Double-reflux anaerobic treatment system for papermaking wastewater

Abstract

The invention discloses a double-backflow papermaking wastewater anaerobic treatment system which comprises an anaerobic treatment system and a sedimentation tank, the anaerobic treatment system comprises an anaerobic reaction tank, a water distributor, a water distribution well, a water distribution pipeline, a wastewater inlet pipeline, a backflow well and a backflow pipeline, and the wastewater inlet pipeline is connected with a water inlet in the lower portion of the water distribution well; a sludge discharge port of the sedimentation tank is connected with the water distributor through a sludge discharge pipeline, the backflow well is connected with a backflow pipeline arranged in the anaerobic reaction tank, and the backflow well is connected with the water distributor through a water pumping pipeline. The backflow well and the backflow pipeline are additionally arranged in the anaerobic reaction tank, wastewater enters the backflow well through the backflow pipeline, backflow wastewater, production wastewater and backflow sludge are evenly mixed through the water distributor and sprayed out from the water distribution pipeline, a strong stirring effect is formed, rising pushing force is improved, and reaction is promoted; the removal efficiency of organic matters in the wastewater can reach 80-90%, the sludge form is between flocculent sludge and granular sludge, and the influence that the sludge in the papermaking wastewater is easy to calcify is effectively relieved.

Description

Technical Field

[0001] The invention relates to the field of treatment of industrial wastewater generated by papermaking, and in particular to a double-reflux papermaking wastewater anaerobic treatment system. Background Art

[0002] In the secondary papermaking process of waste paper, high-concentration and difficult-to-degrade industrial wastewater is often produced. At present, this type of industrial wastewater needs to be treated anaerobicly to reduce the concentration of organic matter, alleviate the operating pressure of the back-end aerobic biological treatment, and ensure the stable operation of the overall process and the stable compliance of the final effluent. The traditional anaerobic treatment method for wastewater is to discharge the production wastewater into the anaerobic tank through a water distribution pipe. The wastewater passes upward through the sludge bed containing granular sludge or flocculent sludge. The organic matter in the wastewater is decomposed into methane, carbon dioxide and other products during the contact with the anaerobic sludge bed composed of anaerobic microorganisms such as hydrolytic acidifying bacteria, hydrogen-producing acid-producing bacteria and methanogens. The gas produced under anaerobic conditions plays a beneficial role in the formation and maintenance of granular sludge. At present, the existing anaerobic treatment systems mostly use upflow anaerobic reactors (UASB), which have problems such as low temperature and low efficiency, easy sludge calcification, sludge leakage in the effluent, insufficient sludge-water mixing, low sludge concentration, and short sludge age during the reaction process. In addition, the existing anaerobic treatment generally adopts a bottom-up flow method, with a long wastewater treatment cycle and low effluent water quality. Summary of the invention

[0003] In view of this, the present invention proposes a double-reflux anaerobic treatment system for papermaking wastewater, which can not only realize the flow of wastewater from bottom to top during the anaerobic reaction process, but also realize the self-circulation of wastewater, with good treatment effect, greatly improving the treatment efficiency of industrial wastewater.

[0004] To achieve the above object, the present invention adopts the following technical solutions: The double-return papermaking wastewater anaerobic treatment system of the present invention comprises an anaerobic treatment system and a sedimentation tank, wherein the anaerobic treatment system comprises an anaerobic reaction tank, a water distributor arranged at the top of the anaerobic reaction tank, a water distribution well, a water distribution pipeline, and a wastewater inlet pipeline arranged in the anaerobic reaction tank, wherein one end of the wastewater inlet pipeline is connected to the water inlet at the bottom of the water distribution well, and the other end thereof is connected to external wastewater; the water distribution pipeline is located below the water inlet; the upper part of the anaerobic reaction tank is provided with a drain outlet, the drain outlet is connected to the sedimentation tank through a drain pipeline, the mud discharge outlet at the bottom of the sedimentation tank is connected to the water distributor through a mud discharge pipeline with a mud discharge pump, and the outlet of the water distributor is connected to the top of the water distribution well; The anaerobic treatment system further comprises a return well arranged on a side wall of the anaerobic reaction tank and a return pipeline arranged in the anaerobic reaction tank, wherein the return well is connected to the water distributor through a pumping pipeline, and a circulating pump is arranged on the pumping pipeline; the return pipeline is located in the middle and upper part of the anaerobic reaction tank and is connected to the inlet at the bottom of the return well; the anaerobic treatment system further comprises a three-stage separator arranged in the anaerobic reaction tank and above the return pipeline, wherein a plurality of downwardly concave drainage grooves are arranged at intervals on the top of the three-stage separator; A water collecting trough is provided on one side wall of the anaerobic reaction tank, each of the drainage troughs is connected to the water collecting trough, and the drainage port is opened on the side wall of the anaerobic reaction tank corresponding to the water collecting trough; A mud discharge pipeline is arranged in the anaerobic reaction tank below the water distribution pipeline.

[0005] The beneficial effects are as follows: the present invention adds a return well and a return pipeline in the anaerobic reaction tank, and the wastewater enters the return well through the return pipeline, and enters the water distribution well under the action of the external circulation pump and the water distributor, thereby realizing the circulation and reflux of the wastewater in the anaerobic reaction tank, and there is a circulation loop between the sedimentation tank and the anaerobic reaction tank, thereby increasing the rising flow rate of the wastewater; in addition, the return wastewater, production wastewater and return sludge can be evenly mixed through the water distributor, and sprayed from the bottom water distribution pipeline, forming a strong stirring effect and rising flow driving force, and the organic matter in the mixed wastewater fully contacts and reacts with the anaerobic sludge bed of the system during the rising process, ensuring the treatment effect. The gas generated by the reaction carries part of the sludge flocs to continue to move upward, and collides with the three-phase separator, thereby causing the sludge to degas, and the released gas will be stored in the gas collecting chamber of the three-phase separator, the sludge particles are precipitated to the surface of the sludge bed, the liquid flows into the drainage trough at the top through the gap, and enters the sedimentation tank through the water collecting trough and drainage pipeline for precipitation, effectively reducing the organic matter content in the wastewater.

[0006] According to practice, when the circulating flow of wastewater in the anaerobic reaction tank accounts for 50% to 100% of the total volume, the mixing effect and removal effect of the wastewater are the best, and the removal efficiency of organic matter in the wastewater can reach 80% to 90%. At the same time, the sludge morphology in this state is between flocculent sludge and granular sludge, which can effectively alleviate the influence of easy calcification of papermaking wastewater sludge. Among them, in actual installation, the water distributor of the present invention is preferably an adjustable pulse water distributor.

[0007] Preferably, the water distribution pipeline includes a primary main pipe connected to the water distribution well and a secondary pipe connected to the primary main pipe, the secondary pipe is an I-shaped structure, and its four ports are connected to a tertiary pipe with an I-shaped structure, and the middle part of the connecting pipe of the tertiary pipe is connected to the port of the secondary pipe; each port of the tertiary pipe is connected to a quaternary pipe with an I-shaped structure, and the middle part of the connecting pipe of the quaternary pipe is fixedly connected to the port of the tertiary pipe. The beneficial effect is that the water distribution pipeline of the present invention can be laid flat in the anaerobic reaction tank to make the water distribution more uniform.

[0008] A fixing column is arranged on the bottom wall of the anaerobic reaction tank, and each end pipe of the secondary pipe is correspondingly fixed on the fixing column, so that the water distribution pipeline is erected above the bottom wall.

[0009] Preferably, a mounting frame is horizontally arranged in the middle and upper part of the anaerobic reaction tank, and the reflux pipeline is installed on the mounting frame, and the mounting frame provides mounting support for the reflux pipeline to ensure the installation of the reflux pipeline. More preferably, the reflux pipeline includes a reflux main pipe connected to the reflux well and a primary reflux branch pipe connected to the reflux main pipe, and the two ends of the primary reflux branch pipe are connected to secondary reflux branches parallel to the reflux main pipe, and each port of each secondary reflux branch pipe is connected to a tertiary reflux branch pipe in an I-shaped structure.

[0010] Preferably, a walking platform with a guardrail is provided on the upper portion of the outer side wall of the anaerobic reaction tank; and a maintenance platform is provided on the top of the anaerobic reaction tank above the drainage trough.

[0011] Compared with the prior art, the advantages of the present invention are as follows: a return well and a return pipeline are newly added in the anaerobic reaction tank, and the wastewater enters the return well through the return pipeline, and enters the water distribution well under the action of an external circulation pump and a water distributor, thereby realizing the circulation and return of the wastewater in the anaerobic reaction tank, and a circulation loop exists between the sedimentation tank and the anaerobic reaction tank, thereby increasing the rising flow rate of the wastewater; in addition, the return wastewater, production wastewater and return sludge can be uniformly mixed through the water distributor, and sprayed out from the water distribution pipeline at the bottom, forming a strong stirring effect and rising flow driving force, and the organic matter in the mixed wastewater contacts and reacts with the anaerobic sludge bed of the system during the rising process, thereby ensuring the treatment effect. The gas generated by the reaction carries part of the sludge flocs and continues to move upward, colliding with the three-phase separator, thereby causing the sludge to degas. The released gas will be stored in the gas collecting chamber of the three-phase separator, and the sludge particles will settle to the surface of the sludge bed. The liquid will flow into the drainage trough at the top through the gap, and enter the sedimentation tank through the sump and drainage pipeline for sedimentation, effectively reducing the organic matter content in the wastewater. According to practice, when the circulating flow of wastewater in the anaerobic reaction tank accounts for 50%~100% of the total volume, the mixing effect and removal effect of the wastewater are the best, and the removal efficiency of organic matter in the wastewater can reach 80~90%. At the same time, the sludge morphology in this state is between flocculent sludge and granular sludge, which can effectively alleviate the impact of easy calcification of papermaking wastewater sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the present invention.

[0013] Figure 2 It is a plan view of the anaerobic treatment system of the present invention.

[0014] Figure 3 yes Figure 2 AA section view.

[0015] Figure 4 It is a plan view of the return pipeline described in the present invention.

[0016] Figure 5 It is a plan view of the water distribution pipeline described in the present invention. DETAILED DESCRIPTION

[0017] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0018] It should be noted that, in the description of the present invention, relational terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0019] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" that may appear should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] like Figure 1-5 As shown, the double recirculation papermaking wastewater anaerobic treatment system (i.e., DCP-UASB) of the present invention comprises an anaerobic treatment system and a sedimentation tank 13, wherein the anaerobic treatment system comprises an anaerobic reaction tank 1, a water distributor 11 (preferably an adjustable pulse water distributor 11) arranged at the top of the anaerobic reaction tank 1, a water distribution well 4 (the water distribution well 4 is located at the center of the anaerobic reaction tank 1 to ensure uniform water distribution) arranged in the anaerobic reaction tank 1, a water distribution pipeline 2, and a wastewater inlet pipeline 5, wherein one end of the wastewater inlet pipeline is connected to the water inlet at the bottom of the water distribution well 4, and the other end thereof is connected to external wastewater, and production wastewater enters the water distribution well 4 through the wastewater inlet pipeline; the water distribution pipeline 2 is located below the water inlet, and the wastewater entering the water distribution well 4 is evenly distributed through the water distribution pipe 2; a drain outlet is provided at the upper part of the anaerobic reaction tank 1, and the drain outlet is connected to the sedimentation tank 13 through the drain pipe 15. The supernatant water treated by the anaerobic reaction tank 1 enters the sedimentation tank 13 for further sedimentation treatment, thereby improving the effluent quality; the sewage outlet at the bottom of the sedimentation tank 13 is connected to the water distributor 11 through the sewage pipe 17 with the sewage pump 14, and the outlet of the water distributor 11 is connected to the top of the water distribution well 4. The bottom mud precipitated in the sedimentation tank 13 enters the water distributor 11 under the action of the mud pump 14, and enters the water distribution well 4 through the water distributor 11 to achieve reflux treatment; The anaerobic treatment system also includes a reflow well 7 (located in the anaerobic reaction tank 1 and located in the middle and upper part of the anaerobic reaction tank 1) arranged at the center of the left side wall of the anaerobic reaction tank 1 and a reflow pipeline 6 arranged in the anaerobic reaction tank 1. The reflow well 7 is connected to the water distributor 11 through a pumping pipeline 12, and a circulating pump 8 is arranged on the pumping pipeline 12. The water inlet pipe of the circulating pump 8 extends to the lower part of the reflow well 7 to ensure that the wastewater entering the reflow well 7 is pumped out; the reflow pipeline 6 is located in the middle and upper part of the anaerobic reaction tank 1 and is connected to the inlet at the bottom of the reflow well 7 to ensure that the wastewater in the anaerobic reaction tank 1 smoothly enters the reflow well. 7; The anaerobic treatment system also includes a three-phase separator 9 arranged in the anaerobic reaction tank 1 and located above the return pipe 6, and a plurality of downwardly concave drainage grooves 10 are arranged at intervals on the top of the three-phase separator 9; a water collecting groove 16 is arranged on the front side wall of the anaerobic reaction tank 1, and each drainage groove 10 is connected to the water collecting groove 16, and the drainage port is opened on the side wall of the anaerobic reaction tank 1 corresponding to the water collecting groove 16 to ensure that the supernatant water in the water collecting groove 16 smoothly overflows into the sedimentation tank 13; a sludge discharge pipeline 3 is arranged in the anaerobic reaction tank 1 located below the water distribution pipeline 2 to facilitate the discharge of sludge in the anaerobic reaction tank 1.

[0021] During actual construction, the water collecting trough 16 can be processed with a certain slope (such as 5%) from the front and rear directions, that is, the front is low and the back is high, so that the upper clear water can be smoothly discharged into the water collecting trough 16 on one side along the drainage trough 10 to achieve rapid drainage.

[0022] In actual operation, production wastewater can enter the water distribution well 4 through the wastewater inlet pipe 5, and enter the anaerobic reaction tank 1 through the water distribution pipe 2 to achieve uniform water distribution; when the water level rises to above the return pipe 6, the circulation pump 8 is started, and the power provided by the circulation pump 8 causes part of the wastewater in the anaerobic reaction tank 1 to enter the return well 7 through the return pipe 6, and enter the water distributor 11 through the return well 7. The water distributor 11 is connected to the top of the water distribution well 4, so that the returned wastewater is sprayed into the anaerobic reaction tank 1 again, so that the wastewater and sludge in the anaerobic reaction tank 1 are strongly agitated and provide an upward flow driving force. The organic matter in the mixed wastewater contacts and reacts with the anaerobic sludge during the rising process, and the gas (biogas) generated by the reaction carries part of the sludge flocs. The body continues to move upward and collides with the three-phase separator 9, thereby causing the sludge to be degassed. The released gas is stored in the gas collecting chamber of the three-phase separator 9, and the sludge particles are settled to the surface of the sludge bed. The liquid flows into the drainage trough 10 on the top through the gap, and enters the sedimentation tank 13 through the water collecting trough 16 and the drainage pipe 15 for sedimentation, thereby improving the effluent quality of the anaerobic reaction tank 1; the primary treated water is precipitated in the sedimentation tank 13, and the sludge is precipitated downward. The sludge deposited in the sedimentation tank 13 is pumped into the water distributor 11 by the sludge pump 14, and enters the water distribution well 4 through the water distributor 11. The sludge, return wastewater and newly introduced wastewater are mixed in the water distribution well 4, further enhancing the disturbance of the three and improving the system's ability to resist shock loads.

[0023] Combination Figure 5 It can be seen that the water distribution pipeline 2 includes a primary main pipe 2a connected to the water distribution well 4 and a secondary pipe 2b connected to the primary main pipe 2a. The secondary pipe 2b is an I-shaped structure, and its four ports are connected to a tertiary pipe 2c with an I-shaped structure, and the middle part of the connecting pipe of the tertiary pipe 2c is connected to the port of the secondary pipe 2b; each port of the tertiary pipe 2c is connected to a quaternary pipe 2d with an I-shaped structure, and the middle part of the connecting pipe of the quaternary pipe 2d is fixedly connected to the port of the tertiary pipe 2c. During actual installation, the diameters of the primary main pipe 2a, the secondary pipe 2b, the tertiary pipe 2c and the quaternary pipe 2d are successively smaller, and each port of the quaternary pipe 2d is a water distribution port. The quaternary pipes 2d are evenly arranged in the anaerobic reaction tank to achieve uniform water distribution. The secondary pipe 2b, tertiary pipe 2c and quaternary pipe 2d (the quaternary pipe needs to avoid the return well and the water distribution well) of the present invention all adopt an I-shaped structure, so that the water distribution pipeline 2 is laid flat in the anaerobic reaction tank 1, making the water distribution more uniform and further ensuring the removal effect of organic matter.

[0024] During actual installation, a fixing column F1 is provided on the bottom wall of the anaerobic reaction tank 1, and each end pipe of the secondary pipe 2b is correspondingly fixed on the fixing column F1, so that the water distribution pipeline 2 is erected above the bottom wall; a mounting frame is horizontally provided at the middle and upper part of the anaerobic reaction tank 1, and the mounting frame includes a cross beam F2 and a longitudinal beam F3 fixedly connected to the fixing column F1, and the return pipeline 6 includes a return main pipe 6a connected to the return well 7 (installed on the cross beam F2 located in the middle) and a return main pipe 6a connected to the return well 7. The primary return branch pipe 6b is arranged front and back, and is fixedly connected to the water distribution well 4. The two ends of the primary return branch pipe 6b are respectively connected to the secondary return branch pipe 6c parallel to the return main pipe 6a. The secondary return branch pipe 6c is fixed to the cross beam F2 on both sides, and each end of the secondary return branch pipe 6c is connected to the tertiary return branch pipe 6d in an I-shaped structure. The tertiary return branch pipe 6d is fixedly connected to the cross beam F2 to ensure the fixing effect of the return pipeline 6. Each tertiary return branch pipe 6d has four water inlets, which are evenly distributed in the anaerobic reaction tank 1, thereby achieving uniform reflux. See Figure 4 .

[0025] During the actual installation, a walking platform 18 with a guardrail is provided on the upper part of the outer wall of the anaerobic reaction tank 1, and a maintenance platform 19 is provided on the top of the anaerobic reaction tank 1 above the drainage trough 10. The maintenance platform 19 is arranged horizontally and located at the water distribution well 4 and the return well 7, so as to facilitate the maintenance and installation of the water distributor. Figure 2-3 .

[0026] By adopting the scheme of the present invention, a certain amount of active anaerobic sludge containing hydrolytic acidifying bacteria, hydrogen-producing acid-producing bacteria and methanogenic bacteria is added to the anaerobic reaction tank 1 during treatment, so that the active anaerobic sludge and wastewater are fully in contact, and the removal efficiency and removal rate of organic matter in the wastewater are significantly improved through reflux and bottom-up flow. According to practice, when the circulating flow of wastewater in the anaerobic reaction tank 1 accounts for 50% to 100% of the total volume, the mixing effect and removal effect of the wastewater are the best, and the removal efficiency of organic matter in the wastewater can reach 80% to 90%, and in this state, the sludge morphology is between flocculent sludge and granular sludge, which effectively alleviates the influence of easy calcification of sludge.

[0027] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-reflux papermaking wastewater anaerobic treatment system, comprising an anaerobic treatment system and a sedimentation tank, characterized in that: The anaerobic treatment system comprises an anaerobic reaction tank, a water distributor arranged at the top of the anaerobic reaction tank, a water distribution well, a water distribution pipeline, and a wastewater inlet pipeline arranged in the anaerobic reaction tank, one end of the wastewater inlet pipeline is connected to the water inlet at the bottom of the water distribution well, and the other end thereof is connected to external wastewater; the water distribution pipeline is located below the water inlet; the upper part of the anaerobic reaction tank is provided with a drain port, the drain port is connected to the sedimentation tank through a drain pipeline, the mud discharge port at the bottom of the sedimentation tank is connected to the water distributor through a mud discharge pipeline with a mud discharge pump, and the outlet of the water distributor is connected to the top of the water distribution well; The anaerobic treatment system further comprises a return well arranged on a side wall of the anaerobic reaction tank and a return pipeline arranged in the anaerobic reaction tank, wherein the return well is connected to the water distributor through a pumping pipeline, and a circulating pump is arranged on the pumping pipeline; the return pipeline is located in the middle and upper part of the anaerobic reaction tank and is connected to the inlet at the bottom of the return well; the anaerobic treatment system further comprises a three-stage separator arranged in the anaerobic reaction tank and above the return pipeline, wherein a plurality of downwardly concave drainage grooves are arranged at intervals on the top of the three-stage separator; A water collecting trough is provided on one side wall of the anaerobic reaction tank, each of the drainage troughs is connected to the water collecting trough, and the overflow port is opened on the side wall of the anaerobic reaction tank corresponding to the water collecting trough; A mud discharge pipeline is arranged in the anaerobic reaction tank below the water distribution pipeline.

2. The double-reflux papermaking wastewater anaerobic treatment system according to claim 1, characterized in that: The water distribution pipeline includes a primary main pipe connected to the water distribution well and a secondary pipe connected to the primary main pipe. The secondary pipe is an I-shaped structure, and its four ports are connected to tertiary pipes with an I-shaped structure, and the middle part of the connecting pipe of the tertiary pipe is connected to the port of the secondary pipe; each port of the tertiary pipe is connected to a quadruple pipe with an I-shaped structure, and the middle part of the connecting pipe of the quadruple pipe is fixedly connected to the port of the tertiary pipe.

3. The double reflux papermaking wastewater anaerobic treatment system according to claim 2, characterized in that: A fixing column is arranged on the bottom wall of the anaerobic reaction tank, and each end pipe of the secondary pipe is correspondingly fixed on the fixing column, so that the water distribution pipeline is erected above the bottom wall.

4. The double reflux papermaking wastewater anaerobic treatment system according to claim 1, characterized in that: A mounting frame is horizontally arranged at the middle and upper part of the anaerobic reaction tank, and the reflux pipeline is mounted on the mounting frame.

5. The double-reflux papermaking wastewater anaerobic treatment system according to claim 4 is characterized in that: The reflux pipeline includes a reflux main pipe connected to the reflux well and a primary reflux branch pipe connected to the reflux main pipe. Both ends of the primary reflux branch pipe are connected to secondary reflux branches parallel to the reflux main pipe. Each port of each secondary reflux branch pipe is connected to a tertiary reflux branch pipe in an I-shaped structure.

6. The double-reflux papermaking wastewater anaerobic treatment system according to claim 1, characterized in that: A walking platform with a guardrail is arranged on the upper part of the outer side wall of the anaerobic reaction tank; and an inspection platform is arranged on the top of the anaerobic reaction tank above the drainage trough.

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