Method for removing foam from a sewage treatment biological tank

Abstract

The present application relates to sewage treatment technical field, specifically to a kind of sewage treatment biological pool foam removal method, biological pool foam is collected to biological pool effluent, is intercepted by the interception device at effluent, falls from biological pool effluent, foam is broken, elimination in falling process, the elimination of biological pool foam is realized;The interception device includes interception mechanism and traction adjusting mechanism, and the foam is enriched by the interception mechanism interception, so that foam is discharged from effluent, and the interception mechanism is adjusted by traction adjusting mechanism, to adapt to different forms of foam.The present application relies on the mode of sequence start-stop submersible pusher to continuously push the foam enriched at the corner of biological pool body to the effluent of biological pool, without adding any chemical reagent in the process, without consuming spray water, with low operating cost, with good popularization and application prospect.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and specifically to a method for removing foam from a biological wastewater treatment tank. Background Technology

[0002] In wastewater treatment processes, foam and scum accumulation are common problems in biological treatment tanks during operation. The causes of foam formation are complex, primarily including: firstly, excessive proliferation of foaming filamentous bacteria such as Nocardia in the biological tank; the hydrophobic surface of these bacteria easily forms stable foam under aeration; secondly, the presence of oily substances (animal and vegetable oils, mineral oils, etc.) in the influent reduces the surface tension of the water, promoting foam formation; and thirdly, a high scum content in the influent provides a carrier for filamentous bacteria, further exacerbating the foam problem. Scum formation mainly stems from low efficiency in the pretreatment stage, resulting in the ineffective removal of suspended solids, grease, and light impurities carried in the influent. These substances float to the surface and form scum upon entering the biological treatment tank.

[0003] In a fully mixed biological treatment system, the liquid level is slightly higher at the aeration point of the aeration head during aeration in the aerobic corridor; the liquid level above the propeller is also slightly higher when the propeller starts. The aeration head density is lower at the curved bend, and the hydraulic conditions are worse, causing foam to frequently accumulate between the curved bend and the propeller, forming a dead zone that is difficult to remove with the water flow. Even if some foam flows out with the effluent, due to the aerobic backflow, most of the foam will return to the anoxic corridor, ultimately circulating within the system and failing to be effectively removed.

[0004] The long-term accumulation of foam and scum can cause multiple harms to wastewater treatment systems, such as affecting the oxygen mass transfer efficiency in biological treatment tanks and reducing aeration effects; leading to activated sludge loss and impairing sludge settling performance; and in severe cases, overflowing the tank and polluting the surrounding environment. Currently, common treatment methods include spray defoaming, adding chemical defoamers, or adding flocculants. Spray defoaming breaks up foam with high-pressure water, but it consumes a large amount of water, has unstable effects, and cannot treat scum. Adding chemical defoamers, while fast-acting, has high operating costs, and long-term use may inhibit the activity of microorganisms in the biological treatment tank. Therefore, there is an urgent need for a method to remove foam from biological treatment tanks that requires no chemical additives, operates stably, and is low-cost. Summary of the Invention

[0005] The purpose of this invention is to provide a method for removing foam from biological wastewater treatment ponds, so as to achieve the goal of not requiring the addition of chemical agents, not consuming spray water, and having low operating costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for removing foam from a biological wastewater treatment pond, comprising the following steps: S1. Install an interception device at the outlet of the biological aerobic tank; S2. Collect the foam at the corner of the biological aerobic tank and bring it to the outlet of the biological aerobic tank. S3. The collected foam is intercepted by the interception device and flows out from the outlet of the biological aerobic tank. The foam breaks during the fall, thus removing the foam.

[0007] Furthermore, the interception device is installed based on the biological pool body, including a second steel wire rope. One end of the second steel wire rope is fixed to a third wall in the biological pool. A plastic float is strung on the second steel wire rope. The lower side of the plastic float is immersed in the water. The other end of the second steel wire rope extends to the outside of the outlet, forming a flow channel between the second wall and the plastic float.

[0008] Furthermore, it also includes a first steel wire rope, the two ends of which are fixed to the first wall and the second wall on both sides of the outlet of the biological pool, respectively; the other end of the second steel wire rope is attached to the first steel wire rope.

[0009] Furthermore, the wire rope is fixed to the corresponding wall through anchor points; the anchor points include mounting holes set in the wall and eye nuts installed through the mounting holes, and the corresponding eye nuts are connected to the rope sleeves of the corresponding wire ropes.

[0010] Furthermore, the sheath of the wire rope is a ring structure formed by pressing an aluminum sheath.

[0011] Furthermore, the total length of the connected plastic floats is not less than the width of the aerobic corridor at the outlet of the biological tank, and a limiter that cooperates with the last-stage plastic float is installed on the second steel wire rope near the other end of the second steel wire rope.

[0012] Furthermore, the limiter is an aluminum sleeve, which is pressed and fixed onto the second steel wire rope.

[0013] Furthermore, the other end of the second wire rope is a movable end, which is slidably sleeved on the first wire rope; it also includes a third wire rope, one end of which is connected to the movable end of the second wire rope, and the other end of which is connected to the traction device.

[0014] Furthermore, the traction device includes a mounting column fixed to the second wall, and a fixed pulley mounted on the mounting column; the other end of the third wire rope passes over the fixed pulley and is connected to a self-locking hand-cranked winch.

[0015] Furthermore, the foam is gradually collected at the outlet of the biological aerobic pool by sequentially starting and stopping the submersible propeller in the biological aerobic pool.

[0016] The beneficial effects of this invention are: 1. This invention relies on the sequential start and stop of the submersible propeller to continuously push the foam accumulated at the corner of the biological pool to the outlet of the biological pool, and then discharge and eliminate it after being intercepted by the interception device at the outlet, making the operation simpler and more convenient.

[0017] 2. This invention relies entirely on water drop to break and eliminate foam, without the need for any chemical agents, without consuming spray water, with low operating costs, and without affecting the activity of microorganisms in the biological tank.

[0018] 3. This invention uses plastic floats connected in series on a steel wire rope to form an interception surface. The collected foam is intercepted by the plastic floats and then falls out. During the falling process, the foam breaks, thereby preventing the foam from spinning and accumulating in the pool and ensuring the stability of the biological pool operation.

[0019] 4. This invention uses a self-locking hand-cranked winch to pull a third steel wire rope, which can flexibly adjust the position of the plastic float interception surface. Different interception positions can be selected according to the thickness of foam or scum accumulation, ensuring interception effect and making it more convenient to use. Attached Figure Description

[0020] Figure 1 This is a schematic diagram showing the location of the foam enrichment area in the background technology; Figure 2 This is a schematic diagram of the installation arrangement of the interception device of the present invention; Figure 3 This is a schematic diagram of the plastic pontoon installation structure of the present invention; Figure 4 This is a schematic diagram of the plastic pontoon structure of the present invention; Figure 5 This is a schematic diagram of the connection and fit of the various wire ropes in this invention; Figure 6 This is a schematic diagram of the connection between the self-locking hand-cranked winch and the third steel wire rope of the present invention.

[0021] The names corresponding to each mark in the diagram: 1. Pool body; 11. First wall; 111. Mounting hole; 12. Second wall; 13. Third wall; 14. Outlet; 2. Interception device; 21. First anchor point; 22. Second anchor point; 23. Third anchor point; 24. First wire rope; 25. Second wire rope; 251. Wire rope sleeve; 26. Plastic float; 261. Through hole; 27. Lifting eye nut; 28. Third wire rope; 29. ​​Traction device; 291. Mounting column; 292. Fixed pulley; 293. Self-locking hand winch; a. Areas rich in foam. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0023] Embodiments of the present invention: like Figure 1 As shown, in the biological tank, in the aerobic tank 1, water flows through aerobic channel 1, then sequentially through channels 2-8, and from outlet 14, part of it flows out to the secondary sedimentation tank at the rear end, while part returns to the front end of the anoxic tank through the internal return gate. In the biological tank, changes in aeration, water quality, and environmental conditions may lead to the overgrowth of foaming filamentous bacteria such as Nocardia, resulting in foam production. For example, if the lipid content in the influent is high, it may cause excessive proliferation of Nocardia, resulting in foam. The foam will accumulate at the bends of each channel. Figure 1 Point a (foam-rich area).

[0024] like Figure 2-6 As shown, in this embodiment, the interception device 2 of the present invention is installed and arranged according to the wall of the biological pool. A first anchor point 21 is set on the first wall 11, a second anchor point 22 is set on the second wall 12, and a third anchor point 23 is set on the third wall 13. A first steel wire rope 24 is installed and fixed through the first anchor point 21 and the second anchor point 22, and a second steel wire rope 25 is installed and fixed through the second anchor point 22 and the third anchor point 23. In other embodiments of the present invention, each anchor point is installed by drilling installation holes 111 on the corresponding wall, and then installing the eye nut 27 by chemical anchor bolts. A steel wire rope sleeve 251 is set at both ends of each steel wire rope. At each anchor point, the steel wire rope sleeve 251 is sleeved with the eye nut 27. In other embodiments of the present invention, the steel wire rope sleeve 251 can be made by using an aluminum sleeve. One end of the steel wire rope is passed through one side of the aluminum sleeve and the installed eye nut 27 in sequence, and then through the other side of the aluminum sleeve to form the steel wire rope sleeve 251, and then pressed and fixed by the aluminum sleeve.

[0025] In this embodiment, plastic floats 26 are sequentially connected to the second steel wire rope 25, and a through hole 261 is provided in the center of the plastic float 26, which cooperates with the steel wire rope. In other embodiments of the present invention, a limiter is provided on the second steel wire rope 25 near the rear end of the plastic float 26 close to the first steel wire rope 24. The limiter restricts the uncontrolled movement of the plastic float 26 along the second steel wire rope 25. In this embodiment, the limiter can be an aluminum sleeve, which can be inserted and pressed.

[0026] In this embodiment, the end of the second wire rope 25 that engages with the first wire rope 24 is in a movable engagement, that is, the wire rope sleeve 251 at the end of the second wire rope 25 that engages with the first wire rope 24 is sleeved on the first wire rope 24. At the same time, the wire rope sleeve 251 is also sleeved on one end of the third wire rope 28. The other end of the third wire rope 28 is connected to the traction device 29 on the second wall 12. The traction device 29 is provided with a mounting column 291, and a fixed pulley 292 is provided on the mounting column 291. The other end of the third wire rope 28 is connected to the self-locking hand-cranked winch 293 via the fixed pulley 292.

[0027] The principle of this invention is as follows: For dead zones where foam accumulates, such as bends in the aerobic tank corridors, the foam and scum can be gradually collected and pushed to interception device 2 by alternately starting and stopping the flow promoters. The specific operating steps are as follows: Figure 1 As shown, multiple propellers are arranged sequentially along the water flow direction in the aerobic pool corridor, and are labeled as propeller #1, propeller #2, etc. along the aerobic 1 corridor.

[0028] When foam accumulates at the bend in the corridor, such as at the end of the aerobic 1 corridor, stop the No. 3 propeller in the aerobic 2 corridor. The foam will flow with the water to between the No. 3 and No. 4 propellers. Then stop the No. 4 propeller and start the No. 3 propeller. The foam will continue to flow forward with the water. Repeat this process until the foam is pushed to the vicinity of the aerobic end outlet 14, thereby achieving effective collection of foam and scum in dead corners.

[0029] When the foam buildup becomes thick, the self-locking hand-cranked winch 293 is released, the third wire rope 28 is loosened, and the second wire rope 25, which is connected to the plastic float 26, moves along the first wire rope 24 under the push of the water flow, forming a foam layer. Figure 1 As shown by the dotted line, the water flow curves or continues to move to form a straight line. At this time, the water outlet area between the plastic float 26 and the second wall 12 becomes larger. After the accumulated foam is intercepted, it falls and is discharged with the water through the outlet 14 (the water outlet area between the plastic float 26 and the second wall 12). The water force is used to break up the foam and remove it from the system. (Note: If a small amount of foam is not intercepted, it will not affect the stability of the biological tank.)

[0030] When the foam buildup is thick, if the foam interception device 2 is located... Figure 1 At the location indicated by the solid line, due to the small surface area of ​​the plastic float 26, the force on the plastic float 26 is large. When the foam interception device 2 is impacted, it will rise as a whole. Some foam will overflow from below the plastic float 26 and enter the rear of the plastic float 26. Some will flow out with the water outlet, and some will re-enter the entire system from the aerobic return port and will not be removed from the system. Therefore, it is necessary to adjust the position of the interception device 2 to a larger surface area.

[0031] When the foam layer is thin or when it is necessary to intercept scum, crank the self-locking hand winch 293 to tighten the third wire rope 28. The third wire rope 28 pulls the second wire rope 25 through the wire rope sleeve 251, causing the plastic float 26 to slide along the first wire rope 24, thus forming a... Figure 1 As shown by the solid line, a thin layer of foam or scum is quickly discharged with the water in a small outlet area and removed after being broken up by the falling water. If it is scum, an intercepting net can be set up at the outlet drop point to remove the scum.

[0032] When the foam layer is thin or when it is necessary to intercept scum, the foam interception device 2 is located at the solid line position. Although the water-facing surface is subjected to a large force and the plastic float 26 is squeezed and rises as a whole, compared with when the foam layer is thick, the foam and scum are completely above the liquid surface and will not flow out from below the plastic float 26. Moreover, the position where the foam and scum fall in front of the plastic float 26 becomes smaller, and the foam flows out faster.

[0033] It should be noted that under mature operating conditions, the foam generated in the biological tank due to the proliferation of filamentous bacteria or excessive oil in the influent will be effectively broken up as it falls with the effluent. However, under immature operating conditions, such as in the early stages of biological tank startup when the activated sludge system in the tank is not yet perfect, if the influent contains a large amount of surfactant, the foam formed will not be effectively removed during the fall. But as the process stabilizes, this situation will also disappear.

[0034] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this invention falls within the protection scope of this invention.

Claims

1. A method for removing foam from a biological wastewater treatment tank, characterized in that, Includes the following steps: S1. Install an interception device at the outlet of the biological aerobic tank; S2. Collect the foam at the corner of the biological aerobic tank and bring it to the outlet of the biological aerobic tank. S3. The collected foam is intercepted by the interception device and flows out from the outlet of the biological aerobic tank. The foam breaks during the fall, thus removing the foam.

2. The removal method according to claim 1, characterized in that: The interception device is installed on the biological pool body and includes a second steel wire rope. One end of the second steel wire rope is fixed to the third wall in the biological pool. A plastic float is connected to the second steel wire rope. The lower side of the plastic float is immersed in the water. The other end of the second steel wire rope extends to the outside of the outlet, forming a flow channel between the second wall and the plastic float.

3. The removal method according to claim 1, characterized in that: It also includes a first steel wire rope, the two ends of which are fixed to the first wall and the second wall on both sides of the outlet of the biological tank, respectively; the other end of the second steel wire rope is attached to the first steel wire rope.

4. The removal method according to claim 2 or 3, characterized in that: The wire rope is fixed to the corresponding wall through anchor points; the anchor points include mounting holes set in the wall and eye nuts installed through the mounting holes, and the corresponding eye nuts are connected to the rope sleeves of the corresponding wire ropes.

5. The removal method according to claim 4, characterized in that: The sheath of the wire rope is a ring structure formed by pressing an aluminum sheath.

6. The removal method according to claim 1, characterized in that: The total length of the connected plastic floats is not less than the width of the aerobic corridor at the outlet of the biological tank. A limiter that works with the last-stage plastic float is installed on the second steel wire rope at the rear end of the last-stage plastic float, which is close to the other end of the second steel wire rope.

7. The removal method according to claim 6, characterized in that: The limit switch is made of aluminum sleeve, which is pressed and fixed to the second steel wire rope.

8. The removal method according to claim 3, characterized in that: The other end of the second wire rope is a movable end, which is slidably sleeved on the first wire rope; it also includes a third wire rope, one end of which is connected to the movable end of the second wire rope, and the other end of which is connected to the traction device.

9. The removal method according to claim 8, characterized in that: The traction device includes a mounting column, which is fixed to the second wall, and a fixed pulley is mounted on the mounting column; the other end of the third wire rope passes over the fixed pulley and is connected to a self-locking hand-cranked winch.

10. The removal method according to claim 1, characterized in that: The foam is gradually collected at the outlet of the biological aerobic pool by sequentially starting and stopping the submersible propeller in the biological aerobic pool.

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