A BAF aeration pipe and a method for removing COD by BAF denitrification

Abstract

The invention discloses a BAF aeration pipe and a method for removing COD by BAF denitrification, belonging to the field of sewage treatment, comprising an aeration pipeline, the aeration pipeline comprising a loop main pipe and an underwater suspension main pipe, the underwater suspension main pipe and the loop main pipe are interconnected, the underwater suspension main pipe is arranged above the loop main pipe, the loop main pipe is provided with an aeration branch pipe, two rows of aeration holes are arranged above the aeration branch pipe, and the aeration pipes are arranged densely in the middle and sparsely on both sides. The invention improves the aeration volume and aeration uniformity, improves the sewage treatment effect, and flange connection is adopted between the pipes, which is convenient for subsequent maintenance and overhaul.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a BAF aeration pipe and a method for removing COD by BAF denitrification. Background Art

[0002] Aeration is a commonly used method in sewage treatment, which refers to forced oxygenation in sewage. Its purpose is to make sewage obtain enough dissolved oxygen, strengthen the contact between organic matter in the pool and microorganisms and dissolved oxygen, so as to ensure that the microorganisms in the pool can oxidize and decompose organic matter in sewage under the condition of sufficient dissolved oxygen. The BAF process began to be applied and emerged in European and American countries in the 1980s, and has since been widely studied and applied worldwide. It is a new type of biofilm sewage treatment process. The BAF section is an important means of removing TN and NH3-N in the treatment system, and it also realizes the effects of biodegradation and adsorption filtration. The water quality of the BAF section directly affects the effluent quality.

[0003] The uniformity of aeration has an important impact on BAF. Uniform bubbles can stir the filter layer, so that the biofilm around the filter is continuously in an aerobic environment, which can increase the oxygen concentration gradient on the surface of the biofilm and increase the mass transfer efficiency of oxygen in the biofilm, thereby promoting the transformation of organic matter by microorganisms and the removal of nitrogen-containing compounds. Uneven distribution of aeration volume will cause anaerobic phenomena in part of the pool body and turbulence in part. The pipeline layout of the existing BAF aeration pipe is unreasonable, and the opening setting on the aeration pipe is unreasonable, resulting in uneven aeration and inconvenient subsequent maintenance. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a BAF aeration pipe and a method for removing COD by BAF denitrification.

[0005] The technical solution of the present invention is as follows: a BAF aeration pipe, comprising an aeration pipeline, wherein the aeration pipeline comprises a loop main pipe and an underwater suspension main pipe, the underwater suspension main pipe is connected to the loop main pipe, the underwater suspension main pipe is arranged above the loop main pipe, the loop main pipe is provided with an aeration branch pipe, and the aeration branch pipe is provided with aeration holes.

[0006] Furthermore, two rows of aeration holes are provided above the aeration branch pipes, and the aeration pipes are arranged densely in the middle and sparsely on both sides.

[0007] Furthermore, the diameter of the aeration hole is 1.5 mm.

[0008] Furthermore, the underwater suspension main pipe and the loop main pipe are connected via a flange.

[0009] Furthermore, the two ends of the loop main pipe and the aeration branch pipe are connected via flanges.

[0010] Furthermore, the loop main pipe includes four sections of pipelines, and the four sections of pipelines are connected to each other through flanges to form a closed loop.

[0011] Furthermore, the loop main pipe and the aeration branch pipe are arranged in an aeration tank, a pebble layer is arranged above the loop main pipe and the aeration branch pipe, a filter material is arranged above the pebble layer, and both ends of the aeration branch pipe are 10 cm away from the inner wall of the aeration tank.

[0012] Furthermore, the underwater suspended main pipe is connected to a fan.

[0013] A method for removing COD by BAF denitrification using a BAF aeration pipe, first filtering out large particles in sewage through pretreatment, then introducing sewage into the aeration tank through the water inlet pipe of the aeration tank, and at the same time, a fan aerates the aeration tank through the BAF aeration pipe so that the sewage and filter material in the aeration tank are fully contacted and reacted with oxygen, and the sewage is removed from the filter material loaded with a biofilm to remove COD, total nitrogen and ammonia nitrogen, and then discharged through the outlet pipe of the aeration tank. The outlet pipe of the aeration tank is arranged above the inlet pipe.

[0014] The main pipeline of the present invention is a closed loop, and two rows of aeration holes are arranged on the aeration branch pipe, which are densely arranged in the middle and sparsely arranged on both sides, thereby increasing the aeration volume and aeration uniformity and improving the sewage treatment effect; flange connections are used between the pipelines to facilitate subsequent maintenance and overhaul. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of the BAF aeration pipe;

[0016] Figure 2 It is the structural diagram of the aeration tank;

[0017] Figure 3 It is a schematic diagram of the detection points of the present invention;

[0018] Figure 4 for Figure 3 Aeration uniformity of seven test points;

[0019] Figure 5 It is the TN removal rate diagram of the present invention and the existing aeration tank;

[0020] Figure 6 The COD removal rate diagram of the present invention and the existing aeration tank;

[0021] Figure 7 It is a graph of NH3-N removal rate of the present invention and the existing aeration tank;

[0022] In the figure: 1- underwater hanging main pipe, 2- loop main pipe, 3- aeration branch pipe, 4- aeration hole, 5- flange, 6- aeration tank, 7- fan, 8- filter material, 9- water inlet pipe, 10- water outlet pipe, 11- pebble layer. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings:

[0024] like Figure 1 As shown, a BAF aeration pipe includes an aeration pipeline, wherein the aeration pipeline includes a loop main pipe 2 and an underwater suspension main pipe 1. The underwater suspension main pipe 1 is connected to the loop main pipe 2 through a flange. The underwater suspension main pipe 1 is arranged above the loop main pipe 2. The loop main pipe 2 includes four sections of pipelines, and the four sections of pipelines are connected to each other through flanges to form a closed loop. An aeration branch pipe 3 is arranged on the loop main pipe 2. The two ends of the loop main pipe 2 and the aeration branch pipe 3 are connected through flanges. The flange connection is adopted, which is convenient for disassembly and assembly, and is convenient for subsequent maintenance and repair. Two rows of aeration holes 4 are arranged above the aeration branch pipe 3. The aeration pipes 4 are arranged densely in the middle and sparsely on both sides. The diameter of the aeration holes 4 is 1.5 mm, which increases the aeration volume and aeration uniformity, so that the gas has a stirring effect on the sludge at the bottom of the aeration tank. The underwater suspension main pipe 1 is connected to the fan 7.

[0025] like Figure 2-4 As shown, the loop main pipe 2 and the aeration branch pipe 3 are arranged in the aeration tank 6. A pebble layer 11 is arranged above the loop main pipe 2 and the aeration branch pipe 3. A filter material 8 is arranged above the pebble layer 11. The pebble layer 11 is a large piece of pebble, which can give a shear force to the bubbles emerging from the aeration holes 4 below it to break up the bubbles, and at the same time prevent the filter material 8 from falling and blocking the aeration holes 4. The two ends of the aeration branch pipe 3 are 10 cm away from the inner wall of the aeration tank 6 to improve the aeration uniformity (DO) and prevent the bubbles at the outlet from violently bringing out sludge. The underwater hanging main pipe 1, the loop main pipe 2 and the aeration branch pipe 3 are made of 304 stainless steel, which improves the tolerance of the aeration pipe, reduces the aging rate of the pipeline, and increases the service life. The outlet pipe 10 of the aeration tank is arranged above the inlet pipe 9.

[0026] A method for removing COD by BAF denitrification using a BAF aeration tube, first filtering out large particles in sewage through pretreatment, then introducing sewage into an aeration tank 6 through an inlet pipe 9 of the aeration tank, and at the same time, a fan 7 aerates the aeration tank through the BAF aeration tube so that the sewage and filter material in the aeration tank are fully contacted and reacted with oxygen, and the sewage is discharged through an outlet pipe 10 of the aeration tank after COD, total nitrogen and ammonia nitrogen are removed from the filter material loaded with a biofilm.

[0027] like Figure 5As shown in the figure, after the aeration pipes were modified and covered with biofilm, aerobic bacteria consumed part of the dissolved oxygen, and the gaps between the BAF aeration holes showed a low DO. The resulting high-carbon and low-oxygen zones provided growth conditions for anaerobic heterotrophic denitrifying bacteria. The total nitrogen removal rate increased by 13.8% in the experiment. Considering that the aerobic aeration tank mainly played a nitrification role, and the subsequent anaerobic part mainly played a denitrification role, the total nitrogen (TN) removal rate basically met the requirements.

[0028] like Figure 6 As shown in Figure 2, although the COD base of the influent is high, the difference in removal rate before and after the transformation is not particularly obvious. The comparison data is as follows: Figure 6 As shown. This is because the main denitrifying bacteria in the leachate water plant are aerobic autotrophic. Secondly, the low BOD:COD of the leachate water quality determines that the organic matter that can be biologically removed in the sewage is limited. In addition, the hydraulic retention time of sewage in the BAF pool is short, and the removable organic matter has not been completely biologically reacted. The COD removal rate has increased compared with that before the construction. The reason is that there are a large number of aerobic heterotrophic nitrifying bacteria such as aerobic heterotrophic bacteria and various saprophytic bacteria in the filter biofilm, which need to consume carbon sources for growth, and high DO conditions can increase the metabolic rate of aerobic active bacteria and improve the removal rate of organic matter. In addition, although the BAF is coated, the microorganisms are still in a period of continuous growth, and the demand for carbon sources is relatively large during this period.

[0029] like Figure 7 As shown in Figure 2, during aerobic digestion, the aeration effect has a significant effect on the removal of ammonia nitrogen (NH3-N). The removal rates of NH3-N at different concentrations before and after the aeration tube modification are shown in Figure 2. Figure 7 As shown in the figure, the removal rate of NH3-N decreases with the increase of concentration. When the influent concentration is less than 18 mg / l, the removal rate is relatively constant. When the concentration is greater than 18 mg / l, the removal rate of NH3-N shows a downward trend, which is significantly improved compared with the aeration pipe before the modification.

Claims

1. A BAF aeration pipe, comprising an aeration pipeline, characterized in that: The aeration pipeline comprises a loop main pipe (2) and an underwater hanging main pipe (1), the underwater hanging main pipe (1) and the loop main pipe (2) being interconnected, the underwater hanging main pipe (1) being arranged above the loop main pipe (2), the loop main pipe (2) being provided with an aeration branch pipe (3), the aeration branch pipe (3) being provided with aeration holes (4), two rows of aeration holes (4) being arranged above the aeration branch pipe (3), the aeration holes (4) being arranged densely in the middle and sparsely on both sides, the loop main pipe (2) and the aeration branch pipe (3) being arranged in an aeration tank, a pebble layer (11) being provided above the loop main pipe (2) and the aeration branch pipe (3), a filter material (8) being provided above the pebble layer (11), and both ends of the aeration branch pipe (3) being 10 cm away from the inner wall of the aeration tank (6).

2. A BAF aeration tube as claimed in claim 1, characterized in that: The diameter of the aeration hole (4) is 1.5 mm.

3. A BAF aeration tube as claimed in claim 1, characterized in that: The underwater hanging main pipe (1) and the loop main pipe (2) are connected via a flange.

4. A BAF aeration tube as claimed in claim 1, characterized in that: The two ends of the loop main pipe (2) and the aeration branch pipe (3) are connected via flanges.

5. A BAF aeration tube as claimed in claim 1, characterized in that: The loop main pipe (2) comprises four sections of pipelines, and the four sections of pipelines are connected to each other via flanges to form a closed loop.

6. A BAF aeration tube as claimed in claim 1, characterized in that: The underwater suspended main pipe (1) is connected to the fan (7).

7. A method for removing COD by BAF denitrification using the BAF aeration tube as claimed in any one of claims 1 to 6, characterized in that: First, large particles in the sewage are filtered out through pretreatment, and then the sewage is introduced into the aeration tank (6) through the water inlet pipe (9) of the aeration tank. At the same time, the fan aerates the aeration tank through the BAF aeration pipe as described in any one of claims 1 to 6 so that the sewage and filter material in the aeration tank are fully contacted and reacted with oxygen. After the COD, total nitrogen and ammonia nitrogen are removed from the sewage through the filter material loaded with the biofilm, the sewage is discharged through the outlet pipe (10) of the aeration tank. The outlet pipe (10) of the aeration tank is arranged above the water inlet pipe (9).

Images