A Symmetrical Siphon Separation Method for Water Pollution Control

Abstract

The present invention relates to the field of water pollution control, and discloses a symmetric siphon separation method for water pollution control, which includes using a symmetric double-siphon centrifuge to perform solid-liquid separation on the suspension of polluted water, adding the suspension into the drum of the siphon centrifuge for centrifugal separation treatment, and performing siphon drainage at both the front and rear ends of the drum of the siphon centrifuge; after the filter cake thickness in the drum reaches the preset loading amount, adding the suspension is stopped, the drum continues to operate for a preset time and then discharging is carried out, and after discharging, backwashing is carried out on the filter medium of the drum. The present invention can solve the problems of low separation efficiency and poor separation effect caused by unbalanced separation existing in the single-sided siphon separation used for solid-liquid separation in the existing sewage and wastewater treatment processes.

Description

Technical Field

[0001] The present invention relates to the field of water pollution treatment, and particularly to a symmetric siphon separation method for water pollution control. Background Art

[0002] With the rapid development of industry and the continuous growth of population, the discharge of wastewater has been increasing year by year, seriously polluting rivers, lakes and groundwater and significantly deteriorating the water quality. First of all, the main source of water pollution is industrial wastewater. Since a large amount of wastewater is generated during industrial production, which contains various harmful substances such as heavy metals, organic substances, acids and alkalis, these substances cause serious pollution to water bodies. In addition, in order to pursue economic benefits, some factories often discharge wastewater directly into rivers and lakes without treatment, which is also one of the main reasons for water pollution. Secondly, domestic sewage is also an important source of water pollution. Various sewage generated in people's daily lives, such as water used for washing and sanitation, contains a large amount of pollutants such as organic substances and nutrient salts. These sewage not only pollute rivers and lakes, but also affect the quality of groundwater.

[0003] In the process of sewage treatment and industrial wastewater treatment, centrifugal separation is a commonly used solid-liquid separation technology. Among the commonly used solid-liquid separation equipment, the siphon scraper centrifuge can effectively separate solid suspended matters from liquid, thereby improving water quality. At the same time, it can also remove pollutants such as grease and heavy metal ions in water, so it is widely used in the treatment of food processing wastewater, electroplating wastewater, etc. In addition, in circulating water treatment, the siphon scraper centrifuge can effectively remove impurities, algae, microorganisms, etc. in water, thereby preventing pipeline blockage and corrosion. However, the existing siphon scraper centrifuge has a single-side siphon for liquid discharge. After the liquid phase of the separated slurry passes through the filter medium (filter cloth), the liquid phase at the front end of the drum needs to pass from the very front end of the drum through the entire length of the drum to the rear end of the drum in the filter channel of the filter plate, then pass through the siphon hole at the bottom of the drum into the siphon chamber, and then be discharged out of the centrifuge through the siphon chamber at the rear end. The liquid phase drainage path is relatively long, and the liquid phase separation efficiency is relatively low. During the separation process, some small particle solids will pass through the filter medium (filter cloth). Especially at the siphon end, due to the siphon force brought by the siphon chamber, more materials at the bottom of the drum pass through the filter, which may lead to imbalance of the materials at the front and rear of the drum, and further cause vibration of the drum during operation. Long-term vibration reduces the service life of the equipment. And due to the asymmetry of single-side drainage, imbalance will occur in the separation of some materials, resulting in poor separation effect of solid phases in sewage and wastewater, not meeting the preset standards, and increasing the cost of re-treatment of sewage and wastewater. Summary of the Invention

[0004] The present invention aims to provide a symmetric siphon separation method for water pollution control, so as to solve the problems of low separation efficiency and poor separation effect caused by unbalanced separation in the existing solid-liquid separation using unilateral siphon separation during the treatment of sewage and wastewater.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A symmetric siphon separation method for water pollution control, comprising the following steps:

[0006] A. Prepare a siphon centrifuge;

[0007] B. Treat the polluted water to be subjected to solid-liquid separation into a suspension;

[0008] C. Start the siphon centrifuge to rotate its drum, add the suspension into the drum of the siphon centrifuge for centrifugal separation treatment, and perform siphon drainage at both the front and rear ends of the drum of the siphon centrifuge;

[0009] D. Stop adding the suspension after the filter cake thickness in the drum reaches the preset loading amount, continue to operate the drum for a preset time and then unload the material, and perform backwashing on the filter medium of the drum after unloading;

[0010] E. Perform the next solid-liquid separation process.

[0011] Preferably, as an improvement, in step A, a front siphon chamber is provided at the front end of the drum of the siphon centrifuge, a rear siphon chamber is provided at the rear end, and a front siphon pipe that can rotate into the front siphon chamber and a rear siphon pipe that can rotate into the rear siphon chamber are provided on the siphon centrifuge.

[0012] Preferably, as an improvement, in step A, the front siphon pipe and the rear siphon pipe are symmetrically distributed with respect to the geometric center of the drum, so as to perform balanced siphon drainage at both the front and rear ends of the drum in step C.

[0013] Preferably, as an improvement, in step C, the front siphon pipe and the rear siphon pipe enter the front siphon chamber and the rear siphon chamber simultaneously for siphon drainage.

[0014] Preferably, as an improvement, in step A, the front siphon chamber and the rear siphon chamber have the same size and volume, and the inner diameters of the front siphon pipe and the rear siphon pipe are the same, so as to balance the siphon drainage amounts at both ends of the drum in step C.

[0015] Preferably, as an improvement, in step C, after the suspension enters the siphon centrifuge, a conical distribution hopper is used to evenly distribute the suspension along the axial direction of the drum into the drum.

[0016] Preferably, as an improvement, in step D, a front backwashing pipe is provided at the front end of the drum of the siphon centrifuge, a rear backwashing pipe is provided at the rear end of the drum, and the liquid discharged by siphon is respectively injected into the front siphon chamber and the rear siphon chamber through the front backwashing pipe and the rear backwashing pipe for backwashing.

[0017] Preferably, as an improvement, in step D, the front backflush pipe and the front siphon pipe are symmetrically distributed at right angles on both sides of the axis of the drum, and the rear backflush pipe and the rear siphon pipe are symmetrically distributed at right angles on both sides of the axis of the drum.

[0018] Preferably, as an improvement, in step D, the front backflush pipe and the rear backflush pipe simultaneously inject liquid into the front siphon chamber and the rear siphon chamber for backflushing.

[0019] Preferably, as an improvement, the suspension in step B is a suspension containing particles with a diameter of 0.01 mm - 5 mm, or a suspension containing fibers with a length of less than 4 mm, and the concentration range of the suspension is between 10% and 60%.

[0020] The principle and advantages of this solution are as follows: In practical applications, for sewage and wastewater, after preliminary sedimentation and filtration, there are still a large number of harmful substances. Usually, a flocculant is added to flocculate some of the harmful substances, and then solid-liquid separation is carried out. The technical solution of the present invention treats the polluted water to be treated into a suspension, injects it into a symmetric double-siphon centrifuge at a certain concentration, and centrifuges the suspension through the drum in the symmetric double-siphon centrifuge, so that the solid phase settles on the filter plate, and the liquid phase passes through the filter plate and enters the siphon chamber. By setting a front siphon chamber and a rear siphon chamber on the drum and using symmetrically distributed front siphon pipes and rear siphon pipes, siphon drainage is carried out at both ends of the drum simultaneously and with the same flow rate. After solid-liquid separation, the filter plate is backwashed by simultaneously injecting the liquid phase discharged by siphon through the symmetrically distributed front backflush pipe and rear backflush pipe, and the liquid phase separated is fully utilized for filter screen regeneration.

[0021] The advantages of the present invention include:

[0022] 1. The liquid at the front end of the drum is siphoned and discharged from the front side, only passing through half of the length of the drum. Compared with the drainage path of a single-side siphon centrifuge, it is reduced by half; and the liquid at the rear end of the drum is discharged from the rear side of the drum, also only passing through half of the length of the drum. Compared with the drainage path of a single-side siphon centrifuge, it is reduced by half. Therefore, the overall liquid phase drainage path is shorter, and the liquid phase separation and discharge efficiency is higher during the treatment of polluted water.

[0023] 2. By adopting the double-siphon method, since it is arranged front and back, and at the same time, symmetric distribution and simultaneous and same-flow-rate siphon drainage are adopted, both the drum and the materials inside the drum can maintain a good balance state during the liquid phase separation process. The drum will not vibrate, and the materials will not be unbalanced. Furthermore, the liquid phase separation can be carried out efficiently and stably, and the solid-liquid separation effect on polluted water is better.

[0024] 3. By adopting the double-siphon suction force, the separation time is shorter than that of ordinary centrifuges, the liquid phase separation is more thorough, and the output per unit time is higher. Therefore, the double-siphon centrifugation method has a higher separation efficiency than the traditional single-side siphon centrifugation.

[0025] 4. Meanwhile, according to different material requirements, a program can be set to select front siphon to drain mother liquor and rear siphon to drain washing liquid to achieve the purpose of separate discharge; or they can be discharged together to reduce the discharge time and improve efficiency.

[0026] 5. The backflush liquid can be added to both siphon chambers simultaneously to wash the residual filter cake. The backflush liquid can be the mother liquor or washing liquid discharged by siphon, reducing the water consumption cost; with simultaneous backflushing on both sides, the washing is more thorough, the filter cake regeneration ability is stronger, ensuring better permeability of the filter medium, longer service life of the filter cloth, and lower solid-liquid separation cost for polluted water. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the symmetric double-siphon centrifuge in the embodiment of the present invention.

[0028] Figure 2 is Figure 1 a partial enlarged view of A in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following is a further detailed description through specific embodiments:

[0030] The reference numerals in the attached drawings of the specification include: housing 1, drum cylinder 2, scraper 3, siphon hole 4, rear siphon pipe 5, rotating arm 6, rear support plate 7, motor 8, rear backflush pipe 9, rear siphon chamber 10, washing pipe 11, cloth feeding hopper 12, filter plate 13, front siphon pipe 14, support seat 15, slag discharge port 16, discharge cylinder 17, door cover 18, discharge screw 19, front backflush pipe 20, feed pipe 21, front siphon chamber 22.

[0031] Embodiment, a symmetric siphon separation method for water pollution control, includes the following steps:

[0032] A. Prepare a siphon centrifuge; the front end of the drum of the siphon centrifuge is provided with a front siphon chamber, and the rear end is provided with a rear siphon chamber. The siphon centrifuge is provided with a front siphon pipe that can rotate into the front siphon chamber and a rear siphon pipe that can rotate into the rear siphon chamber. The front siphon pipe and the rear siphon pipe are symmetrically distributed with respect to the geometric center of the drum. The front siphon chamber and the rear siphon chamber have the same size and volume, and the inner diameters of the front siphon pipe and the rear siphon pipe are the same; a front backflush pipe is arranged at the front end of the drum of the siphon centrifuge, and a rear backflush pipe is arranged at the rear end of the drum. The front backflush pipe and the front siphon pipe are symmetrically distributed at right angles on both sides of the drum axis, and the rear backflush pipe and the rear siphon pipe are symmetrically distributed at right angles on both sides of the drum axis;

[0033] B. Treat the polluted water to be subjected to solid-liquid separation into a suspension. The suspension is a suspension containing particles with a diameter of 0.01 mm - 5 mm, or a suspension containing fibers with a length less than 4 mm. The concentration range of the suspension is between 10% and 60%;

[0034] C. Start the siphon centrifuge to rotate its drum, add the suspension into the drum of the siphon centrifuge for centrifugal separation treatment. After the suspension enters the siphon centrifuge, a conical cloth hopper is used to evenly distribute the suspension along the axial direction of the drum into the drum. The front siphon pipe and the rear siphon pipe enter the front siphon chamber and the rear siphon chamber at the front and rear ends of the drum simultaneously for balanced siphon drainage.

[0035] D. After the filter cake thickness in the drum reaches the preset loading amount, stop adding the suspension. After the drum continues to run for a preset time, unload the material. After unloading, use the front backwash pipe and the rear backwash pipe to simultaneously inject the liquid drained by siphon into the front siphon chamber and the rear siphon chamber respectively to backwash the filter medium of the drum.

[0036] E. Conduct the next solid-liquid separation process.

[0037] This embodiment provides a symmetric double-siphon centrifuge used in conjunction with the symmetric siphon separation method for water pollution control. It is basically as shown in the appendix Figure 1 、 Figure 2 : It includes a frame housing 1. The frame housing 1 includes a housing 1 welded to the frame. A rear support plate 7 is welded to the rear end of the housing 1. The front end of the housing 1 is hinged with a door cover 18 through a hinge. The door cover 18 can be locked on the housing 1 by means of hydraulic locking. The specific structure is the same as that of the existing siphon scraper centrifuge 3 and will not be elaborated here. A drum is installed inside the frame housing 1. The drum is welded with a main shaft. The main shaft is connected to the rear support plate 7 through bearings. The rear end of the main shaft is connected to a motor 8 through belt drive. The front end of the drum is open and integrally formed with an annular liquid retaining plate. An annular front siphon chamber 22 is provided on the drum in front of the liquid retaining plate. The middle section of the drum is the drum cylinder 2. The rear end of the drum is provided with an annular rear siphon chamber 10. The front siphon chamber 22 and the rear siphon chamber 10 are both provided with openings facing the axis of the drum. A plurality of filter plates 13 are embedded along the circumferential direction on the inner wall of the drum cylinder 2. A dehydration chamber is formed between the filter plates 13 and the inner wall of the drum cylinder 2. Siphon holes 4 communicating with the dehydration chamber are provided at the bottoms of the front siphon chamber 22 and the rear siphon chamber 10. A plurality of siphon holes 4 are evenly distributed along the circumference of the drum. Siphon pipe assemblies are provided on both the door cover 18 and the rear support plate 7. The two siphon pipe assemblies are centrosymmetrically distributed with the geometric center of the drum. The siphon pipe assembly includes an L-shaped siphon pipe. The short side of the siphon pipe extends into the inner side of the frame housing 1. The long side of the siphon pipe is installed on a support seat 15 through a bearing. The support seat 15 is bolted to the door cover 18 and the rear support plate 7. A swivel arm 6 is bolted to the long side of the siphon pipe. The swivel arm 6 is hinged with an oil cylinder bolted to the frame housing 1. The oil cylinder can push the swivel arm 6 to rotate the siphon pipe, and then the short side of the siphon pipe rotates into the front siphon chamber 22 and the rear siphon chamber 10.

[0038] The counterflush pipe assemblies are bolted to both the door cover 18 and the rear support plate 7. The counterflush pipe assembly includes an L-shaped counterflush pipe, and a flange is welded on the counterflush pipe. The flange is bolted to the door cover 18 and the rear support plate 7. The short-side outlet of the counterflush pipe faces the front siphon chamber 22 and the rear siphon chamber 10. The two counterflush pipe assemblies are centrosymmetrically distributed with respect to the geometric center of the drum. The counterflush pipe assemblies and the siphon pipe assemblies are symmetrically distributed at right angles on both sides of the drum axis.

[0039] A horizontally penetrating discharge cylinder 17 is welded in the middle of the door cover 18. The discharge cylinder 17 extends horizontally into the drum. A discharge screw 19 is provided in the discharge cylinder 17. A slag discharge port 16 is formed at the end of the discharge cylinder 17 located outside the door cover 18, and the end of the discharge cylinder 17 located inside the drum opens upward. A scraper 3 holder extending into the drum body 2 is connected to the door cover 18 above the discharge cylinder 17 through a bearing. A scraper 3 facing the upper side of the drum body 2 is bolted to the scraper 3 holder. The scraper 3 is located above the opening of the discharge cylinder 17. A feed pipe 21 penetrates through the door cover 18 above the discharge cylinder 17. The feed pipe 21 extends horizontally into the drum and is welded with a distribution hopper 12. The distribution hopper 12 faces the inner wall of the drum body 2. A washing pipe 11 extending into the drum penetrates through the door cover 18 below the discharge cylinder 17. Openings facing the inner wall of the drum body 2 are formed on the washing pipe 11. This part of the discharge, feeding, and washing structures are the same as those of the prior art siphon scraper 3 centrifuge, and reference can be made to the prior art siphon scraper 3 centrifuge for details.

[0040] The operation process of this symmetric double-siphon centrifuge is as follows: The motor 8 drives the main shaft and the drum to rotate through belt transmission. Materials enter the drum from the feed pipe 21 and the distribution hopper 12. The rotation of the drum causes the materials to be centrifuged, and the solid phase settles on the filter plate 13 to form a filter cake. The liquid phase passes through the filter cake and enters the dehydration chamber, the siphon holes 4, the front siphon chamber 22, and the rear siphon chamber 10. The siphon pipes in the front siphon pipe 14 assembly and the rear siphon pipe 5 assembly are driven to rotate by the oil cylinder driving the rotary arm 6, and the pipe orifices of the siphon pipes enter the front siphon chamber 22 and the rear siphon chamber 10.

[0041] The filtration driving force of the siphon scraper 3 centrifuge depends on the pressure difference on both sides of the filter mesh. At the same time, it is directly proportional to the liquid level height Ho in the drum and inversely proportional to the thickness H' of the filter cake layer. The siphon scraper 3 centrifuge uses the siphon principle on the outside of the filter mesh to increase the pressure difference on both sides of the filter medium, ultimately achieving the purpose of increasing the filtration speed. Since the siphon pipe can swing back and forth, there is a variable liquid level difference Hu between the siphon pipe orifice and the outside of the filter mesh. When the position of the siphon suction port is lower than the outside of the filter mesh, Hu is positive. At this time, in addition to the centrifugal force generated by high-speed rotation, the filtration driving force of the siphon scraper 3 centrifuge also has an additional siphon suction force on the outside of the filter mesh. When the siphon suction port is at the same height as the outside of the filter mesh, Hu is 0, and there is no siphon effect at this time. The filtration driving force is only the centrifugal force. When the position of the siphon liquid suction port is higher than the outside of the filter mesh, Hu is negative. At this time, not only is there no siphon effect, but it also hinders the filtration. The siphon scraper 3 centrifuge precisely uses the change of Hu to achieve the filtration, washing, and separation of materials.

[0042] The centrifugal speed of the centrifuge depends on the pressure difference between the two sides of the filter medium (7) and the liquid level height of the drum, that is:

[0043] V = K'(△P / H') = K(H0 / H')

[0044] In the formula:

[0045] V - Filtration speed

[0046] △P - Pressure difference between the two sides of the filter medium

[0047] K, K' - Proportional constants

[0048] H' - Thickness of the filter cake layer

[0049] H0 - Liquid level height

[0050] In addition to this, for the centrifugal speed of this centrifuge, the front and rear siphon pipe 5 components also increase the siphon suction force. Therefore, its separation speed is also related to the position of the siphon pipe orifice, that is:

[0051] V = K(Ho + Hu) / H'

[0052] Hu - Height difference between the siphon liquid suction port and the outer side of the filter medium.

[0053] The main functions of the siphon device:

[0054] Recoil stage: Hu is negative, and the recoil liquid enters the front siphon chamber 22 and the rear siphon chamber 10 through the front recoil pipe 20 and the rear recoil pipe 9; under the action of centrifugal force, the recoil liquid in the front siphon chamber 22 and the rear siphon chamber 10 enters the drum through the front siphon pipe 14 and the rear siphon pipe 5. After adding a certain amount, the recoil liquid will penetrate reversely through the filter medium, playing a role in reverse flushing the residual filter cake, softening the residual filter cake, and regenerating the filter plate 13.

[0055] Feeding stage: Hu is positive, zero or negative. The solid-liquid mixture slurry is added into the drum through the feeding pipe 21. Under the action of centrifugal force, the solid phase is intercepted by the filter medium to form a filter cake with a uniform thickness; the liquid phase passes through the filter cake, the filter medium, the filter plate 13 and then through the filter channels of the filter plate 13, flows towards the front and rear ends of the drum, and enters the front siphon chamber 22 and the rear siphon chamber 10 respectively through the front and rear siphon holes 4; finally, it is discharged out of the centrifuge through the front siphon pipe 14 and the rear siphon pipe 5.

[0056] Washing stage: Hu is zero or negative. The washing liquid passes through the washing pipe 11 and will first be evenly sprayed on the solid-phase filter cake layer. Then, under the action of centrifugal force, the washing liquid will pass through the solid-phase filter cake layer to achieve the effect of washing the entire filter cake; at the same time, at this time, the front siphon pipe 14 and the rear siphon pipe 5 can be controlled to return to the starting position. Then, at this time, the washing liquid will not be discharged out of the centrifuge, but will reach a certain liquid level height, so as to achieve the effect of immersion washing; the washing of materials is more thorough, the washing liquid is more saved, and the washing effect is better.

[0057] Drying stage: Hμ reaches the maximum positive value. At this time, the filtration driving force is the largest and the centrifugal effect is the best.

[0058] Since the diameter of the siphon chamber is larger than the diameter of the drum, as long as the liquid phase that can be separated from the solid-liquid under the action of centrifugal force will all enter the front siphon chamber 22 and the rear siphon chamber 10 and be discharged out of the centrifuge.

[0059] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the solutions are not described in detail herein. It should be pointed out that for those skilled in the art, without departing from the technical solutions of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A symmetric siphon separation method for water pollution control, characterized in that: It includes the following steps: A. Prepare a siphon centrifuge; a front siphon chamber is provided at the front end of the drum of the siphon centrifuge, and a rear siphon chamber is provided at the rear end. A front siphon pipe that can rotate into the front siphon chamber and a rear siphon pipe that can rotate into the rear siphon chamber are provided on the siphon centrifuge. The front siphon pipe and the rear siphon pipe are symmetrically distributed with respect to the geometric center of the drum. The sizes and volumes of the front siphon chamber and the rear siphon chamber are the same, and the inner diameters of the front siphon pipe and the rear siphon pipe are the same; B. Treat the contaminated water to be subjected to solid-liquid separation into a suspension; C. Start the siphon centrifuge to rotate its drum, add the suspension into the drum of the siphon centrifuge for centrifugal separation treatment. The front siphon pipe and the rear siphon pipe simultaneously enter the front siphon chamber and the rear siphon chamber for siphon drainage, and balanced siphon drainage is carried out at both the front and rear ends of the drum of the siphon centrifuge. The siphon drainage volumes at both ends of the drum are balanced; D. Stop adding the suspension after the filter cake thickness in the drum reaches the preset loading amount. The drum continues to run for a preset time and then discharges the material. After discharging, backflush the filter medium of the drum; E. Conduct the next solid-liquid separation process.

2. The symmetric siphon separation method for water pollution control according to claim 1, wherein: In step C, after the suspension enters the siphon centrifuge, a conical cloth hopper is used to evenly distribute the suspension along the axial direction of the drum into the drum.

3. A symmetric siphon separation method for water pollution control according to claim 1, characterized in that: In step D, a front backflush pipe is provided at the front end of the drum of the siphon centrifuge, and a rear backflush pipe is provided at the rear end of the drum. The front backflush pipe and the rear backflush pipe are used to inject the siphon-discharged liquid into the front siphon chamber and the rear siphon chamber respectively for backflushing.

4. A symmetric siphon separation method for water pollution control according to claim 3, characterized in that: In step D, the front backflush pipe and the front siphon pipe are symmetrically distributed at right angles on both sides of the drum axis, and the rear backflush pipe and the rear siphon pipe are symmetrically distributed at right angles on both sides of the drum axis.

5. A symmetric siphon separation method for water pollution control according to claim 4, characterized in that: In step D, the front backflush pipe and the rear backflush pipe simultaneously inject liquid into the front siphon chamber and the rear siphon chamber for backflushing.

6. A symmetric siphon separation method for water pollution control according to claim 1, characterized in that: The suspension in step B is a suspension containing particles with a diameter of 0.01 mm - 5 mm, or a suspension containing fibers with a length less than 4 mm, and the concentration range of the suspension is between 10% and 60%.

Images