A thin-wall weir type water outlet distribution device and a method for deep denitrification of domestic sewage

Abstract

The present invention discloses a thin-walled weir type effluent water distribution device and a method for deep denitrification treatment of domestic sewage, which belongs to the technical field of sewage treatment. The device is located between an upper flow unit and a lower flow unit with a liquid level difference, and includes a baffle, a flow weir plate and a cover plate; the baffle plate is arranged in parallel with the flow weir plate, the upper part of the baffle plate is higher than the water inlet level of the upper flow unit, and the lower part is provided with a rainbow-breaking hole; a flow weir is arranged on the flow weir plate; the cover plate and the baffle plate are sealed and connected to form an η-shaped structure, which is located at the top of the flow weir plate, and the lower part of the cover plate is immersed below the liquid level of the lower flow unit; the liquid flows in along the flow channel formed by the baffle plate and the flow weir plate, and flows out along the flow channel formed by the flow weir plate and the cover plate. The present invention overcomes the problem of the conventional thin-walled weir device waterfall increasing the air and dissolved oxygen in the sewage through the structural design, and further, the domestic sewage treatment process using the thin-walled weir type effluent water distribution device is efficient and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a thin-wall weir-type water outlet distribution device and a method for deep denitrification treatment of domestic sewage. Background Art

[0002] In order to control water pollution and inhibit eutrophication of water bodies caused by nutrients such as nitrogen and phosphorus, it is necessary to remove nitrogen and phosphorus from wastewater. However, traditional A 2 / O process (Anaerobic-Anoxic-Oxic, anaerobic-anoxic-aerobic secondary sewage treatment process) is difficult to ensure stable effluent quality. The sewage treatment process based on denitrification filter has short hydraulic retention time, rapid denitrification, and good removal effect on suspended solids in water, and is more widely used. The general high-standard sewage deep treatment process is secondary sedimentation tank effluent → high-efficiency sedimentation tank → denitrification filter.

[0003] In the prior art, water is discharged from the secondary sedimentation tank and the high-efficiency sedimentation tank through a thin-wall weir. In order to meet the water distribution requirements, the conventional deep-bed denitrification filter also distributes water to the filter through a water distribution weir. Although the conventional thin-wall weir device (such as the design of a large overflow thin-wall weir in a plant tailwater arrangement structure with a large downstream water level fluctuation in the Chinese patent document with publication number CN209603104U and the design of a triangular thin-wall weir flow trough in the Chinese patent document with publication number CN214939891U) has uniform water discharge and water distribution, there are problems such as collision, turbulence, etc. that produce water drops and increase the air and dissolved oxygen in the sewage.

[0004] As mentioned above, the process of secondary sedimentation tank effluent → high-efficiency sedimentation tank → denitrification filter will go through three drops of water reoxygenation in actual operation. According to practice, the dissolved oxygen DO at the end of the biochemical tank is generally controlled below 2 mg / L. However, when entering the filter, the dissolved oxygen is almost saturated. Too high a dissolved oxygen concentration will inhibit the denitrification process. In order to meet the anoxic environment required for denitrification and denitrification in the denitrification filter, additional carbon sources need to be added to consume the dissolved oxygen in the sewage, which is expensive and even exceeds the carbon source required for the denitrification process, resulting in the denitrification filter not being able to operate normally.

[0005] Therefore, it is necessary to improve the existing thin-wall weir device to achieve uniform water discharge or water distribution while avoiding the problem of dissolved oxygen being brought into the thin-wall weir drop. At the same time, further, on this basis, the traditional domestic sewage treatment process is improved in order to achieve a better domestic sewage treatment effect. Summary of the invention

[0006] The present invention provides a thin-wall weir type effluent distribution device, which overcomes the problem of conventional thin-wall weir devices causing water drops due to impact, turbulence, etc., which increases the air and dissolved oxygen in sewage, reduces the consumption of ineffective carbon sources in denitrification reactions, and uses the thin-wall weir type effluent distribution device to achieve a deep denitrification treatment process for domestic sewage with high efficiency and good effects.

[0007] The specific technical solutions adopted are as follows:

[0008] A thin-wall weir-type water outlet and water distribution device is located between an upper flow unit and a lower flow unit with a liquid level difference, and includes a baffle 4, a flow weir plate 2 and a cover plate 5; the baffle 4 is arranged in parallel with the flow weir plate 2, the upper part of the baffle 4 is higher than the water inlet level of the upper flow unit, and the lower part is provided with a rainbow-breaking hole 7; the flow weir plate 2 is provided with a flow weir opening 1; the cover plate 5 and the baffle plate 4 are sealed and connected to form an η-shaped structure, which is located on the top of the flow weir plate 2, and the lower part of the cover plate 5 is immersed below the liquid level of the lower flow unit; the liquid flows in along the flow channel formed by the baffle plate 4 and the flow weir plate 2, and flows out along the flow channel formed by the flow weir plate 2 and the cover plate 5.

[0009] The device of the present invention can solve the problem of air mixing into the outlet weir or water distribution weir during the operation of the secondary sedimentation tank, high-efficiency sedimentation tank, denitrification filter tank and other existing sewage treatment plants, and the reoxygenation of the waterfall causing the deep treatment denitrification to be unable to operate normally through the structural design, reduce the consumption of invalid carbon sources in the denitrification reaction, and reduce the operating cost of the sewage treatment plant.

[0010] Preferably, the lower flow unit includes an outlet channel 8, and the flow weir plate 2 and the cover plate 5 are installed on the vertical wall of the outlet channel 8; or the upper flow unit includes a distribution channel 9, and the flow weir plate 2 and the cover plate 5 are installed on the vertical wall of the distribution channel 9.

[0011] Further preferably, the weir plate 2 is mounted on the vertical wall of the outlet channel 8 or the water distribution channel 9 through the horizontal adjustment nut 3, and the cover plate 5 is mounted on the vertical wall of the outlet channel 8 or the water distribution channel 9 through the channel adjustment nuts 6 arranged horizontally at intervals. The height of the weir is adjusted by the horizontal adjustment nut 3 and the width L of the η-shaped flow channel is adjusted by the channel adjustment nut 6, so as to adjust the local resistance of the flow channel and realize uniform water discharge or water distribution within the length of the outlet channel.

[0012] When the vertical wall of the outlet channel 8 or the water distribution channel 9 is a curved structure, a plurality of the thin-walled weir-type outlet water distribution devices described above can be set up and connected in sequence to prevent reoxygenation of falling water, and sealing measures are taken at the connections; when the vertical wall of the outlet channel 8 or the water distribution channel 9 is a straight structure, a plurality of the thin-walled weir-type outlet water distribution devices described above can be set up and connected in sequence to prevent reoxygenation of falling water, and sealing measures are taken at the connections and sealing plates are set at both ends to maintain the independent airtightness of the flow channel.

[0013] Preferably, the height of the weir plate 2 is 200-400 mm, 100-200 mm higher than the top of the outlet channel 8 or the distribution channel 9; the height of the baffle plate 4 is 300-500 mm, the horizontal spacing from the weir plate 2 is 50-300 mm, and it is 100-200 mm higher than the top of the cover plate 5; the horizontal spacing between the horizontal adjustment nuts 3 is 400-600 mm, and the horizontal spacing between the channel adjustment nuts 6 is 400-600 mm.

[0014] Preferably, the weir 1 is a polygonal structure, further a triangular structure.

[0015] Preferably, the diameter of the rainbow-breaking hole 7 is 10 mm, and the distance from the bottom of the baffle plate 4 is 100 to 150 mm.

[0016] The above-mentioned designs of height, distance, aperture, etc., help to control the water distribution to be more uniform.

[0017] Specifically, taking the water discharge process as an example, when using the thin-wall weir-type water discharge distribution device, step one: when the liquid level of the upper flow unit is at a', the sewage enters the flow channel through the bottom of the baffle 4, and crosses the evenly distributed flow weir 1 to enter the outlet channel 8 of the lower flow unit. In this process, uniform water discharge between the upper flow unit and the lower flow unit is achieved, and the sewage avoids direct contact with the atmosphere, reducing the mixing of dissolved oxygen; step two: the sealed air in the flow channel is carried out by the outlet water, and the flow channel forms a negative pressure, which increases the sewage level in the flow channel, and can further reduce the sealed air in the channel and reduce the dissolved oxygen. Step three: when the liquid level of the upper flow unit is at level a, the air in the flow channel is gradually emptied to form a siphon channel, the sewage is no longer in contact with the air, reducing the mixing of dissolved oxygen, adjusting the channel adjustment nuts 6 arranged at horizontal intervals, changing the flow width L of the "η"-type flow channel, achieving uniform water discharge in the length direction of the outlet channel of the lower flow unit, and maintaining the liquid level of the upper flow unit above the siphon hole 7 for optimal operation; Step four: when the water volume is small, the liquid level of the upper flow unit reaches the position of the siphon hole 7 downward, the siphon in the flow channel is destroyed, and the liquid level of the upper flow unit gradually rises to level a', and step one is performed.

[0018] The present invention also provides a method for deep denitrification of domestic sewage, comprising the following steps:

[0019] (1) Domestic sewage first enters the biochemical pool, and uses the activated sludge method or the mud film mixed microorganisms to perform preliminary organic matter degradation and denitrification to obtain a mud-water mixture. The biochemical pool is equipped with the thin-wall weir type effluent water distribution device, and the mud-water mixture enters the secondary sedimentation tank through the thin-wall weir type effluent water distribution device;

[0020] (2) The sludge-water mixture enters the secondary sedimentation tank for sludge sedimentation and sludge-water separation (under gravity), and the secondary sedimentation tank is equipped with the thin-wall weir-type effluent water distribution device. The sewage treated in the secondary sedimentation tank passes through the thin-wall weir-type effluent water distribution device and enters the denitrification deep bed filter tank;

[0021] (3) The sewage entering the denitrification deep bed filter is further denitrified. The denitrification deep bed filter adopts a downflow type. The sewage enters the water distribution area, filler area, support layer and effluent collection area in the denitrification deep bed filter from top to bottom. The water distribution weir in the water distribution area is installed with the thin-walled weir type effluent distribution device to avoid the problem of dissolved oxygen reoxygenation caused by falling water during the water distribution process.

[0022] Preferably, the dissolved oxygen of the mud-water mixture in step (1) is ≤2 mg / L; the dissolved oxygen of the effluent from the secondary sedimentation tank in step (2) is ≤2 mg / L; and the dissolved oxygen of the denitrification deep bed filter after water distribution in step (3) is ≤2.5 mg / L.

[0023] Preferably, the filler area of ​​the denitrification deep bed filter comprises a quartz sand filter layer, and the density of the quartz sand is 2.5-2.7 g / cm 3 , effective particle size is 2.0~4.0mm, K80<1.4, and packing layer thickness is 1000~2000mm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention can solve the problem of air mixing and waterfall reoxygenation during the operation of the existing sewage treatment plant secondary sedimentation tank, high-efficiency sedimentation tank, denitrification filter tank and other effluent weirs or water distribution weirs through the design of a thin-walled weir-type effluent water distribution device. On the one hand, the flow channel formed by the thin-walled weir-type effluent water distribution device is isolated from the atmosphere, reducing the mixing of dissolved oxygen. During the siphon operation, the air is completely emptied and no waterfall reoxygenation occurs, ensuring a low dissolved oxygen content in the wastewater effluent distribution process, thereby reducing the consumption of ineffective carbon sources for subsequent denitrification, saving energy and reducing carbon emissions. On the other hand, the upper part of the baffle is higher than the water inlet level of the upper flow unit, and the water flows into the flow channel from the bottom, which can prevent floating objects in the upper flow unit from entering the sewage, thereby improving the water quality.

[0026] (2) The device of the present invention can be implemented by modifying the thin-wall weir of an existing sewage treatment plant. It is easy to install and is suitable for new sewage treatment plants and upgrading existing sewage treatment plants.

[0027] (3) The deep denitrification treatment of domestic sewage using a system equipped with the device of the present invention can control the dissolved oxygen content in the sewage, and combined with a specific sewage treatment process, it can achieve efficient removal of nitrogen-containing compounds in domestic sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a schematic diagram of the first cross-sectional structure of the thin-wall weir type water outlet and water distribution device in Example 1.

[0029] Figure 2 It is a second cross-sectional structural schematic diagram of the thin-wall weir type water outlet and water distribution device in Example 1.

[0030] Figure 3 It is a third cross-sectional structural schematic diagram of the thin-wall weir type water outlet and water distribution device in Example 1.

[0031] Figure 4 It is a schematic diagram of the first cross-sectional structure of the thin-wall weir-type water outlet and water distribution device in Example 2.

[0032] Description of the drawings: flow weir 1, flow weir plate 2, horizontal adjustment nut 3, baffle 4, cover 5, channel adjustment nut 6, rainbow-breaking hole 7, outlet channel 8, water distribution channel 9. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the embodiments and drawings. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] like Figure 1-3 As shown, a thin-walled weir-type outlet water distribution device is located between an upper flow unit and a lower flow unit with a liquid level difference, and can be installed on an outlet channel of a sedimentation tank (such as a secondary sedimentation tank, a high-efficiency sedimentation tank, etc.), and the thin-walled weir-type outlet water distribution device includes a baffle 4, an overflow weir plate 2 and a cover plate 5; the baffle 4 is arranged in parallel with the overflow weir plate 2, the upper part of the baffle 4 is higher than the water inlet level of the upper overflow unit, and a rainbow-breaking hole 7 is provided at the lower part; the overflow weir plate 2 is in the shape of a long strip, and triangular overflow weir openings 1 are evenly distributed on it; the cover plate 5 and the baffle plate 4 are sealed and connected to form an η-shaped structure, which is located on the top of the overflow weir plate 2, and the lower part of the cover plate 5 is immersed below the liquid level of the lower overflow unit; the liquid flows in along the overflow channel formed by the baffle plate 4 and the overflow weir plate 2, and flows out along the overflow channel formed by the overflow weir plate 2 and the cover plate 5.

[0036] Specifically, the lower flow unit includes an outlet channel 8, a flow weir plate 2 is mounted on the vertical wall of the outlet channel 8 through a horizontal adjustment nut 3, and a cover plate 5 is mounted on the vertical wall of the outlet channel 8 through a channel adjustment nut 6 arranged at intervals horizontally. The width L of the "η"-shaped flow channel is adjusted through the channel adjustment nut 6 to adjust the local resistance of the flow channel, so that uniform water discharge or water distribution can be achieved within the length of the outlet channel.

[0037] Specifically, the total height of the flow weir plate 2 is set to 350mm, 150mm higher than the top of the outlet channel 8, the height of the baffle plate 4 is set to 450mm, the horizontal spacing between the flow weir plate 2 is set to 150mm, 100mm higher than the top of the covering plate 5, the horizontal spacing of the horizontal adjustment nuts 3 is set to 500mm, the horizontal spacing of the channel adjustment nuts 6 is set to 500mm, the aperture of the rainbow breaking hole 7 is 10mm, and it is 100mm away from the bottom of the baffle plate 4.

[0038] When using the thin-wall weir type water outlet distribution device, step one: when the liquid level of the upper flow unit is at a', the sewage enters the flow channel through the bottom of the baffle 4, and crosses the evenly distributed flow weir 1 to enter the outlet channel 8 of the lower flow unit. In this process, uniform water discharge between the upper flow unit and the lower flow unit is achieved, and the sewage avoids direct contact with the atmosphere, reducing the mixing of dissolved oxygen; step two: the sealed air in the flow channel is carried out by the outlet water, and the flow channel forms a negative pressure, which increases the sewage level in the flow channel, which can further reduce the sealed air in the channel and reduce the mixing of dissolved oxygen; step three: When the liquid level of the upper flow unit is at level a, the air in the flow channel is gradually emptied to form a siphon channel. The sewage is no longer in contact with the air, reducing the mixing of dissolved oxygen. The channel adjusting nuts 6 arranged at horizontal intervals are adjusted to change the flow width L of the "η"-shaped flow channel, so that the water discharge in the length direction of the outlet channel of the lower flow unit is uniform, and the liquid level of the upper flow unit is maintained above the siphon-breaking hole 7 for optimal operation; Step 4: When the water volume is small, the liquid level of the upper flow unit moves downward to the position of the siphon-breaking hole 7, the siphon in the flow channel is destroyed, and the liquid level of the upper flow unit gradually rises to level a', and step 1 is performed, and repeated.

[0039] Example 2

[0040] Reference Figure 4 As shown, the thin-walled weir type water outlet distribution device is installed on the water distribution channel 9 of the deep bed filter tank, the upper flow unit includes the water distribution channel 9, the flow weir plate 2 is installed on the vertical wall of the water distribution channel 9 through the horizontal adjustment nut 3, and the cover plate 5 is installed on the vertical wall of the water distribution channel 9 through the channel adjustment nut 6. The c liquid level is the liquid level in the water distribution area, and d is the liquid level in the filter tank. The horizontal adjustment nut 3 is adjusted to make the water distribution in the direction of the water distribution channel 9 uniform in the non-siphon state; the channel adjustment nuts 6 arranged at intervals horizontally are adjusted to make the water outlet in the length direction of the water distribution channel 9 uniform, and the c liquid level can be maintained above the siphon breaking hole 7 for optimal operation, and the rest is the same as in Example 1.

[0041] Example 3

[0042] Domestic sewage flows through the AO biochemical tank, the secondary sedimentation tank, and the denitrification deep bed filter in sequence for deep denitrification treatment. Domestic sewage first enters the biochemical tank, and uses the activated sludge method to perform preliminary organic matter degradation and denitrification to obtain a mud-water mixture. The biochemical tank is equipped with the thin-wall weir-type effluent water distribution device, and the mud-water mixture enters the secondary sedimentation tank through the thin-wall weir-type effluent water distribution device.

[0043] The mud-water mixture enters the secondary sedimentation tank for sludge sedimentation and mud-water separation. The secondary sedimentation tank is equipped with a thin-wall weir-type effluent water distribution device. The sewage treated in the secondary sedimentation tank passes through the thin-wall weir-type effluent water distribution device and enters the denitrification deep bed filter tank;

[0044] The sewage entering the denitrification deep bed filter is further deeply denitrified. The denitrification deep bed filter adopts a downflow type. The sewage enters the water distribution area, filler area, supporting layer and effluent collection area in the denitrification deep bed filter from top to bottom. The water distribution weir in the water distribution area is installed with the thin-wall weir type effluent distribution device.

[0045] At the same time, a domestic sewage deep denitrification treatment method without using a thin-wall weir type effluent water distribution device was used as a control. Except for not using a thin-wall weir type effluent water distribution device, the other processes and parameters were the same as those in this embodiment.

[0046] Analysis of the dissolved oxygen concentrations of the wastewater of Example 3 and the control process in Table 1 shows that Example 3 can control the dissolved oxygen level of the wastewater in the denitrification deep bed filter to a lower level, ensure that the denitrification deep bed filter is in an anoxic state, improve the denitrification reaction efficiency, and reduce the addition of carbon source.

[0047] Table 1 Dissolved oxygen concentration of sewage along the route of Example 3

[0048]

[0049] The denitrification effects of Example 3 and the control process on domestic sewage were analyzed. Sodium acetate was added as a carbon source in both Example 3 and the control process, and the addition amount was 5 mg / L wastewater in terms of COD.

[0050] Table 2 Denitrification effect statistics of Example 3

[0051]

[0052] The results in Table 2 show that deep denitrification of domestic sewage using a system equipped with the thin-wall weir-type effluent distribution device can control the dissolved oxygen content in the sewage, and combined with a specific sewage treatment process, it can achieve efficient removal of nitrogen-containing compounds in domestic sewage.

[0053] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thin-wall weir type water outlet and water distribution device, characterized in that: Located between an upper flow unit and a lower flow unit having a liquid level difference, the device comprises a baffle plate (4), a flow weir plate (2) and a cover plate (5); the baffle plate (4) is arranged in parallel with the flow weir plate (2), the upper part of the baffle plate (4) is higher than the water inlet level of the upper flow unit, and the lower part is provided with a rainbow-breaking hole (7); the flow weir plate (2) is provided with a flow weir opening (1); the cover plate (5) and the baffle plate (4) are sealed and connected to form an η-shaped structure, which is located at the top of the flow weir plate (2), and the lower part of the cover plate (5) is immersed below the liquid level of the lower flow unit; the liquid flows in along the flow channel formed by the baffle plate (4) and the flow weir plate (2), and flows out along the flow channel formed by the flow weir plate (2) and the cover plate (5); The lower flow unit comprises an outlet channel (8), and the flow weir plate (2) and the cover plate (5) are installed on the vertical wall of the outlet channel (8); or the upper flow unit comprises a water distribution channel (9), and the flow weir plate (2) and the cover plate (5) are installed on the vertical wall of the water distribution channel (9); The flow weir plate (2) is installed on the vertical wall of the outlet channel (8) or the water distribution channel (9) through the horizontal adjustment nut (3), and the cover plate (5) is installed on the vertical wall of the outlet channel (8) or the water distribution channel (9) through the channel adjustment nut (6).

2. The thin-wall weir type water outlet and water distribution device according to claim 1, characterized in that: The height of the weir plate (2) is 200-400 mm, and it is 100-200 mm higher than the top of the outlet channel (8) or the water distribution channel (9). The height of the baffle plate (4) is 300-500 mm, and the horizontal spacing between the baffle plate (4) and the weir plate (2) is 50-300 mm, and it is 100-200 mm higher than the top of the cover plate (5).

3. The thin-wall weir type water outlet and water distribution device according to claim 1, characterized in that: The flow weir (1) is a polygonal structure.

4. The thin-wall weir type water outlet and water distribution device according to claim 1, characterized in that: The diameter of the rainbow-breaking hole (7) is 10 mm and the distance from the bottom of the baffle (4) is 100 to 150 mm.

5. A method for deep denitrification of domestic sewage, characterized in that: The following steps are involved: (1) Domestic sewage first enters the biochemical pool for preliminary organic matter degradation and denitrification to obtain a mud-water mixture. The biochemical pool is equipped with a thin-wall weir-type effluent distribution device as described in any one of claims 1 to 4. The mud-water mixture enters the secondary sedimentation tank through the thin-wall weir-type effluent distribution device; (2) The sludge-water mixture enters the secondary sedimentation tank for sludge sedimentation and sludge-water separation. The secondary sedimentation tank is equipped with the thin-wall weir-type effluent water distribution device. The sewage treated in the secondary sedimentation tank passes through the thin-wall weir-type effluent water distribution device and enters the denitrification deep bed filter tank; (3) The sewage entering the denitrification deep bed filter is further denitrified. The denitrification deep bed filter adopts a downflow type. The sewage enters the water distribution area, filler area, support layer and effluent collection area of ​​the denitrification deep bed filter from top to bottom. The water distribution weir in the water distribution area is installed with the thin-wall weir type effluent distribution device.

6. The method for deep denitrification of domestic sewage according to claim 5, characterized in that: In step (1), the dissolved oxygen of the mud-water mixture is ≤2 mg / L; in step (2), the dissolved oxygen of the effluent from the secondary sedimentation tank is ≤2 mg / L; in step (3), the dissolved oxygen of the denitrification deep bed filter after water distribution is ≤2.5 mg / L.

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