the volume of dredged sediment is large and contains a significant amount of pollutants. Organic matter, total nitrogen, and total phosphorus levels can reach 0.75%-10.86%, 0.05%-0.68%, and 0.04%-0.23%, respectively, making the treatment of dredged sediment a challenging task. Currently, the primary treatment method for dredged sludge involves dehydration and solidification by adding chemicals. However, due to the high concentrations of organic pollutants and nitrogen and phosphorus in sludge, direct addition of chemicals is difficult to achieve effective dehydration and can also cause secondary pollution. In situ remediation involves taking on-site measures to remediate sediment. These include in situ covering, in situ addition of solidifying agents, microbial agents, and redox treatment with chemical agents such as calcium nitrate. Calcium nitrate is the most commonly used chemical agent for in-situ chemical remediation of sediments. Its main functions include: (1) reacting with phosphates in the water to form a chemical precipitate, inhibiting the release of phosphorus from the sediment; (2) acting as an electron acceptor for denitrification to oxidize organic matter; and (3) changing the redox potential of the sediment, alleviating the black and odorous phenomenon of the sediment. However, calcium nitrate is a consumable agent and has a high treatment cost. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method and device for combining in situ and ex situ repair of black and odorous water body sediments, which reduces organic and nitrogen and phosphorus pollutants in dredged sediments, improves the solidification effect of dredged sediments, and reduces the cost of adding calcium nitrate agents.

[0005] The bottom mud is salvaged from the river channel, the bottom mud is gravity concentrated and fermented in an alkaline environment to fully release the pollutants in the bottom mud. After the fermentation is completed, the bottom mud is conditioned and dehydrated to complete the ectopic repair of the bottom mud; the tail water generated by the bottom mud concentration and bottom mud dehydration is aerobically treated, and the purified tail water is injected into the bottom mud, and the nitrate, calcium ion and iron ion in the purified tail water are used to achieve the in-situ repair of the bottom mud. At the same time, a device for applying the above method is also announced, which consists of a sludge suction pump, a sludge concentration tank, a sludge fermentation tank, a tail water treatment tank, a clear water tank, a plate and frame filter press, a tail water storage tank, and a drug injector that are interconnected. The present invention combines the in-situ and ectopic repair technologies of the bottom mud, which can make up for the shortcomings of each technology, reduce the secondary pollution of the ectopic repair of the bottom mud, and reduce the cost of the drug for in-situ repair.

[0006] The technical solution of the present invention is:

[0007] A device for combining in-situ and ex-situ repair of bottom mud in black and odorous water bodies is characterized by comprising a sludge suction pump (1), a sludge concentration tank (2), a sludge fermentation tank (3), a tail water treatment tank (4), a clear water tank (5), a plate and frame filter press (6), a tail water storage tank (7) and a drug injector (8) which are interconnected.

[0008] A hose I (11) is provided at the water inlet of the sludge suction pump (1) for sucking the bottom sludge of the water body, and the water outlet of the sludge suction pump (1) is connected to the sludge concentration tank (2) through a sludge delivery pipe (12).

[0009] A sludge pump I (21) is provided at the bottom of the sludge concentration tank (2), and the sludge pump I (21) is connected to the sludge fermentation tank (3) via a connecting pipe (22); a pipe I (24) is provided on the wall of the sludge concentration tank (2) to connect to the tail water storage tank (7), and a solenoid valve I (23) is provided on the pipe I (24);

[0010] A sludge pump II (32) is provided at the bottom of the sludge fermentation tank (3), and the sludge pump II (32) is connected to the plate and frame filter press (6) through a pipeline II (34). An agitator (31) and an online pH meter I (35) are provided inside the sludge fermentation tank (3); a lime dosing system (33) is connected to the sludge fermentation tank (3) and is used to add lime to the sludge fermentation tank (3). The amount of lime added is controlled by the online pH meter I (35).

[0011] The tailwater treatment tank (4) is connected to the tailwater storage tank (7) through a pipe V (72). An aerator (42) is provided at the bottom of the tailwater treatment tank (4). The aerator (42) is connected to the air pipe (45) via an air branch pipe via a solenoid valve II (46). The air pipe (45) is connected to the fan (41). The tailwater treatment tank (4) is connected to the clean water tank (5) through a siphon (43) for discharging clean water treated in the tailwater treatment tank (4). An online DO meter (47) and an online pH meter II (48) are provided in the tailwater treatment tank (4).

[0012] The clean water tank (5) is equipped with a denitrifying bacteria dosing system (54); a dosing pump (51) is provided at the bottom of the clean water tank (5), and the dosing pump (51) is connected to a hose II (82) on a drug injector (8) through a pipeline III (52), and a solenoid valve V (53) is provided on the pipeline III (52); at the same time, a branch is provided on the pipeline III (52) and connected to an air pipeline (45), and a solenoid valve III (44) is provided on the branch, and the solenoid valve III (44) is usually in a closed state.

[0013] The plate and frame filter press (6) is connected to the ferric chloride dosing system (61) and the sludge storage tank (63) respectively. At the same time, the plate and frame filter press (6) is connected to the tail water storage tank (7) through the pipeline IV (62) for transmitting the filtrate obtained by the plate and frame filter press (6) to the tail water storage tank (7).

[0014] A sewage lifting pump (71) is provided inside the tailwater storage tank (7), and the sewage lifting pump (71) is connected to the tailwater treatment tank (4) through a pipeline V (72) and is used to lift the tailwater in the tailwater storage tank (7) into the tailwater treatment tank (4).

[0015] The drug injector (8) is provided with a plurality of upright injection tubes (81), which are arranged in an array structure. The distance between two adjacent injection tubes (81) is 0.5-1m. Each injection tube (81) is a pointed tube at the lower end. The injection tube (81) is 20-30cm long and has a plurality of dosing holes with a diameter of 2-3mm on the side. The injection tube body has a diameter of 5-10cm and a front end cone angle of 40-50°. The material is stainless steel. A drug dispensing tube (83) is connected to each injection tube (81), and the drug dispensing tube (83) is connected to the hose II (82).

[0016] The drug injector (8) is used for inserting into the bottom mud of the black and smelly water body for repairing.

[0017] The method for implementing the combined in-situ and ex-situ remediation of bottom mud in black and odorous water bodies using the above-mentioned device includes the following steps: salvaging the bottom mud from the river channel, gravity concentrating the bottom mud and fermenting it in an alkaline environment to fully release the pollutants in the bottom mud, conditioning and dehydrating the bottom mud after the fermentation is completed, and completing the ex-situ remediation of the bottom mud; aerobically treating the tail water generated by the bottom mud concentration and bottom mud dehydration, injecting the purified tail water into the bottom mud, and utilizing the nitrate, calcium ions and iron ions in the purified tail water to achieve in-situ remediation of the bottom mud.

[0018] The specific implementation method includes the following steps:

[0019] Step (1): A portion of the black and odorous water body sludge at the bottom of a section of the river enters the sludge concentration tank (2) through a sludge suction pump (1) and is concentrated for 12-16 hours. The supernatant after concentration is discharged into the tail water storage tank (7) through a pipeline I (24). The concentrated sludge is sent to the sludge fermentation tank (3) through a sludge pump (21). The lime dosing system (33) adds lime to the sludge fermentation tank (3) to control the pH value of the sludge to 8-9. The sludge retention time in the sludge fermentation tank (3) is 2-4 days. The sludge undergoes hydrolysis reaction in an alkaline anaerobic environment, and the organic matter and nitrogen pollutants in the sludge are removed. Phosphorus is fully released, and chemical precipitation occurs under alkaline conditions to be removed. The hydrolyzed sludge is lifted by sludge pump II (32) and enters the plate and frame filter press (6). The ferric chloride dosing system (61) adds 2% DS (DS is the dry weight of the sludge, and 2% DS means the amount of ferric chloride added is 2% of the dry weight of the sludge) of ferric chloride to the sludge in the plate and frame filter press (6) for chemical conditioning. The chemically conditioned sludge is dehydrated in the plate and frame filter press (6), and the dehydrated sludge is loaded into the sludge storage tank (63) for transportation. The filtrate produced is transmitted to the tail water storage tank (7) through pipeline IV (62);

[0020] Step (2): The tail water storage tank (7) collects the sludge filtrate and the supernatant of the concentration tank (2), which contains a large amount of organic pollutants and ammonia nitrogen. The mixed liquid of the tail water storage tank (7), i.e., the tail water, is sent to the tail water treatment tank (4) for tail water treatment through the sewage lifting pump (71). The tail water treatment process adopts the SBR process, the dissolved oxygen is controlled at 3-4 mg / L, the sludge concentration is controlled at 3000-4000 mg / L, and the aeration treatment is stopped until the ammonia nitrogen concentration is less than 1 mg / L. After the sewage settles for 1 hour, the solenoid valve II (46) is opened for discharge, and the drainage ratio is about 0.5. The tail water after treatment is discharged into the clear water tank (5). The tail water after treatment contains a large amount of nitrate and Ca 2+ and Fe 3+ ion;

[0021] Step (3): add the denitrifying bacteria to the clear water pool through the denitrifying bacteria dosing system (54), insert the drug injection tube (81) of the drug injector (8) into the remaining bottom mud corresponding to the bottom of the river in step (1) to a depth of 15-20 cm, open the electromagnetic valve V (53), start the drug dosing pump (51), and inject the nitrate and Ca-rich water in the clear water pool into the drug injection tube (81). 2+ and Fe 3+ The aqueous solution of ions and denitrifying bacteria are injected into the bottom mud through the hose II (82), the pipeline (83) and the reagent injection tube (81). The amount of nitrate added to the bottom mud is 0.15-0.3g / L, and the amount of bacteria added is 3-5g / L. The added nitrate and Ca 2+ and Fe 3+ The ions remove organic matter and phosphorus from the bottom mud through denitrification and chemical precipitation reactions, completing the in-situ remediation of the bottom mud of black and smelly water bodies.

[0022] Step (4) When the dosing hole on the medicine injection tube (81) is blocked, close the solenoid valve II (46) and the solenoid valve V (53), open the solenoid valve III (44), and use the fan (41) to purge the medicine injection tube (81).

[0023] The steps (1) to (3) or / and the steps (1) to (4) of the present invention are carried out in a cycle.

[0024] The beneficial effects of the present invention are:

[0025] 1. Traditional sludge is extracted and directly dehydrated, as it contains organic matter, nitrogen, and phosphorus, which is not conducive to sludge dehydration and can lead to secondary pollution. The technology of this invention subjects the sludge to alkaline fermentation before dehydration, which decomposes the organic matter, releases nitrogen, solidifies phosphorus, stabilizes the sludge, reduces secondary pollution, and facilitates sludge dehydration and solidification.

[0026] 2. After the sludge is alkaline fermented and dehydrated, the sludge dehydrated liquid contains a large amount of ammonia nitrogen, which is converted into nitrate nitrogen through nitrification by aeration. The nitrate nitrogen is then used to repair the sludge in situ, thereby reducing the cost of adding nitrate agents and realizing the resource utilization of the sludge.

[0027] 3. Combining in situ and ex situ repair technologies can make up for the shortcomings of each technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Structural schematic diagram of the present invention

[0029] In the figure, 1 - sludge suction pump; 2 - sludge thickening tank; 3 - sludge fermentation tank; 4 - tailwater treatment tank; 5 - clear water tank; 6 - plate and frame filter press; 7 - tailwater storage tank; 8 - reagent injector; 11 - hose I; 12 - sludge delivery pipe; 21 - sludge pump I; 22 - connecting pipe; 23 - solenoid valve I; 24 - pipeline I; 31 - agitator; 32 - sludge pump II; 33 - lime dosing system; 34 - pipeline II; 35 - pH meter I; 41 - fan; 42-aerator; 43-siphon; 44-solenoid valve III; 45-air line; 46-solenoid valve II; 47-DO meter; 48-pH meter II; 51-dosing pump; 52-pipeline III; 53-solenoid valve V; 54-denitrifying bacteria dosing system; 61-ferric chloride dosing system; 62-pipeline IV; 63-sludge storage tank; 71-sewage lifting pump; 72-pipeline V; 81-injection tube; 82-hose II; 83-drug distribution pipe. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the following embodiments.

[0031] Example 1

[0032] The device used will Figure 1 .

[0033] A black and smelly river channel is 1km long, 5m wide, and has a bottom mud thickness of 30cm. The bottom mud needs to be repaired. The sludge thickening tank 2, sludge fermentation tank 3, tailwater treatment tank 4 and clear water tank 5 adopt an integrated design, made of carbon steel anti-corrosion material, with a size of 12m×2.2m×2.2m, and built into a 40-foot container with internal dimensions of: 12.032m×2.352m×2.393m. The plate and frame filter press 6, lime dosing system 33, fan 41, denitrifying bacteria dosing system 54 and ferric chloride dosing system 61 are built into a 20-foot container with internal dimensions of: 5.898m×2.352m×2.393m. The system was transported to the site by two trucks and the pipes and valve accessories were installed. The system was also configured with a flow rate of 20m 3 / h sludge suction pump 1, 2m 3 Tailwater storage tank 7, 10m 3 The sludge storage tank 63 and the medicament injector 8 with a size of 5m×4m are used. The 6m long sludge of the river section is transported to the sludge thickening tank 2 through the water inlet hose Ⅰ 11 of the sludge pump 1 and the sludge pipe 12. The sludge has a water content of 90% and a volume of 9m 3 , sludge thickening tank 2 effective volume 9.7m 3 , gravity concentration for 12 hours, run twice a day. After concentration, the water content of the sludge is reduced to 80%. The tail water storage tank 7 is placed on the ground, and the solenoid valve I23 is opened to transfer the supernatant 4.5m of the sludge concentration tank 2 to the sludge concentration tank 2 by gravity.3 The supernatant is then pumped into the tailwater treatment tank 4 by the sewage lifting pump 71. The flow rate of the sewage lifting pump 71 is 10m 3 / h. After the supernatant of sludge thickening tank 2 is discharged, open the flow rate to 10m 3 / h sludge pump Ⅱ32, transporting 4.5m3 / h through pipeline Ⅱ34 3 The fermented sludge is sent to the plate and frame filter press 6, and then to the 4.5m 3 Concentrated sludge from 10m 3 The sludge is pumped by a pump I21 at a speed of 1 / h and transported to the sludge fermentation tank 3 via a connecting pipe 22. The lime dosing system 33 adds lime milk to the sludge fermentation tank 3. The pH is controlled at about 9 by an online pH meter 35. The sludge fermentation tank 3 is also equipped with a 2.2 kW agitator to stir the sludge to ensure that it is fully fermented. The effective volume of the sludge fermentation tank 3 is 27 m 3 , sludge retention time 3d. In the alkaline anaerobic environment, the solid organic pollutants in the sludge are fully hydrolyzed, releasing nitrogen elements, phosphorus and heavy metal ions that are precipitated and solidified through chemical reactions. The ferric chloride dosing system 61 adds 2% DS ferric chloride to the fermented sludge transported to the plate and frame filter press 6 to condition the sludge. The conditioned sludge enters the plate and frame filter press 6 for deep dehydration. After dehydration, the moisture content of the sludge is reduced to about 40% and then it is loaded into the sludge storage tank 63 and transported out to complete the ex situ remediation of the bottom sludge. And about 3.5m 3 The sludge dewatering liquid is gravity-transported to the tailwater storage tank 7 via pipeline IV 62 , and then lifted by the sewage lifting pump 71 and enters the tailwater treatment tank 4 via pipeline V 72 .

[0034] Tailwater treatment pool 4 total effective volume 15m 3 , using the SBR process, the sludge concentration is controlled at 3000-4000 mg / L. Aeration begins after the sludge dewatering liquid is transported. The aeration time is 5-6 hours. Dissolved oxygen is supplied by the fan 41 through the air pipe 45 and the microporous aerator 42. The dissolved oxygen concentration is controlled at 3-4 mg / L. The organic matter in the tail water is fully degraded and the ammonia nitrogen is fully nitrified. After aeration, it is allowed to settle for 1 hour. The siphon 43 is opened for drainage. The drainage ratio is 0.5. The purified sewage enters the clear water tank 5. The effective volume of the clear water tank is 7.5m 3 The purified sewage contains 40-50 mg / L of nitrate and 300-400 mg / L of Ca 2+ ions. Open the denitrifying bacteria dosing system 54 and add bacteria to the clear water tank 5. Insert the 5m×4m agent syringe 8 into the bottom mud to a depth of 20cm, open the solenoid valve V 53, turn on the dosing pump 51, and remove the nitrate, Ca 2+Ions and bacteria are injected into the bottom mud through hose II 82, reagent distribution pipe 83 and injection pipe 81 for in-situ remediation. The dosage of nitrate in the bottom mud is 150-200 mg / L, and the dosage of denitrifying bacteria is 0.3%. The denitrifying bacteria use the organic matter in the bottom mud and the added nitrate to carry out denitrification reaction, thereby removing the organic matter in the bottom mud. 2+ The ions react with the phosphates in the sediment to generate chemical precipitation, solidifying the phosphates; at the same time, nitrates can change the redox potential of the sediment, alleviating the black and smelly phenomenon of the sediment, thereby achieving in-situ remediation of the sediment.

[0035] When the dosing hole on the medicine injection tube 81 is blocked, the solenoid valve II 46 and the solenoid valve V 53 are closed, the solenoid valve III 44 is opened, and the blower 41 is used to purge the medicine injection tube 81 .

[0036] Water body restoration can be carried out one by one in sections of 100 meters. When the restoration of a 100-meter section of the river is completed, a truck can be used to transport the equipment to another 100-meter section of the river until the restoration of the entire river is completed.

Claims

1. A device for combining in-situ and ex-situ remediation of black and odorous water sediments, characterized by: The system comprises a sludge suction pump (1), a sludge concentration tank (2), a sludge fermentation tank (3), a tail water treatment tank (4), a clear water tank (5), a plate and frame filter press (6), a tail water storage tank (7) and a drug injector (8) which are connected in sequence; the sludge concentration tank (2), the sludge fermentation tank (3), the tail water treatment tank (4) and the clear water tank (5) adopt an integrated design; A hose I (11) is provided at the water inlet of the sludge suction pump (1) for sucking the bottom sludge of the water body, and the water outlet of the sludge suction pump (1) is connected to the sludge thickening tank (2) through a sludge delivery pipe (12); A sludge pump I (21) is provided at the bottom of the sludge thickening tank (2), and the sludge pump I (21) is connected to the sludge fermentation tank (3) via a connecting pipe (22); a pipe I (24) is provided on the wall of the sludge thickening tank (2) to be connected to the tail water storage tank (7), and a solenoid valve I (23) is provided on the pipe I (24); A sludge pump II (32) is provided at the bottom of the sludge fermentation tank (3), and the sludge pump II (32) is connected to the plate and frame filter press (6) through a pipe II (34). An agitator (31) and an online pH meter I (35) are provided inside the sludge fermentation tank (3). A lime dosing system (33) is connected to the sludge fermentation tank (3) and is used to add lime to the sludge fermentation tank (3). The amount of lime added is controlled by the online pH meter I (35). The tailwater treatment tank (4) is connected to the tailwater storage tank (7) through the pipe V (72). A microporous aerator (42) is provided at the bottom of the tailwater treatment tank (4). The microporous aerator (42) is connected to the air pipe (45) via the solenoid valve II (46) through the air branch pipe. The air pipe (45) is connected to the fan (41). The tailwater treatment tank (4) is connected to the clean water tank (5) through the siphon (43) for discharging the clean water treated by the tailwater treatment tank (4). An online DO meter (47) and an online pH meter II (48) are provided in the tailwater treatment tank (4). The clear water tank (5) is equipped with a denitrifying bacteria dosing system (54); a dosing pump (51) is provided at the bottom of the clear water tank (5), and the dosing pump (51) is connected to the hose II (82) on the drug injector (8) through the pipeline III (52), and a solenoid valve V (53) is provided on the pipeline III (52); at the same time, the pipeline III (52) is provided with a branch connected to the air pipeline (45), and a solenoid valve III (44) is provided on the branch, and the solenoid valve III (44) is usually in a closed state; The plate and frame filter press (6) is connected to the ferric chloride dosing system (61) and the sludge storage tank (63), respectively. At the same time, the plate and frame filter press (6) is connected to the tail water storage tank (7) through the pipeline IV (62), so as to transmit the filtrate obtained by the plate and frame filter press (6) to the tail water storage tank (7); A sewage lifting pump (71) is provided inside the tailwater storage tank (7), and the sewage lifting pump (71) is connected to the tailwater treatment tank (4) through a pipe V (72) for lifting the tailwater in the tailwater storage tank (7) into the tailwater treatment tank (4); The drug injector (8) is provided with a plurality of upright injection tubes (81), which are arranged in an array structure. The distance between two adjacent injection tubes (81) is 0.5-1m. Each injection tube (81) is a pointed tube at the lower end. The injection tube (81) is 20-30cm long and has a plurality of dosing holes with a diameter of 2-3mm on the side. The diameter of the injection tube body is 5-10cm, the angle of the front cone is 40-50°, and the material is stainless steel. The drug dispensing tube (83) is connected to each injection tube (81), and the drug dispensing tube (83) and the hose II (82) are connected.

2. The device for combining in-situ and ex-situ remediation of black and odorous water sediment according to claim 1 is characterized in that: The drug syringe (8) is used to be inserted into the bottom mud of the black and smelly water body for repairing.

3. A method for combining in-situ and ex-situ remediation of black and odorous water sediments, characterized in that: The device according to claim 1 or 2 specifically comprises the following steps: Step (1): A portion of the black and smelly sludge at the bottom of the river enters the sludge thickening tank (2) through the sludge suction pump (1) and is concentrated for 12-16 hours. The supernatant after concentration is discharged into the tail water storage tank (7) through the pipeline I (24). The concentrated sludge is sent to the sludge fermentation tank (3) through the sludge pump I (21). The lime dosing system (33) adds lime to the sludge fermentation tank (3) to control the pH value of the sludge to 8-9. The sludge retention time in the sludge fermentation tank (3) is 2-4 days. The sludge undergoes hydrolysis reaction in the alkaline anaerobic environment, and the organic matter and nitrogen pollutants in the sludge are filled. Phosphorus is chemically precipitated and removed under alkaline conditions. The hydrolyzed sludge is lifted by sludge pump II (32) and enters the plate and frame filter press (6). The ferric chloride dosing system (61) adds 2% DS of ferric chloride to the sludge in the plate and frame filter press (6) for chemical conditioning, wherein DS is the dry weight of the sludge and 2% DS is the amount of ferric chloride added, which is 2% of the dry weight of the sludge. The chemically conditioned sludge is dehydrated in the plate and frame filter press (6). The dehydrated sludge is loaded into the sludge storage tank (63) for transportation, and the filtrate produced is transported to the tail water storage tank (7) through pipeline IV (62). Step (2): The tailwater storage tank (7) collects the sludge filtrate and the supernatant of the concentration tank (2), which contains a large amount of organic pollutants and ammonia nitrogen. The mixed liquid of the tailwater storage tank (7), i.e., the tailwater, is sent to the tailwater treatment tank (4) for tailwater treatment through the sewage lifting pump (71). The tailwater treatment process adopts the SBR process, the dissolved oxygen is controlled at 3-4 mg / L, the sludge concentration is controlled at 3000-4000 mg / L, and the aeration treatment is stopped until the ammonia nitrogen concentration is less than 1 mg / L. After the sewage settles for 1 hour, the solenoid valve II (46) is opened for discharge, and the drainage ratio is 0.

5. The tailwater treated in the tailwater treatment tank (4) is discharged into the clear water tank (5). The tailwater after treatment contains a large amount of nitrate and Ca 2+ and Fe 3+ ion; Step (3): Add the denitrifying bacteria to the clear water pool through the denitrifying bacteria dosing system (54), insert the drug injection tube (81) of the drug syringe (8) into the remaining bottom mud corresponding to the bottom of the river in step (1) to a depth of 15-20 cm, open the solenoid valve V (53), start the drug dosing pump (51), and inject the nitrate-rich Ca in the clear water pool. 2+ and Fe 3+ The aqueous solution of ions and denitrifying bacteria are injected into the bottom mud through the hose II (82), the reagent distribution pipe (83) and the reagent injection pipe (81). The amount of nitrate added to the bottom mud is 0.15-0.3g / L, and the amount of bacteria added is 3-5g / L. 2+ and Fe 3+ Ions remove organic matter and phosphorus from the bottom mud through denitrification and chemical precipitation reactions, completing the in-situ remediation of black and odorous water body bottom mud; Step (4) When the dosing hole on the drug injection tube (81) is blocked, close the solenoid valve II (46) and the solenoid valve V (53), open the solenoid valve III (44), and use the fan (41) to purge the drug injection tube (81).

4. The method according to claim 3, characterized in that Step (1) to step (3) are executed in a loop.

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