Treatment device for nitrogen and sulfur removal of wastewater

Abstract

The utility model relates to a wastewater denitrification and desulfurization treatment device which is characterized in that a water distributor is arranged at the lower part of an anaerobic reaction tank of an anaerobic reactor, a three-phase separator is arranged at the upper part of the anaerobic reaction tank of the anaerobic reactor, and a stirrer is arranged on an anoxic reaction tank of an anoxic reactor; an overflow port of the anaerobic reaction tank is connected and communicated with the anoxic reaction tank, a reflux port of the anaerobic reaction tank is connected and communicated with the anaerobic reaction tank through a wastewater reflux pipe, an aerator is arranged at the bottom of an aerobic reaction tank of the aerobic reactor, the anoxic reaction tank is connected and communicated with the aerobic reaction tank, a partition plate is arranged in the settling pond, a water inlet area is arranged on one side of the partition plate, and a settling area is arranged on the other side of the partition plate. A clear liquid outlet pipe is arranged at the upper part of the inclined plate of the sedimentation tank, a communicated clear liquid return pipe is arranged at the front part of the clear liquid valve of the clear liquid outlet pipe, and the clear liquid return pipe is communicated with the anoxic reaction tank. According to the device, the sulfate radical removal rate is high, nitrate in the wastewater can be simultaneously removed while sulfate radicals in the wastewater are removed, and the equipment investment and the treatment cost are reduced.

Description

Technical Field

[0001] This utility model relates to a wastewater denitrification and desulfurization treatment device, belonging to the field of wastewater treatment technology. Background Technology

[0002] The common method for removing sulfate from wastewater containing sulfate is chemical precipitation, which involves adding lime or calcium chloride to the wastewater in the reaction tank. The calcium ions introduced into the wastewater react with the sulfate ions to form calcium sulfate precipitate, thus removing the sulfate ions. This chemical precipitation method has the following disadvantages: (1) It requires a large dosage of reagents, resulting in high costs; (2) According to the principle of chemical equilibrium, an excess of calcium ions is needed to facilitate the formation of calcium sulfate precipitate, while unreacted calcium ions require further addition of reagents (such as sodium carbonate) for removal to avoid adverse effects on downstream treatment. The large-scale addition of these reagents increases the conductivity of the wastewater, reducing the recovery rate of the membrane treatment unit; (3) Because calcium sulfate is a slightly soluble compound, a high concentration of sulfate ions is always present in the solution, resulting in a low sulfate removal rate.

[0003] To address the issues of high treatment costs and low sulfate removal rates, existing methods employ biochemical treatment for sulfate-containing wastewater. This treatment device utilizes interconnected reduction reaction tanks, SRB anaerobic reactors, ferrous sulfate reaction tanks, and sedimentation tanks. The wastewater is first reduced, then treated sequentially with carbon sources and sodium bicarbonate to obtain pretreated wastewater. This pretreated wastewater undergoes an anaerobic reaction in the presence of sulfate-reducing bacteria and anaerobic flocculent sludge, converting sulfate into sulfide ions. The ferrous sulfate reaction tank then allows ferric salts to react with sulfide ions, forming ferric sulfide precipitate, thereby improving sulfate removal efficiency.

[0004] However, wastewater not only contains sulfate, but also often contains a certain concentration of nitrate organic matter such as ammonia nitrogen and nitrate nitrogen. Therefore, different equipment is needed to treat denitrification and desulfurization separately, which not only increases investment costs, but also requires a large area. Summary of the Invention

[0005] The purpose of this invention is to provide a wastewater denitrification and desulfurization treatment device that has a high sulfate removal rate and can simultaneously remove nitrates from wastewater, thereby reducing equipment investment and treatment costs.

[0006] The technical solution of this utility model to achieve the above-mentioned objective is: a wastewater denitrification and desulfurization treatment device, characterized in that: it includes an anaerobic reactor, an anoxic reactor, an aerobic reactor and a sedimentation tank connected in sequence;

[0007] The anaerobic reactor includes an anaerobic reaction tank. The lower part of the anaerobic reaction tank is equipped with a water distributor and the upper part is equipped with a three-phase separator. The anaerobic water inlet pipe is connected to the water distributor through the water inlet of the anaerobic reaction tank. The anaerobic reaction tank is equipped with an outlet weir at the upper part of the three-phase separator. The overflow port at the upper part of the anaerobic reaction tank is connected to the outlet weir. The top of the anaerobic reaction tank is equipped with an exhaust pipe.

[0008] The anoxic reactor includes an anoxic reaction tank, which has an inlet at the top, a reflux port at the bottom, and an outlet at the bottom. The anoxic reaction tank is equipped with a stirrer. The overflow port of the anaerobic reaction tank is connected to the inlet of the anoxic reaction tank through an anoxic inlet pipe, and the reflux port is connected to the inlet of the anaerobic reaction tank through a wastewater reflux pipe. A wastewater reflux pump is installed on the wastewater reflux pipe.

[0009] The aerobic reactor includes an aerobic reaction tank, an aerator is provided at the bottom of the aerobic reaction tank, a blower is connected to the aerator outside the aerobic reaction tank, an inlet and an outlet are provided at the top of the aerobic reaction tank, the outlet of the anoxic reaction tank is connected to the inlet of the aerobic reaction tank through an aerobic water inlet pipe, and an aerobic water inlet pump is provided on the aerobic water inlet pipe;

[0010] The sedimentation tank is equipped with a baffle plate. One side of the baffle plate has an inlet area and the other side has a sedimentation area. The bottom of the inlet area and the sedimentation area are connected. The sedimentation area is equipped with an inclined plate. The outlet of the aerobic reaction tank is connected to the inlet area of ​​the sedimentation tank through a sedimentation inlet pipe. The sedimentation tank is equipped with a clear liquid outlet pipe at the top of the inclined plate. The clear liquid outlet pipe is equipped with a clear liquid valve. The clear liquid outlet pipe is also equipped with a clear liquid return pipe in front of the clear liquid valve. The clear liquid return pipe is connected to the anoxic reaction tank. A clear liquid return pump is installed on the clear liquid return pipe. The bottom of the sedimentation tank is equipped with a sewage discharge pipe.

[0011] This invention relates to a wastewater denitrification and desulfurization treatment device that sequentially connects an anaerobic reactor, an anoxic reactor, an aerobic reactor, and a sedimentation tank. In the anaerobic reactor, sulfate ions in the wastewater are reduced to sulfides by sulfate-reducing bacteria. The sulfides are then converted to elemental sulfur through an aerobic reaction. Elemental sulfur is discharged through solid-liquid separation, thus achieving sulfate removal. Meanwhile, ammonia nitrogen in the wastewater is converted to nitrate nitrogen through nitrification, and subsequently reduced to nitrogen gas by denitrifying bacteria in the anoxic reactor. This invention features a wastewater return pipe between the anoxic and anaerobic reactors. A wastewater return pump keeps the anaerobic sludge concentration in the anaerobic reactor stable, resulting in a high sulfate removal rate. Simultaneously, a portion of the clarified liquid after sedimentation is returned to the anoxic reactor for denitrification, thus simultaneously completing denitrification and sulfur oxidation. This reduces equipment investment and treatment costs, as well as the footprint of the equipment. Attached Figure Description

[0012] The embodiments of this utility model will now be described in further detail with reference to the accompanying drawings.

[0013] Figure 1 This is a schematic diagram of the structure of a wastewater denitrification and desulfurization treatment device according to the present invention.

[0014] Wherein: 1—Anaerobic inlet pump, 2—Anaerobic reactor, 2-1—Water distributor, 2-2—Anaerobic reaction tank, 2-3—Three-phase separator, 2-4—Effluent weir; 3—Anoxic inlet pipe, 4—Anoxic reactor, 4-1—Anoxic reaction tank, 4-2—Agitator, 5—Online wastewater quality monitor, 6—Aerobic inlet pump, 7—Aerobic reactor, 7-1—Aerobic reaction tank, 7-2—Aerator, 7-3—Blower, 8—Sedimentation tank, 8-1—Baffle plate, 8-2—Inclined plate, 8-3—Clear liquid valve, 8-4—Sewage valve, 9—Sedimentation inlet pipe, 10—Clear liquid online water quality monitor, 11—Clear liquid return pipe, 12—Clear liquid return pump, 13—Wastewater return pump, 14—Wastewater return pipe, 15—Aerobic inlet pipe. Detailed Implementation

[0015] See Figure 1 As shown, the present invention provides a wastewater denitrification and desulfurization treatment device, comprising an anaerobic reactor 2, an anoxic reactor 4, an aerobic reactor 7, and a sedimentation tank 8 connected in sequence.

[0016] See Figure 1 As shown, the anaerobic reactor 2 of this utility model includes an anaerobic reactor 2-2. The lower part of the anaerobic reactor 2-2 is equipped with a water distributor 2-1, and the upper part is equipped with a three-phase separator 2-3. The water distributor 2-1 can be made of multiple existing water distribution pipes, and each row of water distribution pipes has multiple outlets. The outlets are oriented in the same direction. The anaerobic inlet pipe is connected to the water distributor 2-1 through the inlet of the anaerobic reactor 2-2. An anaerobic inlet pump 1 is installed on the anaerobic inlet pipe, which introduces the wastewater to be treated into the anaerobic reactor 2-2 through the water distributor 2-1. The anaerobic reactor 2-2 is inoculated with sulfate-reducing bacteria sludge. Therefore, nitrogen-containing and sulfate-containing wastewater enters the anaerobic reactor 2-2, where sulfate is reduced to sulfides by sulfate-reducing bacteria. See Figure 1 As shown, the anaerobic reactor 2-2 of this utility model is provided with an outlet weir 2-4 at the upper part of the three-phase separator 2-3. The overflow port at the upper part of the anaerobic reactor 2-2 is connected to the outlet weir 2-4. The top of the anaerobic reactor 2-2 is provided with an exhaust pipe. The liquid phase, solid phase and gas phase are separated by the three-phase separator 2-3. The separated wastewater is discharged through the overflow port. The exhaust pipe is connected to the gas pipe to collect biogas for resource utilization.

[0017] See Figure 1As shown, the anoxic reactor 4 of this utility model includes an anoxic reaction tank 4-1. The anoxic reaction tank 4-1 has an inlet at the top, a reflux port at the bottom, and an outlet at the bottom. A stirrer 4-2 is installed on the anoxic reaction tank 4-1. The overflow port of the anaerobic reaction tank 2-2 is connected to the inlet of the anoxic reaction tank 4-1 via an anoxic inlet pipe 3. The anoxic reaction tank 4-1 is inoculated with denitrifying bacteria sludge. Anaerobic effluent overflows into the anoxic reaction tank 4-1. The nitrates in the wastewater are reduced to nitrogen by the denitrifying bacteria. Under the action of the stirrer 4-2, the degradation of organic matter is accelerated, continuously... Nitrogen gas is discharged. The return port of the anoxic reactor 4-1 is connected to the inlet of the anaerobic reactor 2-2 via the wastewater return pipe 14, allowing part of the sludge-water mixture in the anoxic reactor 4-1 to be returned to the anaerobic reactor 2-2. The sulfate concentration in the sludge-water mixture in the anoxic reactor 4-1 is low. After entering the anaerobic reactor 2-2 and mixing with the anaerobic influent, it not only reduces the sulfate concentration and the anaerobic sludge load, but also returns part of the sludge to the anaerobic reactor, reducing anaerobic sludge loss, maintaining a stable anaerobic sludge concentration, and improving the sulfate removal rate. The anoxic reactor 4-1 of this invention adopts an unsealed structure, or has a vent at the top to discharge nitrogen gas without affecting the subsequent aerobic reaction treatment.

[0018] See Figure 1 As shown, the top of the anoxic reaction tank 4-1 of this utility model is provided with a clear liquid return port, which is connected to the clear liquid return pipe. After the mud and water are separated, the nitrate contained in the clear liquid is returned to the anoxic reaction tank 4-1 to continue the denitrification and denitrification treatment.

[0019] See Figure 1 As shown, the aerobic reactor 7 of this utility model includes an aerobic reaction tank 7-1. An aerator 7-2 is provided at the bottom of the aerobic reaction tank 7-1. A blower 7-3 located outside the aerobic reaction tank 7-1 is connected to the aerator 7-2. The aerator 7-2 continuously jets aeration to provide dissolved oxygen required for the aerobic reaction. The upper part of the aerobic reaction tank 7-1 is provided with an inlet and an outlet. The outlet of the anoxic reaction tank 4-1 is connected to the inlet of the aerobic reaction tank 7-1 through an aerobic inlet pipe 15. An aerobic inlet pump 6 is provided on the aerobic inlet pipe 15. Aerobic bacteria sludge is inoculated inside the aerobic reaction tank 7-1. After the anoxic reaction, the effluent enters the aerobic reaction tank 7-1 through the aerobic inlet pump 6, where the sulfides and ammonia in the wastewater are oxidized by aerobic bacteria into elemental sulfur and nitrate.

[0020] See Figure 1As shown, the sedimentation tank 8 of this utility model is equipped with a baffle 8-1. One side of the baffle 8-1 has an inlet area, and the other side has a sedimentation area. The bottom of the inlet area and the sedimentation area are connected. An inclined plate 8-2 is provided in the sedimentation area, and the area above the inclined plate 8-2 is the clear liquid area. The outlet of the aerobic reaction tank 7-1 is connected to the inlet area of ​​the sedimentation tank 8 through a sedimentation inlet pipe 9. A clear liquid outlet pipe is located above the inclined plate 8-2 in the sedimentation tank 8. A clear liquid valve 8-3 is installed on the clear liquid outlet pipe, and a connecting pipe is located in front of the clear liquid valve. A clear liquid return pipe 11 is connected to the anoxic reaction tank 4-1. A clear liquid return pump 12 is installed on the clear liquid return pipe 11. A drain pipe is provided at the bottom of the sedimentation tank 8. The effluent from the aerobic reaction tank 7-1 overflows into the sedimentation tank 8, where the mud-water mixture is separated by sedimentation. The sulfur-containing sludge is discharged from the bottom of the sedimentation tank 8 through the drain pipe. The upper part of the clear liquid flows into the subsequent treatment unit, while the other part flows into the anoxic reaction tank 4-1 through the clear liquid return pipe 11 to treat the nitrates in the clear liquid. After mud-water separation, the clear liquid has a low sulfide concentration. After entering the anoxic reaction tank 4-1, it can reduce the sulfide concentration in the treatment system, which not only reduces the inhibition of microorganisms by sulfides, but also returns the nitrates to the anoxic reaction tank 4-1 for denitrification and denitrification, while simultaneously removing sulfate, ammonia nitrogen, nitrate nitrogen, and other organic matter from the wastewater. See Figure 1 As shown, the bottom of the sedimentation tank 8 of this utility model is V-shaped, and a sewage pipe is provided at the bottom of the tank, with a sewage valve 8-4 on the sewage pipe.

[0021] See Figure 1 As shown, an online wastewater quality monitor 5 for monitoring sulfate concentration in wastewater is installed at the lower part of the anoxic reactor 4-1 of this invention. The online wastewater quality monitor 5 communicates with a PCL controller, which controls the start and stop of the wastewater return pump 13. The online wastewater quality monitor 5 is a conventional water quality monitor. When the sulfate concentration in the wastewater exceeds a set value, the online wastewater quality monitor 5 sends a communication signal. After receiving the communication signal, the PCL controller controls the start of the wastewater return pump 13, returning the sludge-water mixture at the bottom of the anoxic reactor 4-1 to the anaerobic reactor 2-2 to continue removing sulfate from the wastewater.

[0022] See Figure 1As shown, the sedimentation tank 8 of this invention is equipped with an online water quality monitor 10 on the effluent side of the clarified liquid for monitoring the nitrate nitrogen concentration in the clarified liquid. The online water quality monitor 10 communicates with the PCL controller, which controls the frequency of the clarified liquid return pump 12 and the opening degree of the clarified liquid valve 8-3 to return a portion of the clarified liquid to the anoxic reaction tank 4-1. After the online water quality monitor 10 detects that the nitrate nitrogen concentration in the clarified liquid is within different set ranges, it sends a communication signal. Upon receiving the communication signal from the online wastewater monitoring system, the PCL controller controls the frequency of the wastewater return pump 13 and the opening degree of the clarified liquid valve 8-3 to adjust the return ratio.

[0023] See Figure 1 As shown, the wastewater denitrification and desulfurization treatment device of this utility model is used to treat wastewater containing sulfate, ammonia nitrogen, nitrate nitrogen and other nitrate organic matter.

[0024] (1) Turn on the anaerobic inlet pump 1. The wastewater is fed into the water distributor 2-1 at the bottom of the anaerobic reactor 2-2 through the anaerobic inlet pipe. The wastewater is fed into the anaerobic reactor 2-2 through the water distributor 2-1 and reacts with the sulfate-reducing bacteria sludge. At this time, the temperature of the wastewater is controlled at 25-35℃ and the pH is controlled at 6.5-8. If necessary, a carbon source can be added to control the carbon-sulfur ratio (C / S) of the wastewater between 1.5 and 5 and the hydraulic retention time between 12-48h. The sulfate in the wastewater is reduced to sulfide and separated by the three-phase separator 2-3. The wastewater enters the effluent weir 2-4 and the biogas is collected through the exhaust pipe and gas pipe.

[0025] (2) The effluent from anaerobic reactor 2-2 overflows into anoxic reactor 4-1. Agitator 4-2 is turned on, and the dissolved oxygen inside anoxic reactor 4-1 is controlled to be ≤0.5mg / L, the carbon-to-nitrogen ratio (C / N) is between 3 and 5, and the hydraulic retention time is 2-10h. Nitrate nitrogen in the anaerobic effluent is reduced to nitrogen gas by denitrifying bacteria. When the online wastewater quality monitor 5 detects that the sulfate concentration is higher than the set concentration, the online wastewater quality monitor 5 communicates with the PCL controller. The PCL controller controls the wastewater return pump 13 to turn on, so that the mud-water mixture at the bottom of anoxic reactor 4-1 is returned to anaerobic reactor 2-2 through wastewater return pipe 14 to continue removing sulfate.

[0026] (3) The effluent from the lower part of the anoxic reaction tank 4-1 enters the aerobic reaction tank 7-1 through the aerobic inlet pump 6 and the aerobic inlet pipe 15. The blower 7-3 works and the aerator 7-2 continuously jets aeration to control the dissolved oxygen in the aerobic reaction tank 7-1 between 2-4 mg / L, the temperature between 25-35℃, the pH between 6.5-8, and the hydraulic retention time between 4-12h. The wastewater reacts with the aerobic bacteria sludge, and ammonia nitrogen is oxidized to nitrate nitrogen. At the same time, sulfides are oxidized to elemental sulfur.

[0027] (4) The effluent from the aerobic reaction tank 7-1 overflows into the sedimentation tank 8 through the sedimentation inlet pipe 9. The mud-water mixture is separated after sedimentation. The sludge containing sulfur is discharged through the bottom of the sedimentation tank 8. Part of the clear liquid is discharged for subsequent treatment, and the other part flows into the anoxic reaction tank 4-1 through the clear liquid return pump 12 and the clear liquid return pipe 11 to treat the nitrate nitrogen in the wastewater. When the clear liquid online water quality monitor 10 detects different nitrate nitrogen concentrations in the effluent within the set range, the clear liquid online water quality monitor 10 communicates with the PCL controller to adjust the frequency of the clear liquid return pump 12 and the opening and closing of the clear liquid valve to adjust the clear liquid return ratio.

Claims

1. A wastewater denitrification and desulfurization treatment device, characterized in that: It includes an anaerobic reactor (2), an anoxic reactor (4), an aerobic reactor (7), and a sedimentation tank (8) connected in sequence. The anaerobic reactor (2) includes an anaerobic reactor (2-2). The lower part of the anaerobic reactor (2-2) is equipped with a water distributor (2-1) and the upper part is equipped with a three-phase separator (2-3). The anaerobic inlet pipe is connected to the water distributor (2-1) through the inlet of the anaerobic reactor (2-2). The anaerobic reactor (2-2) is equipped with an outlet weir (2-4) above the three-phase separator (2-3). The overflow port at the top of the anaerobic reactor (2-2) is connected to the outlet weir (2-4). The top of the anaerobic reactor (2-2) is equipped with an exhaust pipe. The anoxic reactor (4) includes an anoxic reaction tank (4-1), which has an inlet at the top, a reflux port at the bottom, and an outlet at the bottom. The anoxic reaction tank (4-1) is equipped with a stirrer (4-2). The overflow port of the anaerobic reaction tank (2-2) is connected to the inlet of the anoxic reaction tank (4-1) through an anoxic water inlet pipe (3), and the reflux port is connected to the inlet of the anaerobic reaction tank (2-2) through a wastewater reflux pipe (14). A wastewater reflux pump (13) is installed on the wastewater reflux pipe (14). The aerobic reactor (7) includes an aerobic reaction tank (7-1), an aerator (7-2) is provided at the bottom of the aerobic reaction tank (7-1), a blower (7-3) located outside the aerobic reaction tank (7-1) is connected to the aerator (7-2), the aerobic reaction tank (7-1) is provided with an inlet and an outlet at the top, the outlet of the anoxic reaction tank (4-1) is connected to the inlet of the aerobic reaction tank (7-1) through an aerobic water inlet pipe (15), and an aerobic water inlet pump (6) is provided on the aerobic water inlet pipe (15). The sedimentation tank (8) is equipped with a baffle (8-1). The baffle (8-1) has an inlet area on one side and a sedimentation area on the other side. The bottom of the inlet area and the sedimentation area are connected. The sedimentation area is equipped with an inclined plate (8-2). The outlet of the aerobic reaction tank (7-1) is connected to the inlet area of ​​the sedimentation tank (8) through the sedimentation inlet pipe (9). The sedimentation tank (8) is equipped with a clear liquid outlet pipe at the top of the inclined plate (8-2). A clear liquid valve (8-3) is provided on the clear liquid outlet pipe. A clear liquid return pipe (11) is also provided in front of the clear liquid valve (8-3). The clear liquid return pipe (11) is connected to the anoxic reaction tank (4-1). A clear liquid return pump (12) is installed on the clear liquid return pipe (11). The bottom of the sedimentation tank (8) is equipped with a sewage pipe.

2. The device for treating wastewater to remove nitrogen and sulfur according to claim 1, characterized in that: The lower part of the anoxic reaction tank (4-1) is equipped with an online wastewater quality monitor (5) for monitoring the sulfate concentration in the wastewater. The online wastewater quality monitor (5) communicates with the PCL controller, which is used to control the opening and closing of the wastewater return pump (13).

3. The wastewater denitrification and desulfurization treatment device according to claim 1, characterized in that: The sedimentation tank (8) is equipped with an online water quality monitor (10) for monitoring the nitrate concentration in the clear liquid on the side of the clear liquid outlet. The online water quality monitor (10) communicates with the PCL controller, which is used to control the frequency of the clear liquid return pump (12) and the opening degree of the clear liquid valve (8-3).

4. The wastewater denitrification and desulfurization treatment device according to claim 1, characterized in that: The top of the anoxic reaction vessel (4-1) is provided with a clear liquid return port, which is connected to the clear liquid return pipe (11).

5. The wastewater denitrification and desulfurization treatment device according to claim 1, characterized in that: An anaerobic inlet pump (1) is installed on the anaerobic inlet pipe.

6. The wastewater denitrification and desulfurization treatment device according to claim 1, characterized in that: The bottom of the sedimentation tank (8) is V-shaped, and a drain pipe is provided at the bottom of the tank. A drain valve (8-4) is provided on the drain pipe.

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