Urban sewage advanced treatment system and sewage treatment process

Abstract

The invention discloses an urban sewage advanced treatment system and a sewage treatment process, and relates to the technical field of sewage treatment.The urban sewage advanced treatment system comprises an oxidation assembly and a denitrification biological filter, the oxidation assembly comprises an oxidation pond, activated carbon and a peracetic acid feeder, the activated carbon is located in the oxidation pond, and the peracetic acid feeder is located in the denitrification biological filter; the peracetic acid supplier is connected with the oxidation pond and is used for inputting peracetic acid into the oxidation pond. The denitrification biofilter comprises a tank body and a filler layer, the tank body is connected with the oxidation tank, the filler layer is arranged in the tank body, the filler layer is located below a water outlet of the oxidation tank, and the filler layer is composed of a plurality of porous ceramsite. The peroxyacetic acid feeder can input peroxyacetic acid into the oxidation pond, the peroxyacetic acid can oxidize organic pollutants difficult to degrade in sewage into organic pollutants easy to be utilized by microorganisms, meanwhile, the peroxyacetic acid is converted into acetic acid, and the acetic acid can provide a carbon source for the subsequent denitrification process after flowing into the denitrification biofilter. The sewage can be deeply purified.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an urban sewage deep treatment system and a sewage treatment process. Background Art

[0002] In recent years, with the rapid development of my country's economy and society, the types of pollutants in water have become more and more complex. In addition to nitrogen, phosphorus, and common organic matter, new pollutants composed of antibiotics, endocrine disruptors, etc. have become an important problem in water pollution control. With the release of increasingly stringent pollutant emission control standards, the secondary biochemical treatment process commonly used in sewage treatment plants is difficult to meet the needs of deep sewage purification. Therefore, seeking high-efficiency, low-consumption, and secondary pollution-free sewage treatment plant deep purification technology is a hot topic in today's water treatment field. Commonly used deep treatment processes include ozone / biofilter processes, which have both complex pollutant degradation and by-product control functions. However, excessive ozone oxidation often causes unnecessary energy consumption and makes it difficult for subsequent biofilters to meet the needs of deep denitrification due to insufficient carbon sources, and the ozone control management concentration is relatively high.

[0003] Although peracetic acid can remove pollutants in sewage through its strong oxidizing ability, peracetic acid itself is also corrosive. After the first round of sewage treatment, peracetic acid will flow into the denitrification biological filter with the sewage, causing damage to the organisms in the denitrification biological filter, thereby affecting the further treatment effect of the organisms in the denitrification biological filter on the sewage. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, propose an urban sewage deep treatment system and a sewage treatment process, and solve the technical problems in the prior art that peracetic acid has a pungent odor, strong oxidizing properties, and the oxidation by-product acetic acid easily introduces organic matter into water, posing a certain ecological threat to the water body, thereby limiting its application in sewage treatment plants.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a system for deep treatment of urban sewage, comprising: An oxidation assembly, comprising an oxidation tank, activated carbon and a peracetic acid supplier, wherein the activated carbon is located in the oxidation tank, and the peracetic acid supplier is connected to the oxidation tank and used to input peracetic acid into the oxidation tank; and The denitrification biofilter comprises a tank body and a filler layer, wherein the tank body is connected to the oxidation tank, the filler layer is connected to the side wall of the tank body and encloses the bottom inner wall of the tank body to form a channel for water to enter, the filler layer is located below the water outlet of the oxidation tank, and the filler layer is composed of a plurality of porous ceramsite particles.

[0006] In some embodiments, the oxidation component also includes a first supporting layer disposed inside the oxidation tank, the first supporting layer dividing the interior of the oxidation tank into a pre-oxidation zone and a treatment zone, the pre-oxidation zone is connected to the peracetic acid supplier, and the treatment zone is filled with the activated carbon.

[0007] In some embodiments, the top of the oxidation pond has a weir and an outlet channel, the treatment zone is located between the pre-oxidation zone and the weir, the water channel is inclined and the higher and lower parts are connected to the treatment zone and the outlet channel respectively, and the outlet channel is located above the packing layer.

[0008] In some embodiments, the oxidation assembly further comprises a diverter, wherein the diverter is located in the pre-oxidation zone and divides the pre-oxidation zone into a first chamber and a second chamber, wherein the first chamber is located between the treatment zone and the second chamber, the first chamber is connected to the peracetic acid supplier, and the second chamber is used to connect to a sewage pipe.

[0009] In some embodiments, the pool body is provided with a water outlet weir, which is located between the water outlet of the oxidation pool and the packing layer. An overflow trough is provided in the middle of the water outlet weir, and purification tanks are provided on both sides. When the sewage in the overflow trough is full, the sewage can overflow into the purification tanks on both sides. A plurality of zero-valent irons are provided on the tank wall of the purification tank, and the zero-valent iron can degrade organic matter in the sewage.

[0010] In some embodiments, the denitrifying biological filter tank further includes a clean water drain pipe and a backwashing assembly, wherein the clean water drain pipe is connected to the water outlet of the tank body, and the backwashing assembly is connected in parallel to the clean water drain pipe and is used to pass clean water into the tank body through the clean water drain pipe to flush the packing layer.

[0011] In some embodiments, the backwash assembly includes a backwash water inlet pipe, a backwash pump and a backwash clear water tank, wherein the backwash water inlet pipe connects the backwash clear water tank and the tank body, and the backwash pump is connected to the backwash clear water tank and is used to drive the clean water in the backwash clear water tank into the tank body to backwash the packing layer.

[0012] In some embodiments, the backwash assembly further includes a backwash outlet pipe, the pool body is provided with an overflow trough, the overflow trough is located above the packing layer, and the backwash outlet pipe is connected to the overflow trough.

[0013] In a second aspect, the present invention further provides a sewage treatment process, which is implemented by the above-mentioned urban sewage deep treatment system, characterized in that the sewage treatment process comprises the following steps: Controlling the peracetic acid supplier to input peracetic acid into the oxidation tank; Inputting the sewage to be treated into the oxidation pond so that the sewage is mixed with peracetic acid; Continuously feeding peracetic acid and sewage into the oxidation tank simultaneously so that the sewage mixture passes through the activated carbon; The sewage treated with activated carbon flows into the packing layer in the denitrification biological filter from the outlet of the oxidation tank and contacts with the porous ceramsite on the packing layer. The clean water formed by the purification of the porous ceramsite is discharged from the outlet of the tank body.

[0014] In some embodiments, the mixed solution of the sewage and the peracetic acid flows from the bottom of the oxidation pond to the top of the oxidation pond.

[0015] Compared with the prior art, the peracetic acid feeder of the urban sewage deep treatment system provided by the present invention can input peracetic acid into the oxidation tank, and the peracetic acid can oxidize the difficult-to-degrade organic pollutants in the sewage into organic pollutants that are easily used by microorganisms through its strong oxidizing property. Activated carbon can be used as a green and non-toxic environmentally friendly catalyst to activate peracetic acid, so as to improve the degradation ability of peracetic acid on sewage, and at the same time, peracetic acid is converted into acetic acid, which will not cause harm to the active organisms on the surface of porous ceramsite in the denitrification biological filter. After acetic acid flows into the denitrification biological filter, it can also provide a carbon source for the subsequent denitrification process, and through the denitrification of the active organisms on the surface of the porous ceramsite, it is finally possible to achieve efficient denitrification of sewage and remove difficult-to-degrade organic matter in sewage, so that the sewage can be deeply purified. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a system for deep treatment of urban sewage provided by an embodiment of the present invention; Figure 2 It is a top view schematic diagram of the connection between the oxidation pond and the denitrification biological filter provided by an embodiment of the present invention.

[0017] Figure 3 is a schematic structural diagram of a water outlet weir provided in an embodiment of the present invention; Figure 4 It is a structural schematic diagram of another embodiment of the porous ceramsite provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In order to solve the technical problem in the prior art that peracetic acid itself has a certain corrosiveness and will cause harm to the organisms in the subsequent denitrification biological filter, thereby affecting the further treatment effect of the subsequent denitrification biological filter on sewage, the present invention provides a system for deep treatment of urban sewage, which can generate acetic acid while initially purifying sewage. The acetic acid not only does not cause harm to the active organisms on the surface of porous ceramsite in the denitrification biological filter, but also can provide a carbon source for the subsequent denitrification treatment of sewage, and finally achieves deep purification of sewage through the denitrification action of the active organisms on the surface of the porous ceramsite.

[0020] See also Figure 1 , Figure 1 Schematic diagram of the structure of a system for deep treatment of urban sewage in one embodiment of the present invention, the system for deep treatment of urban sewage includes an oxidation component and a denitrification biological filter, the oxidation component includes an oxidation tank 1, activated carbon 2 and a peracetic acid supplier 3, the activated carbon 2 is located in the oxidation tank 1, and the peracetic acid supplier 3 is connected to the oxidation tank 1 and is used to input peracetic acid into the oxidation tank 1; The denitrification biological filter includes a tank body 4 and a packing layer 5. The tank body 4 is connected to the oxidation tank 1. The packing layer 5 is connected to the side wall of the tank body 4 and is combined with the bottom inner wall of the tank body 4 to form a water outlet channel, so that water treated by the packing layer 5 can be discharged through the water outlet channel. The packing layer 5 is located below the water outlet of the oxidation tank 1, and the packing layer 5 is composed of a plurality of porous expanded clay 6.

[0021] In the present embodiment, the substances that have a purifying effect on sewage are mainly peracetic acid, activated carbon 2 and porous ceramsite 6, wherein peracetic acid can destroy the chemical structure of organic pollutants in sewage by its strong oxidizing property, and oxidize the difficultly degradable organic pollutants in sewage into organic pollutants that are easily utilized by microorganisms. Activated carbon 2 can also activate peracetic acid to improve the purifying ability of peracetic acid to sewage in addition to being able to adsorb pollutants in sewage. Porous ceramsite 6 utilizes the microorganism adsorbed thereon to treat the remaining organic matter in oxidation pond 1. After sewage enters oxidation pond 1, it is first mixed with the peracetic acid in oxidation pond 1, and the mixed solution contacts activated carbon 2. While activated carbon 2 is adsorbing and purifying sewage, it also activates peracetic acid to improve the purifying ability of peracetic acid. Peracetic acid forms acetic acid after sewage treatment, and acetic acid is non-corrosive and will not harm the organisms in denitrification biological filter, so that the organisms can participate in denitrification reaction, and sewage is deeply treated.

[0022] The peracetic acid supplier 3 is provided with a dosing pump 31, which is connected to the oxidation pond 1 through a liquid inlet pipe 32. When working, the dosing pump 31 can drive the peracetic acid in the peracetic acid supplier 3 to be input into the oxidation pond 1 through the liquid inlet pipe 32 to purify the sewage in the oxidation pond 1.

[0023] Activated carbon is divided into different zones in oxidation tank 1 according to the particle size. Figure 1 There are three main particle sizes of activated carbon. From the bottom to the top of the oxidation tank 1, the particle size of activated carbon gradually increases. The activated carbon at the bottom uses small-particle powder activated carbon (100 mesh), the activated carbon in the middle area uses large-particle powder (60 mesh), and the top uses block activated carbon. Small-particle activated carbon has better adsorption and catalytic oxidation effects, but it is easy to expand and lose during operation. Through hierarchical stratification, it is beneficial for the activated carbon at the bottom to be retained in the oxidation tank and reduce the loss of activated carbon.

[0024] In one embodiment, see Figure 1 The oxidation assembly further includes a first supporting layer 11 disposed inside the oxidation pool 1. The first supporting layer 11 divides the inside of the oxidation pool 1 into a pre-oxidation zone 12 and a treatment zone 13. The pre-oxidation zone 12 is connected to the oxyacetic acid supplier 3, and the treatment zone 13 is filled with activated carbon 2. The first supporting layer 11 of this embodiment is mainly used to support the activated carbon 2. In addition, the first supporting layer 11 can be used for sewage and peracetic acid to penetrate and enter the treatment zone 13 to contact the activated carbon 2.

[0025] In one embodiment, see Figure 1 and Figure 2 The top of the oxidation pond 1 is provided with a weir 14 and an outlet channel 15. The treatment area 13 is located between the pre-oxidation area 12 and the weir 14. The weir 15 is inclined and the higher and lower parts of the treatment area 13 and the outlet channel 15 are connected respectively. The outlet channel 15 is located above the packing layer 5. In this embodiment, the sewage flows into the weir 14 after being treated by the activated carbon 2. The weir 14 is inclined. The sewage flows from the higher part of the weir 14 to the lower part, flows into the outlet channel 15, and then flows into the tank body 4 of the denitrification biological filter from the outlet channel 15, contacts with the porous ceramsite 6 of the packing layer 5, and performs deep purification treatment on the sewage.

[0026] In one embodiment, see Figure 1 The oxidation assembly further includes a flow divider 16, which is located in the pre-oxidation zone 12 and divides the pre-oxidation zone 12 into a first chamber and a second chamber. The first chamber is located between the treatment zone 13 and the second chamber. The first chamber is connected to the peroxyacetic acid supplier 3, and the second chamber is used to connect to the sewage pipe 17. The sewage to be treated flows into the second chamber through the sewage pipe 17. The peroxyacetic acid output by the peroxyacetic acid supplier 3 of this embodiment is input into the first chamber through the liquid inlet pipe, and the sewage in the sewage pipe 17 enters the second chamber. As the sewage in the second chamber is filled, the liquid level of the sewage gradually rises, and the sewage enters the first chamber through the flow divider 16 and mixes with the peroxyacetic acid in the first chamber. The flow divider 16 has a plurality of water holes evenly arranged in an array, and the sewage in the second chamber can flow into the first chamber through the plurality of water holes at the same time, and fully mix with the peroxyacetic acid in the first chamber to improve the purification efficiency of the sewage.

[0027] In one embodiment, see Figure 1 A water outlet weir 42 is arranged near the top of the pool body 4. The water outlet weir 42 spans the pool body 4. The water outlet weir 42 is arc-shaped and has an overflow groove 421 inside. The overflow groove 421 is connected to the outlet of the water outlet channel 15 so that all the water flowing out of the water outlet channel 15 can flow into the overflow groove 421. When the water in the overflow groove 421 is full, the water can overflow from both sides of the overflow groove 421 and flow into the pool body 4, so that the sewage can flow evenly to the packing layer 5, and the sewage can be fully purified.

[0028] Purification tanks 422 are provided on both sides of the outlet weir 42. When the sewage in the overflow tank 421 is full, it overflows and flows into the purification tank 422. A plurality of zero-valent irons 423 are provided on the tank wall of the purification tank 422. The zero-valent iron 423 can degrade organic matter in the sewage and remove residual peracetic acid to prevent the residual peracetic acid in the sewage from flowing into the tank body 4.

[0029] The two sides of the outlet weir 42 are provided with an inclined first water guide slope 43 and a second water guide slope 44. The sewage flowing out of the purification tank 422 can flow from the first water guide slope 43 and the second water guide slope 44 into the packing layer 5 at the lower part of the tank body 4, so that the sewage can flow evenly to the packing layer 5 and the sewage can be fully purified.

[0030] In one embodiment, see Figure 1 The denitrification biofilter also includes a clean water drainage pipe 7 and a backwashing assembly 8. The clean water drainage pipe 7 is connected to the water outlet of the tank body 4. The backwashing assembly 8 is connected in parallel to the clean water drainage pipe 7 and is used to pass clean water into the tank body 4 through the clean water drainage pipe 7 to wash the packing layer 5. In this embodiment, the clean water formed after the sewage is purified in the tank body 4 can be discharged through the water outlet of the tank body 4. A part of the clean water is discharged through the clean water drainage pipe 7, and the other part of the clean water is discharged into the backwashing assembly 8, so that the backwashing assembly 8 can re-input the clean water into the tank body 4 to wash the packing layer 5 of the tank body 4 and discharge the pollutants on the surface of the packing layer 5 out of the tank body 4. The clean water in the tank body 4 continues to increase, and the liquid level gradually rises. When the liquid level of the clean water is higher than the packing layer 5, the pollutants on the surface of the packing layer 5 will float on the liquid level of the clean water, and the liquid level continues to rise until it reaches another drainage port of the tank body 4. The pollutants can be discharged from the drainage port. After the pollutants are discharged, the clean water can be discharged from the water outlet at the bottom of the tank body 4 to the backwashing assembly 8 again for secondary use. The clean water drainage pipe 7 is provided with a first switch valve 71. By controlling the first switch valve 71 to be opened or closed, the clean water in the pool body 4 can be controlled to be discharged or not.

[0031] In one embodiment, see Figure 1The backwash assembly 8 includes a backwash water inlet pipe 81, a backwash pump 82 and a backwash clear water tank 83. The backwash water inlet pipe 81 connects the backwash clear water tank 83 and the tank body 4. The backwash pump 82 connects the backwash clear water tank 83 and is used to drive the clean water in the backwash clear water tank 83 into the tank body 4 to backwash the packing layer 5. In this embodiment, the backwash clear water tank 83 is used to store clean water, and the backwash pump 82 is used to drive the clean water in the backwash clear water tank 83 to flow into the tank body 4 through the backwash water inlet pipe 81, flush the packing layer 5 of the tank body 4, and discharge the pollutants on the surface of the packing layer 5 to the outside of the tank body 4.

[0032] The backwash water inlet pipe 81 is provided with a second switch valve 811. When the second switch valve 811 is closed and the first switch valve 71 is opened, all the clean water in the pool body 4 can be discharged through the clean water drain pipe 7. When the second switch valve 811 is opened and the first switch valve 71 is closed, all the clean water in the pool body 4 can be discharged into the backwash clean water tank 83 through the backwash water inlet pipe 81. In actual operation, by opening the first switch valve 71 and closing the second switch valve 811, a part of the clean water can be discharged through the clean water drain pipe 7 first, and then the first switch valve 71 is closed and the second switch valve 811 is opened, so that the other part of the clean water is discharged into the backwash clean water tank 83 through the backwash water inlet pipe 81.

[0033] In one embodiment, see Figure 1 , the backwash assembly 8 also includes a backwash outlet pipe 84, the tank body 4 is provided with an outlet trough 41, the outlet trough 41 is located above the packing layer 5, and the backwash outlet pipe 84 is connected to the outlet trough 41. In this embodiment, when the liquid level of the clean water in the tank body 4 continues to rise, the pollutants on the packing layer 5 will float on the liquid surface of the clean water until the liquid level reaches the outlet trough 41, and the pollutants on the liquid surface are discharged from the outlet trough 41 through the backwash outlet pipe 84. In addition, the position of the outlet trough 41 is staggered with the above-mentioned outlet weir 42 to prevent the sewage overflowing from the outlet weir 42 from directly flowing into the outlet trough 41.

[0034] In one embodiment, see Figure 1 The urban sewage deep treatment system also includes a backflow detection component, which is used to detect the water discharged from the clean water drainage pipe 7. If the target pollutants are detected to exceed the standard, the water will be returned to the oxidation pond 1 or the biological filter to continue purification until the test is qualified; if the target pollutants are detected to be qualified, the water discharge will be controlled.

[0035] The backflow detection assembly includes a detector 51, a backflow main pipe 52, a first branch pipe 53, a second branch pipe 54 and a drain pipe 55. The first branch pipe 53 connects the backflow main pipe 52 and the sewage pipe 17, and a first valve 531 is provided on the first branch pipe 53; the second branch pipe 54 connects the backflow main pipe 52 and the tank body 4, and a second valve 541 is provided on the second branch pipe 54. The backflow main pipe 52 is connected to the water outlet end of the clean water drain pipe 7 to receive the water discharged from the clean water drain pipe 7. The detector 51 is provided on the backflow main pipe 52 to detect the water discharged from the clean water drain pipe 7. The drain pipe 55 is connected to the detector 51. When the detector detects that the target pollutants in the water do not exceed the standard, the water valve on the drain pipe 55 is controlled to open to discharge the water.

[0036] When the detector 51 detects that the COD in the water exceeds the standard, it means that the refractory organic matter in the water has not been completely removed. The detector 51 controls the first valve 531 to open and the second valve 541 to close, so that the water flows into the oxidation pond 1 together with the sewage in the sewage pipe 17 for purification again, and appropriately controls the peracetic acid supplier 3 to increase the output of peracetic acid. When the detector 51 detects that the TN in the water exceeds the standard, the detector 51 controls the first valve 531 to close and the second valve 541 to open, so that the water flows into the pool body 4 for purification again. The return main 52 can also be equipped with a water pump 56 to quickly send the water detected by the detector 51 to the oxidation pond 1 or the pool body 4.

[0037] In a second aspect, the present invention further provides a sewage treatment process, which is implemented by the above-mentioned urban sewage deep treatment system, and the sewage treatment process comprises the following steps: The peracetic acid supplier 3 is controlled to input peracetic acid into the oxidation pond 1 ; the content of the input peracetic acid needs to be adapted to the content of the sewage to avoid excess peracetic acid in the oxidation pond 1 .

[0038] The sewage to be treated is input into the oxidation tank 1 so that the sewage is mixed with peracetic acid; when the peracetic acid is initially mixed with the sewage, the chemical structure of the organic pollutants in the sewage can be destroyed, and the difficult-to-degrade organic pollutants in the sewage are oxidized into organic pollutants that are easily utilized by microorganisms.

[0039] Peracetic acid and sewage are continuously input into the oxidation pool 1 at the same time, so that the sewage and peracetic acid mixture passes through the activated carbon 2; the activated carbon 2 adsorbs pollutants in the sewage and activates the peracetic acid, thereby improving the purification ability of the peracetic acid on the sewage and improving the purification efficiency.

[0040] The sewage treated by the activated carbon 2 flows into the packing layer 5 in the denitrification biological filter from the outlet of the oxidation tank 1, and contacts with the porous ceramsite 6 on the packing layer 5. The clean water formed by the purification of the porous ceramsite 6 is discharged from the outlet of the tank body 4. The porous ceramsite 6 uses the microorganisms adsorbed thereon to biodegrade the remaining organic matter in the sewage, and simultaneously denitrifies in a coordinated manner.

[0041] In other embodiments, see Figure 4 The pool body 4 can also use a filter material filler layer in the form of a mixture of iron and ceramsite, with the ratio of iron to ceramsite being 1:10. Ceramsite 61 is used as an attachment carrier for microorganisms, and its main function is to absorb COD and TN in sewage through microorganisms. Iron 62 is a zero-valent iron particle, and its main functions are two-fold: first, it is an insurance measure. Incompletely reacted oxidants from the oxidation zone may pose a threat to microorganisms. Adding zero-valent iron is conducive to fully reducing incompletely reacted oxidants and reducing the harm to the organisms in the pool body 4; second, it plays an electron transfer role and promotes the activity of extracellular polymers between biofilms. At the same time, microorganisms, as electron donors, can also promote the reduction and regeneration of zero-valent iron.

[0042] In one embodiment, see Figure 1 The mixed liquid after the sewage and peracetic acid are mixed flows from the bottom of the oxidation tank 1 to the top of the oxidation tank 1, so that the sewage and peracetic acid can fully contact with the activated carbon, and the activated carbon fully activates the peracetic acid and fully adsorbs the pollutants in the sewage, so as to further improve the purification effect of the sewage.

[0043] The feasibility of the sewage deep treatment system of the present application in purifying sewage is demonstrated through actual tests below.

[0044] Experimental conditions: PH=7 Specific implementation method: First, granular activated carbon (GAC) is biofilmed to form biological activated carbon (BAC), and a continuous flow reactor is constructed based on this, which is divided into an oxidation zone and a biological zone. The oxidation zone is filled with GAC, and the biological zone is filled with BAC. The residence time in the oxidation zone is 4 minutes, and the residence time in the biological zone is 5 minutes. Sulfadimethoxazole SMX is used as a representative pollutant. Detectors are set at the water inlet of the oxidation pond 1 and the water outlet of the biological filter to detect various water quality indicators of the inlet and outlet water.

[0045] Example 1 (PAA-GAC / BAC): The oxidant peracetic acid (PAA) was added to the influent of the oxidation zone, the residence time in the oxidation zone was controlled to be 4 min, the PAA concentration was 100 μmol / L, the SMX concentration was 10 μmol / L, the TN20 mg / L biozone residence time was 5 min, and the data on the first, third, fifth and seventh days were counted respectively.

[0046] Example 2 (GAC / BAC): Different from Example 1, Example 2 does not add PAA to form a control group with Example 1 to compare the effect of adsorption. The residence time of sewage in the adsorption zone is controlled to be 4 minutes, and the residence time in the biological zone is controlled to be 5 minutes. In the sewage to be treated, the SMX concentration is 10 μmol / L, and the TN concentration is 20 mg / L. The data of the first day, third day, fifth day and seventh day are respectively counted.

[0047] From the above treatment results, it can be seen that after 7 days of continuous treatment, the stable removal rate of pollutants in sewage is: The TOC (total organic carbon) removal rate of Example 1 is 67.4%, and the TOC removal rate of Example 2 is 55.1%.

[0048] The TN (total nitrogen) removal rate of Example 1 is 47.1%, and the TN removal rate of Example 2 is 12.7%.

[0049] The SMX removal rate in Example 1 is 73.0%, and the SMX removal rate in Example 2 is 28.7%.

[0050] In order to better understand the present invention, the following Figures 1 to 4 The technical solution of the present invention is described in detail: The peracetic acid feeder 3 of the urban sewage deep treatment system provided by the present invention can input peracetic acid into the oxidation pool 1. The peracetic acid can oxidize the difficult-to-degrade organic pollutants in the sewage into organic pollutants that are easily used by microorganisms through its strong oxidizing property. The activated carbon 2 can be used as a green and non-toxic environmentally friendly catalyst to activate the peracetic acid, so as to improve the degradation ability of the peracetic acid on the sewage. At the same time, the peracetic acid is converted into acetic acid, which will not cause harm to the organisms in the denitrification biological filter. After flowing into the denitrification biological filter, the acetic acid can also provide a carbon source for the subsequent denitrification process. Through the denitrification of the activated sludge on the surface of the porous ceramsite 6, the efficient denitrification of the sewage and the removal of the difficult-to-degrade organic matter in the sewage are finally achieved, so that the sewage can be deeply purified.

[0051] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A system for deep treatment of urban sewage, characterized in that: include: An oxidation assembly, comprising an oxidation tank, activated carbon and a peracetic acid supplier, wherein the activated carbon is located in the oxidation tank, and the peracetic acid supplier is connected to the oxidation tank and is used to input peracetic acid into the oxidation tank; and The denitrification biofilter comprises a tank body and a filler layer, wherein the tank body is connected to the oxidation tank, the filler layer is connected to the side wall of the tank body and encloses the bottom inner wall of the tank body to form a channel for water to enter, the filler layer is located below the water outlet of the oxidation tank, and the filler layer is composed of a plurality of porous ceramsite particles.

2. The urban sewage deep treatment system according to claim 1, characterized in that: The oxidation assembly also includes a first supporting layer arranged inside the oxidation tank, the first supporting layer divides the inside of the oxidation tank into a pre-oxidation zone and a treatment zone, the pre-oxidation zone is connected to the peracetic acid supplier, and the treatment zone is filled with the activated carbon.

3. The urban sewage deep treatment system according to claim 2 is characterized in that: The top of the oxidation pond is provided with a weir and an outlet channel, the treatment zone is located between the pre-oxidation zone and the weir, the outlet channel is inclined and the higher and lower parts thereof are connected to the treatment zone and the outlet channel respectively, and the outlet channel is located above the packing layer.

4. The urban sewage deep treatment system according to claim 2, characterized in that: The oxidation assembly also includes a diverter, which is located in the pre-oxidation zone and divides the pre-oxidation zone into a first chamber and a second chamber, the first chamber is located between the treatment zone and the second chamber, the first chamber is connected to the peracetic acid supplier, and the second chamber is used to connect to a sewage pipe.

5. The urban sewage deep treatment system according to claim 1, characterized in that: The pool body is provided with a water outlet weir, and the water outlet weir is located between the water outlet of the oxidation pool and the packing layer. An overflow trough is provided in the middle part of the water outlet weir, and purification tanks are provided on both sides. When the sewage in the overflow trough is full, the sewage can overflow and flow into the purification tanks on both sides. A plurality of zero-valent irons are provided on the tank wall of the purification tank, and the zero-valent iron can degrade organic matter in the sewage.

6. The urban sewage deep treatment system according to claim 1, characterized in that: The denitrification biofilter also includes a clean water drainage pipe and a backwashing assembly. The clean water drainage pipe is connected to the water outlet of the tank body. The backwashing assembly is connected in parallel to the clean water drainage pipe and is used to pass clean water into the tank body through the clean water drainage pipe to flush the packing layer.

7. The urban sewage deep treatment system according to claim 6, characterized in that: The backwash component includes a backwash water inlet pipe, a backwash pump and a backwash clear water tank. The backwash water inlet pipe connects the backwash clear water tank and the tank body. The backwash pump is connected to the backwash clear water tank and is used to drive the clear water in the backwash clear water tank into the tank body to backwash the packing layer.

8. The urban sewage deep treatment system according to claim 6, characterized in that: The backwash component also includes a backwash outlet pipe. The pool body is provided with an overflow trough, the overflow trough is located above the packing layer, and the backwash outlet pipe is connected to the overflow trough.

9. A sewage treatment process, implemented by the urban sewage deep treatment system according to any one of claims 1 to 8, characterized in that: The sewage treatment process comprises the following steps: Controlling the peracetic acid supplier to input peracetic acid into the oxidation tank; Inputting the sewage to be treated into the oxidation pond so that the sewage is mixed with peracetic acid; Continuously feeding peracetic acid and sewage into the oxidation tank simultaneously so that the sewage mixture passes through the activated carbon; The sewage treated with activated carbon flows into the packing layer in the denitrification biological filter from the outlet of the oxidation tank and contacts with the porous ceramsite on the packing layer. The clean water formed by the purification of the porous ceramsite is discharged from the outlet of the tank body.

10. The sewage treatment process according to claim 9, characterized in that: The mixed liquid after the sewage and the peracetic acid are mixed flows from the bottom of the oxidation pond to the top of the oxidation pond.

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