An advanced treatment system for urban sewage and a sewage treatment process

Abstract

The present invention discloses an advanced urban sewage treatment system and a sewage treatment process, which relate to the technical field of sewage treatment. The advanced urban sewage treatment system includes an oxidation component and a denitrifying biological filter. The oxidation component includes an oxidation tank, activated carbon, and a peracetic acid feeder. The activated carbon is located in the oxidation tank, and the peracetic acid feeder is connected to the oxidation tank and is used to input peracetic acid into the oxidation tank. The denitrifying biological filter includes a tank body and a packing layer. The tank body is connected to the oxidation tank, and the packing layer is arranged in the tank body. The packing layer is located below the water outlet of the oxidation tank and is composed of a plurality of porous ceramsites. The peracetic acid feeder can input peracetic acid into the oxidation tank. Peracetic acid can oxidize the refractory organic pollutants in the sewage into organic pollutants that are easily utilized by microorganisms. At the same time, peracetic acid is converted into acetic acid. After the acetic acid flows into the denitrifying biological filter, it can provide a carbon source for the subsequent denitrification process, so that the sewage can be deeply purified.

Description

Technical Field

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

[0002] In addition to nitrogen, phosphorus, and common organic substances, new pollutants composed of antibiotics, endocrine disruptors, etc. have become important problems in water pollution control. With the release of increasingly strict pollutant discharge control standards, the commonly used secondary biochemical treatment process in sewage treatment plants is difficult to meet the need for advanced sewage purification. Therefore, seeking advanced purification technologies for sewage treatment plants that are efficient, low-consumption, and have no secondary pollution is a research hotspot in the field of water treatment today. Commonly used advanced treatment processes include the ozone / biofilter process, which has both the functions of complex pollutant degradation and by-product control. However, the excessive oxidation of ozone often causes unnecessary energy consumption and leads to the subsequent biofilter being difficult to meet the need for advanced denitrification due to insufficient carbon source, and the ozone control and management concentration is relatively large.

[0003] Although peracetic acid can remove pollutants in sewage through its strong oxidation ability, peracetic acid itself also has certain corrosiveness. After the first-round treatment of sewage with peracetic acid, it will flow into the denitrifying biofilter along with the sewage, causing harm to the organisms in the denitrifying biofilter, thereby affecting the further treatment effect of the organisms in the denitrifying biofilter on the sewage. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, and propose an advanced urban sewage treatment system and a sewage treatment process to solve the technical problems in the prior art that peracetic acid has a pungent smell, strong oxidizing property, and the oxidation by-product acetic acid is likely to introduce organic substances into water, causing a certain ecological threat to the water body, thereby restricting its application in sewage treatment plants.

[0005] To achieve the above technical purpose, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides an advanced urban sewage treatment system, including:

[0007] An oxidation component, including an oxidation tank, activated carbon, and a peracetic acid feeder. The activated carbon is located in the oxidation tank, and the peracetic acid feeder is connected to the oxidation tank and is used to input peracetic acid into the oxidation tank; and

[0008] A denitrifying biofilter, including a tank body and a filler layer. The tank body is connected to the oxidation tank. The filler layer is connected to the side wall of the tank body and encloses a channel for water to enter with the bottom inner wall of the tank body. The filler layer is located below the water outlet of the oxidation tank, and the filler layer is composed of a plurality of porous ceramsites.

[0009] In some embodiments, the oxidation assembly further includes a first supporting layer disposed 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 feeder, and the treatment zone is filled with the activated carbon.

[0010] In some embodiments, the top of the oxidation tank has a water overflow weir and a water outlet channel. The treatment zone is located between the pre-oxidation zone and the water overflow weir, and the water outlet channel is located above the packing layer.

[0011] In some embodiments, the oxidation assembly further includes a flow divider. The flow divider 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 feeder, and the second chamber is used to connect to the sewage pipe.

[0012] In some embodiments, the pool body is provided with a water outlet weir. The water outlet weir is located between the water outlet of the oxidation tank and the packing layer. An overflow trough is formed in the middle part of the water outlet weir, and purification troughs are formed on both sides. When the sewage in the overflow trough is full, the sewage can overflow and flow into the purification troughs on both sides. A plurality of zero-valent irons are provided on the trough walls of the purification troughs, and the zero-valent irons can degrade the organic matter in the sewage.

[0013] In some embodiments, the denitrifying biological filter further includes a purified water drain pipe and an anti-flushing assembly. The purified water drain pipe is connected to the water outlet of the pool body. The anti-flushing assembly is connected in parallel to the purified water drain pipe and is used to introduce clean water into the pool body through the purified water drain pipe to flush the packing layer.

[0014] In some embodiments, the anti-flushing assembly includes an anti-flushing inlet pipe, an anti-flushing pump, and an anti-flushing clean water tank. The anti-flushing inlet pipe connects the anti-flushing clean water tank and the pool body. The anti-flushing pump is connected to the anti-flushing clean water tank and is used to drive the clean water in the anti-flushing clean water tank into the pool body to perform anti-flushing on the packing layer.

[0015] In some embodiments, the anti-flushing assembly further includes an anti-flushing outlet pipe. The pool body is provided with an overflow trough. The overflow trough is located above the packing layer. The anti-flushing outlet pipe is connected to the overflow trough.

[0016] In a second aspect, the present invention also provides a sewage treatment process, which is realized by the above-mentioned urban sewage advanced treatment system. It is characterized in that the sewage treatment process includes the following steps:

[0017] Controlling the peracetic acid feeder to input peracetic acid into the oxidation tank;

[0018] Input the sewage to be treated into the oxidation pond so that the sewage is mixed with peracetic acid;

[0019] Continuously input peracetic acid and sewage into the oxidation pond at the same time so that the sewage mixture passes through activated carbon;

[0020] The sewage treated by activated carbon flows from the water outlet of the oxidation pond into the packing layer in the denitrifying biological filter and contacts the porous ceramsite on the packing layer. The clean water formed by the purification of the porous ceramsite is discharged from the water outlet of the pond body.

[0021] In some embodiments, the mixed liquid after the sewage is mixed with peracetic acid flows from the lower part of the oxidation pond towards the upper part of the oxidation pond.

[0022] Compared with the prior art, the peracetic acid feeder of the urban sewage advanced treatment system provided by the present invention can input peracetic acid into the oxidation pond. Peracetic acid can oxidize the refractory organic pollutants in the sewage into organic pollutants that are easily utilized by microorganisms through its strong oxidizing property. Activated carbon can be used as a green and non-toxic environmental protection catalyst to activate peracetic acid, so as to improve the degradation ability of peracetic acid to sewage. At the same time, peracetic acid is converted into acetic acid, and acetic acid will not harm the active organisms on the surface of the porous ceramsite in the denitrifying biological filter. After flowing into the denitrifying biological filter, acetic acid can also provide a carbon source for the subsequent denitrification process. Through the denitrification of the active organisms on the surface of the porous ceramsite, the efficient denitrification of sewage and the removal of refractory organic matter in the sewage are finally realized, so that the sewage can be deeply purified. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of the urban sewage advanced treatment system provided by the embodiment of the present invention;

[0024] Figure 2 is a schematic top view of the connection between the oxidation pond and the denitrifying biological filter provided by the embodiment of the present invention.

[0025] Figure 3 is a schematic structural diagram of the water outlet weir provided by the embodiment of the present invention;

[0026] Figure 4 is a schematic structural diagram of another embodiment of the porous ceramsite provided by the embodiment of the present invention. Detailed Embodiments

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0028] To solve the technical problem that peracetic acid in the prior art has certain corrosiveness, which will cause harm to the organisms in the subsequent denitrifying biological filter, thus affecting the further treatment effect of the subsequent denitrifying biological filter on sewage, the present invention provides an advanced treatment system for urban sewage, which can generate acetic acid while preliminarily purifying the sewage. Acetic acid will not only not harm the active organisms on the surface of the porous ceramsite in the denitrifying biological filter, but also can provide a carbon source for the subsequent sewage denitrification treatment. Through the denitrification of the active organisms on the surface of the porous ceramsite, the advanced purification of sewage is finally realized.

[0029] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the advanced treatment system for urban sewage in an embodiment of the present invention. The advanced treatment system for urban sewage includes an oxidation component and a denitrifying biological filter. The oxidation component includes an oxidation tank 1, activated carbon 2, and a peracetic acid feeder 3. The activated carbon 2 is located in the oxidation tank 1, and the peracetic acid feeder 3 is connected to the oxidation tank 1 and is used to input peracetic acid into the oxidation tank 1.

[0030] The denitrifying 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 encloses a water outlet channel with the inner wall of the bottom of the tank body 4, so that the 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 ceramsites 6.

[0031] In this embodiment, the substances that have a purification effect on sewage are mainly peracetic acid, activated carbon 2, and porous ceramsite 6. Among them, peracetic acid can destroy the chemical structure of organic pollutants in sewage through its strong oxidizing property, and oxidize the refractory organic pollutants in sewage into organic pollutants that are easy to be utilized by microorganisms. In addition to adsorbing pollutants in sewage, activated carbon 2 can also activate peracetic acid to improve the purification ability of peracetic acid for sewage. The porous ceramsite 6 uses the microorganisms adsorbed on it to treat the remaining organic matter in the oxidation tank 1. After the sewage enters the oxidation tank 1, it first mixes with the peracetic acid in the oxidation tank 1. The mixed liquid contacts the activated carbon 2. While the activated carbon 2 adsorbs and purifies the sewage, it also activates the peracetic acid to improve the purification ability of peracetic acid. After peracetic acid treats the sewage, acetic acid is formed. Acetic acid has no corrosiveness and will not harm the organisms in the denitrifying biological filter, so that the organisms can participate in the denitrification reaction and deeply treat the sewage.

[0032] The peracetic acid feeder 3 is provided with a dosing pump 31. The dosing pump 31 is connected to the oxidation tank 1 through a liquid inlet pipe 32. When the dosing pump 31 is working, it can drive the peracetic acid in the peracetic acid feeder 3 to be input into the oxidation tank 1 through the liquid inlet pipe 32 to purify the sewage in the oxidation tank 1.

[0033] The activated carbon is partitioned and set in the oxidation tank 1 according to different particle sizes. Please refer to Figure 1 , there are mainly three particle sizes of activated carbon. From the bottom to the top of the oxidation tank 1, the particle size of the activated carbon gradually increases. The activated carbon at the bottom uses small particle size powdered activated carbon (100 mesh), the activated carbon in the middle area uses large particle size powder (60 mesh), and the top uses block-shaped activated carbon. The small particle size activated carbon has good adsorption and catalytic oxidation effects. However, it is prone to swelling and loss during operation. Through hierarchical stratification, it is beneficial for the activated carbon at the bottom to remain in the oxidation tank and reduce the loss of activated carbon.

[0034] In one embodiment, please refer to Figure 1 , the oxidation component further includes a first support layer 11 arranged inside the oxidation tank 1. The first support layer 11 divides the inside of the oxidation tank 1 into a pre-oxidation area 12 and a treatment area 13. The pre-oxidation area 12 is connected to the peracetic acid feeder 3, and the treatment area 13 is filled with activated carbon 2. The first support layer 11 in this embodiment is mainly used to support the activated carbon 2. In addition, the first support layer 11 can be used for sewage and peracetic acid to penetrate and enter the treatment area 13 to contact the activated carbon 2.

[0035] In one embodiment, please refer to Figure 1 and Figure 2 , the top of the oxidation tank 1 has a water overflow weir 14 and an outlet channel 15. The treatment area 13 is located between the pre-oxidation area 12 and the water overflow weir 14. The outlet channel 15 is inclined, and the higher and lower parts are respectively connected to the water overflow weir 14 and the outlet weir 42. The outlet channel 15 is located above the packing layer 5. In this embodiment, after the sewage is treated by the activated carbon 2, it flows into the water overflow weir 14. The outlet channel 15 is inclined, and the sewage flows from the higher part of the water overflow weir 14 to the lower part, flows into the outlet channel 15, and then flows from the outlet channel 15 into the tank body 4 of the denitrifying biological filter, contacts the porous ceramsite 6 of the packing layer 5, and performs deep purification treatment on the sewage.

[0036] In one embodiment, please refer to Figure 1 , the oxidation component further includes a shunt member 16. The shunt member 16 is located in the pre-oxidation area 12 and divides the pre-oxidation area 12 into a first chamber and a second chamber. The first chamber is located between the treatment area 13 and the second chamber. The first chamber is connected to the peracetic acid feeder 3, and the second chamber is used to connect the sewage pipe 17. The sewage to be treated flows into the second chamber through the sewage pipe 17. In this embodiment, the peracetic acid output by the peracetic acid feeder 3 enters the first chamber through the inlet pipe. The sewage in the sewage pipe 17 enters the second chamber. As the second chamber is filled with sewage, the liquid level of the sewage gradually rises, and the sewage passes through the shunt member 16 into the first chamber and mixes with the peracetic acid in the first chamber. The shunt member 16 has a plurality of water passing holes arranged evenly in an array. The sewage in the second chamber can simultaneously pass through a plurality of water passing holes and flow into the first chamber to fully mix with the peracetic acid in the first chamber, so as to improve the purification efficiency of the sewage.

[0037] In one embodiment, please refer to Figure 1 , a water outlet weir 42 is arranged at a position near the top in the pond body 4. The water outlet weir 42 straddles the pond body 4. The water outlet weir 42 is arc-shaped and is internally provided with an overflow groove 421. The overflow groove 421 communicates with the outlet of the water outlet channel 15, so that all the water flowing out from the water outlet channel 15 can flow into the overflow groove 421. After 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 pond body 4, so that the sewage can flow evenly to the packing layer 5, and the sewage can be fully purified.

[0038] Purification grooves 422 are formed on both sides of the water outlet weir 42. After the sewage in the overflow groove 421 is full, it overflows and flows into the purification grooves 422. A plurality of zero-valent irons 423 are arranged on the groove walls of the purification grooves 422. The zero-valent irons 423 can degrade the organic matter in the sewage and can also remove the residual peracetic acid, so as to prevent the residual peracetic acid in the sewage from flowing into the pond body 4.

[0039] First water guiding inclined surfaces 43 and second water guiding inclined surfaces 44 which are inclined are arranged on both sides of the water outlet weir 42. The sewage flowing out from the purification grooves 422 can flow into the packing layer 5 at the lower part of the pond body 4 from the first water guiding inclined surface 43 and the second water guiding inclined surface 44, so that the sewage can flow evenly to the packing layer 5, and the sewage can be fully purified.

[0040] In one embodiment, please refer to Figure 1 , the denitrifying biological filter further includes a purified water drain pipe 7 and an anti-flushing assembly 8. The purified water drain pipe 7 is connected to the water outlet of the pond body 4. The anti-flushing assembly 8 is connected in parallel to the purified water drain pipe 7 and is used to flush the packing layer 5 by introducing clean water into the pond body 4 through the purified water drain pipe 7. In this embodiment, the clean water formed after the sewage is purified in the pond body 4 can be discharged through the water outlet of the pond body 4. A part of the clean water is discharged through the purified water drain pipe 7, and another part of the clean water is discharged into the anti-flushing assembly 8, so that the anti-flushing assembly 8 can re-introduce the clean water into the pond body 4 to flush the packing layer 5 of the pond body 4 and discharge the pollutants on the surface of the packing layer 5 outside the pond body 4. The clean water continuously increases in the pond body 4 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. The liquid level continues to rise until it reaches another drain port of the pond body 4, and the pollutants can be discharged from this drain port. After the pollutants are discharged, the clean water can be discharged from the water outlet at the bottom of the pond body 4 to the anti-flushing assembly 8 again for secondary utilization. The purified water drain pipe 7 is provided with a first on-off valve 71. By controlling the opening or closing of the first on-off valve 71, it is possible to control the discharge or non-discharge of the clean water in the pond body 4.

[0041] In one embodiment, please refer to Figure 1, the backwashing assembly 8 includes a backwashing water inlet pipe 81, a backwashing pump 82 and a backwashing clean water tank 83. The backwashing water inlet pipe 81 connects the backwashing clean water tank 83 and the tank body 4. The backwashing pump 82 is connected to the backwashing clean water tank 83 and is used to drive the clean water in the backwashing clean water tank 83 into the tank body 4 to backwash the packing layer 5. In this embodiment, the backwashing clean water tank 83 is used to store clean water, and the backwashing pump 82 is used to drive the clean water in the backwashing clean water tank 83 to flow into the tank body 4 through the backwashing water inlet pipe 81 to wash the packing layer 5 of the tank body 4 and discharge the pollutants on the surface of the packing layer 5 outside the tank body 4.

[0042] A second switch valve 811 is provided on the backwashing water inlet pipe 81. When the second switch valve 811 is closed and the first switch valve 71 is opened, all the clean water in the tank body 4 can pass through the clean water drain pipe 7 and be discharged. When the second switch valve 811 is opened and the first switch valve 71 is closed, all the clean water in the tank body 4 can be discharged into the backwashing clean water tank 83 through the backwashing water inlet pipe 81. In actual operation, part of the clean water can be discharged through the clean water drain pipe 7 by opening the first switch valve 71 and closing the second switch valve 811 first, and then the first switch valve 71 is closed and the second switch valve 811 is opened to discharge another part of the clean water into the backwashing clean water tank 83 through the backwashing water inlet pipe 81.

[0043] In one embodiment, please refer to Figure 1 , the backwashing assembly 8 further includes a backwashing water outlet pipe 84. The tank body 4 is provided with a water outlet groove 41. The water outlet groove 41 is located above the packing layer 5, and the backwashing water outlet pipe 84 is connected to the water outlet groove 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 level of the clean water until the liquid level reaches the water outlet groove 41, and the pollutants on the liquid level are discharged from the water outlet groove 41 through the backwashing water outlet pipe 84. In addition, the position of the water outlet groove 41 is arranged in a staggered manner with the above-mentioned water outlet weir 42 to prevent the sewage overflowing from the water outlet weir 42 from directly flowing into the water outlet groove 41.

[0044] In one embodiment, please refer to Figure 1 , the urban sewage advanced treatment system further includes a reflux detection assembly. The reflux detection assembly is used to detect the water discharged from the clean water drain pipe 7. If it is detected that the target pollutant exceeds the standard, the water will be refluxed to the oxidation tank 1 or the biological filter for continuous purification until the detection is qualified; if it is detected that the target pollutant is qualified, the water discharge will be controlled.

[0045] The reflux detection assembly includes a detector 51, a main reflux pipe 52, a first branch pipe 53, a second branch pipe 54, and a drain pipe 55. The first branch pipe 53 connects the main reflux 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 main reflux pipe 52 and the tank body 4, and a second valve 541 is provided on the second branch pipe 54. The main reflux pipe 52 is connected to the water outlet end of the purified water drain pipe 7 to receive the water discharged from the purified water drain pipe 7. The detector 51 is arranged on the main reflux pipe 52 and is used to detect the water discharged from the purified 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 so that the water is discharged.

[0046] 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 tank 1 again for purification together with the sewage in the sewage pipe 17, and appropriately controls the peracetic acid feeder 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 tank body 4 again for purification. A water pump 56 can also be installed on the main reflux pipe 52 to facilitate quickly sending the water after being detected by the detector 51 to the oxidation tank 1 or the tank body 4.

[0047] In a second aspect, the present invention also provides a sewage treatment process, which is implemented by the above-mentioned advanced urban sewage treatment system. The sewage treatment process includes the following steps:

[0048] Control the peracetic acid feeder 3 to input peracetic acid into the oxidation tank 1; the input content of peracetic acid needs to be adapted to the content of the sewage to avoid having excess peracetic acid in the oxidation tank 1.

[0049] Input the sewage to be treated into the oxidation tank 1 so that the sewage is mixed with peracetic acid; when peracetic acid is initially mixed with the sewage, it can destroy the chemical structure of the organic pollutants in the sewage and oxidize the refractory organic pollutants in the sewage into organic pollutants that are easily utilized by microorganisms.

[0050] Continuously input peracetic acid and sewage into the oxidation tank 1 at the same time so that the sewage and peracetic acid mixture pass through the activated carbon 2; the activated carbon 2 adsorbs the pollutants in the sewage and activates the peracetic acid, improving the purification ability of peracetic acid for the sewage and enhancing the purification efficiency.

[0051] The sewage treated by activated carbon 2 flows into the packing layer 5 in the denitrifying biological filter from the water outlet of the oxidation tank 1, and contacts with the porous ceramsite 6 on the packing layer 5. The clean water formed after purification by the porous ceramsite 6 is discharged from the water outlet of the tank body 4. The porous ceramsite 6 uses the microorganisms adsorbed on it to biodegrade the remaining organic matter in the sewage and simultaneously cooperate in nitrogen removal.

[0052] In other embodiments, please refer to Figure 4 , the tank body 4 can also adopt a filter packing layer in the form of a mixture of iron / ceramsite, with the ratio of iron to ceramsite being 1:10. The ceramsite 61 serves as the attachment carrier for microorganisms, and its main function is to absorb COD and TN in the sewage through microorganisms. The iron 62 is zero-valent iron particles, and it has two main functions: one is an insurance measure. The unreacted oxidant from the oxidation zone may pose a threat to microorganisms, and adding zero-valent iron is beneficial for fully reducing the unreacted oxidant and reducing the harm to the organisms in the tank body 4; the other is to play an electron transfer role and promote 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.

[0053] In one of the embodiments, please refer to Figure 1 , the mixed liquid after mixing the sewage with peracetic acid flows from the lower part to the upper part of the oxidation tank 1, so that the sewage and peracetic acid can fully contact with the activated carbon. The activated carbon fully activates the peracetic acid and fully adsorbs the pollutants in the sewage to further improve the purification effect of the sewage.

[0054] The following uses actual tests to illustrate the feasibility of the sewage advanced treatment system of the present application in purifying sewage.

[0055] Experimental conditions: PH = 7

[0056] Specific implementation method: First, form biological activated carbon (BAC) by hanging a film on granular activated carbon (GAC), and based on this, construct a continuous flow reactor, which is divided into an oxidation zone and a biological zone. The oxidation zone uses GAC as the packing, and the biological zone uses BAC as the packing. The residence time in the oxidation zone is 4 min, and the residence time in the biological zone is 5 min. Using sulfamethoxazole SMX as the representative pollutant, detectors are respectively set at the water inlet of the oxidation tank 1 and the water outlet of the biological filter to detect various water quality indicators of the influent and effluent.

[0057] Example 1 (PAA - GAC / BAC): Add the oxidant peracetic acid (PAA) to the influent of the oxidation zone, control the residence time in the oxidation zone to be 4 min, the PAA concentration to be 100 μmol / L, the SMX concentration to be 10 μmol / L, and the TN to be 20 mg / L. The residence time in the biological zone is 5 min. Data for the first day, the third day, the fifth day, and the seventh day are respectively counted.

[0058] Example 2 (GAC / BAC): Different from Example 1, PAA was not added in Example 2 to form a control group with Example 1 to compare the influence of the adsorption effect. The residence time of the sewage in the adsorption zone was controlled to be 4 min, and the residence time in the biological zone was 5 min. In the sewage to be treated, the SMX concentration was 10 μmol / L and the TN concentration was 20 mg / L. The data on the first day, the third day, the fifth day, and the seventh day were respectively counted.

[0059] From the above treatment results, it can be seen that after continuous treatment for 7 days, the stable removal rates of pollutants in the sewage were:

[0060] The TOC (total organic carbon) removal rate of Example 1 was 67.4%, and the TOC removal rate of Example 2 was 55.1%.

[0061] The TN (total nitrogen) removal rate of Example 1 was 47.1%, and the TN removal rate of Example 2 was 12.7%.

[0062] The SMX removal rate of Example 1 was 73.0%, and the SMX removal rate of Example 2 was 28.7%.

[0063] To better understand the present invention, the following is combined with Figures 1 to 4 to detail the technical solution of the present invention:

[0064] The urban sewage advanced treatment system provided by the present invention has a peracetic acid feeder 3 that can input peracetic acid into the oxidation tank 1. Peracetic acid can oxidize the refractory organic pollutants in the sewage into organic pollutants that are easily utilized by microorganisms through its strong oxidizing property. Activated carbon 2 can be used as a green and non-toxic environmental protection catalyst to activate peracetic acid, so as to improve the degradation ability of peracetic acid to sewage. At the same time, peracetic acid is converted into acetic acid, and acetic acid will not cause harm to the organisms in the denitrifying biological filter. After flowing into the denitrifying biological filter, acetic acid can also provide a carbon source for the subsequent denitrification process. Through the denitrification of the surface activated sludge of the porous ceramsite 6, the efficient denitrification of sewage and the removal of refractory organic matter in the sewage are finally realized, so that the sewage can be deeply purified.

[0065] The above specific embodiments of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An advanced treatment system for urban sewage, characterized in that, Comprising: An oxidation assembly, including an oxidation tank, activated carbon, and a peracetic acid feeder. The activated carbon is located in the oxidation tank, and the peracetic acid feeder is connected to the oxidation tank and used to input peracetic acid into the oxidation tank. And A denitrifying biological filter, including a tank body and a filler layer. The tank body is connected to the oxidation tank. The filler layer is connected to the side wall of the tank body and encloses a channel for water to enter with the inner wall of the bottom of the tank body. The filler layer is located below the water outlet of the oxidation tank and is composed of multiple porous ceramsites. The tank body is provided with an overflow weir, which is located between the water outlet of the oxidation tank and the filler layer. An overflow groove is opened in the middle part of the overflow weir, and purification grooves are opened on both sides. When the sewage in the overflow groove is full, the sewage can overflow and flow into the purification grooves on both sides. A plurality of zero-valent irons are arranged on the groove walls of the purification grooves, and the zero-valent irons can degrade the organic matter in the sewage.

2. The advanced treatment system for urban sewage according to claim 1, wherein The oxidation assembly further 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 area and a treatment area. The pre-oxidation area is communicated with the peracetic acid feeder, and the treatment area is filled with the activated carbon.

3. The advanced treatment system for municipal wastewater according to claim 2, wherein The top of the oxidation tank has a water passing weir and a water outlet channel. The treatment area is located between the pre-oxidation area and the water passing weir, and the water outlet channel is located above the filler layer.

4. The advanced treatment system for municipal wastewater according to claim 2, characterized in that The oxidation assembly further includes a flow dividing member, which is located in the pre-oxidation area and divides the pre-oxidation area into a first chamber and a second chamber. The first chamber is located between the treatment area and the second chamber. The first chamber is communicated with the peracetic acid feeder, and the second chamber is used to communicate with a sewage pipe.

5. The advanced treatment system for municipal wastewater according to claim 1, characterized in that, The denitrifying biological filter further includes a purified water drain pipe and an anti-flushing assembly. The purified water drain pipe is connected to the water outlet of the tank body. The anti-flushing assembly is connected in parallel to the purified water drain pipe and is used to flush the filler layer by introducing clean water into the tank body through the purified water drain pipe.

6. The advanced urban sewage treatment system according to claim 5, characterized in that The anti-flushing assembly includes an anti-flushing inlet pipe, an anti-flushing pump, and an anti-flushing clean water tank. The anti-flushing inlet pipe is connected to the anti-flushing clean water tank and the tank body. The anti-flushing pump is connected to the anti-flushing clean water tank and is used to drive the clean water in the anti-flushing clean water tank into the tank body to anti-flush the filler layer.

7. The advanced treatment system for municipal wastewater according to claim 5, wherein The anti-flushing assembly further includes an anti-flushing outlet pipe. The tank body is provided with an overflow groove, which is located above the filler layer. The anti-flushing outlet pipe is connected to the overflow groove.

8. A sewage treatment process is realized by the advanced treatment system for municipal sewage as described in any one of claims 1 - 7, characterized in that, The sewage treatment process includes the following steps: Controlling the peracetic acid feeder to input peracetic acid into the oxidation tank; Inputting the sewage to be treated into the oxidation tank so that the sewage is mixed with peracetic acid; Continuously inputting peracetic acid and sewage into the oxidation tank at the same time so that the sewage mixture passes through the activated carbon; The sewage treated by the activated carbon flows from the water outlet of the oxidation tank into the filler layer in the denitrifying biological filter and contacts the porous ceramsites on the filler layer. The clean water formed by the purification of the porous ceramsites is discharged from the water outlet of the tank body.

9. The sewage treatment process according to claim 8, characterized in that, The mixed liquid after the sewage is mixed with peracetic acid flows from the lower part of the oxidation tank towards the upper part of the oxidation tank.

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