Denitrification filter tank

Abstract

A denitrification filter comprises: a first unit comprising: an inlet located at the lower portion of the first unit; the autotrophic filler layer is positioned at the upper part of the first unit, and the wastewater is purified by autotrophic microorganisms in the autotrophic filler layer; a second unit disposed adjacent to the first unit in a horizontal direction, the second unit including: an outlet at a lower portion of the second unit; the heterotrophic filler layer is positioned at the upper part of the second unit, and the wastewater is purified by heterotrophic microorganisms in the heterotrophic filler layer; wherein in the filtering mode, wastewater sequentially flows through the inlet, the autotrophic filler layer, the heterotrophic filler layer and the outlet.

Description

TECHNICAL FIELD

[0001] The utility model relates to a denitrification filter, more particularly to a denitrification filter comprising autotrophic denitrifying microorganisms and heterotrophic denitrifying microorganisms. BACKGROUND

[0002] Denitrification by denitrifying bacteria is a common way to treat nitrogen-containing wastewater, and denitrifying bacteria can be divided into autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria.

[0003] Traditionally, heterotrophic denitrification processes are generally used, but they require a large amount of carbon source, resulting in high operating costs and a large amount of sludge. Compared with heterotrophic denitrification processes, autotrophic denitrification processes use inorganic substances (e.g., S, S 2- , H2, Fe, etc.) as electron donors, eliminating the need for carbon source addition and significantly reducing sludge.

[0004] Sulfur autotrophic denitrification (SAD) is a common autotrophic denitrification process, but SAD technology has the following disadvantages. In SAD technology, a large amount of alkaline agent is consumed, and the higher the nitrogen removal requirement of the wastewater, the more alkaline agent needs to be supplemented. The product of SAD technology, sulfate, can be harmful to the environment or limited in emission amount by relevant regulations. The filler in the SAD filter is easily crushed and lost, resulting in poor purification performance.

[0005] For advanced denitrification treatment, the characteristics of common heterotrophic denitrification filters and autotrophic denitrification filters are shown in Table 1.

[0006] Table 1

[0007]

[0008]

[0009] Among them, the upflow heterotrophic denitrification filter is disclosed in patent CN214299499U, and the downflow heterotrophic denitrification filter is disclosed in patent CN105060476B. As shown in Table 1, both autotrophic denitrification filters and heterotrophic denitrification filters have some technical defects.

[0010] Therefore, it is desirable to propose a denitrification filter to improve the deficiencies in the above prior art. SUMMARY

[0011] According to one aspect of the present application, a denitrification filter is provided, comprising: a first unit, comprising: an inlet, located at the lower part of the first unit; an autotrophic filler layer, located at the upper part of the first unit, wastewater is purified by autotrophic microorganisms in the autotrophic filler layer; a second unit, arranged adjacent to the first unit in the horizontal direction, comprising: an outlet, located at the lower part of the second unit; a heterotrophic filler layer, located at the upper part of the second unit, wastewater is purified by heterotrophic microorganisms in the heterotrophic filler layer; wherein in the filtration mode, the wastewater flows through the inlet, the autotrophic filler layer, the heterotrophic filler layer and the outlet in sequence.

[0012] According to the scheme, by combining autotrophic denitrification filter and heterotrophic denitrification filter, the advantages of autotrophic denitrification filter and heterotrophic denitrification filter can be realized at the same time. This process not only can reduce the sludge yield, but also can form complementary in alkalinity, reduce the dosage of alkaline reagent and carbon source. In addition, the ceramsite filler in the second unit can intercept the lost sulfur particle filler in the first unit, so that this part of the filler can continue to play a purifying role.

[0013] In some schemes, the wastewater can flow upwards in the first unit and downwards in the second unit.

[0014] According to the scheme, for the autotrophic denitrification process in the first unit, the wastewater flows upwards, which can improve the hydraulic load and prolong the backwashing period.

[0015] In some schemes, the first unit can further comprise: a first water distribution area, located at the lower part of the first unit and communicating with the inlet; a first supporting layer, located above the first water distribution area, the autotrophic filler layer is located above the first supporting layer and supported by the first supporting layer; the second unit can further comprise: a second water distribution area, located at the lower part of the second unit and communicating with the outlet; a second supporting layer, located above the second water distribution area, the heterotrophic filler layer is located above the second supporting layer and supported by the second supporting layer; in the filtration mode, the wastewater flows through the inlet, the first water distribution area, the first supporting layer, the autotrophic filler layer, the heterotrophic filler layer, the second supporting layer, the second water distribution area and the outlet in sequence.

[0016] In some schemes, the first unit can further comprise a first intermediate wall, the first intermediate wall is located between the upper part and the lower part of the first unit, and the first supporting layer is placed on the first intermediate wall; the second unit can further comprise a second intermediate wall, the second intermediate wall is located between the upper part and the lower part of the second unit, and the second supporting layer is placed on the second intermediate wall.

[0017] In some embodiments, the denitrification filter tank can further comprise a partition wall separating the lower part of the first unit and the lower part of the second unit; a drain channel, the bottom of the drain channel being closed and the upper part of the drain channel being open, the drain channel being located between the upper part of the first unit and the upper part of the second unit, the drain channel extending upward beyond the autotrophic filler layer and the heterotrophic filler layer, wherein the bottom of the drain channel is connected to the partition wall, and in the filtration mode, the wastewater fills and overflows the drain channel to communicate the upper part of the first unit with the upper part of the second unit.

[0018] In some embodiments, the cross-sectional area of the first unit can be greater than the cross-sectional area of the second unit.

[0019] According to the above-mentioned embodiment, the relatively large cross-sectional area of the first unit can result in a relatively low flow rate in the first unit, thereby reducing the loss of sulfur filler caused by crushing.

[0020] In some embodiments, the first unit can further comprise a first drain channel located above the autotrophic filler layer, and the second unit can further comprise a second drain channel located above the heterotrophic filler layer, the first drain channel and the second drain channel being in communication with the drain channel.

[0021] In some embodiments, the top of the first drain channel and the second drain channel is provided with a sieve plate, and a plurality of sieve holes are provided on the sieve plate.

[0022] According to the above-mentioned embodiment, the sieve holes can trap the filler during the flushing, thereby reducing the loss of the filler.

[0023] In some embodiments, the denitrification filter tank can further comprise a first flushing inlet, a second flushing inlet, and a flushing outlet, the first flushing inlet being arranged at the bottom wall of the first unit, the second flushing inlet being arranged at the bottom wall of the second unit, and the flushing outlet being arranged at the drain channel.

[0024] In some embodiments, in the filtration mode, the first flushing inlet, the second flushing inlet, and the flushing outlet are closed, and the inlet and the outlet are open; in the flushing mode, the inlet and the outlet are closed, and the first flushing inlet, the second flushing inlet, and the flushing outlet are open.

[0025] In some embodiments, the denitrification filter tank can further comprise a reflux pump, the water inlet of the reflux pump being connected to the outlet, and the water outlet of the reflux pump being connected to the inlet.

[0026] According to the above-mentioned embodiment, the recycling of the filler can be achieved, thereby reducing the cost of the filler. In addition, the cost of the acid-base reagent can also be reduced.

[0027] In some embodiments, the denitrification filter tank can further comprise an alkali liquid adding device, the alkali liquid adding device being configured to add an alkaline substance to the wastewater in the inlet.

[0028] In some schemes, the height of the autotrophic filler layer and the heterotrophic filler layer can be between 1.5m and 2.0m.

[0029] In some schemes, the hydraulic load of the wastewater flowing through the denitrification filter tank can be between 5m / h and 10m / h.

[0030] In some schemes, in the flushing mode, air backwashing and water backwashing are adopted in the first unit, and air backwashing, air-water combined backwashing and water backwashing are adopted in the second unit. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A schematic diagram of a denitrification filter tank according to an embodiment of the present application is shown.

[0032] Reference signs:

[0033] 1 inlet

[0034] 2 outlet

[0035] 3 first flushing inlet

[0036] 4 second flushing inlet

[0037] 5 water distribution area

[0038] 6 support layer

[0039] 7 autotrophic filler layer

[0040] 8 heterotrophic filler layer

[0041] 9 drainage channel

[0042] 10 intermediate wall

[0043] 11 drainage groove

[0044] 12 clear water area

[0045] 13 super-high area

[0046] 14 partition wall DETAILED DESCRIPTION

[0047] In order to make the purpose, scheme and advantages of the technical scheme of the present application more clear, the technical scheme of the present application embodiment will be described clearly and completely in the following with reference to the drawings of the specific embodiment of the present application. Unless otherwise specified, the terms used herein have the usual meaning in the art. The same reference signs in the drawings represent the same parts.

[0048] Figure 1The schematic diagram of the denitrification filter according to the embodiment of the present application is shown, the denitrification filter 1 is mainly divided into two parts in the horizontal direction, which are the first part on the left side and the second part on the right side. The environment of the first part is suitable for the growth of autotrophic denitrifying bacteria, so that the wastewater is purified by the autotrophic denitrifying bacteria in the first part. The second part is suitable for the growth of heterotrophic denitrifying bacteria, so that the wastewater is purified by the heterotrophic denitrifying bacteria in the second part. The denitrification filter of the present application is composed of the autotrophic denitrification filter and the heterotrophic denitrification filter, which has the advantages of both the autotrophic denitrification filter and the heterotrophic denitrification filter.

[0049] Because the first intermediate wall of the first part and the second intermediate wall of the second part are basically completely the same, in the following, the first intermediate wall and the second intermediate wall can be collectively referred to as the intermediate wall. Similarly, the first water distribution area of the first part and the second water distribution area of the second part can be collectively referred to as the water distribution area, the first supporting layer of the first part and the second supporting layer of the second part can be collectively referred to as the supporting layer, and the first drainage groove of the first part and the second drainage groove of the second part can be collectively referred to as the drainage groove.

[0050] The first part mainly includes the inlet 1, the water distribution area 5, the intermediate wall 10, the supporting layer 6 and the autotrophic filler layer 7, and the intermediate wall 10 divides the first part into two parts in the vertical direction, which are the upper part and the lower part. The inlet 1 and the water distribution area 5 are located in the lower part of the first part, and the supporting layer 6 and the autotrophic filler layer 7 are located in the upper part of the first part. For example, the inlet 1 can be arranged on the side wall of the pool body.

[0051] The supporting layer 6 is placed on the intermediate wall 10 and provides support for the autotrophic filler layer 7, and the supporting layer 6 can be gravel, which is formed by gravel with a thickness of 20 cm and a size of 18 mm-25 mm and gravel with a thickness of 10 cm and a size of 9 mm-18 mm from bottom to top.

[0052] The autotrophic filler layer 7 provides an environment suitable for the growth of autotrophic denitrifying bacteria, for example, the autotrophic filler layer 7 can be sulfur particles or other commercially available sulfur-containing fillers, and the autotrophic denitrifying bacteria can use elemental sulfur as an electron donor to occur denitrification, thereby removing nitrogen elements in the nitrogen-containing wastewater. The thickness of the filler of the autotrophic filler layer 7 can be between 1.5 m and 2.0 m, and the particle size of the filler can be between 2.0 mm and 5.0 mm.

[0053] The second part mainly includes outlet 2, water distribution zone 5, intermediate wall 10, support layer 6, and heterotrophic filler layer 8. The intermediate wall 10 vertically divides the second part into upper and lower sections. Outlet 2 and water distribution zone 5 are located in the lower part of the second part, while support layer 6 and heterotrophic filler layer 8 are located in the upper part. For example, outlet 2 can be located on the side wall of the tank. The support layer 6 of the second part provides support for the heterotrophic filler layer 8. Other features of the support layer 6 of the second part are similar to those of the support layer 6 of the first part, and therefore will not be described again.

[0054] The heterotrophic packing layer 8 provides a suitable environment for the growth of heterotrophic denitrifying bacteria. For example, the heterotrophic packing layer 8 can be heavy ceramsite packing. The heterotrophic denitrifying bacteria cause denitrification of the wastewater, thereby removing nitrogen from the nitrogen-containing wastewater. The thickness of the heterotrophic packing layer 8 can be between 1.5m and 2.0m, and the particle size of the packing can be between 2.0mm and 5.0mm.

[0055] The first and second units are separated at the bottom by a partition wall 14, meaning that wastewater from the lower part of the first unit will not directly flow into the lower part of the second unit. A drainage channel 9 is provided between the upper parts of the first and second units, and the drainage channel 9 has two side walls and a bottom wall. The left side wall of the drainage channel 9 forms the right side wall of the first unit, and the right side wall of the drainage channel 9 forms the left side wall of the second unit. The bottom wall of the drainage channel 9 is adjacent to the partition wall 14, so that wastewater can only flow from the first unit to the second unit by passing over the top of the drainage channel 9.

[0056] Wastewater flows from inlet 1 to the water distribution area 5 of the first unit, then flows upward through the support layer 6 of the first unit to the autotrophic packing layer 7. In the autotrophic packing layer 7, autotrophic denitrification occurs to remove some nitrogen. Then it flows over the top of the drainage ditch 9 to the heterotrophic packing layer 8. In the heterotrophic packing layer 8, heterotrophic denitrification occurs to remove some nitrogen. Then it flows downward through the support layer 6 of the second unit to the water distribution area 5 of the second unit, and finally leaves the tank from outlet 2.

[0057] It should be noted that in the autotrophic denitrification process of the first unit, the wastewater flows upwards, which can increase the hydraulic load and extend the backwash cycle. For example, the hydraulic load can be between 5 m / h and 10 m / h, and the backwash cycle can be approximately 24 hours. Furthermore, the sulfur-containing packing material in the autotrophic packing layer 7 is easily crushed under the impact of the water flow, thus no longer being retained (the retention method is described below) in the autotrophic packing layer 7. The crushed sulfur-containing packing material flows into the heterotrophic packing layer 8, where the heavy ceramic particles can retain the crushed sulfur-containing packing material, thereby allowing the wastewater purification capacity of this portion of the sulfur-containing packing material to continue to be utilized.

[0058] The first part may further include a first flushing inlet 3 and a drainage trough 11 located above the self-nourishing packing layer 7, and the second part may further include a second flushing inlet 4 and a drainage trough 11 located above the heterotrophic packing layer 8. The drainage trough 11 communicates with the drainage channel 9; for example, the bottom of the drainage trough 11 may be flush with the top of the drainage channel 9, thereby allowing liquid in the drainage trough 11 to drain into the drainage channel 9. In filtration mode, the first flushing inlet 3, the second flushing inlet 4, and the flushing outlet (not shown) are closed, while inlet 1 and outlet 2 are open. After filtration for a period of time, the packing may need to be flushed, requiring the filtration mode to be switched to flushing mode. The first flushing inlet 3 and the second flushing inlet 4 may be located on the bottom wall of the tank, and the flushing outlet may be located on the drainage channel 9.

[0059] In flushing mode, inlet 1 and outlet 2 are closed, while the first flushing inlet 3, the second flushing inlet 4, and the flushing outlet are open. A portion of the flushing water (or air) enters the first section's water distribution zone 5 from the first flushing inlet 3, then flows upward through the support layer 6 to the self-growth packing layer 7 to flush the packing, then flows into the drainage channel 9 via the drainage trough 11, and finally exits the tank from the flushing outlet. Another portion of the flushing water (or air) enters the second section's water distribution zone 5 from the second flushing inlet 4, then flows upward through the support layer 6 to the heterotrophic packing layer 8 to flush the packing, then flows into the drainage channel 9 via the drainage trough 11, and finally exits the tank from the flushing outlet. Preferably, the top of the drainage trough 11 may be provided with a sieve plate with multiple sieve holes. The sieve holes can trap packing in the self-growth packing layer 7 and the heterotrophic packing layer 8 during flushing, thereby reducing packing loss. The sieve plate has an aperture smaller than the particle size of the two types of packing materials (autotrophic packing and heterotrophic packing) (e.g., between 1.0 mm and 2.0 mm) to retain both types of packing materials. The sieve plate can be made of SS304.

[0060] For the backwashing process of the first unit, air backwashing (fan-driven) and water backwashing (pump-driven) can be used. Air backwashing time can be between 1 and 3 minutes, and the air backwashing intensity can be up to 40 Nm. 3 / (m 2 .h) to 60Nm 3 / (m 2 The water backwash time can be between 10 and 15 minutes, and the water backwash intensity can be between 10 Nm. 3 / (m 2 .h) to 20Nm 3 / (m 2 Between .h). Not using combined air-water backwashing in the first unit can reduce the impact on the sulfur-containing packing in the self-supporting packing layer 7, thereby reducing the possibility of the sulfur-containing packing being crushed.

[0061] For the backwashing process of the second unit, air backwashing, combined air-water backwashing, and water backwashing can be used. Air backwashing time can be between 4 and 6 minutes, and the air backwashing intensity can be up to 60 Nm. 3 / (m 2 .h) to 80Nm 3 / (m 2 The water backwash time can be between 10 and 15 minutes, and the water backwash intensity can be between 20 Nm. 3 / (m 2 .h) to 30Nm 3 / (m 2 The combined air-water backwashing time can be between 10 and 15 minutes, and the combined air-water backwashing intensity can be between 7 Nm. 3 / (m 2 .h) to 15Nm 3 / (m 2 Between .h).

[0062] Preferably, the cross-sectional area (the section perpendicular to the water flow) of the first unit can be larger than that of the second unit. The ratio of the cross-sectional area of ​​the first unit to that of the second unit can be, for example, 3:1, 2:1, or 1:1. When the cross-sectional area of ​​the first unit is larger, the flow velocity in the first unit is relatively lower, thereby reducing the loss caused by the crushing of sulfur packing in the self-supporting packing layer 7.

[0063] Preferably, the denitrification filter may further include a return pump (not shown), with its inlet connected to outlet 2 and its outlet connected to inlet 1. This allows for the recycling of the packing material, reducing the cost of the packing material. Simultaneously, because the heterotrophic denitrification process produces alkaline products, these alkaline products, when returned to the autotrophic denitrification tank, can serve as the alkaline reagent required for the autotrophic denitrification process, thus reducing the cost of acid and alkali reagents. During the operation of the denitrification filter, the return flow rate can be adjusted according to the water quality.

[0064] In addition, the denitrifying filter may also include an alkali dosing device, configured to add an alkaline substance to the wastewater at inlet 1. The alkaline substance could be, for example, 98% pure sodium bicarbonate. The amount of alkaline substance added at inlet 1 can be determined based on the pH value of the effluent from the first unit, so that the pH of the effluent from the first unit is between 6 and 7. A carbon source dosing device can be installed above the clear water zone 12 to add a carbon source to the second unit, making the second unit more suitable for the growth of heterotrophic denitrifying bacteria. The carbon source could be, for example, 58% pure solid sodium acetate.

[0065] This invention relates to a denitrification filter that can be applied to the advanced treatment of municipal wastewater and industrial park wastewater with nitrate concentrations ranging from 20 mg / L to 150 mg / L, as well as the treatment of reverse osmosis concentrate. For example, for wastewater with a nitrate concentration of approximately 100 mg / L, the effluent nitrate concentration can be less than 15 mg / L, achieving a nitrate removal rate greater than 85%.

[0066] This document describes in detail several exemplary embodiments of the present invention with reference to preferred embodiments. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of the present invention, and various technical features and structures proposed in the present invention can be combined without exceeding the protection scope of the present invention, which is determined by the appended claims.

Claims

1. A denitrification filter, characterized in that, include: Unit 1 includes: - The entrance is located at the lower part of the first unit; - An autotrophic packing layer is located above the first unit, where wastewater is purified by autotrophic microorganisms. The second unit, arranged horizontally adjacent to the first unit, includes: - The outlet is located at the bottom of the second unit; - A heterotrophic packing layer, located above the second unit, where wastewater is purified by heterotrophic microorganisms; In filtration mode, wastewater flows sequentially through the inlet, the self-nourishing packing layer, the heterotrophic packing layer, and the outlet.

2. The denitrification filter according to claim 1, characterized in that, Wastewater flows upward in the first unit and downward in the second unit.

3. The denitrification filter according to claim 2, characterized in that, The first unit further includes: - The first water distribution area is located at the lower part of the first unit and is connected to the inlet; - A first supporting layer is located above the first water distribution area, and the self-supporting filler layer is located above the first supporting layer and is supported by the first supporting layer; The second unit also includes: - The second water distribution zone is located at the lower part of the second unit and is connected to the outlet; - A second supporting layer is located above the second water distribution area, and the heterotrophic filler layer is located above the second supporting layer and is supported by the second supporting layer; In the filtration mode, wastewater flows sequentially through the inlet, the first water distribution zone, the first support layer, the self-nourishing packing layer, the heterotrophic packing layer, the second support layer, the second water distribution zone, and the outlet.

4. The denitrification filter according to claim 3, characterized in that, The first unit further includes a first intermediate wall, which is located between the upper and lower parts of the first unit, and the first support layer is placed on the first intermediate wall; The second unit also includes a second intermediate wall located between the upper and lower parts of the second unit, and the second support layer is placed on the second intermediate wall.

5. The denitrification filter according to claim 4, characterized in that, Also includes: A partition wall separates the lower part of the first unit from the lower part of the second unit; A drainage ditch, the bottom of which is closed and the top of which is open, is located between the upper part of the first unit and the upper part of the second unit, and extends upward beyond the self-nourishing packing layer and the heterotrophic packing layer. The bottom of the drainage ditch is connected to the partition wall. In filtration mode, wastewater fills and overflows the drainage ditch to connect the upper part of the first unit with the upper part of the second unit.

6. The denitrification filter according to claim 1, characterized in that, The cross-sectional area of ​​the first unit is greater than that of the second unit.

7. The denitrification filter according to claim 5, characterized in that, The first unit further includes a first drainage trough located above the self-nourishing packing layer. The second unit further includes a second drainage trough located above the heterotrophic packing layer. The first drainage trough and the second drainage trough are connected to the drainage channel.

8. The denitrification filter according to claim 7, characterized in that, The top of the first drainage trough and the second drainage trough is provided with a sieve plate, and the sieve plate is provided with a plurality of sieve holes.

9. The denitrification filter according to claim 8, characterized in that, It also includes a first flushing inlet, a second flushing inlet, and a flushing outlet. The first flushing inlet is located on the bottom wall of the first unit, the second flushing inlet is located on the bottom wall of the second unit, and the flushing outlet is located on the drainage ditch.

10. The denitrification filter according to claim 9, characterized in that, In the filtration mode, the first flushing inlet, the second flushing inlet, and the flushing outlet are closed, while the inlet and the outlet are open; In the flushing mode, the inlet and the outlet are closed, and the first flushing inlet, the second flushing inlet, and the flushing outlet are open.

11. The denitrification filter according to claim 1, characterized in that, It also includes a reflux pump, the inlet of which is connected to the outlet, and the outlet of which is connected to the inlet.

12. The denitrification filter according to claim 1, characterized in that, It also includes an alkaline solution dosing device, which is configured to add an alkaline substance to the wastewater in the inlet.

13. The denitrification filter according to claim 1, characterized in that, The height of the self-nourishing packing layer and the heterotrophic packing layer is between 1.5m and 2.0m.

14. The denitrification filter according to claim 1, characterized in that, The hydraulic load of the wastewater flowing through the denitrification filter is between 5 m / h and 10 m / h.

15. The denitrification filter according to claim 10, characterized in that, In the rinsing mode, backwashing is performed in the first unit using air backwashing and water backwashing, and in the second unit using air backwashing, combined air-water backwashing, and water backwashing.

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