Double coagulant high pH hardness removal and turbidity reduction system for circulating water and blowdown water

Abstract

The utility model relates to sewage recovery technical field, concretely is a kind of circulating water sewage double coagulant high pH hardening and turbidity reduction system, including adjusting pool, clean water pool, ceramic membrane filter, adjusting pool is connected with two integrated clarifiers, one integrated clarifier is connected with ferric chloride dosing pump and alkali pump, another integrated clarifier is connected with first PAC dosing pump and alkali pump, the water inlet of clean water pool is connected with the water outlet of two integrated clarifiers, hydrochloric acid pump is connected between clean water pool and integrated clarifier, ceramic membrane filter is connected with the water outlet of clean water pool, and ceramic membrane filter is connected with second PAC dosing pump.The utility model reduces the hardness of water by adding sodium hydroxide, then adds ferric chloride to reduce turbidity, and polyaluminium chloride is added in effluent to prolong the water production cycle of ceramic membrane filter, and the treated circulating water and reverse osmosis sewage can be recycled, reducing water waste and saving the use of fresh water.

Description

Technical Field

[0001] This utility model relates to the field of wastewater recycling technology, specifically a high-pH hardening and turbidity reduction system for circulating water wastewater discharge using dual coagulants. Background Technology

[0002] If the circulating water and reverse osmosis concentrate from a power plant are highly polluting, they need to be treated before being discharged.

[0003] In related technologies, circulating water discharge and reverse osmosis concentrate are generally treated by using lime tanks to reduce water hardness, and then entering sedimentation tanks where coagulants are added to reduce turbidity. Alternatively, ordinary sedimentation tanks and filters are used to add sodium hydroxide and PAC (polyaluminum chloride) for hardness removal and turbidity reduction.

[0004] However, lime ponds require frequent lime replacement, which generates a large amount of solid waste that also needs to be treated. Since polyaluminum chloride is suitable for pH ranges of 5.0-9.0, its coagulation effect in alkaline water is poor, making it impossible to stably guarantee the turbidity of the effluent, and the discharged water is difficult to reuse. Utility Model Content

[0005] The purpose of this invention is to provide a high-pH hardening and turbidity reduction system for circulating water wastewater discharge using dual coagulants, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: A circulating water wastewater discharge system with dual coagulants and high pH for hardening and turbidity reduction includes an equalization tank, a clear water tank, and a ceramic membrane filter. The equalization tank is connected to two integrated clarifiers. One integrated clarifier is connected to the ferric chloride dosing pump and the alkali dosing pump, and the other integrated clarifier is connected to the first PAC dosing pump and the alkali dosing pump. This avoids the limitations of using a single coagulant to treat complex water quality and allows for treatment according to water quality, making it highly adaptable. The inlet of the clear water tank is connected to the outlet of the two integrated clarifiers. A hydrochloric acid pump is connected between the clear water tank and the integrated clarifiers, which can flexibly adjust the pH value of the water. This ensures the high pH reaction conditions for hard removal during the clarification stage and avoids problems such as scaling and corrosion on the membrane surface of the ceramic membrane filter due to the high pH environment, thus extending the service life of the membrane element. The ceramic membrane filter is connected to the outlet of the clear water tank, and a second PAC dosing pump is connected between the ceramic membrane filter and the clear water tank to improve the ceramic membrane's retention efficiency for suspended solids and colloids.

[0007] Furthermore, the integrated clarifier is equipped with a sludge scraper in the center, which ensures that the sediment falls to the bottom of the integrated clarifier and the sludge scraping effect is stable. The inlet area of ​​the integrated clarifier is equipped with a mixer to promote the rapid mixing of coagulant, alkali agent and sewage, creating reaction conditions for hardness ion precipitation and colloidal destabilization.

[0008] Furthermore, the outlet of the equalization tank is connected to a backup discharge pipe, so that in an emergency, the sewage can be discharged into the municipal pipe network. The inlet of the equalization tank is connected to several inlet pipes, which can accept sewage from different sources and facilitate centralized sewage treatment.

[0009] Furthermore, a heat exchanger is installed between the hydrochloric acid pump and the clear water tank, which can precisely control the water temperature when hydrochloric acid is added, avoid local pH fluctuations caused by uneven mixing of hydrochloric acid and water in low-temperature environments, and ensure the accuracy of pH adjustment.

[0010] Furthermore, the sludge outlets of the two integrated clarifiers are connected to sludge tanks, enabling unified collection, concentration, and subsequent disposal of sludge, avoiding secondary pollution caused by indiscriminate sludge discharge. The sludge outlets are also connected to industrial water inlet pipes, allowing some water that does not require hardening or turbidity reduction to be discharged together with the sludge, thus meeting the needs of various water treatment requirements.

[0011] Furthermore, the ceramic membrane filter is connected to a reverse osmosis filter, and the dual membrane filtration significantly improves the quality of the effluent, meeting higher standards for reuse. The outlet of the reverse osmosis filter is connected to a circulating water tank and a freshwater tank to realize water recycling.

[0012] Compared with the prior art, the beneficial effects of this utility model are: (1) The water hardness is reduced by adding sodium hydroxide, and turbidity is reduced by adding ferric chloride. Polyaluminum chloride is added to the effluent to extend the water production cycle of the ceramic membrane filter. The circulating water and reverse osmosis wastewater can be recycled after treatment, reducing water waste and saving the amount of fresh water used.

[0013] (2) Two integrated clarifiers are added with different agents. Ferric chloride and PAC are used as coagulants respectively, and alkali pumps are added to adapt to the circulating water discharge of different water quality characteristics. The hardness removal and turbidity reduction effects under high pH conditions are specifically enhanced, avoiding the limitations of single coagulant in the treatment of complex water quality. Attached Figure Description

[0014] Figure 1 This is a flow chart of the wastewater treatment process of this utility model; Figure 2 This is an enlarged view of the regulating tank portion of this utility model; Figure 3 This is an enlarged view of the integrated clarifier part of this utility model; Figure 4 This is an enlarged view of the clear water tank part of this utility model.

[0015] In the diagram: 1. Equalization tank; 2. First elbow; 3. First lift pump; 4. Integrated clarifier; 5. Mixer; 6. Sludge scraper; 7. Second lift pump; 8. Third lift pump; 9. Clear water tank; 10. Second elbow; 11. Fourth lift pump; 12. Inlet pipe; 13. Pipe blind flange; 14. Temperature indicator; 15. Manual valve; 16. PI-PT instrument; 17. Pipe filter; 18. TI-TT instrument; 19. 20. NTU instrument; 21. FI-FT instrument; 22. Backup discharge pipe; 23. Automatic valve; 24. pH instrument; 25. Industrial water inlet pipe; 26. Sludge tank; 27. Second PAC dosing pump; 28. Ceramic membrane filter; 29. ​​Reverse osmosis filter; 30. Circulating water tank; 31. Fresh water tank; 32. Hydrochloric acid pump; 33. Heat exchanger; 34. Ferric chloride dosing pump; 35. Alkali dosing pump; 36. First PAC dosing pump. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example: Please see Figure 1-4 This utility model provides a technical solution: A circulating water wastewater discharge system with dual coagulants, high pH, ​​hardness removal, and turbidity reduction includes an equalization tank 1, a clear water tank 9, and a ceramic membrane filter 27.

[0018] The equalization tank 1 is connected to two integrated clarifiers 4. The equalization tank 1 is equipped with three first elbows 2 and three first booster pumps 3. The outlet pipe of the first booster pump 3 is equipped with a pipeline filter 17, a TI-TT instrument 18, an NTU instrument 19, and a FI-FT instrument 20. The TI-TT instrument 18 is a combination instrument for temperature indication and temperature transmission, the NTU instrument is a turbidity analyzer, and the FI-FT instrument 20 is a combination instrument for flow indication and flow transmission.

[0019] One integrated clarifier 4 is connected to a ferric chloride dosing pump 33 and an alkali dosing pump 34, and the other integrated clarifier 4 is connected to a first PAC dosing pump 35 and an alkali dosing pump 34. Ferric chloride and PAC are used respectively for water quality, and the wastewater is treated in the two integrated clarifiers 4 to avoid problems caused by the confusion of chemical use.

[0020] The inlet of the clear water tank 9 is connected to the outlet of the two integrated clarifiers 4. The outlet of the integrated clarifier 4 is equipped with an NTU instrument 19 and a pH instrument 23 to facilitate the viewing of turbidity and pH value and to facilitate the control of the amount of hydrochloric acid added. A hydrochloric acid pump 31 is connected between the clear water tank 9 and the integrated clarifier 4 to add hydrochloric acid to adjust the pH of the water to neutral and ensure that the pH of the water is qualified.

[0021] The ceramic membrane filter 27 is connected to the outlet of the clear water tank 9. The outlet of the clear water tank 9 is equipped with three second elbows 10 and three fourth lift pumps 11. The outlet pipe of the fourth lift pump 11 is equipped with a manual valve 15, a temperature indicator 14, a pipeline filter 17, and a PI-PT instrument 16 (a combination instrument of pressure indication and pressure transmission). Multiple ceramic membrane filters 27 are installed to increase the water filtration capacity. A second PAC dosing pump 26 is connected between the ceramic membrane filter 27 and the clear water tank 9 to make small flocs clump together into large flocs, which is beneficial for the ceramic membrane filter 27 to better intercept flocs and other impurities.

[0022] In this embodiment, as Figure 3 As shown, a sludge scraper 6 is installed in the center of the integrated clarifier 4. The sludge scraper 6 efficiently collects and removes the sludge at the bottom, ensuring the continuous and stable operation of the integrated clarifier 4. A mixer 5 is installed in the water inlet area of ​​the integrated clarifier 4, which can fully mix the added chemicals with the sewage to remove suspended solids from the sewage.

[0023] In this embodiment, as Figure 1 and Figure 2 As shown, the outlet of the equalization tank 1 is connected to a backup discharge pipe 21. In case of an accident, sewage is discharged from the backup discharge pipe 21 to the municipal sewage. The backup discharge pipe 21 is equipped with a pipe blind flange 13, which cuts off the flow of sewage in the backup discharge pipe 21. The inlet of the equalization tank 1 is connected to several inlet pipes 12. The inlet pipes 12 are equipped with temperature indicators 14 and manual valves 15. The inlet pipes 12 receive water from the unit's circulating water system and also receive reverse osmosis concentrate from the boiler makeup water treatment system.

[0024] In this embodiment, as Figure 4 As shown, a heat exchanger 32 is installed between the hydrochloric acid pump 31 and the clear water tank 9. The temperature of the hydrochloric acid is regulated by the heat exchanger 32. A pH instrument 23 is installed in this pipeline to detect the pH value of the water and check whether the water is neutral.

[0025] In this embodiment, as Figure 1 and Figure 3As shown, the sludge outlets of the two integrated clarifiers 4 are connected to sludge tanks 25. The inlet area and sludge discharge pipe of the integrated clarifier 4 share the same sludge discharge area. Two sets of sludge discharge pipes are set up, and the second lift pump 7 and the third lift pump 8 are used to pump out the sludge water. At the same time, an automatic valve 22, an FI-FT instrument 20, a temperature indicator 14, and a pressure transmitter (PT) are set on the sludge discharge pipes to realize the detection of sludge water. The sludge outlet is also connected to an industrial water inlet pipe 24. Some other water that does not require hardness removal and turbidity reduction is discharged into the sludge discharge pipes. The water treatment is flexible, and the sludge discharge pipes can also be flushed by drainage to prevent blockage.

[0026] In this embodiment, as Figure 1 As shown, the ceramic membrane filter 27 is connected to a reverse osmosis filter 28, and several reverse osmosis filters 28 are also provided to meet the filtration of a large amount of water. The outlet of the reverse osmosis filter 28 is connected to a circulating water tank 29 and a fresh water tank 30. The clean water in the circulating water tank 29 and the fresh water tank 30 can be reused.

[0027] Specifically, during use, circulating water and reverse osmosis wastewater are first discharged into equalization tank 1 for storage, achieving unified collection of wastewater. The first lift pump 3 draws wastewater and sends it into integrated clarifier 4. For wastewater with high turbidity and high organic matter, a combination of ferric chloride and sodium hydroxide is used for treatment. For wastewater with low turbidity and high hardness, a combination of PAC and sodium hydroxide is used for treatment. The system can be switched in real time or operated in parallel according to the influent water quality to avoid the decrease in treatment efficiency of a single coagulant when the water quality changes abruptly. Wastewater undergoes solid-liquid separation in the integrated clarifier 4, with water as the upper layer and sediment (sludge) as the lower layer. Wastewater discharged from the integrated clarifier 4 flows into the clear water tank 9. During this flow process, hydrochloric acid is added to the wastewater using the hydrochloric acid pump 31 to make the wastewater neutral. The sludge is sent to the sludge tank 25 and treated by a filter press to achieve sludge-water separation. The water discharged here can be sent to the integrated clarifier 4 for recycling and to reduce wastewater discharge. The fourth booster pump 11 draws water from the clear water tank 9 and sends it to the ceramic membrane filter 27. During the sending process, PAC is added to extend the water production cycle of the ceramic membrane filter 27. The net-catching effect generated by PAC improves the water production capacity of the ceramic membrane filter 27 and enhances the filtration effect. The water filtered by the ceramic membrane filter 27 is sent to the reverse osmosis filter 28 to achieve dual filtration of water. The water quality of the effluent from the reverse osmosis filter 28 meets the reusable standard.

[0028] The overall process is as follows: water to be treated → 250m 3 Equalization tank → booster pump → add sodium hydroxide and ferric chloride → 2×165t / h integrated high-efficiency flocculation clarifier → add hydrochloric acid → 250m 3Clear water tank → booster pump → addition of polyaluminum chloride → subsequent ultrafiltration and reverse osmosis system → recycling; clarified sludge is sent to the existing sludge dewatering system of the water treatment plant. This reduces wastewater discharge, and the water recycling enables reuse, thus reducing the need for fresh water.

[0029] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-pH hardening and turbidity reduction system for circulating water discharge using dual coagulants, characterized in that, include: The equalization tank is connected to two integrated clarifiers. One integrated clarifier is connected to the ferric chloride dosing pump and the alkali dosing pump, and the other integrated clarifier is connected to the first PAC dosing pump and the alkali dosing pump. The clear water tank has an inlet that connects to the outlets of two integrated clarifiers. A hydrochloric acid pump is connected between the clear water tank and the integrated clarifiers. A ceramic membrane filter is connected to the outlet of the clear water tank, and a second PAC dosing pump is connected between the ceramic membrane filter and the clear water tank.

2. The circulating water discharge wastewater dual-coagulant high pH hardening and turbidity reduction system according to claim 1, characterized in that: The integrated clarifier is equipped with a sludge scraper in the center and a mixer in the water inlet area.

3. The circulating water discharge wastewater dual-coagulant high pH hardening and turbidity reduction system according to claim 1, characterized in that: The outlet of the equalization tank is connected to a spare discharge pipe, and the inlet of the equalization tank is connected to several inlet pipes.

4. The circulating water discharge wastewater dual-coagulant high pH hardening and turbidity reduction system according to claim 1, characterized in that: A heat exchanger is installed between the hydrochloric acid pump and the clear water tank.

5. The circulating water discharge wastewater dual-coagulant high pH hardening and turbidity reduction system according to claim 1, characterized in that: The sludge outlets of the two integrated clarifiers are connected to a sludge tank, and the sludge outlets are also connected to an industrial water inlet pipe.

6. The circulating water discharge wastewater dual-coagulant high pH hardening and turbidity reduction system according to claim 1, characterized in that: The ceramic membrane filter is connected to a reverse osmosis filter, and the outlet of the reverse osmosis filter is connected to a circulating water tank and a freshwater tank.

Images