Sewage defluorination device for enhancing coagulating sedimentation

Abstract

The sewage defluorination device comprises a first-stage coagulation reaction tank, a second-stage coagulation reaction tank, a third-stage coagulation reaction tank, a water distribution area and an inclined tube sedimentation tank which are sequentially communicated in series through reserved holes, a fluorine removal agent feeding pipe and a liquid caustic soda feeding pipe are arranged in the first-stage coagulation reaction tank, and a PAM feeding pipe is arranged in the third-stage coagulation reaction tank; a sludge return pipe is connected between the bottom of the inclined tube sedimentation tank and the top of the second-stage coagulation reaction tank, and a residual sludge pipe is arranged at the bottom of the inclined tube sedimentation tank; and a fluorine ion meter and a pH meter are mounted at the top of the tail end of the inclined tube sedimentation tank or the front end of the first-stage coagulation reaction tank. The utility model provides a high-efficiency coagulative precipitation tank combining three-stage coagulation reaction with inclined tube precipitation, which is suitable for removing fluorine in sewage. The fluorine removal effect is further improved through the design of pool type structure, automatic adjustment of the dosage, sludge backflow and the like, the effects of reducing the medicine consumption and optimizing the effluent quality are achieved, the occupied area of facilities is greatly reduced, and the engineering investment is reduced.

Description

Technical Field

[0001] The utility model relates to a device for defluorinating sewage, belonging to the technical field of sewage treatment. Background Art

[0002] Fluoride-containing wastewater must be properly treated before discharge, otherwise it will cause great harm to the natural environment and human health. Excessive intake of fluoride will cause damage to the human body, such as suffering from skeletal fluorosis and dental fluorosis.

[0003] Currently, the defluorination technologies widely used in engineering mainly include: chemical precipitation method, coagulation precipitation method, adsorption method, electrochemistry method and ion exchange resin; and composite defluorination technologies that combine the above several processes.

[0004] Coagulation precipitation method for defluorination is the most widely used defluorination process at present. The coagulation precipitation method mainly adds aluminum salts and iron salts coagulants to fluoride-containing wastewater, makes them hydrolyze in water, and then destabilizes with fluoride ions through methods such as net trapping, sweeping, adsorption bridging and electric neutralization, and forms flocs to settle, and then defluorinates through solid-liquid separation. Compared with other process technologies, in the treatment of low-concentration fluoride-containing wastewater, the coagulation precipitation method has a lower cost.

[0005] However, the existing coagulation precipitation process has a high project cost, and the defluorination effect also needs to be further improved. Summary of the Invention

[0006] Aiming at the deficiencies of the existing coagulation precipitation defluorination technology, the utility model provides a sewage defluorination device with low operating cost and good defluorination effect by enhanced coagulation precipitation.

[0007] The sewage defluorination device with enhanced coagulation precipitation of the utility model adopts the following technical solutions:

[0008] The device includes a first-stage coagulation reaction tank, a second-stage coagulation reaction tank, a third-stage coagulation reaction tank, a water distribution area and an inclined tube sedimentation tank connected in series and communicated through a reserved hole in sequence; an agent adding pipe for defluorination agent and a liquid caustic soda adding pipe are arranged in the first-stage coagulation reaction tank, and a PAM adding pipe is arranged in the third-stage coagulation reaction tank; a sludge return pipe is connected between the bottom of the inclined tube sedimentation tank and the top of the second-stage coagulation reaction tank, and a surplus sludge pipe is arranged at the bottom of the inclined tube sedimentation tank; a fluoride ion meter and a pH meter are installed at the top end of the inclined tube sedimentation tank or at the front end of the first-stage coagulation reaction tank.

[0009] The agent adding pipe for defluorination agent is connected to a defluorination agent storage tank through a defluorination agent adding pump. The liquid caustic soda adding pipe is connected to a liquid caustic soda storage tank through a liquid caustic soda adding pump. The PAM adding pipe is connected to a PAM storage tank through a PAM adding pump. The defluorination agent adding pump, the liquid caustic soda adding pump and the PAM adding pump are all variable-frequency metering pumps.

[0010] The inclined tube sedimentation tank is divided into an upper clear water area, a middle sedimentation area, and a bottom sludge area. A perforated collecting trough is installed in the upper clear water area, inclined tubes are installed in the middle sedimentation area, and a sludge scraper is installed in the bottom sludge area. Two groups of the inclined tube sedimentation tanks are arranged in parallel. The middle and upper parts of the two groups of inclined tube sedimentation tanks are separated, and the bottoms are connected.

[0011] A sludge return pump is connected to the sludge return pipe, and a surplus sludge pump is connected to the surplus sludge pipe. Both the sludge return pump and the surplus sludge pump are driven by variable frequency motors.

[0012] A magnetic powder dosing and recycling machine is installed at the top of the second-stage coagulation reaction tank.

[0013] The fluoride ion meter, pH meter, and each chemical dosing pump are all connected to the control unit.

[0014] The fluoride-containing sewage first enters the first-stage coagulation reaction tank, and a defluorinating agent is added through the defluorinating agent dosing pipe. The defluorinating agent undergoes a polymerization reaction with the fluoride ions in the water and then enters the second-stage coagulation reaction tank for polymerization reaction. Then it enters the third-stage coagulation reaction tank, and PAM is added through the PAM dosing pipe to undergo a flocculation reaction to form large sludge flocs. The sewage enters the inclined tube sedimentation tank from the third-stage coagulation reaction tank through the water distribution area. The sludge flocs precipitate, and the mud and water are separated. The fluoride ions enter the sludge, and the sewage with fluoride ions removed enters the upper layer of the inclined tube sedimentation tank. A part of the sludge at the bottom of the inclined tube sedimentation tank is transported to the sludge tank by the surplus sludge pump. The sludge at the bottom of the inclined tube sedimentation tank is transported to the second-stage coagulation reaction tank to improve the utilization rate of the chemicals. The fluoride ion meter automatically detects the fluoride ion concentration and pH value of the upper-layer effluent of the inclined tube sedimentation tank, and the control unit is based on the set chemical dosing mode.

[0015] The utility model is applicable to fluoride removal from sewage. It mainly includes an efficient coagulation sedimentation tank composed of three-stage coagulation reaction tanks and an inclined tube sedimentation tank, and is equipped with an automatic detection system for fluoride ions and pH and an automatic chemical dosing control system, realizing automatic adjustment of the chemical dosing amount. The supporting sludge return system improves the utilization rate of the chemicals. Through designs such as the tank type structure, automatic adjustment of the chemical dosing amount, and sludge return, the coagulation sedimentation fluoride removal effect can be significantly enhanced, achieving the effects of reducing chemical consumption and optimizing the effluent quality. Compared with the conventional technology, it can also significantly reduce the floor area of the facilities and reduce the project investment. Description of the Drawings

[0016] Figure 1 is the schematic plan view of the sewage fluoride removal device with enhanced coagulation sedimentation of the utility model.

[0017] Figure 2 is Figure 1 the sectional view taken along A-A in

[0018] In the figure: 1. First-stage coagulation reaction tank; 2. Second-stage coagulation reaction tank; 3. Third-stage coagulation reaction tank; 4. Water distribution area; 5. Inclined tube sedimentation tank; 6. Defluorinating agent dosing pump; 7. Liquid caustic soda dosing pump; 8. PAM dosing pump; 9. Fluoride ion meter; 10. pH meter; 11. Control unit; 12. Reserved hole; 13. Sludge return pump; 14. Surplus sludge pump; 15. Defluorinating agent dosing pipe; 16. Liquid caustic soda dosing pipe; 17. PAM dosing pipe; 18. PAM storage tank; 19. Liquid caustic soda storage tank; 20. Defluorinating agent storage tank; 21. Sludge return pipe; 22. Surplus sludge pipe; 23. Scraper; 24. Water collecting trough; 25. Inclined tube. Detailed implementation mode

[0019] As Figure 1 and Figure 2 shown, the sewage defluorination device for enhanced coagulation sedimentation of the present utility model includes a first-stage coagulation reaction tank 1, a second-stage coagulation reaction tank 2, a third-stage coagulation reaction tank 3, a water distribution area 4 and an inclined tube sedimentation tank 5 which are connected in series and communicated in sequence through a reserved hole. A defluorinating agent dosing pipe 15 and a liquid caustic soda dosing pipe 16 are arranged in the first-stage coagulation reaction tank 1. The defluorinating agent dosing pipe 15 is connected to a defluorinating agent storage tank 20 through a defluorinating agent dosing pump 6, and the liquid caustic soda dosing pipe 16 is connected to a liquid caustic soda storage tank 19 through a liquid caustic soda dosing pump 7. A PAM dosing pipe 17 is arranged in the third-stage coagulation reaction tank 3, and the PAM dosing pipe 17 is connected to a PAM storage tank 18 through a PAM dosing pump 8. The defluorinating agent dosing pump 6, the liquid caustic soda dosing pump 7 and the PAM dosing pump 8 are all variable-frequency metering pumps. The PAM added through the PAM dosing pump 8 in the third-stage coagulation reaction tank 3 is anionic.

[0020] The inclined tube sedimentation tank 5 is divided into an upper clear water area, a middle sedimentation area and a bottom sludge area. There are two parallel groups of inclined tube sedimentation tanks 5. Refer to Figure 2 , the middle and upper parts of the two groups of inclined tube sedimentation tanks are separated, and the bottoms are connected; a stainless steel perforated water collecting trough 24 is installed in the upper clear water area, inclined tubes 25 are installed in the middle sedimentation area, and a scraper 23 is installed in the bottom sludge area.

[0021] A sludge return pipe 21 is connected between the bottom of the inclined tube sedimentation tank 5 and the top of the second-stage coagulation reaction tank 2. Refer to Figure 1 , a sludge return pump 13 is connected to the sludge return pipe 21, and the sludge flow direction is from the bottom of the inclined tube sedimentation tank 5 to the top of the second-stage coagulation reaction tank 2. The bottom of the inclined tube sedimentation tank 5 is connected to a sludge disposal unit through a surplus sludge pipe 22, and a surplus sludge pump 14 is connected to the surplus sludge pipe 22. Both the sludge return pump 13 and the surplus sludge pump 14 are driven by variable-frequency motors. A magnetic powder dosing and recovery machine can be installed at the top of the second-stage coagulation reaction tank 2.

[0022] At the top of the end of the inclined tube sedimentation tank 5, a fluoride ion meter 9 and a pH meter 10 are installed. The fluoride ion meter 9, the pH meter 10, the defluorinating agent dosing pump 6 and the liquid caustic soda dosing pump 7 are all connected to the control unit 11 through signal lines. The fluoride ion meter 9 is connected to the control unit 11 through a signal line. The control unit 11 processes the received fluoride ion concentration signal and automatically adjusts the operating frequency of the defluorinating agent dosing pump 6 according to the set dosing strategy. The pH meter 10 is connected to the control unit 11 through a signal line. The control unit 11 processes the received pH signal and automatically adjusts the operating frequency of the liquid caustic soda dosing pump 7 according to the set dosing strategy. The control unit 11 can be a single-chip microcomputer, a PLC, etc.

[0023] The fluoride ion meter 9 and the pH meter 10 can also be installed at the front end of the first-stage coagulation reaction tank 1, and there are appropriate differences in the dosing strategies of the control unit 11.

[0024] The specific process of defluorinating sewage by the above device is described as follows.

[0025] (1) Coagulation of sewage

[0026] The fluorine-containing sewage enters the first-stage coagulation reaction tank 1, and the defluorinating agent is added through the defluorinating agent dosing pump 6. The defluorinating agent polymerizes with the fluoride ions in the water. The hydraulic retention time of the first-stage coagulation reaction tank 1 is not less than 5 minutes. The polymerization reaction continues in the second-stage coagulation reaction tank 2. The sewage enters the third-stage coagulation reaction tank 3, and PAM is added through the PAM dosing pump 8 to carry out a flocculation reaction to form large sludge flocs.

[0027] (2) Sedimentation of sewage

[0028] The sewage enters the inclined tube sedimentation tank 5 from the third-stage coagulation reaction tank 3 through the water distribution area 4. The sludge flocs settle and the mud and water are separated. The fluoride ions enter the sludge, and the fluoride ions in the upper layer of the inclined tube sedimentation tank 5 are removed. A part of the sludge at the bottom of the inclined tube sedimentation tank 5 is transported to the sludge tank through the surplus sludge pump 14 and further undergoes sludge dewatering treatment.

[0029] (3) Feedback regulation of dosing amount

[0030] The fluoride ion meter 9 automatically detects the fluoride ion concentration in the upper layer of the inclined tube sedimentation tank 5 and transmits the fluoride ion concentration signal to the control unit 11. The control unit 11 automatically adjusts the operating frequency of the defluorinating agent dosing pump 6 according to the set dosing amount mode, and then adjusts the defluorinating agent dosing amount.

[0031] The pH meter 10 automatically detects the pH value of the upper layer of the inclined tube sedimentation tank 5 and transmits the pH value signal to the control unit 11. The control unit 11 automatically adjusts the operating frequency of the liquid caustic soda dosing pump 7 according to the set dosing amount mode, and then adjusts the liquid caustic soda dosing amount. Keep the pH greater than 6.5.

[0032] (4) Sludge return

[0033] The sludge return pump 13 transports part of the sludge at the bottom of the inclined tube sedimentation tank 5 to the second-stage coagulation reaction tank 2, which can improve the utilization rate of the chemical agent. The sludge return flow can be adjusted by adjusting the operating frequency of the sludge return pump 13 according to the operating conditions.

Claims

1. A sewage defluorination device for enhanced coagulation sedimentation, characterized in that, It includes a first-stage coagulation reaction tank, a second-stage coagulation reaction tank, a third-stage coagulation reaction tank, a water distribution area and an inclined tube sedimentation tank that are connected in series through reserved holes in sequence; an anti-fluoride agent dosing pipe and a liquid caustic soda dosing pipe are arranged in the first-stage coagulation reaction tank, and a PAM dosing pipe is arranged in the third-stage coagulation reaction tank; a sludge return pipe is connected between the bottom of the inclined tube sedimentation tank and the top of the second-stage coagulation reaction tank, and a surplus sludge pipe is arranged at the bottom of the inclined tube sedimentation tank; a fluoride ion meter and a pH meter are installed at the top end of the inclined tube sedimentation tank or at the front end of the first-stage coagulation reaction tank.

2. The fluorine removal device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, The anti-fluoride agent dosing pipe is connected to an anti-fluoride agent storage tank through an anti-fluoride agent dosing pump, the liquid caustic soda dosing pipe is connected to a liquid caustic soda storage tank through a liquid caustic soda dosing pump, and the PAM dosing pipe is connected to a PAM storage tank through a PAM dosing pump.

3. The defluorination device for sewage by enhanced coagulation sedimentation according to claim 2, characterized in that, The anti-fluoride agent dosing pump, the liquid caustic soda dosing pump and the PAM dosing pump are all variable-frequency metering pumps.

4. The defluorination device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, The inclined tube sedimentation tank is divided into an upper clear water area, a middle sedimentation area and a bottom sludge area. A perforated water collecting trough is installed in the upper clear water area, inclined tubes are installed in the middle sedimentation area, and a sludge scraper is installed in the bottom sludge area.

5. The fluorine removal device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, Two groups of parallel inclined tube sedimentation tanks are provided. The middle parts and upper parts of the two groups of inclined tube sedimentation tanks are separated, and the bottoms are connected.

6. The defluorination device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, A sludge return pump is connected to the sludge return pipe, and a surplus sludge pump is connected to the surplus sludge pipe.

7. The defluorination device for sewage by enhanced coagulation sedimentation according to claim 6, characterized in that, Both the sludge return pump and the surplus sludge pump are driven by variable-frequency motors.

8. The fluorine removal device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, A magnetic powder dosing and recycling machine is installed at the top of the second-stage coagulation reaction tank.

9. The defluorination device for sewage by enhanced coagulation sedimentation according to claim 1, characterized in that, The fluoride ion meter, the pH meter and each dosing pump are all connected to a control unit.

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