Membrane bioreactor coupled membrane distillation system for hydrofracture flow-back fluid treatment

Abstract

The utility model provides a membrane bioreactor coupled membrane distillation system for hydraulic fracturing flow-back fluid treatment, and relates to the technical field of wastewater treatment. The membrane bioreactor coupled membrane distillation system for treating the hydraulic fracturing flow-back fluid comprises a membrane bioreactor and a membrane distillation device, the membrane bioreactor comprises a membrane biological reaction tank, a first membrane component arranged in the membrane biological reaction tank, an air blower for introducing gas into the membrane biological reaction tank and a dosing mechanism for feeding filler into the membrane biological reaction tank; the membrane distillation device comprises a membrane distillation reactor, a heating device, a first pumping mechanism, a distilled water pool and a second membrane assembly arranged in the membrane distillation reactor; the heating device is used for heating water discharged from the membrane biological reaction tank, the first pumping mechanism is used for pumping water heated by the heating device into the membrane distillation reactor, and the membrane distillation reactor is communicated with the distilled water tank so as to discharge water into the distilled water tank. Wastewater is firstly treated through the membrane bioreactor, and the water inlet condition of the membrane distillation device is improved, so that the wastewater treatment effect is better.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and more particularly, to a membrane bioreactor coupled with a membrane distillation system for treating hydraulic fracturing flowback fluid. Background Technique

[0002] Due to the energy shortage, the exploitation of unconventional resources represented by shale gas and shale oil has shown an explosive growth globally. As a country with the largest shale gas reserves and the third largest shale oil reserves in the world, China is in the rapid expansion stage of shale gas and shale oil development. The horizontal well technology and hydraulic fracturing technology widely used in the process of shale gas and shale oil exploitation consume a large amount of fresh water resources and at the same time generate most of the flowback wastewater. The composition of hydraulic fracturing flowback fluid is complex, containing a large amount of cations, anions, organic matter, natural radioactive substances, etc., mainly characterized by high total dissolved solids (TDS) and high organic matter content. If not properly treated, the existence of these pollutants will seriously affect the water quality safety of local surface water and groundwater and the health of residents. In addition, the lack of relevant standards for hydraulic fracturing flowback fluid makes the treatment of hydraulic fracturing flowback fluid more difficult.

[0003] Due to the differences in the storage conditions of shale gas and shale oil, the hydraulic fracturing flowback fluid in China has unique characteristics. Compared with the relatively mature shale gas exploitation in the United States, the water consumption for shale gas exploitation in China is large (23,650 - 34,000 m 3 ), the amount of flowback wastewater is large (about 19,800 m 3 ), and at the same time, the concentration of pollutants in the wastewater is relatively low. After appropriate treatment, the hydraulic fracturing flowback fluid can be used for surface water discharge or irrigation of farmland, and usually desalination treatment is required to reduce the content of TDS and ions. Due to the excellent desalination effect, low energy consumption and stable flow rate of membrane distillation, membrane distillation is an economical and effective desalination technology; however, the influent conditions will affect the treatment effect of membrane distillation. Utility Model Content

[0004] The present application provides a membrane bioreactor coupled with a membrane distillation system for treating hydraulic fracturing flowback fluid, which first treats the wastewater through a membrane bioreactor to improve the influent conditions of the membrane distillation device, so that the wastewater treatment effect is better.

[0005] The embodiments of the present application are implemented as follows:

[0006] In a first aspect, the present application provides a membrane bioreactor coupled with a membrane distillation system for treating hydraulic fracturing flowback fluid, including:

[0007] A membrane bioreactor, the membrane bioreactor comprising a membrane bioreaction tank, a first membrane module disposed within the membrane bioreaction tank, a blower for introducing gas into the membrane bioreaction tank, and a dosing mechanism for introducing packing into the membrane bioreaction tank; and

[0008] A membrane distillation device, the membrane distillation device comprising a membrane distillation reactor, a heating device, a first pumping mechanism, a distillation water tank, and a second membrane module disposed within the membrane distillation reactor; the heating device is used for heating the water discharged from the membrane bioreaction tank, the first pumping mechanism is used for pumping the water heated by the heating device into the membrane distillation reactor, and the membrane distillation reactor is communicated with the distillation water tank for draining water into the distillation water tank.

[0009] In a possible implementation manner, the membrane bioreactor further comprises a raw water tank communicated with the membrane bioreaction tank and a water inlet lift pump for pumping the return wastewater into the raw water tank.

[0010] In a possible implementation manner, the raw water tank and the membrane bioreaction tank are integrally arranged, the raw water tank and the membrane bioreaction tank are separated by a partition board, and the partition board is provided with through holes, and the raw water tank and the membrane bioreaction tank are communicated through the through holes.

[0011] In a possible implementation manner, the raw water tank and the water inlet lift pump are communicated through a first pipeline, and the first pipeline is provided with a first water inlet valve.

[0012] In a possible implementation manner, the membrane bioreactor further comprises a booster pump, the booster pump is communicated with the membrane bioreaction tank and the heating device, and the booster pump is used for pumping the water discharged from the membrane bioreaction tank into the heating device.

[0013] In a possible implementation manner, the booster pump and the heating device are communicated through a second pipeline, and the second pipeline is provided with a water production valve.

[0014] In a possible implementation manner, the first pumping mechanism and the membrane distillation reactor are communicated through a third pipeline, and the third pipeline is provided with a second water inlet valve.

[0015] In a possible implementation manner, the distillation water tank is communicated with the membrane distillation reactor through a second pumping mechanism, and the second pumping mechanism is used for pumping the water in the distillation water tank into the membrane distillation reactor for cyclic treatment; a fourth pipeline is arranged between the second pumping mechanism and the membrane distillation reactor, and the fourth pipeline is provided with a third water inlet valve.

[0016] In a possible implementation, the outlet of the membrane distillation reactor communicates with the inlet of the heating device through a circulation pipeline.

[0017] In a possible implementation, the first membrane module uses a hydrophilic polyvinylidene fluoride hollow fiber membrane, and the second membrane module uses a hydrophobic polyvinylidene fluoride hollow fiber membrane or a hydrophobic polyvinylidene fluoride flat membrane.

[0018] The present application has at least the following beneficial effects:

[0019] The membrane bioreactor-coupled membrane distillation system for treating hydraulic fracturing flowback fluid of the present application first treats the wastewater through a membrane bioreactor, improves the inlet conditions of the membrane distillation device, and makes the wastewater treatment effect better. Among them, gas is introduced into the membrane bioreactor through a blower for aeration, and a filler is added to the membrane bioreactor in combination with a dosing mechanism, so that the first membrane module in the membrane bioreactor can effectively intercept particulate matter, ammonia nitrogen and some organic matter in the wastewater, greatly alleviating the membrane pollution and wetting trend of the subsequent membrane distillation device. Among them, through the coupling of the membrane bioreactor and the membrane distillation device, multiple barriers ensure the water quality purification efficiency of the membrane bioreactor-coupled membrane distillation system for treating hydraulic fracturing flowback fluid. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic diagram of the membrane bioreactor-coupled membrane distillation system for treating hydraulic fracturing flowback fluid in the specific implementation manner of the present application;

[0022] Figure 2 It is the test results of the flux and product water conductivity of the membrane distillation process in the embodiment of the present application.

[0023] Icons: 10 - Membrane bioreactor coupled with membrane distillation system for hydraulic fracturing flowback fluid treatment; 11 - Membrane bioreactor; 111 - Membrane bioreaction tank; 112 - First membrane module; 113 - Blower; 114 - Chemical dosing mechanism; 115 - Raw water tank; 116 - Feed water lift pump; 117 - Circulation pump; 118 - First feed water valve; 119 - Booster pump; 120 - Product water valve; 13 - Membrane distillation device; 131 - Membrane distillation reactor; 1311 - Second membrane module; 132 - Heating device; 133 - First pumping mechanism; 134 - Distilled water tank; 135 - Second feed water valve; 136 - Second pumping mechanism; 137 - Third feed water valve; 138 - Circulation pipeline. Detailed implementation manners

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application to be protected, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0026] In the description of the present application, it should be noted that the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "set" and "connected" 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0028] The present application provides a membrane bioreactor coupled with membrane distillation system 10 for hydraulic fracturing flowback fluid treatment. Please refer to Figure 1 , which includes a membrane bioreactor 11 and a membrane distillation device 13. The wastewater is first treated by the membrane bioreactor 11 to improve the inlet conditions of the membrane distillation device 13, so that the wastewater treatment effect is better.

[0029] The membrane bioreactor 11 includes a membrane bioreaction tank 111, a first membrane module 112 disposed in the membrane bioreaction tank 111, a blower 113 for introducing gas into the membrane bioreaction tank 111, and a dosing mechanism 114 for adding packing into the membrane bioreaction tank 111. Among them, an air diffuser pipe is provided at the bottom of the membrane bioreaction tank 111, and the blower 113 introduces gas into the membrane bioreaction tank 111 through the air diffuser pipe for aeration, and combines with the dosing mechanism 114 to add packing into the membrane bioreaction tank 111, so that the first membrane module 112 in the membrane bioreaction tank 111 can effectively intercept particulate matter, ammonia nitrogen and some organic matters in the wastewater, greatly alleviating the membrane pollution and wetting tendency of the subsequent membrane distillation device 13. Exemplarily, the added packing can be powdered activated carbon (PAC), activated alumina (AA) or powdered zeolite (PZ), and the average particle size of the packing is 200 - 1500 mesh. Using powdered activated carbon, activated alumina or powdered zeolite as additives in the membrane bioreactor 11 can more significantly improve the treatment effect of the membrane bioreactor 11 on ammonia nitrogen and organic matters.

[0030] Furthermore, the membrane bioreactor 11 further includes a raw water tank 115 communicated with the membrane bioreaction tank 111 and a feed water lift pump 116 for pumping the returned wastewater to the raw water tank 115. Through the feed water lift pump 116, the returned wastewater can be pumped to the raw water tank 115, and then enter the membrane bioreaction tank 111 through the raw water tank 115 for treatment. Exemplarily, the raw water tank 115 and the feed water lift pump 116 are connected through a first pipeline, and a first inlet valve 118 is provided on the first pipeline. The first inlet valve 118 can control the entry of the returned wastewater into the raw water tank 115.

[0031] Exemplarily, the raw water tank 115 and the membrane bioreaction tank 111 are integrally arranged, the raw water tank 115 and the membrane bioreaction tank 111 are separated by a partition board, and the partition board is provided with through holes, and the raw water tank 115 and the membrane bioreaction tank 111 are communicated through the through holes. Among them, the water in the raw water tank 115 can enter the membrane bioreaction tank 111 through the through holes of the partition board for treatment.

[0032] Optionally, a circulation pump 117 is provided between the raw water tank 115 and the membrane bioreaction tank 111. The circulation pump 117 can pump the treated water in the membrane bioreaction tank 111 to the raw water tank 115, and the water in the raw water tank 115 enters the membrane bioreaction tank 111 again for treatment, thus forming a cycle, so that the wastewater can be treated by the first membrane module 112 in the membrane bioreaction tank 111 multiple times, and the wastewater purification effect is better. Among them, the first membrane module 112 in the membrane bioreaction tank 111 operates at a constant flux, and the filtration flux is 10 - 30 L / (m 2·h), the backwashing period is 10 - 300 min; the nominal membrane pore size is 0.01 - 10 μm. The material of the first membrane module 112 is polyvinylidene fluoride or polyvinyl chloride. Exemplarily, the first membrane module 112 uses hydrophilic polyvinylidene fluoride hollow fiber membranes.

[0033] The membrane distillation device 13 includes a membrane distillation reactor 131, a heating device 132, a first pumping mechanism 133, a distillation water tank 134, and a second membrane module 1311 disposed in the membrane distillation reactor 131; the heating device 132 is used to heat the water discharged from the membrane bioreactor 111, and the first pumping mechanism 133 is used to pump the water heated by the heating device 132 into the membrane distillation reactor 131, and the membrane distillation reactor 131 is communicated with the distillation water tank 134 for draining water into the distillation water tank 134.

[0034] The membrane distillation device 13 receives the produced water of the membrane bioreactor 11, the produced water enters the heating device 132 and is heated, the produced water of the heating device 132 enters the membrane distillation reactor 131 through the first pumping mechanism 133 and is processed by the second membrane module 1311, and the processed water enters the distillation water tank 134 and is stored therein. Among them, the first pumping mechanism 133 is optionally a peristaltic pump. In addition, the first pumping mechanism 133 is communicated with the membrane distillation reactor 131 through a third pipeline, and a second inlet valve 135 is provided on the third pipeline. The second inlet valve 135 can control the water of the heating device 132 to enter the membrane distillation reactor 131. Optionally, the water inlet and outlet flow rates of the membrane bioreactor 11 are 0.05 - 0.5 m / s, and the temperature difference is 30 - 50°C; the material of the second membrane module 1311 is polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE). Optionally, the second membrane module 1311 uses hydrophobic polyvinylidene fluoride hollow fiber membranes or hydrophobic polyvinylidene fluoride flat membranes.

[0035] Exemplarily, the outlet of the membrane distillation reactor 131 is communicated with the inlet of the heating device 132 through a circulation pipeline 138. Through the circulation pipeline 138, the water in the membrane distillation reactor 131 can be re-introduced into the heating device 132 and heated, and then the water in the heating device 132 enters the membrane distillation reactor 131 again to be processed, so that the wastewater purification effect is better.

[0036] Among them, the membrane bioreactor 11 further includes a booster pump 119. The booster pump 119 is connected to the membrane bioreactor tank 111 and the heating device 132. The booster pump 119 is used to pump the water discharged from the membrane bioreactor tank 111 into the heating device 132. After the membrane bioreactor 11 treats most of the ammonia nitrogen and organic matter in the influent water, the effluent of the membrane bioreactor 11 enters the heating device 132 through the booster pump 119. The booster pump 119 and the heating device 132 are connected through a second pipeline, and a water production valve 120 is provided on the second pipeline. The water in the membrane bioreactor tank 111 can be controlled to enter the heating device 132 through the water production valve 120.

[0037] The distillation water tank 134 is connected to the membrane distillation reactor 131 through a second pumping mechanism 136. The second pumping mechanism 136 is used to pump the water in the distillation water tank 134 into the membrane distillation reactor 131 for circulation treatment; a fourth pipeline is provided between the second pumping mechanism 136 and the membrane distillation reactor 131, and a third water inlet valve 137 is provided on the fourth pipeline.

[0038] The distilled water produced by the membrane distillation reactor 131 enters the distillation water tank 134, and the distilled water enters the membrane distillation reactor 131 through the second pumping mechanism 136 and the third water inlet valve 137 to achieve circulation treatment. Optionally, the second pumping mechanism 136 is a peristaltic pump.

[0039] The working principle of the membrane bioreactor coupled membrane distillation system 10 for treating hydraulic fracturing flowback fluid in this application is as follows:

[0040] The hydraulic fracturing flowback fluid enters the raw water tank 115 through the inlet lift pump 116. The wastewater enters the membrane bioreactor tank 111 through the through hole of the intermediate partition of the raw water tank 115 and the membrane bioreactor tank 111. The blower 113 introduces gas into the membrane bioreactor tank 111 through the aeration pipe for aeration. After the hydraulic fracturing flowback fluid is cultured (30 - 60 days), packing (powdered activated carbon, activated alumina or powdered zeolite) is put into the membrane bioreactor tank 111 through the dosing mechanism 114. The packing can improve the treatment effect of the membrane bioreactor 11 on ammonia nitrogen and organic matter and relieve membrane fouling. After most of the ammonia nitrogen and organic matter in the influent water are treated, the effluent of the membrane bioreactor 11 enters the heating device 132 through the booster pump 119 and the water production valve 120. After heating is completed, the produced water enters the membrane distillation reactor 131 through the first pumping mechanism 133 and the second water inlet valve 135. The high-concentration wastewater in the membrane distillation reactor 131 returns to the heating device 132 through the circulation pipeline, and the distilled water enters the distillation water tank 134 and returns to the membrane distillation reactor 131 through the second pumping mechanism 136 to achieve circulation. The membrane bioreactor coupled membrane distillation system 10 for treating hydraulic fracturing flowback fluid adopts the combination of the membrane bioreactor 11 and the membrane distillation device 13. Due to the advantages of modularization of the membrane module, small floor area, simple operation and maintenance, etc., it can be set up as a mobile membrane integrated system. Example

[0041] The raw water is hydraulic fracturing flowback wastewater from a shale gas well in the Sichuan Basin. The filler added by the dosing mechanism 114 is powdered activated carbon with an average particle size of 200-1500 mesh, and a one-time addition of 10 g / L (volume of the membrane bioreactor 111) is adopted. The first membrane component 112 of the membrane bioreactor 11 adopts a hydrophilic PVDF hollow fiber membrane with a pore size of 0.01 μm; the second membrane component 1311 of the membrane distillation device 13 adopts a hydrophobic PVDF hollow fiber membrane with a pore size of 0.45 μm. Example

[0042] The only difference between Example 2 and Example 1 is that the filler added by the dosing mechanism 114 is activated alumina. Example

[0043] The only difference between Example 3 and Example 1 is that the filler added by the dosing mechanism 114 is powdered zeolite.

[0044] After testing, without adding filler, adding powdered activated carbon, adding activated alumina or adding powdered zeolite, the normalized flux increased from 0.43 to 0.81, 0.77, 0.78 and 0.75, the permeation conductivity decreased from 42 μS / cm to 18, 7.6, 6.3 and 6.4 μS / cm, the running time was reduced by 1 / 4, and the water contact angle increased from 18.6° to 73.0°. The results are as follows Figure 2 As shown. Among them, Figure 2 (a) is the flux of the tested membrane distillation process, Figure 2 (b) is the conductivity of water produced by membrane distillation.

[0045] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid, characterized in that Comprising: A membrane bioreactor, which includes a membrane bioreaction tank, a first membrane module disposed in the membrane bioreaction tank, a blower for introducing gas into the membrane bioreaction tank, and a dosing mechanism for putting fillers into the membrane bioreaction tank; And A membrane distillation device, which includes a membrane distillation reactor, a heating device, a first pumping mechanism, a distillation water tank, and a second membrane module disposed in the membrane distillation reactor; the heating device is used to heat the water discharged from the membrane bioreaction tank, the first pumping mechanism is used to pump the water heated by the heating device into the membrane distillation reactor, and the membrane distillation reactor is communicated with the distillation water tank for draining water into the distillation water tank.

2. The membrane bioreactor coupled membrane distillation system for treating hydraulic fracturing flowback fluid according to claim 1, wherein, The membrane bioreactor further includes a raw water tank communicated with the membrane bioreaction tank and an inlet lift pump for pumping the return wastewater into the raw water tank.

3. The membrane bioreactor coupled membrane distillation system for treating hydraulic fracturing flowback fluid according to claim 2, wherein, The raw water tank and the membrane bioreaction tank are integrally arranged, separated by a partition board, and the partition board is provided with through holes, and the raw water tank and the membrane bioreaction tank are communicated through the through holes.

4. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to claim 2, wherein The raw water tank and the inlet lift pump are communicated through a first pipeline, and the first pipeline is provided with a first inlet valve.

5. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to any one of claims 1 to 4, characterized in that The membrane bioreactor further includes a booster pump, which is communicated with the membrane bioreaction tank and the heating device, and the booster pump is used to pump the water discharged from the membrane bioreaction tank into the heating device.

6. The membrane bioreactor coupled membrane distillation system for treating hydraulic fracturing flowback fluid according to claim 5, wherein The booster pump and the heating device are communicated through a second pipeline, and the second pipeline is provided with a water production valve.

7. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to any one of claims 1 to 4, characterized in that, The first pumping mechanism and the membrane distillation reactor are communicated through a third pipeline, and the third pipeline is provided with a second inlet valve.

8. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to any one of claims 1 to 4, characterized in that, The distillation water tank is communicated with the membrane distillation reactor through a second pumping mechanism, and the second pumping mechanism is used to pump the water in the distillation water tank into the membrane distillation reactor for circulating treatment; a fourth pipeline is provided between the second pumping mechanism and the membrane distillation reactor, and the fourth pipeline is provided with a third inlet valve.

9. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to any one of claims 1 to 4, characterized in that, The outlet of the membrane distillation reactor is communicated with the inlet of the heating device through a circulation pipeline.

10. The membrane bioreactor coupled with membrane distillation system for treating hydraulic fracturing flowback fluid according to any one of claims 1 to 4, characterized in that, The first membrane module uses a hydrophilic polyvinylidene fluoride hollow fiber membrane, and the second membrane module uses a hydrophobic polyvinylidene fluoride hollow fiber membrane or a hydrophobic polyvinylidene fluoride flat membrane.

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