Biological phosphorus removal and capacitive deionization combined enhanced phosphorus removal and phosphorus recovery device

Abstract

The utility model relates to a biological phosphorus removal and capacitive deionization combined enhanced phosphorus removal and phosphorus recovery device. Phosphorus-containing sewage is pretreated and then enters an anaerobic zone of a bioreactor to release phosphorus; after effluent of the anaerobic zone is settled by a first settling pond, supernate enters a capacitive deionization system for phosphorus recovery; supernate after phosphorus recovery is mixed with sludge in the first sedimentation tank and then flows through an anoxic zone and an aerobic zone of the bioreactor in sequence; part of mud-water mixture at the tail end of the aerobic zone flows back to the anoxic zone; after the rest part of sludge-water mixture is settled by a second settling pond, part of sludge in the second settling pond flows back to the anaerobic front end, and the rest part of sludge is transported outwards after being dewatered; according to the utility model, phosphorus recovery is carried out on the anaerobic terminal supernatant through the capacitive deionization system, the rear-end phosphorus load is reduced, the biological phosphorus removal process is enhanced, the sludge granulation is promoted, the requirement of the traditional biological phosphorus removal on a carbon source is reduced, and the purposes of phosphorus resource recovery and effective control on the effluent quality are achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of sewage treatment and resource utilization, and specifically relates to a device for strengthening phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization. Background Art

[0002] As a non-renewable resource, phosphorus is essential for the growth and development of organisms, and it is also an important industrial raw material. However, phosphorus consumption has exceeded its production, and it is predicted that phosphorus resources will be exhausted in the next 50 to 100 years. At the same time, the organic and inorganic phosphorus contained in municipal sewage increases the cost and difficulty of sewage treatment. Recycling phosphorus in sewage treatment plants can meet 15-20% of the global phosphorus demand, effectively alleviate the phosphorus crisis, and reduce the phosphorus concentration in sewage treatment plant effluent.

[0003] The phosphorus resources recovered from sewage treatment plants mainly come from the excess sludge and return sludge in the biological phosphorus removal system. However, the phosphorus recovered in this process usually needs further treatment, which increases the load of the sewage treatment plant and the overall cost of sewage treatment. Extracting phosphorus directly from the supernatant of the anaerobic phosphorus release stage of the biological treatment process is a more feasible way. The extracted phosphorus is recovered in the form of struvite, blue iron ore or hydroxyapatite by crystallization. However, these methods have problems such as high cost, complex operation, and impact on subsequent biological treatment processes. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the utility model is to provide a device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization. The phosphorus-rich supernatant in the anaerobic zone during the biological phosphorus removal process is treated by using a capacitive deionization system to recover liquid phosphorus; the treated supernatant is returned to the anoxic zone of the bioreactor. Due to the recovery of phosphorus by the capacitive deionization system, the phosphorus load in the aerobic zone can be reduced, the demand for carbon sources for traditional biological phosphorus removal can be reduced, the phosphorus removal capacity of the biological system can be enhanced, granulation can be promoted, and the phosphorus concentration in the effluent of the entire process can be reduced.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization comprises an anaerobic zone 1 of a bioreactor, wherein an anaerobic inlet end 11 of the anaerobic zone 1 of the bioreactor is connected to phosphorus-containing sewage, an anaerobic outlet end 12 of the anaerobic zone 1 of the bioreactor is connected to a first sedimentation inlet end 21 of a first sedimentation tank 2, and the first sedimentation tank 2 is divided into two branch pipelines, wherein one branch pipeline is connected to a liquid inlet 31 of a capacitive deionization system 3 through a first sedimentation outlet 22 of the first sedimentation tank 2, and the other branch pipeline is connected to a liquid inlet 31 of a capacitive deionization system 3 through a first sedimentation outlet end 23 of the first sedimentation tank 2 The anoxic inlet end 41 of the bioreactor anoxic zone 4 is connected, the liquid outlet 32 ​​of the capacitor deionization system 3 is connected with the anoxic liquid inlet 42 of the bioreactor anoxic zone 4, the anoxic outlet end 43 of the bioreactor anoxic zone 4 is connected with the aerobic inlet end 51 of the bioreactor aerobic zone 5, the aerobic outlet end 52 of the bioreactor aerobic zone 5 is respectively connected to the second sedimentation inlet end 61 of the second sedimentation tank 6 and the reflux inlet end 44 of the bioreactor anoxic zone 4, and the outer reflux outlet end 62 of the second sedimentation tank 6 is connected with the anaerobic inlet end 11 of the bioreactor anaerobic zone 1.

[0007] The capacitive deionization system 3 is provided with a phosphorus recovery outlet 33 .

[0008] The second sedimentation tank 6 is provided with a second sedimentation outlet 63 .

[0009] Compared with the prior art, the beneficial effects of the utility model are:

[0010] 1) Recycling phosphorus resources

[0011] Since the supernatant at the anaerobic end of the biological phosphorus removal system is rich in phosphorus, the utility model utilizes the capacitive deionization system 3 to intermittently recover liquid phosphorus in the supernatant in the anaerobic zone 1, which can effectively recover phosphorus and alleviate the phosphorus resource crisis without affecting the sludge biological system.

[0012] 2) Strengthen biological phosphorus removal and promote granulation

[0013] The utility model recovers phosphorus in the supernatant at the end of the anaerobic zone 1 by adopting a capacitive deionization system 3, which can reduce the phosphorus load of the aerobic zone 5, thereby strengthening the biological phosphorus removal process, reducing the phosphorus concentration in the process effluent, and better responding to the challenges faced by the sewage treatment plant; at the same time, after recovering part of the phosphorus in the supernatant at the end of the anaerobic zone 1, the particle size of the sludge increases, which promotes the sludge granulation function and provides a new idea for the cultivation of granular sludge.

[0014] 3) Reduce the demand for carbon sources in traditional biological phosphorus removal

[0015] The utility model recovers part of the phosphorus in the supernatant of the anaerobic zone 1 through the capacitive deionization system 3, so that the phosphorus concentration in the aerobic zone 5 is reduced, and after the biological absorption of phosphorus, the phosphorus concentration stored in the sludge is reduced, and the phosphorus concentration in the second sedimentation tank 6 is reduced, so that the phosphorus concentration of the sludge in the second sedimentation tank 6 that flows back to the anaerobic zone 1 is reduced, and when the anaerobic phosphorus release process is carried out again, the demand for carbon source is reduced.

[0016] In summary, the utility model recovers phosphorus from the supernatant at the end of the anaerobic zone 1 through the capacitive deionization system 3, reduces the phosphorus load at the rear end, has the advantages of strengthening the biological phosphorus removal process and promoting sludge granulation, and reducing the demand for carbon sources for traditional biological phosphorus removal, and can achieve the purpose of phosphorus resource recovery and effectively control the effluent water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 It is a schematic diagram of the device structure of the utility model.

[0019] Figure 2 This is a working principle diagram of the utility model.

[0020] Figure 3 This is a diagram showing the changes in microbial glycogen and polyhydroxyalkanoates at different stages in Example 2 of the present utility model.

[0021] Figure 4 This is a diagram showing the changes in microbial diversity at different stages of Example 2 of the utility model; wherein, Figure 4 (a) is the community composition at the microbial phylum level, Figure 4 (b) is the community composition at the microbial genus level; sample 1 was taken before phosphorus recovery using a capacitive deionization system, sample 2 was taken after phosphorus recovery using a capacitive deionization system, and sample 3 was taken after two cycles of microbial recovery.

[0022] Among them, 1. anaerobic zone of bioreactor; 11. anaerobic inlet; 12. anaerobic outlet; 2. first sedimentation tank 2; 21. first sedimentation inlet; 22. first sedimentation outlet; 23. first sedimentation outlet; 3. capacitive deionization system; 31. liquid inlet; 32. liquid outlet; 33. phosphorus recovery outlet; 4. anoxic zone of bioreactor; 41. anoxic inlet; 42. anoxic liquid inlet; 43. anoxic outlet; 5. aerobic zone of bioreactor; 51. aerobic inlet; 52. aerobic outlet; 6. second sedimentation tank; 61. second sedimentation inlet; 62. external reflux outlet; 63. second sedimentation outlet. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0024] like Figure 1 As shown, a device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization comprises an anaerobic zone 1 of a bioreactor, wherein an anaerobic inlet end 11 of the anaerobic zone 1 of the bioreactor is connected to phosphorus-containing sewage, an anaerobic outlet end 12 of the anaerobic zone 1 of the bioreactor is connected to a first sedimentation inlet end 21 of a first sedimentation tank 2, the first sedimentation tank 2 is divided into two branch pipelines, one of which is connected to a liquid inlet 31 of a capacitor deionization system 3 through a first sedimentation outlet end 22 of the first sedimentation tank 2, and the other branch pipeline is connected to an anoxic inlet end 41 of an anoxic zone 4 of the bioreactor through a first sedimentation outlet end 23 of the first sedimentation tank 2. The liquid outlet 32 ​​of the ion system 3 is connected with the anoxic liquid inlet 42 of the anoxic zone 4 of the bioreactor, and a phosphorus recovery outlet 33 is provided on the capacitor deionization system 3; the anoxic outlet end 43 of the anoxic zone 4 of the bioreactor is connected with the aerobic inlet end 51 of the aerobic zone 5 of the bioreactor, and the aerobic outlet end 52 of the aerobic zone 5 of the bioreactor is respectively connected to the second precipitation inlet end 61 of the second precipitation tank 6 and the reflux inlet end 44 of the anoxic zone 4 of the bioreactor, the outer reflux outlet end 62 of the second precipitation tank 6 is connected with the anaerobic inlet end 11 of the anaerobic zone 1 of the bioreactor, and a second precipitation outlet end 63 is provided on the second precipitation tank 6.

[0025] The working principle of the utility model is:

[0026] After pretreatment, the phosphorus-containing wastewater enters the anaerobic zone 1 of the bioreactor from the anaerobic inlet 11 for stirring, and the organisms release phosphorus to the extracellular space; the effluent from the anaerobic zone 1 of the bioreactor after phosphorus release flows out from the anaerobic outlet 12 and enters the first sedimentation tank 2 through the first sedimentation inlet 21, and the precipitated sludge and water are separated. The supernatant after separation enters the capacitor deionization system 3 from the first sedimentation outlet 22 through the liquid inlet 31 to recover phosphorus; the supernatant after phosphorus recovery flows out from the liquid outlet 32 ​​and enters the anoxic zone 4 of the bioreactor through the anoxic liquid inlet 42. At the same time, the precipitated sludge separated from the first sedimentation tank 2 flows out from the first sedimentation outlet 23 and enters the anoxic zone 4 of the bioreactor from the anoxic inlet 41 for reaction. After nitrification reaction, the substance mixture after the reaction flows out from the anoxic outlet end 43 and enters the aerobic zone 5 of the bioreactor through the aerobic inlet end to carry out nitrification reaction and phosphorus absorption process, and is aerated in the aerobic zone 5 of the bioreactor; part of the mud-water mixture at the end of the aerobic zone 5 of the bioreactor flows back to the anoxic zone 4 of the bioreactor; the remaining part of the mud-water mixture at the end of the aerobic zone 5 of the bioreactor enters the second sedimentation tank 6 from the aerobic outlet end 52 through the second sedimentation inlet end 61, the sedimentation mud and water are separated, the supernatant is discharged, and part of the sludge at the bottom of the second sedimentation tank 6 flows back to the front end of the anaerobic zone 1 of the bioreactor from the external reflux outlet end 62, and the remaining part of the sludge in the second sedimentation tank 6 is subjected to a sludge treatment process and transported out after dehydration.

[0027] Example 1

[0028] Step 1, taking sludge from the return sludge of a sewage treatment plant in Xi'an, bringing it back to the laboratory, passing the sludge through a 1 μm sieve to remove gravel impurities, and transferring it to the anaerobic zone 1 of the bioreactor for acclimatization and cultivation. The volume of the bioreactor is 11 L, the height-to-diameter ratio is 4.13, and the operation setting is 8 hours per cycle, including 10 minutes of water inlet, 60 minutes of anaerobic reaction, 360 minutes of aerobic reaction, 40 minutes of sedimentation, 10 minutes of drainage, the temperature is maintained at 23±2°C, the sludge age is 15 days, and 200 mL of the sludge mixed liquid after anaerobic stirring for 60 minutes in the bioreactor is taken;

[0029] Step 2, after 200 mL of the sludge mixed liquid is precipitated for 30 minutes, the obtained supernatant and sediment are separated in a ratio of 1:1; the supernatant is treated with a capacitive deionization system 3 for 2 hours, wherein the operating voltage of the capacitive deionization system 3 is 1.2V, the activated carbon content is 5wt%, the feed liquid and the flow electrode flow rates are 40mL / min and 30mL / min respectively, the ratio of the electrolyte concentration to the feed liquid concentration is 100:1, the operation mode is a short-circuit closed cycle, and the supernatant after phosphorus recovery is mixed with the sediment;

[0030] Step 3, the mixed sludge passes through the anoxic zone 4 and the aerobic zone 5 of the bioreactor in sequence to undergo denitrification, nitrification and phosphorus absorption processes;

[0031] Step 4, after the sludge-water mixture at the end of the aerobic zone 5 of the bioreactor is precipitated, the supernatant is discharged, and the phosphorus recovery capacity of the capacitive deionization system 3, the particle size of the sludge before and after the experiment, and the effluent phosphorus concentration are measured respectively.

[0032] The experimental results show that the phosphorus recovery rate of the capacitive deionization system 3 is 65%, the phosphorus removal capacity of the bioreactor is increased by 11%, the effluent phosphorus concentration is reduced from 2.41 mg / L to 0.35 mg / L, and the average particle size of the bioreactor sludge increases by 20 μm. After the phosphorus is recovered by the capacitive deionization system 3, the phosphorus removal capacity of the bioreactor is enhanced, and the sludge particle size is increased. This process can enhance the processing capacity of the biological system and promote granulation.

[0033] Example 2

[0034] Step 1, sludge from the return sludge of a sewage treatment plant in Xi'an is taken back to the laboratory, the sludge is sieved through a 1 μm sieve to remove gravel impurities, and then transferred to the anaerobic zone 1 of the bioreactor for acclimatization and cultivation, wherein the bioreactor has a volume of 12 L, a height-to-diameter ratio of 1.4, and an operation setting of 8 h per cycle, wherein water inlet is 20 min, anaerobic reaction is 120 min, aerobic reaction is 300 min, sedimentation is 30 min, drainage is 10 min, the temperature is maintained at 20±1°C, the sludge age is 20 days, and 200 ml of the sludge mixed liquid from the bioreactor anaerobic for 60 min is taken;

[0035] Step 2, after 200mL of the sludge mixed liquid is precipitated in the first sedimentation tank 2 for 30min, the obtained supernatant and sediment are separated in a ratio of 1:1; the supernatant is treated with a capacitive deionization system 3 for 2h to recover phosphorus, wherein the operating voltage of the capacitive deionization system 3 is 1.2V, the activated carbon content is 5wt%, the feed liquid and the flow electrode flow rates are 40mL / min and 30mL / min respectively, the ratio of the electrolyte concentration to the feed liquid concentration is 100:1, the operation mode is a short-circuit closed cycle, and the recovered supernatant is mixed with the sediment;

[0036] Step 3, the mixed sludge passes through the anoxic zone 4 and the aerobic zone 5 of the bioreactor in sequence to undergo denitrification, nitrification and phosphorus absorption processes;

[0037] Step 4, after the mud-water mixture at the end of the aerobic zone 5 of the bioreactor is precipitated, the supernatant is discharged, part of the sludge is discharged, and the remaining part of the sludge continues to the next cycle;

[0038] Step 5, the remaining part of the sludge is mixed with the influent and the next biological treatment cycle is carried out. The capacitor deionization system 3 is not added for phosphorus recovery for two consecutive biological treatment cycles, and the phosphorus is recovered by the microorganisms themselves. The energy metabolism and biodiversity during the experiment are measured. The results are as follows Figure 3 and Figure 4 As shown, Figure 4 (a) is the community composition at the microbial phylum level, Figure 4 (b) is the community composition at the microbial genus level, sample 1 was taken before phosphorus recovery using a capacitive deionization system, sample 2 was taken after phosphorus recovery using a capacitive deionization system, and sample 3 was taken after two cycles of microbial recovery;

[0039] from Figure 3 and Figure 4 It can be seen that the recovery of phosphorus in the supernatant of the anaerobic zone by the capacitor deionization system 3 did not change the energy metabolism pattern and biodiversity in the sludge phosphorus removal process. The sludge system remained stable. After recovery, the sludge phosphorus removal capacity returned to the level before phosphorus recovery. By recovering phosphorus from the anaerobic terminal supernatant, the rear-end phosphorus load is reduced, the biological phosphorus removal process is strengthened, and sludge granulation is promoted, the demand for carbon sources for traditional biological phosphorus removal is reduced without causing serious impact on the sludge system.

[0040] The above is only a preferred specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by a technician familiar with the technical field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model.

Claims

1. A device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization, characterized in that: The invention comprises an anaerobic zone (1) of a bioreactor, wherein the anaerobic inlet end (11) of the anaerobic zone (1) is connected to phosphorus-containing sewage, the anaerobic outlet end (12) of the anaerobic zone (1) is connected to a first sedimentation inlet end (21) of a first sedimentation tank (2), and the first sedimentation tank (2) is divided into two branch pipelines, one of which is connected to a liquid inlet (31) of a capacitive deionization system (3) through a first sedimentation liquid outlet (22) of the first sedimentation tank (2), and the other branch pipeline is connected to an anoxic inlet end (41) of an anoxic zone (4) of the bioreactor through a first sedimentation liquid outlet end (23) of the first sedimentation tank (2). The liquid outlet (32) of the capacitive deionization system (3) is connected to the anoxic liquid inlet (42) of the anoxic zone (4) of the bioreactor, the anoxic outlet end (43) of the anoxic zone (4) of the bioreactor is connected to the aerobic inlet end (51) of the aerobic zone (5) of the bioreactor, the aerobic outlet end (52) of the aerobic zone (5) of the bioreactor is respectively connected to the second sedimentation inlet end (61) of the second sedimentation tank (6) and the reflux inlet end (44) of the anoxic zone (4) of the bioreactor, and the external reflux outlet end (62) of the second sedimentation tank (6) is connected to the anaerobic inlet end (11) of the anaerobic zone (1) of the bioreactor.

2. The device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization according to claim 1 is characterized in that: The capacitive deionization system (3) is provided with a phosphorus recovery outlet (33).

3. The device for enhancing phosphorus removal and phosphorus recovery by combining biological phosphorus removal with capacitive deionization according to claim 1 is characterized in that: The second sedimentation tank (6) is provided with a second sedimentation outlet (63).

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