Short-cut nitrification membrane aeration bio-membrane reactor and operation method thereof

Abstract

The invention discloses a short-cut nitrification membrane aeration bio-membrane reactor and an operation method thereof. The reactor comprises a sludge deposition area, a bio-membrane reaction area and a separation area, the sludge deposition area is connected with a sludge discharge pipe; an annular carrying disc is arranged in the biological membrane reaction area, a membrane assembly is arranged on the annular carrying disc, the biological membrane reaction area is connected with an air inlet / outlet, a water inlet disc connected with a water inlet pipe is arranged below the membrane assembly, a sampling port is formed in the middle of the biological membrane reaction area, and a sludge backflow port is formed in the top of the biological membrane reaction area; a three-phase separator is arranged in the separation area, a return pipe is arranged in the middle of the three-phase separator, an exhaust port is formed in the top of the three-phase separator, a sludge discharge port is formed in the bottom of the separation area, and an overflow groove is formed in the upper part of the separation area and provided with a water outlet. Activated sludge deposited at the bottom of the reactor is extracted and introduced into the reaction area again through the sludge reflux inlet, the uniform distribution rate of the activated sludge in the reaction area can be increased, the contact rate of the activated sludge and a membrane assembly carrier is increased, and the enrichment growth time of a biological membrane is shortened, so that the reactor is quickly started.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a short-range nitrification membrane aeration biofilm reactor and an operation method thereof. Background Art

[0002] With the increase of global population, the acceleration of urbanization and the improvement of industrialization level, nitrogen pollution has become an important problem of water pollution. The ammonia nitrogen content in sewage is too high, especially in agricultural wastewater, domestic sewage and industrial wastewater. Nitrogen pollution not only affects water quality, but also may lead to eutrophication of water bodies, causing algae to multiply in large numbers, seriously affecting the ecological balance. The traditional nitrification process usually includes two stages: oxidation of ammonia nitrogen to nitrite and then oxidation of nitrite to nitrate. This process requires a high oxygen supply, and the conversion of ammonia nitrogen to nitrate is a high-energy process. Especially at low nitrogen concentrations, the system requires a lot of oxygen, resulting in high operating costs. Short-range nitrification can reduce the demand for oxygen by inhibiting the further oxidation of nitrite, so it has obvious energy-saving advantages. As a new type of sewage treatment technology, short-range nitrification can make full use of the characteristics of microorganisms in the treatment process while improving the nitrogen removal efficiency. With the continuous development of sewage treatment technology, researchers are also exploring how to combine other technologies (such as membrane bioreactors, redox potential control, etc.) to further improve the effect of short-range nitrification and ensure the efficient and stable operation of the treatment system.

[0003] Membrane aerated biofilm reactor (MABR) has significant advantages in terms of operating energy consumption and denitrification efficiency. During the MABR membrane aeration process, oxygen penetrates the biofilm in molecular form under the pressure difference and fully contacts with microorganisms, which greatly reduces the mass transfer resistance, so the oxygen utilization efficiency and mass transfer rate are significantly improved. The electron donor and electron acceptor in the MABR have the characteristics of "heterogeneous mass transfer". Oxygen or air can be transferred to the biofilm through the membrane material. As oxygen is transferred to the biofilm, oxygen is gradually used by microorganisms in the biofilm, and its concentration shows a decreasing trend from the inside to the outside. However, the transfer direction of pollutants in water is opposite to that of oxygen. Pollutants are transferred from the outside to the inside of the biofilm and are gradually degraded during the transfer process. Therefore, the biofilm forms an aerobic layer-anoxic layer-anaerobic layer structure from the membrane side to the water body side. Due to this special structure, different microorganisms grow in the biofilm at different depths of the MABR. The oxygen concentration at the bottom of the biofilm is high and the organic matter concentration is low. Aerobic nitrifying bacteria grow here, which is conducive to the nitrification reaction. Since the biofilm on the MABR can be a carrier of microorganisms, nitrifying bacteria can be enriched on the biofilm. Therefore, short-range nitrification can be carried out in the MABR, and efficient nitrite accumulation can be achieved at a lower aeration rate and carbon-nitrogen ratio.

[0004] During the operation of MABR, the growth of biofilm faces many challenges. In order to solve these problems, it is necessary to take corresponding control measures and strengthen the monitoring and regulation of the biofilm growth process. Under the condition of a certain reactor volume, the enrichment growth rate of the biofilm determines the efficiency of the reactor's short-range nitrification. Based on sludge reflow, it can provide more opportunities for microorganisms at the bottom of the sedimentation reactor to attach to the carrier and enhance their activity. Accelerate the growth and formation of biofilm, achieve rapid startup of the reactor, and improve the treatment performance of the reactor. Summary of the invention

[0005] The present invention aims to solve the problems existing in the prior art and provides a short-range nitrification membrane aeration biofilm reactor and an operation method thereof. By extracting the activated sludge deposited at the bottom of the reactor and re-entering the reaction zone from the sludge reflux port above the reaction zone, the uniform distribution rate of the activated sludge in the reaction zone is increased, the contact rate with the membrane component carrier is improved, and the biofilm enrichment growth time is shortened, thereby quickly starting the reactor.

[0006] The technical scheme of the present invention is: a short-range nitrification membrane aeration biofilm reactor, the reactor comprises a sludge deposition zone, a biofilm reaction zone, and a separation zone arranged in sequence from bottom to top; the bottom of the sludge deposition zone is connected to a sludge discharge pipe; the bottom of the biofilm reaction zone is provided with an annular carrier plate, and a membrane assembly is provided on the annular carrier plate, and the membrane assembly comprises membrane filaments and hollow aeration rings respectively arranged at the upper and lower ends of the membrane filaments; the biofilm reaction zones below and above the membrane assembly are respectively connected with air inlets and air outlets; the biofilm reaction zone below the membrane assembly is provided with a water inlet tray, and the water inlet tray is connected to A water inlet pipe is connected, and the water inlet pipe passes through the biofilm reaction zone to the outside. A sampling port is provided in the middle of the biofilm reaction zone, and a plurality of sludge return ports arranged around the biofilm reaction zone are provided on the top of the biofilm reaction zone; the separation zone and the biofilm reaction zone are connected by a flange, a three-phase separator is provided in the separation zone, a return pipe is provided in the middle of the three-phase separator, and the return pipe passes through the separation zone to the outside, an exhaust port is provided on the top of the three-phase separator, a sludge discharge port is provided at the bottom of the separation zone, an overflow trough is provided on the upper part of the separation zone, and a water outlet is provided on the overflow trough.

[0007] Furthermore, the longitudinal section height ratio of the sludge deposition zone, biofilm reaction zone and separation zone in the present invention is 1:(17-19):6, and the maximum cross-sectional area ratio of the sludge deposition zone, biofilm reaction zone and separation zone is 1:1:(1.2-1.5).

[0008] Furthermore, the ratio of the diameter of the sludge discharge pipe in the present invention to the cross-sectional area of ​​the biofilm reaction zone is 1:5; the bottom of the sludge deposition zone includes two left and right arcs, the angle of the left arc is 32 to 36°, and the angle of the right arc is 6 to 8°, and the sludge discharge pipe is connected between the left and right arcs, and the sludge discharge pipe is located on the right side of the bottom of the sludge deposition zone, and the sludge discharge pipe is arranged on the same side as the water inlet pipe.

[0009] Furthermore, the water inlet tray of the present invention is provided with a plurality of guide ports evenly distributed around the water inlet tray, the diameter of the guide ports is 1 / 3 of the diameter of the water inlet pipe, the water inlet pipe is arranged parallel to the horizontal plane, and the water outlet of the water inlet tray flows out through the guide ports.

[0010] A short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that the ratio of the difference between the inner and outer diameters of the annular carrier plate to the cross-sectional area of ​​the biofilm reaction zone is 1:(7-10), and the distance between the annular carrier plate and the water inlet pipe is 20 mm.

[0011] Furthermore, the ratio of the diameter of the sludge return port to the diameter of the water inlet pipe in the present invention is 1:1; the sludge return port has three portions which are evenly distributed around the biofilm reaction zone, and the angle between two adjacent portions is 120°; the ratio of the distance between the sludge return port and the top of the separation zone to the distance between the sludge return port and the bottom of the biofilm reaction zone is 1:(2.7-2.9).

[0012] Furthermore, in the present invention, the centers of the water inlet tray and the hollow aeration ring are on the same vertical line, and the ratio of the cross-sectional area of ​​the water inlet tray to that of the hollow aeration ring is 2:3.

[0013] Furthermore, the angle between the reflux pipe and the horizontal plane in the present invention is 30° to 40°.

[0014] A method for operating a short-range nitrification membrane aeration biofilm reactor, the method comprising: acclimatizing and culturing sludge in a biofilm reaction zone inside the reactor, and allowing the sludge to settle and accumulate at the bottom of the reactor to form a sludge deposition zone; discharging the sludge in the sludge deposition zone from a sludge discharge pipe by reflux for 4-8 minutes every 3-6 hours, and then re-entering the biofilm reaction zone from a sludge reflux port, so that the sludge maintains high activity and fully contacts with membrane fibers to enrich and colonize to form a biofilm; aerating the biofilm reaction zone through an air inlet, and gas passes through The hollow aeration ring achieves dispersion, and the different oxygen distribution gradients of MABR are used to form a unique biofilm layered structure: outer layer, middle layer, and inner layer. The aeration intensity is adjusted to control the internal pressure of the membrane module and the thickness of the biofilm to accurately supply oxygen, ensuring the realization of short-range nitrification in the reactor; wastewater is introduced into the reactor through the water inlet pipe and flows out evenly through the water inlet plate, enters the separation zone through the biofilm reaction zone, and is separated into gas, liquid, and solid through the three-phase separator. The sludge is discharged from the sludge outlet, the gas is discharged from the top exhaust port, and the effluent is discharged from the water outlet after passing through the overflow tank.

[0015] Compared with the prior art, the present invention has the following advantages: the present invention extracts the activated sludge deposited at the bottom of the reactor and re-enters the reaction zone through the sludge return port above the reaction zone, thereby increasing the uniform distribution rate of the activated sludge in the reaction zone, improving the contact rate with the membrane component carrier, and shortening the biofilm enrichment growth time, thereby quickly starting the reactor; the reactor is provided with a sludge return port, and the sludge return flow is utilized to achieve rapid biofilm formation, and after the biofilm formation is successful, the operating parameters can be adjusted to quickly start the reactor to achieve short-range nitrification; the water inlet tray in the reactor can buffer the water inlet disturbance, thereby achieving stable enrichment growth of the biofilm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a short-range nitrification membrane aeration biofilm reactor of the present invention;

[0017] Figure 2 It is a schematic diagram of the specific structure of the hollow aeration ring described in the present invention;

[0018] Figure 3 It is a side view of the water inlet tray of the present invention;

[0019] Figure 4 A top view of the water inlet tray of the present invention;

[0020] Figure 5 It is a distribution diagram of the sludge return port described in the present invention.

[0021] Among them: 1. Sludge discharge pipe; 2. Annular loading plate; 3. Membrane filaments; 4. Hollow aeration ring; 5. Air inlet; 6. Air outlet; 7. Water inlet plate; 7a. Diversion port; 8. Water inlet pipe; 9. Sampling port; 10. Sludge return port; 11. Three-phase separator; 12. Return pipe; 13. Exhaust port; 14. Sludge discharge port; 15. Overflow trough; 16. Water outlet; A. Sludge deposition area; B. Biofilm reaction area; C. Separation area. DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0023] Example:

[0024] As shown in the accompanying drawings, a specific embodiment of a short-range nitrification membrane aeration biofilm reactor and an operation method thereof of the present invention is shown. The reactor includes a sludge deposition zone A, a biofilm reaction zone B, and a separation zone C arranged in sequence from bottom to top. The longitudinal section height ratio of the sludge deposition zone A, the biofilm reaction zone B, and the separation zone C is 1:(17-19):6, and the maximum cross-sectional area ratio of the sludge deposition zone A, the biofilm reaction zone B, and the separation zone C is 1:1:(1.2-1.5).

[0025] The bottom of the sludge deposition area A is connected with a sludge discharge pipe 1, and the ratio of the diameter of the sludge discharge pipe 1 to the cross-sectional area of ​​the biofilm reaction area B is 1:5. The bottom of the sludge deposition area A includes two left and right arcs, the angle of the left arc is 32-36°, and the angle of the right arc is 6-8°. The sludge discharge pipe 1 is connected between the left and right arcs, and is located at the bottom of the sludge deposition area A slightly to the right.

[0026] An annular carrier plate 2 is provided at the bottom of the biofilm reaction zone B, and a membrane assembly is provided on the annular carrier plate 2. The membrane assembly includes membrane filaments 3 and hollow aeration rings 4 respectively provided at the upper and lower ends of the membrane filaments 3. An air inlet 5 and an air outlet 6 are respectively connected to the biofilm reaction zone B below and above the membrane assembly. A water inlet plate 7 is provided in the biofilm reaction zone B below the membrane assembly, and the water inlet plate 7 is connected to a water inlet pipe 8, which passes through the biofilm reaction zone B to the outside. A sampling port 9 is provided in the middle of the biofilm reaction zone B, and a plurality of sludge return ports 10 arranged around the biofilm reaction zone B are provided at the top of the biofilm reaction zone B.

[0027] The water inlet pipe 8 is arranged on the same side as the mud discharge pipe 1, and the water inlet pipe 8 is arranged parallel to the horizontal plane. The water inlet pipe 8 is partially diverted through the water inlet tray 7, combined with Figure 3 , Figure 4The water inlet tray 7 is provided with a plurality of guide ports 7a evenly distributed around the water inlet tray 7. The diameter of the guide ports 7a is 1 / 3 of the diameter of the water inlet pipe 8. The water outflow from the water inlet tray 7 flows out through the guide ports 7a. This can make the inlet water quality more evenly distributed, avoid short-flow of water in the reaction zone during sludge return, and reduce the internal disturbance of the water flow caused by the inlet water.

[0028] The ratio of the difference between the inner and outer diameters of the annular carrier plate 2 to the cross-sectional area of ​​the biofilm reaction zone B is 1:(7-10), and the distance between the annular carrier plate 2 and the water inlet pipe 8 is 20 mm.

[0029] The centers of the water inlet tray 7 and the hollow aeration ring 4 are on the same vertical line, and the cross-sectional area ratio of the water inlet tray 7 to the hollow aeration ring 4 is 2:3. Figure 2 The hollow aeration ring 4 adopts a circular ring structure, which can avoid the closure from hindering the water inlet.

[0030] The ratio of the diameter of the sludge return port 10 to the diameter of the water inlet pipe 8 is 1:1. Figure 5 There are three sludge return ports 10, which are evenly distributed around the biofilm reaction zone B, and the angle between two adjacent sludge return ports 10 is 120°. The ratio of the distance between the sludge return port 10 and the top of the separation zone C to the distance between the sludge return port 10 and the bottom of the biofilm reaction zone B is 1:(2.7-2.9).

[0031] The separation zone C is connected to the biofilm reaction zone B by a flange. A three-phase separator 11 is provided in the separation zone C, and a reflux pipe 12 is provided in the middle of the three-phase separator 11. The reflux pipe 12 passes through the separation zone C to the outside, and the angle between the reflux pipe 12 and the horizontal plane is 30° to 40°. An exhaust port 13 is provided at the top of the three-phase separator 11, a mud discharge port 14 is provided at the bottom of the separation zone C, an overflow trough 15 is provided at the top of the separation zone C, and a water outlet 16 is provided on the overflow trough 15.

[0032] In this embodiment, the reactor is constructed of organic glass and steel plates.

[0033] The operation method of the reactor of this embodiment includes: sludge is domesticated and cultured in the biofilm reaction zone B inside the reactor, and settles and accumulates at the bottom of the reactor to form a sludge deposition zone A; the sludge in the sludge deposition zone A is discharged from the sludge discharge pipe 1 by reflux for four minutes every four hours, and then re-enters the biofilm reaction zone B from the sludge reflux port 10, so that the sludge maintains high activity and fully contacts with the membrane filaments 3 to enrich and colonize to form a biofilm; aeration is introduced into the biofilm reaction zone B through the air inlet 5, and the gas is dispersed through the hollow aeration ring 4, and the MA is used to generate a gas. Different oxygen distribution gradients in BR form a unique biofilm layered structure: an outer aerobic layer, a middle anoxic layer, and an inner anaerobic layer. The aeration intensity is adjusted to control the internal pressure of the membrane module and the thickness of the biofilm to accurately supply oxygen, ensuring the realization of short-range nitrification in the reactor; wastewater is introduced into the reactor through the water inlet pipe 8 and flows out evenly through the water inlet tray 7, enters the separation zone C through the biofilm reaction zone B, and is separated into gas, liquid, and solid phases through the three-phase separator 11. The sludge is discharged from the sludge outlet 14, the gas is discharged from the top exhaust port 13, and the effluent is discharged from the water outlet 16 after passing through the overflow tank 15.

[0034] Of course, the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any modifications made according to the spirit of the main technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A short-range nitrification membrane aeration biofilm reactor, characterized in that: The reactor comprises a sludge deposition zone (A), a biofilm reaction zone (B), and a separation zone (C) which are arranged in sequence from bottom to top; the bottom of the sludge deposition zone (A) is connected to a sludge discharge pipe (1); the bottom of the biofilm reaction zone (B) is provided with an annular carrier plate (2), and a membrane assembly is arranged on the annular carrier plate (2), and the membrane assembly comprises a membrane filament (3), and hollow aeration rings (4) respectively arranged at the upper and lower ends of the membrane filament (3); the biofilm reaction zone (B) below and above the membrane assembly are respectively connected to an air inlet (5) and an air outlet (6); a water inlet plate (7) is provided in the biofilm reaction zone (B) below the membrane assembly, and the water inlet plate (7) is connected to a water inlet pipe (8), and the water inlet pipe (8) passes through the biofilm reaction zone (B) ) to the outside, a sampling port (9) is provided in the middle of the biofilm reaction zone (B), and a plurality of sludge return ports (10) arranged around the biofilm reaction zone (B) are provided at the top of the biofilm reaction zone (B); the separation zone (C) is connected to the biofilm reaction zone (B) via a flange, a three-phase separator (11) is provided in the separation zone (C), a return pipe (12) is provided in the middle of the three-phase separator (11), and the return pipe (12) passes through the separation zone (C) to the outside, an exhaust port (13) is provided at the top of the three-phase separator (11), a sludge discharge port (14) is provided at the bottom of the separation zone (C), an overflow trough (15) is provided at the top of the separation zone (C), and a water outlet (16) is provided on the overflow trough (15).

2. A short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The longitudinal section height ratio of the sludge sedimentation zone (A), the biofilm reaction zone (B), and the separation zone (C) is 1:(17-19):6, and the maximum cross-sectional area ratio of the sludge sedimentation zone (A), the biofilm reaction zone (B), and the separation zone (C) is 1:1:(1.2-1.5).

3. A short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The ratio of the diameter of the sludge discharge pipe (1) to the cross-sectional area of ​​the biofilm reaction zone (B) is 1:5; the bottom of the sludge deposition zone (A) includes two left and right arcs, the angle of the left arc is 32 to 36°, and the angle of the right arc is 6 to 8°, the sludge discharge pipe (1) is connected between the left and right arcs, the sludge discharge pipe (1) is located on the right side of the bottom of the sludge deposition zone (A), and the sludge discharge pipe (1) is arranged on the same side as the water inlet pipe (8).

4. A short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The water inlet tray (7) is provided with a plurality of flow guide ports (7a) evenly distributed around the water inlet tray (7), the diameter of the flow guide ports (7a) being 1 / 3 of the diameter of the water inlet pipe (8), the water inlet pipe (8) being arranged parallel to the horizontal plane, and the water outflowing from the water inlet tray (7) flows out through the flow guide ports (7a).

5. The short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The ratio of the difference between the inner and outer diameters of the annular carrier plate (2) to the cross-sectional area of ​​the biofilm reaction zone (B) is 1:(7-10), and the distance between the annular carrier plate (2) and the water inlet pipe (8) is 20 mm.

6. A short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The ratio of the diameter of the sludge return port (10) to the diameter of the water inlet pipe (8) is 1:1; the sludge return port (10) has three portions which are evenly distributed around the biofilm reaction zone (B), and the angle between two adjacent sludge return ports (10) is 120°; the ratio of the distance between the sludge return port (10) and the top of the separation zone (C) to the distance between the sludge return port (10) and the bottom of the biofilm reaction zone (B) is 1:(2.7-2.9).

7. The short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The centers of the water inlet disk (7) and the hollow aeration ring (4) are located on the same vertical line, and the ratio of the cross-sectional areas of the water inlet disk (7) and the hollow aeration ring (4) is 2:

3.

8. The short-range nitrification membrane aeration biofilm reactor according to claim 1, characterized in that: The angle between the return pipe (12) and the horizontal plane is 30° to 40°.

9. The method for operating a short-range nitrification membrane aeration biofilm reactor according to any one of claims 1 to 8, characterized in that: The method comprises: acclimatizing and culturing the sludge in a biofilm reaction zone (B) inside a reactor, and allowing the sludge to settle and accumulate at the bottom of the reactor to form a sludge deposition zone (A); discharging the sludge in the sludge deposition zone (A) from a sludge discharge pipe (1) by reflux for 4-8 minutes every 3-6 hours, and then re-entering the biofilm reaction zone (B) from a sludge reflux port (10), so that the sludge maintains high activity and fully contacts with the membrane filaments (3) to be enriched and colonized to form a biofilm; aerating the biofilm reaction zone (B) through an air inlet (5), dispersing the gas through a hollow aeration ring (4), and utilizing the MABR oxygen Different distribution gradients form a unique biofilm layered structure: outer layer (aerobic layer), middle layer (anoxic layer), inner layer (anaerobic layer). By adjusting the aeration intensity to control the internal pressure of the membrane assembly and the thickness of the biofilm, accurate oxygen supply is achieved to ensure the realization of short-range nitrification in the reactor; wastewater is introduced from the water inlet pipe (8) and flows out evenly through the water inlet plate (7), enters the separation zone (C) through the biofilm reaction zone (B) and is separated into gas, liquid and solid three phases by the three-phase separator (11), the sludge is discharged from the sludge outlet (14), the gas is discharged from the top exhaust port (13), and the effluent is discharged from the water outlet (16) after passing through the overflow tank (15).

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