An oxidation ditch process based on influent mixing and global dissolved oxygen control

Abstract

The present application discloses an oxidation ditch process based on influent mixing and global dissolved oxygen control, which is used to accelerate the mixing of newly-incoming sewage and muddy water mixture and improve sewage treatment efficiency. The present application includes: oxidation ditch facilities and sedimentation tanks connected in sequence along the sewage flow direction, a loop corridor is provided in the oxidation ditch facility, a through-wall reflux pump is provided in the loop corridor, and a global aeration device is provided at the bottom of the loop corridor. The oxidation ditch process includes the following steps: setting the corresponding residence time, reflux ratio value and cultivating the corresponding biochemical bacteria according to the pollutant information in the pretreated water; introducing the pretreated water into the through-wall reflux pump of the oxidation ditch facility, mixing the pretreated water with the muddy water mixture in the loop corridor through the through-wall reflux pump and then pushing it to the loop corridor, removing the pollutants in the loop corridor and introducing it into the sedimentation tank for treatment, the upper clear liquid in the sedimentation tank is discharged after being treated to meet the standards, and the lower residual sludge is introduced into the sludge tank for treatment.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to an oxidation ditch process based on influent mixing and global dissolved oxygen control. Background Art

[0002] The oxidation ditch is an activated sludge treatment system. Its aeration tank is a closed ditch type. It is a circulating flow aeration ditch connected end to end, also known as a circulating aeration tank. Common oxidation ditch treatment processes include Orbell oxidation ditch, Pacewell oxidation ditch, Carrousel oxidation ditch, etc.

[0003] The entire process of the oxidation ditch sewage treatment process, such as water intake, aeration, sedimentation, sludge stabilization and water discharge, is all concentrated in the oxidation ditch and completed. There is a mud-water mixture of sludge and biochemical bacteria in the oxidation ditch. When the sewage circulates in the oxidation ditch, the pollutants in the sewage are removed by the biochemical bacteria contained in the mud-water mixture. In the water intake process, the water intake method of the prior art is direct water intake, that is, a specific water inlet is provided on the oxidation ditch, and the original mud-water mixture in the oxidation ditch keeps flowing at a certain speed. The sewage flows directly into the oxidation ditch through the water inlet and mixes with the flowing mud-water mixture. The sewage flows along the ditch on the oxidation ditch together with the mud-water mixture.

[0004] However, there are differences in density and flow between the mud-water mixture in the oxidation ditch and the newly incoming sewage, so the direct water intake method in the prior art is prone to stratification between the newly incoming sewage and the mud-water mixture. It takes a long time for the newly incoming sewage and the mud-water mixture to be fully mixed, which is not conducive to the contact between biochemical bacteria and the newly incoming sewage, thereby reducing the efficiency of sewage treatment. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides an oxidation ditch process based on influent mixing and global dissolved oxygen control, so as to accelerate the mixing of newly-incoming sewage and muddy water mixture and improve sewage treatment efficiency.

[0006] The present application provides an oxidation ditch process based on influent mixing and global dissolved oxygen control, including:

[0007] An oxidation ditch facility and a sedimentation tank are connected in sequence along the flow direction of sewage, wherein the oxidation ditch facility is provided with a loop corridor, a through-wall reflux pump is provided in the loop corridor, and a full-area aeration device is provided at the bottom of the loop corridor;

[0008] The oxidation ditch process specifically comprises the following steps:

[0009] S1: Pre-treating the sewage to obtain pre-treated water, detecting pollutant information contained in the pre-treated water, setting the residence time and reflow ratio of the pre-treated water according to the pollutant information, and cultivating corresponding biochemical bacteria in the mud-water mixture in the loop corridor;

[0010] S2: introducing the pretreated water into the through-wall return pump of the oxidation ditch facility, mixing the pretreated water with the forcibly extracted muddy water mixture through the through-wall return pump and pushing it to the loop gallery, and controlling the dissolved oxygen concentration in the loop gallery to be between 0 and 0.8 mg / L through the aeration device;

[0011] S3: adjusting the operating states of the through-the-wall reflux pump and the aeration device according to the reflux ratio value, controlling the pretreated water to circulate in the oxidation ditch facility for the retention time, and obtaining primary treated water after the pollutants in the pretreated water are removed by the biochemical bacteria;

[0012] S4: The primary treated water is introduced into the sedimentation tank by overflow, and an upper clear liquid and a lower sludge are formed by coagulation, sedimentation and filtration. The upper clear liquid is disinfected and discharged after the treatment meets the standards, and the lower sludge is introduced into the sludge tank for treatment.

[0013] Optionally, in step S4, before forming the supernatant and the lower sludge by coagulation, sedimentation and filtration, the oxidation ditch process further comprises:

[0014] Detect and determine whether there are residual pollutants in the primary treated water. If so, add reagents to the sedimentation tank according to the residual pollutants, and the reagents are used to remove the residual pollutants.

[0015] Optionally, in step S1, the detecting of pollutant information contained in the pretreated water includes:

[0016] A sample of the pre-treated water is collected, and the sample is tested by a pollutant detection device or manually tested to determine the pollutant information contained in the pre-treated water.

[0017] Optionally, in step S4, the oxidation ditch process further comprises:

[0018] The overflowing primary treated water is returned to the through-wall reflux pump of the oxidation ditch facility according to a preset ratio. The preset ratio represents the ratio of the pretreated water entering the oxidation ditch facility to the primary treated water returning into the oxidation ditch facility, and the ratio is 500% to 3000%:1.

[0019] Optionally, in step S2, the carbon source content in the circular corridor is detected by a carbon source detection device, and when the carbon source content is less than a preset value, the carbon source is added into the circular corridor by a carbon source dispenser.

[0020] Optionally, the carbon source is one or more of sodium acetate, glucose, methanol or biomass carbon sources.

[0021] Optionally, after step S4, the oxidation ditch process further comprises:

[0022] A preset amount of lower layer sludge is returned to the loop corridor through the sludge return pipe, and the sludge concentration in the loop corridor is maintained between 4000 and 8000 mg / L.

[0023] Optionally, in step S3, the denitrification process further comprises:

[0024] Controlling the operation of a gallery water flow booster located on the loop gallery and arranged diagonally to the through-wall reflux pump;

[0025] The operating state of the corridor water flow booster is adjusted according to the operating state of the through-wall return pump.

[0026] Optionally, the gallery water flow booster is a submersible flow booster or a submersible mixer.

[0027] Optionally, the aerator used in the aeration device is a microporous disc aerator or a microporous tube aerator.

[0028] It can be seen from the above technical solutions that this application has the following effects:

[0029] By introducing pre-treated water to the position of the through-the-wall return pump, the through-the-wall return pump will forcibly extract the muddy water mixture on the return corridor and mix it with the treated water before pushing it back to the return corridor. The through-the-wall return pump can achieve the mutual mixing of the newly entered sewage and the muddy water mixture, reduce the occurrence of stratification, and improve the efficiency of sewage treatment;

[0030] Secondly, the aeration device is used to aerate the entire area of ​​the circular corridor to stabilize the dissolved oxygen concentration range in the circular corridor, so that the aerobic bacteria in the biochemical bacteria can react to the pollutants in the sewage throughout the process, thereby further improving the sewage treatment efficiency;

[0031] In addition, the present application can set different corresponding reflow ratios, residence times and cultivate corresponding biochemical bacteria for different pollutants, and can cope with a variety of sewage types. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution in the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic diagram of an oxidation ditch process based on influent mixing and global dissolved oxygen control provided in this application;

[0034] Figure 2 Another schematic diagram of an oxidation ditch process based on influent mixing and global dissolved oxygen control provided in this application;

[0035] Figure 3 A schematic diagram of an oxidation ditch facility in an oxidation ditch process based on influent mixing and global dissolved oxygen control provided in this application. DETAILED DESCRIPTION

[0036] The present application provides an oxidation ditch process based on influent mixing and global dissolved oxygen control, which is used to accelerate the mixing of newly incoming sewage and muddy water mixture and improve sewage treatment efficiency.

[0037] See also Figures 1 to 3 The present application provides an oxidation ditch process based on influent mixing and global dissolved oxygen control, including:

[0038] An oxidation ditch facility 1 and a sedimentation tank 2 are sequentially connected along the flow direction of sewage, a loop corridor is provided in the oxidation ditch facility 1, a through-wall return pump 3 is provided in the loop corridor, and a full-area aeration device 4 is provided at the bottom of the loop corridor;

[0039] The oxidation ditch process specifically includes the following steps:

[0040] S1: Pre-treat the sewage to obtain pre-treated water, detect the pollutant information contained in the pre-treated water, set the residence time and reflow ratio of the pre-treated water according to the pollutant information, and cultivate the corresponding biochemical bacteria in the mud-water mixture in the loop corridor;

[0041] S2: Introduce the pretreated water into the through-wall return pump 3 of the oxidation ditch facility 1, mix the pretreated water with the forcedly extracted muddy water mixture through the through-wall return pump 3 and push it to the return gallery, and control the dissolved oxygen concentration in the return gallery to be between 0 and 0.8 mg / L through the aeration device 4;

[0042] S3: adjusting the operating states of the through-wall reflux pump 3 and the aeration device 4 according to the reflux ratio value, controlling the circulation residence time of the pre-treated water in the oxidation ditch facility 1, and obtaining primary treated water after removing pollutants in the pre-treated water by biochemical bacteria;

[0043] S4: The primary treated water is introduced into the sedimentation tank 2 by overflow, and an upper clear liquid and a lower sludge are formed by coagulation, sedimentation and filtration. The upper clear liquid is disinfected and discharged after the treatment meets the standards, and the lower sludge is introduced into the sludge tank 5 for treatment.

[0044] In the circular corridor, a barrier wall is set, and the through-wall return pump is located at the position of the barrier wall and crosses the barrier wall. The partition wall is used to slow down the flow rate of the mud-water mixture in the circular corridor. The sewage inlet and the through-wall return pump are both located behind the barrier wall in the sewage flow direction. Then the through-wall return pump forcibly extracts the mud-water mixture and the newly entered pretreated water. Through the action of the through-wall return pump, the pretreated water and the mud-water mixture are pushed into the circular corridor after mixing. In this way, the stratification between the newly entered sewage and the mud-water mixture is reduced in the circular corridor, which provides convenience for improving the sewage treatment efficiency.

[0045] The aeration device is set at the bottom of the whole area of ​​the loop corridor. When the mixture of pretreated water and muddy water flows to any position on the loop corridor, the aeration device can provide air to the pretreated water, thereby maintaining the oxygen content in the pretreated water and muddy water mixture. The biochemical bacteria cultured in the muddy water mixture are aerobic bacteria, which can consume pollutants in sewage in an aerobic environment, thereby achieving the effect of pollutant removal. Therefore, in this application, an aeration device is set in the whole area of ​​the loop corridor, and air is continuously transported into the mixture of pretreated water and muddy water mixture through the aeration device to maintain the dissolved oxygen concentration range between 0 and 0.8 mg / L, wherein the dissolved oxygen concentration should be greater than 0 mg / L.

[0046] It should be noted that the residence time is the time that the pre-treated water is in the oxidation ditch facility 1. Therefore, in step S3, the pre-treated water is controlled to circulate in the loop corridor for a period of time, which is the residence time set in step S1. For example, if the residence time is 8 hours, it means that the pre-treated water circulates in the oxidation ditch facility 1 for 8 hours and then is discharged from the oxidation ditch facility 1 by overflow.

[0047] In the present application, pretreated water is obtained by pretreatment of sewage. Pretreatment can achieve the removal of large particulate matter and floating matter through one or a combination of artificial grids, mechanical grids, drum grids, regulating tanks, and water collection tanks, and achieve uniform water quality and water volume balance; different pretreated waters contain different pollutants, such as one or more of nitrogen, phosphorus, ammonia, sulfide, petroleum pollutants, etc. Therefore, the pollutants in the pretreatment are detected, and the corresponding reflux ratio value, residence time and corresponding biochemical bacteria are cultured for the detected pollutants.

[0048] After the corresponding biochemical bacteria are cultivated, the pretreated water is introduced into the position of the through-wall reflux pump 3 of the oxidation ditch facility 1. The through-wall reflux pump 3 forcibly extracts the mud-water mixture in the circular corridor and mixes it with the pretreated water. The mixture is then pushed into the circular corridor, and then the aeration device 4 is controlled to perform full-area aeration of the circular corridor to maintain the dissolved oxygen concentration in the circular corridor between 0 and 0.8 mg / L.

[0049] The operation status of the through-wall reflux pump 3 and the aeration device 4 is controlled according to the pre-configured reflux ratio value, such as the operation power, operation time, operation speed, etc. The pre-treated water circulates in the oxidation ditch facility 1 for a certain residence time, and the pollutants are removed by biochemical bacteria to obtain primary treated water. The primary treated water is introduced into the sedimentation tank by overflow, and the upper clear liquid and the lower sludge are formed by coagulation, sedimentation and filtration. The upper clear liquid is disinfected and discharged after the treatment meets the standards, and the lower sludge is introduced into the sludge tank for treatment.

[0050] In the present application, in order to maintain the biochemical bacteria content and sludge content in the oxidation ditch facility 1, two coexisting reflow methods are provided, one is to return the overflowing primary treated water to the oxidation ditch facility 1, and the other is to return part of the sludge in the sedimentation tank 2 to the oxidation ditch facility 1. Therefore, at the water inlet position of the oxidation ditch facility 1, pretreated water and sludge flow in at the same time, and the overflowing primary treated water directly flows back to the position of the through-wall reflux pump 3.

[0051] In this embodiment, firstly, the pre-treated water is directly introduced into the position of the through-wall return pump 3 of the oxidation ditch facility 1, and the muddy water mixture is mixed with the pre-treated water by the through-wall return pump 3 and then pushed into the return corridor together, thereby reducing the occurrence of stratification, facilitating the full mixing of biochemical bacteria and pre-treated water, and thus improving the sewage treatment efficiency;

[0052] Secondly, the present application can configure corresponding reflux ratio values, residence time and culture corresponding biochemical bacteria for different pollutants, and can be applicable to the removal of a variety of pollutants.

[0053] In addition, the present application adopts full-area aeration. Compared with the intermittent aeration in the prior art, the present application can increase the activity of aerobic bacteria, thereby improving the sewage treatment efficiency.

[0054] Optionally, in the process of executing step S4, before the upper clear liquid and the lower sludge are formed in the sedimentation tank 2, the present application will also detect whether there are residual pollutants in the primary treated water, and the residual pollutants are not completely removed in the oxidation ditch facility 1 or cannot be removed by biochemical sludge. If there are, then according to the remaining pollutants, add a reagent to the sedimentation tank 2, and the reagent is used to remove the remaining pollutants in the primary treated water. For example, the pretreated water contains three pollutants A, B and C. After circulating through the oxidation ditch facility 1, the two pollutants A and B are removed, and the overflowing primary treated water contains pollutant C. At this time, after detection, a reagent that can remove pollutant C is added to the sedimentation tank 2 to achieve the removal of pollutant C.

[0055] Optionally, in step S1, detecting the pollutant information contained in the pretreated water includes: first collecting a sample of the pretreated water, and detecting the sample by a pollutant detection device or manually detecting the sample, so as to determine the pollutant information contained in the pretreated water.

[0056] Optionally, in step S4, the present application will also return the overflowing primary treated water to the through-wall reflux pump of the oxidation ditch facility according to a preset ratio. The preset ratio represents the ratio of the primary treated water returning into the oxidation ditch facility to the pretreated water entering the oxidation ditch facility, and the ratio is 500% to 3000%:1.

[0057] After the primary treated water flows out of the oxidation ditch facility 1 in an overflow manner, before entering the sedimentation tank 2, most of the primary treated water is returned to the position of the through-the-wall reflux pump of the oxidation ditch facility 1 through a pipeline reflux. The pipeline is directly connected to the through-the-wall reflux pump 3, and a water pump is provided in the pipeline. The water pump draws an appropriate proportion of the primary treated water and returns it to the through-the-wall reflux pump 3.

[0058] In this embodiment, both the pretreated water and the returned primary treated water enter the circular corridor from the water inlet on the oxidation ditch facility 1. The overflowing primary treated water contains sludge and biochemical bacteria. Returning most of the overflowing primary treated water to the oxidation ditch facility 1 can maintain the concentration of biochemical bacteria in the oxidation ditch facility 1 and ensure the ability of the oxidation ditch facility 1 to continuously remove pollutants.

[0059] Optionally, in step S2, the present application also detects the carbon source content in the circular corridor through a carbon source detection device. When the carbon source content is less than a preset value, the carbon source is added to the circular corridor through a carbon source dispenser. Actually, the carbon source detection device and the carbon source dispenser are both arranged on the oxidation ditch facility 1. According to the detection amount of the carbon source detection device, the carbon source dispenser can automatically set the appropriate amount of carbon source and automatically dispense it into the oxidation ditch facility 1.

[0060] Optionally, in a feasible manner, the carbon source introduced into the carbon source introducer is one or more of sodium acetate, glucose, methanol or biomass carbon sources.

[0061] Optionally, after step S4, the present application also returns a preset amount of lower sludge to the return corridor through the sludge return pipe, and maintains the sludge concentration in the return corridor between 4000 and 8000 mg / L, that is, when the sludge concentration is less than 4000 mg / L, part of the sludge in the sedimentation tank 2 is returned to the oxidation ditch facility 1 through the sludge return pipe. Among them, the sludge return pipe is connected to the sedimentation tank 2 and the oxidation ditch facility 1 respectively, and the sludge is returned to the water inlet position of the oxidation ditch facility 1. The pretreated water, mud-water mixture and sludge are mixed and pushed to the return corridor by the through-wall return pump 3, so that the amount of sludge in the oxidation ditch facility 1 can be maintained, the amount of sludge discharged can be reduced, and the cost of sludge treatment can be reduced. In addition, the amount of sludge reflux is determined according to the sludge discharge amount. For example, when the amount of sludge discharged by overflow is 100 kg / hour, then when refluxing, the amount of refluxed sludge is also set to 100 kg / hour.

[0062] Optionally, the present application further provides a corridor water flow booster 6 on the circular corridor, and the corridor water flow booster 6 is arranged diagonally to the through-wall reflux pump 3. Through the cooperation between the corridor water flow booster 6 and the through-wall reflux pump 3, the mud-water mixture and the pretreated water circulate in the circular corridor to form a double reflux circulation flow pattern. By setting the double reflux flow pattern, it is possible to cope with fluctuations in water quantity and quality, thereby improving the applicability to fluctuations in water quantity and quality.

[0063] In addition, it should be noted that the corridor water flow booster 6 is responsible for the pushing effect. When the scale of sewage treatment is large, multiple corridor water flow boosters 6 can be set in the circular corridor to maintain the fluidity of the liquid in the circular corridor through the cooperation of multiple corridor water flow boosters 6.

[0064] Optionally, in one practicable manner, the gallery water flow booster 6 is a submersible flow propeller or a submersible mixer.

[0065] Optionally, the aerator used in the aeration device of the present application is a microporous disc aerator, a microporous tube aerator, or a microporous hose aerator. In practice, aeration tubes are laid flat on the bottom of the circular corridor, and the aeration tubes are connected to the aerators. When the aerator is in operation, air is continuously transported into the circular corridor through the aeration tubes.

[0066] In the present application, the sewage treatment process can be unattended, and has a high ability to remove organic pollutants, especially denitrification. For example, when the present application is applied to sewage denitrification treatment, aerobic nitrifying bacteria and denitrifying bacteria are simultaneously cultivated in the mud-water mixture. After the sewage and the mud-water mixture are mixed, the sewage that has just completed the nitrification reaction is continuously aerated by the aeration device 4, so that the sewage immediately enters the denitrification stage in the loop corridor, and the oxidation of ammonia nitrogen is controlled in the nitrite stage, limiting NO2 ― Further oxidized to NO3 ― The denitrification process directly uses NO2 ― As an electron acceptor, it generates N2 under the action of the colony mainly composed of nitrite-containing microorganisms, thereby achieving the removal of total nitrogen in one step. In the oxidation ditch facility 1, nitrifying and denitrifying biochemical bacteria that coexist in the same environment are cultivated, and mud, water, and various organic matter are mixed more fully, thereby improving the sewage treatment efficiency.

[0067] In addition, in order to consider the operating costs and operating results, through measurement of actual operation, the daily sewage treatment volume of this application is at least 5,000 cubic meters.

[0068] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0069] It should be noted that the above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined herein can be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An oxidation ditch process based on influent mixing and global dissolved oxygen control, characterized in that: include: An oxidation ditch facility and a sedimentation tank are connected in sequence along the flow direction of sewage, wherein the oxidation ditch facility is provided with a loop corridor, a through-wall reflux pump is provided in the loop corridor, and a full-area aeration device is provided at the bottom of the loop corridor; The oxidation ditch process specifically comprises the following steps: S1: Pre-treating the sewage to obtain pre-treated water, detecting pollutant information contained in the pre-treated water, setting the residence time and reflow ratio of the pre-treated water according to the pollutant information, and cultivating corresponding biochemical bacteria in the mud-water mixture in the loop corridor; S2: introducing the pretreated water into the through-wall return pump of the oxidation ditch facility, mixing the pretreated water with the forcibly extracted muddy water mixture through the through-wall return pump and pushing it to the loop gallery, and controlling the dissolved oxygen concentration in the loop gallery to be between 0 and 0.8 mg / L through the aeration device; S3: adjusting the operating states of the through-the-wall reflux pump and the aeration device according to the reflux ratio value, controlling the pretreated water to circulate in the oxidation ditch facility for the retention time, and obtaining primary treated water after the pollutants in the pretreated water are removed by the biochemical bacteria; S4: The primary treated water is introduced into the sedimentation tank by overflow, and an upper clear liquid and a lower sludge are formed by coagulation, sedimentation and filtration. The upper clear liquid is disinfected and discharged after the treatment meets the standards, and the lower sludge is introduced into the sludge tank for treatment.

2. The oxidation ditch process according to claim 1, characterized in that: In step S4, before forming the supernatant and the lower sludge by coagulation, sedimentation and filtration, the oxidation ditch process further comprises: Detect and determine whether there are residual pollutants in the primary treated water. If so, add reagents to the sedimentation tank according to the residual pollutants, and the reagents are used to remove the residual pollutants.

3. The oxidation ditch process according to claim 1 or 2, characterized in that: In step S1, the detection of pollutant information contained in pre-treated water includes: A sample of the pre-treated water is collected, and the sample is tested by a pollutant detection device or manually tested to determine the pollutant information contained in the pre-treated water.

4. The oxidation ditch process according to claim 1 or 2, characterized in that: In step S4, the oxidation ditch process further comprises: The overflowing primary treated water is returned to the through-wall reflux pump of the oxidation ditch facility according to a preset ratio. The preset ratio represents the ratio of the pretreated water entering the oxidation ditch facility to the primary treated water returning into the oxidation ditch facility, and the ratio is 500% to 3000%:

1.

5. The oxidation ditch process according to claim 1 or 2, characterized in that: In step S2, the carbon source content in the circular corridor is detected by a carbon source detection device. When the carbon source content is less than a preset value, a carbon source is added into the circular corridor by a carbon source dispenser.

6. The oxidation ditch process according to claim 5, characterized in that: The carbon source is one or more of sodium acetate, glucose, methanol or biomass carbon sources.

7. The oxidation ditch process according to claim 1 or 2, characterized in that: After step S4, the oxidation ditch process further comprises: A preset amount of lower layer sludge is returned to the loop corridor through the sludge return pipe, and the sludge concentration in the loop corridor is maintained between 4000 and 8000 mg / L.

8. The oxidation ditch process according to claim 1 or 2, characterized in that: In step S3, the oxidation ditch process further comprises: Controlling the operation of a gallery water flow booster located on the loop gallery and arranged diagonally to the through-wall reflux pump; The operating state of the corridor water flow booster is adjusted according to the operating state of the through-wall return pump.

9. The oxidation ditch process according to claim 8, characterized in that: The gallery water flow booster is a submersible flow booster or a submersible agitator.

10. The oxidation ditch process according to claim 1 or 2, characterized in that: The aerator used in the aeration device is a microporous disc aerator or a microporous tube aerator.

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