Composite biological reaction pool combining oxidation ditch and MBR membrane reactor

Abstract

The invention discloses a composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor, belongs to the technical field of water treatment, and solves the problem that the oxidation ditch and the MBR membrane reactor are difficult to combine. The invention comprises an anaerobic tank, a pre-anoxic tank, an oxidation ditch tank and an MBR membrane reaction pool, a water outlet is provided at the rear end of the oxidation ditch tank, a membrane pool water inlet channel is connected to the water outlet, an electric regulating weir gate is provided at the connection, a membrane pool return sludge pipe is provided between the MBR membrane reaction pool and the oxidation ditch tank, a sludge storage tank is provided at the side of the sludge collecting channel of the MBR membrane reaction pool, one end of the membrane pool return sludge pipe is provided at the upper end of the sludge storage tank, and the other end is provided between the middle partition wall at the water outlet and the arc-shaped guide wall, a membrane pool return sludge pump is provided on the membrane pool return sludge pipe, an anaerobic pool return sludge pipe is provided between the pre-anoxic tank and the anaerobic tank, and an anaerobic pool return sludge pump is provided on the anaerobic pool return sludge pipe. The invention realizes a good combination of the oxidation ditch and the MBR membrane reactor, and has a good water treatment effect.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage and reclaimed water treatment, and specifically relates to a composite biological reaction pool combining an oxidation ditch with an MBR membrane reactor. Background Art

[0002] With the improvement of effluent quality standards of sewage treatment plants and the demand for recycled water reuse, the original secondary biological treatment of sewage treatment plants can no longer meet the demand, and it is necessary to add deep treatment facilities to improve effluent quality standards. The disadvantage of this method is that the process is long and occupies a large area.

[0003] Oxidation ditch biological reactor is commonly used in sewage treatment biological reaction secondary treatment process; it adopts delayed aeration method, has strong impact load resistance, obvious dissolved oxygen gradient formation in hydraulic circulation, thorough denitrification, good phosphorus removal effect in anaerobic zone, etc. Its main disadvantages are large land occupation, effluent cannot directly reach Class A or higher standards, low sludge concentration, large water surface fluctuation, need for secondary sedimentation tank for mud and water separation, and large amount of residual sludge.

[0004] MBR membrane reactor is a sewage treatment facility that combines activated sludge method with membrane separation technology. It has the characteristics of good effluent effect (especially high SS removal rate), stable effluent quality, small footprint, no sludge sedimentation problem, and small amount of residual sludge. Its disadvantages are that the water surface fluctuation should not be too large, the phosphorus removal effect is limited, and the ability to resist shock load is weak.

[0005] If the oxidation ditch is combined with the MBR membrane reactor, the advantages can be complementary. However, the combination of the two has not been applied due to the large fluctuations in the water surface, the need for obvious changes in dissolved oxygen concentration in the oxidation ditch pool, the high oxygen content of the sludge returned from the MBR membrane pool, and the difficulty in setting up the sludge return. Summary of the invention

[0006] The purpose of the present invention is to provide a composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor to solve the problem that the oxidation ditch and the MBR membrane reactor are difficult to combine due to large water surface fluctuations, the influence of dissolved oxygen concentration changes in the oxidation ditch, and the difficulty in setting up sludge return.

[0007] The technical scheme of the present invention is: a composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor, comprising an anaerobic pool, a front anoxic pool and an oxidation ditch pool connected in sequence, wherein the oxidation ditch pool is provided with a surface aerator, an arc-shaped guide wall and a middle partition wall, and further comprising an MBR membrane reaction pool, wherein the rear end of the oxidation ditch pool is provided with a water outlet, the membrane pool water inlet channel of the MBR membrane reaction pool is connected with the water outlet, and an electric regulating weir gate is provided at the connection between the membrane pool water inlet channel and the water outlet, A membrane pool return sludge pipe is provided between the oxidation ditch pools, a sludge storage tank connected to the sludge collecting channel is provided on the side of the sludge collecting channel of the MBR membrane reaction pool, one end of the membrane pool return sludge pipe is provided at the upper end of the sludge storage tank, the other end of the membrane pool return sludge pipe is provided between the middle partition wall and the arc guide wall at the water outlet, a membrane pool return sludge pump is provided on the membrane pool return sludge pipe, an anaerobic tank return sludge pipe is provided between the pre-anoxic tank and the anaerobic tank, and an anaerobic tank return sludge pump is provided on the anaerobic tank return sludge pipe.

[0008] As a further improvement of the present invention, a liquid level sensor is provided on the inner wall of the MBR membrane reaction tank, and the liquid level sensor is connected to the electric regulating weir gate through a PLC.

[0009] As a further improvement of the present invention, an internal reflow control weir gate is provided between the front anoxic tank and the oxidation ditch tank.

[0010] As a further improvement of the present invention, it also includes a residual sludge pipe, one end of which is located in the sludge collecting channel, and the other end of the residual sludge pipe leads to the outside, and a residual sludge pump is provided on the residual sludge pipe.

[0011] The beneficial effects of the present invention are as follows: the present invention provides a composite biological reaction pool which effectively improves the treatment effect, has a short treatment process, a high sludge concentration, a small footprint, a strong ability to resist shock loads, has no sludge sedimentation problem, and has better technical performance than a single oxidation ditch biological reaction pool or a conventional deep treatment facility added after the oxidation ditch, and solves the technical problems of large fluctuations in the water surface entering the membrane reaction pool after the oxidation ditch, changes in dissolved oxygen concentration in the oxidation ditch being affected, and difficulty in setting the return sludge outlet. By setting the membrane pool return sludge pipe and the anaerobic pool return sludge pipe, the sludge mixed liquid in the MBR membrane reaction pool is refluxed step by step, and different sludge concentrations are formed to ensure the environmental balance of the biological reaction. Among them, the location of the membrane pool return sludge pipe is very important. A stable dissolved oxygen gradient needs to be maintained in the oxidation ditch pool. If the return sludge outlet location is improperly selected, the dissolved oxygen gradient in the oxidation ditch pool will be disturbed, and the oxidation ditch will lose its original denitrification function. In the present invention, one end of the membrane pool return sludge pipe is arranged at the upper end of the sludge storage tank on the side of the sludge collection channel. During the flow of sludge, on the one hand, a part of the dissolved oxygen in the sludge is released in the sludge collection channel. On the other hand, by setting a sludge storage tank of a certain volume, the sludge mixed liquid has a certain residence time in this area, so that the dissolved oxygen in the sludge is further reduced, so that the dissolved oxygen content finally returned to the oxidation ditch pool through the membrane pool return sludge pipe is within an appropriate range; the other end of the membrane pool return sludge pipe is arranged between the middle partition wall and the arc-shaped guide wall at the outlet of the oxidation ditch. The advantages of such arrangement are: first, here It is close to the water inlet of the oxidation ditch pool, so the inlet water and the return sludge can be mixed quickly, which will not cause uneven sludge concentration in the oxidation ditch pool. The return sludge pipe is short in length through the oxidation ditch pool, so the construction and maintenance are less difficult. Secondly, the inner side of the arc-shaped diversion wall is the surface aerator, which is the starting point of the oxidation ditch oxygenation stage. As long as the dissolved oxygen content in the return sludge is appropriate and the downstream pool section itself is an aerobic section, it will not affect the overall balanced environment of anoxic / aerobic alternating operation. At the same time, the power of the surface aerator can be appropriately reduced to save energy consumption, which solves the problem of setting the return sludge outlet. By setting an electric regulating weir gate at the connection between the MBR membrane reaction pool and the oxidation ditch pool, the problem of large water surface fluctuations is solved. The electric regulating weir gate is connected to the liquid level sensor in the membrane reaction pool through PLC. The electric regulating weir gate can be automatically controlled and linked with the liquid level in the membrane reaction pool to realize automatic control of the electric regulating weir gate.

[0012] The oxidation ditch pool in the composite biological reaction pool of the present invention is a completely mixed flow state, the water flow in the flow channel circulates continuously, the actual hydraulic retention time and the sludge age are relatively long, and the characteristics of the oxidation ditch process, such as strong impact load resistance and good adaptability to changes in water quantity and water quality, are retained.

[0013] The composite biological reaction pool of the present invention produces effluent after membrane filtration. Due to the efficient separation effect of the membrane, the separation effect is much better than that of a traditional sedimentation tank. The concentration of suspended solids and turbidity in the effluent is low, bacteria and viruses are largely removed, and the effluent quality is better than the quality standard for domestic miscellaneous water.

[0014] The composite biological reaction pool of the invention operates under high volume load and low sludge load, and the residual sludge output is low, thereby reducing the sludge treatment cost.

[0015] The composite biological reaction pool of the present invention can achieve high-standard effluent water quality without the need to set up a secondary sedimentation tank or add a new deep treatment structure, thereby reducing the occupied area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a plan view schematic diagram of the present invention;

[0017] Figure 2 for Figure 1 AA cross-section diagram.

[0018] In the figure: 1- anaerobic tank; 2- anaerobic tank return sludge pipe; 3- pre-anoxic tank; 4- anaerobic tank return sludge pump; 5- internal return control weir gate; 6- surface aerator; 7- oxidation ditch tank; 8- electric adjustment weir gate; 9- membrane pool inlet channel; 10- MBR membrane reaction tank; 11- MBR membrane assembly; 12- water production pipe; 13- sludge collection channel; 14- water production pump; 15- outlet pipe; 16- membrane equipment room; 17- residual sludge pump; 18- residual sludge pipe; 19- membrane pool return sludge pump; 20- membrane pool return sludge pipe; 21- outlet; 22- sludge storage tank; 23- liquid level sensor; 24- arc-shaped diversion wall; 25- middle partition wall. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to the accompanying drawings.

[0020] like Figure 1 , Figure 2As shown, a composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor comprises an anaerobic pool 1, a pre-anoxic pool 3 and an oxidation ditch pool 7 which are connected in sequence, wherein the oxidation ditch pool 7 is provided with a surface aerator 6, an arc-shaped guide wall 24 and a middle partition wall 25, and further comprises an MBR membrane reaction pool 10, wherein the rear end of the oxidation ditch pool 7 is provided with a water outlet 21, a membrane pool water inlet channel 9 at the front end of the MBR membrane reaction pool 10 is connected to the water outlet 21, and an electric regulating weir gate 8 is provided at the connection between the membrane pool water inlet channel 9 and the water outlet 21, and a gate 8 is provided between the MBR membrane reaction pool 10 and the oxidation ditch pool 7. A membrane pool return sludge pipe 20 is provided between the membrane pool, a sludge storage tank 22 connected to the sludge collecting channel 13 is provided on the side of the sludge collecting channel 13 of the MBR membrane reaction tank 10, one end of the membrane pool return sludge pipe 20 is provided at the upper end of the sludge storage tank 22, and the other end of the membrane pool return sludge pipe 20 is provided between the middle partition wall 25 and the arc guide wall 24 at the water outlet 21, a membrane pool return sludge pump 19 is provided on the membrane pool return sludge pipe 20, an anaerobic tank return sludge pipe 2 is provided between the pre-anoxic tank 3 and the anaerobic tank 1, and an anaerobic tank return sludge pump 4 is provided on the anaerobic tank return sludge pipe 2.

[0021] A liquid level sensor 23 is provided on the inner wall of the MBR membrane reaction tank 10 , and the liquid level sensor 23 is connected to the electric regulating weir gate 8 through a PLC.

[0022] An internal reflux control weir gate 5 is provided between the front anoxic tank 3 and the oxidation ditch tank 7 to reflux the mixed liquid in the oxidation ditch tank 7 .

[0023] The system further comprises a residual sludge pipe 18 , one end of which is located in the sludge collecting channel 13 , and the other end of which is connected to the outside. A residual sludge pump 17 is provided on the residual sludge pipe 18 .

[0024] In the present invention, "front end" and "rear end" are defined according to the direction of water flow.

[0025] The MBR membrane reaction tank 10 includes a membrane tank water inlet channel 9, a membrane module 11, a sludge collection channel 13 and a membrane equipment room 16 which are arranged in sequence. The membrane module 11 is provided with a water production pipe 12, which is connected to a water outlet pipe 15 through a water production pump 14. The water production pump 14 and the water outlet pipe 15 are both arranged in the membrane equipment room.

[0026] After the dephosphorization reaction in the anaerobic tank 1, the sewage enters the pre-anoxic tank 3 and the oxidation ditch tank 7 in sequence, and the biological anoxic and aerobic reactions are carried out in the pre-anoxic tank 3 and the oxidation ditch 7. The surface aerator 6 provides the water flow thrust and the aerobic section oxygen supply. Then, through the electric adjustment weir gate 8, the sewage enters the membrane pool inlet channel 9, and the sewage is distributed to the MBR membrane module 11 channel. The sewage is filtered and separated by the MBR membrane module 11, and then the water pump 14 sends the water filtered by the membrane to the outlet pipe 15 for production through the water production pipe 12. The opening and closing of the electric adjustment weir gate 8 is controlled by the PLC according to the signal of the liquid level sensor 23.

[0027] The sludge mixture in the MBR membrane reaction tank 10 enters the sludge collecting channel 13, and then enters the sludge storage tank 22 on the side of the sludge collecting channel 13, and then flows back to the oxidation ditch tank 7 through the membrane pool return sludge pump 19 and the membrane pool return sludge pipe 20, and then flows back to the front anoxic tank 3 through the internal reflux control weir gate 5, and then the sludge mixture flows back to the anaerobic tank 1 through the anaerobic tank return sludge pump 4 and the anaerobic tank return sludge pipe 2, and mixes with the influent to achieve phosphorus removal and nitrogen removal. The sludge mixture flows back step by step and forms different sludge concentrations to ensure the environmental balance of the biological reaction. By setting the sludge storage tank 22 on the side of the sludge collecting channel 13 and selecting the inlet and outlet positions of the membrane pool return sludge pipe 20, the normal operation of the dissolved oxygen gradient in the oxidation ditch can be fully guaranteed.

[0028] The excess sludge is discharged to the sludge disposal system of the sewage treatment plant through the excess sludge pump 17 and the excess sludge pipe 18.

[0029] The composite biological reaction pool combining the oxidation ditch and the MBR membrane reactor of the present invention combines the advantages of the oxidation ditch and the MBR membrane reactor, complements their respective disadvantages, has strong impact load resistance, small footprint, low excess sludge production, and stable effluent water quality.

Claims

1. A composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor, comprising an anaerobic pool (1), a pre-anoxic pool (3) and an oxidation ditch pool (7) connected in sequence, wherein a surface aerator (6), an arc-shaped guide wall (24) and a middle partition wall (25) are provided in the oxidation ditch pool (7), characterized in that: The invention also comprises an MBR membrane reaction pool (10), wherein the rear end of the oxidation ditch pool (7) is provided with a water outlet (21), the membrane pool water inlet channel (9) of the MBR membrane reaction pool (10) is connected to the water outlet (21), an electrically-adjustable weir gate (8) is provided at the connection between the membrane pool water inlet channel (9) and the water outlet (21), a membrane pool return sludge pipe (20) is provided between the MBR membrane reaction pool (10) and the oxidation ditch pool (7), and a sludge collecting channel (13) of the MBR membrane reaction pool (10) is provided at the side thereof, which is connected to the sludge collecting channel (13). A sludge storage tank (22) is provided, one end of the membrane tank return sludge pipe (20) is arranged at the upper end of the sludge storage tank (22), the other end of the membrane tank return sludge pipe (20) is arranged between the middle partition wall (25) and the arc-shaped guide wall (24) at the water outlet (21), a membrane tank return sludge pump (19) is provided on the membrane tank return sludge pipe (20), an anaerobic tank return sludge pipe (2) is provided between the pre-anoxic tank (3) and the anaerobic tank (1), and an anaerobic tank return sludge pump (4) is provided on the anaerobic tank return sludge pipe (2).

2. The composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor according to claim 1, characterized in that: A liquid level sensor (23) is provided on the inner wall of the MBR membrane reaction tank (10), and the liquid level sensor (23) is connected to the electric regulating weir gate (8) via a PLC.

3. The composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor according to claim 1 or 2, characterized in that: An internal reflow control weir gate (5) is provided between the front anoxic tank (3) and the oxidation ditch tank (7).

4. The composite biological reaction pool combining an oxidation ditch and an MBR membrane reactor according to claim 3, characterized in that: It also comprises a residual sludge pipe (18), one end of the residual sludge pipe (18) is located in the sludge collecting channel (13), the other end of the residual sludge pipe (18) is connected to the outside, and a residual sludge pump (17) is provided on the residual sludge pipe (18).

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