CN211712884U - Advanced treatment shale gas fracturing flow-back fluid system based on A2O-MBR method - Google Patents
Advanced treatment shale gas fracturing flow-back fluid system based on A2O-MBR method Download PDFInfo
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Abstract
The utility model discloses a based on A2O-MBR method advanced treatment shale gas fracturing flowback liquid system, including homogeneity buffer pool, shallow layer ion air supporting pond, integration A2O-MBR biochemical treatment system and the fenton oxidation system that connects gradually. The utility model provides a processing system construction cost and use cost are low, and process flow is compact, and process control is stable, can realize the discharge to reach standard of shale atmospheric pressure fracturing flowback fluid treatment back waste water through this system.
Description
Technical Field
The utility model relates to a flowing back degree of depth processing technology field is returned in fracturing, concretely relates to based on A2O-MBR method degree of depth processing shale gas fracturing returns flowing back system.
Background
The development of shale gas becomes a new bright spot for the exploration and development of global oil and gas resources, and the shale gas has the advantages of long mining life, high yield and long production period, and the shale gas has higher development difficulty due to low shale stratum permeability. At present, the shale gas is mainly developed by using a hydraulic fracturing method, and the principle of the method is that natural fractures of a reservoir or a fracture system generated by artificial induction are utilized, fracturing fluid containing various additives is injected into a stratum under high pressure, the reservoir fracture network is further expanded, and then the fracture is propped by a propping agent to improve the reservoir fracture network system, so that the purpose of increasing the production is achieved.
The flowback liquid after fracturing construction is high-viscosity, high-chlorine and low-concentration COD organic wastewater which is difficult to degrade, the content of chloride ions is about 15000mg/L, the COD is about 1000mg/L, and the flowback liquid also contains partial chemical additives such as resistance reducing agent, surfactant, cross-linking agent, demulsifier, gelling agent, preservative and the like.
The existing treatment method of the fracturing flow-back fluid is mainly natural air drying, the fracturing flow-back fluid is stored in a special flow-back fluid tank, drying is carried out by adopting a natural evaporation method, and finally direct landfill is carried out. The method has low treatment efficiency and large occupied area, and the sludge block after landfill still can percolate oil, heavy metals, aldehyde, phenol and other pollutants, so that serious secondary pollution exists.
In recent years, more and more researches are carried out on shale gas fracturing flowback fluid treated by a membrane concentration method, such as a softening system, an ultrafiltration system, a reverse osmosis concentration system, a chemical precipitation system, a tubular microfiltration membrane system, a nanofiltration system and a reverse osmosis system.
Therefore, the development of an economical and practical treatment mode has very important practical significance on the sustainable development of the shale gas.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an economical and practical returns flowing back system based on A2O-MBR method advanced treatment shale gas fracturing, this system use cost is low, and process control is stable, can realize that shale gas fracturing returns the discharge to reach standard of flowing back waste water after liquid treatment.
The utility model discloses a first technical scheme be: a deep treatment shale gas fracturing flowback fluid system based on an A2O-MBR method is characterized by comprising the following steps: the homogenizing buffer tank is used for collecting shale gas fracturing flow-back fluid and balancing water quantity and water quality; an inlet of the shallow ion floatation tank is connected with an outlet of the homogenizing buffer tank and is used for forming flocs with density smaller than that of water, floating to the water surface and then scraping; integration A2O-MBR biochemical treatment system, including the cell body, cell body import and shallow layer ion air supporting pond exit linkage, set gradually anaerobic zone, anoxic zone, aerobic zone and membrane zone from the import to the export in the cell body, the volume ratio in anaerobic zone, anoxic zone, aerobic zone is 1: 1: 3-5, arranging an MBR hollow fiber membrane component in the membrane area, and respectively connecting the membrane area with the anaerobic area, the anoxic area and the aerobic area through a sludge reflux pump and a pipeline; the Fenton oxidation system comprises a Fenton reactor, a neutralization tank, an inclined plate sedimentation tank and a quartz sand filter which are sequentially connected, wherein an inlet of the Fenton reactor is connected with a water outlet of the MBR hollow fiber membrane component, and oxidized wastewater is discharged after neutralization, sedimentation and filtration.
By adopting the technical scheme, firstly, the water quantity and the water quality are balanced through a pretreatment process, namely, a homogenizing buffer tank, then the water enters a shallow ion air floatation tank for air floatation, most of hydrophilic organic additives and gel particles of other components in the wastewater are removed through the air floatation process, the ammonia nitrogen content and the COD content of the pretreated wastewater are reduced, and the biochemical treatment load and the resistance of membrane filtration are reduced; an integrated A2O-MBR biochemical treatment system is adopted, anaerobic, anoxic, aerobic and membrane filtration are arranged in a tank body, so that the building cost and the occupied area are reduced, the process flow is more compact, and the treatment efficiency is improved; the ammonia nitrogen and the COD of the wastewater treated by the integrated A2O-MBR biochemical treatment system can be removed by 85-98 percent, and the COD of the wastewater can be removed by 80-90 percent, and then the wastewater enters a Fenton oxidation system for oxidative degradation, so that the dosage of Fenton oxidant can be reduced, and the use cost of the system is reduced. The effluent can reach the first grade discharge standard of the national Integrated wastewater discharge Standard (GB8978-1996) after Fenton oxidation, neutralization, precipitation and filtration.
The utility model discloses a second technical scheme be the improvement on first technical scheme, the utility model discloses a second technical scheme be: the integrated A2O-MBR biochemical treatment system further comprises a medicament tank and a medicament pump, wherein the medicament tank is used for storing alkali liquor and a carbon source, and the alkali liquor and the carbon source are put into the anoxic zone through the medicament pump so as to adjust the pH value of water in the anoxic tank and improve the denitrification efficiency.
In the shale gas fracturing flowback biochemical treatment process, nitrite is easy to accumulate, in order to avoid toxic influence of the accumulation of the nitrite on microorganisms of a biochemical system, a sodium acetate or glucose carbon source is added into an anoxic pond through a medicament pump, the adding amount is 50-100 ppm, and NaOH or NaCO is added through the medicament pump3The pH of the water solution is adjusted to be within 7.5-8.5 in the anoxic zone, so that the denitrification efficiency is improved.
The utility model discloses a third technical scheme be the improvement on the second technical scheme, the utility model discloses a third technical scheme be: a water production tank is arranged between the integrated A2O-MBR biochemical treatment system and the Fenton oxidation system, purified water separated by the MBR hollow fiber membrane module is pumped into the water production tank by a water production pump, and the water in the water production tank is lifted to the Fenton reactor by a lifting pump.
The water producing tank is used as an intermediate water storage tank, and has the functions of continuous production, stable water flow and improvement of water treatment quality.
The utility model discloses a fourth technical scheme be the improvement on the third technical scheme, the utility model discloses a fourth technical scheme be: the outlet water of the homogeneous buffer tank is lifted to a shallow ion air flotation tank through a lift pump, the outlet water of the shallow ion air flotation tank automatically flows to an A2O-MBR biochemical treatment system, the outlet water of the Fenton reactor automatically flows to a neutralization tank, the outlet water of the neutralization tank automatically flows to an inclined plate sedimentation tank, and the purified water separated by the inclined plate sedimentation tank is lifted to a quartz sand filter through the lift pump.
By adopting the technical scheme, the homogeneous buffer tank can be arranged into an underground or semi-underground tank, the shale gas fracturing flow-back fluid can enter the homogeneous buffer tank in a self-flowing mode, the power for conveying raw water is reduced, and the energy consumption is reduced. The elevation of the shallow ion air flotation tank, the A2O-MBR biochemical tank, the Fenton reactor, the neutralization tank and the inclined plate sedimentation tank is controlled, the gravity flow is utilized to reduce the conveying power and reduce the energy consumption. In order to reduce the elevation of the tank body and reduce the construction cost, the sedimentation tank is generally designed into an underground or semi-underground tank, and the quartz sand filter is designed into the ground for convenient operation and maintenance, so a lifting pump is arranged behind the inclined plate sedimentation tank.
The utility model discloses a fifth technical scheme be the improvement on the fourth technical scheme, the utility model discloses a fifth technical scheme be: the effective hydraulic retention time of the homogeneous buffer tank is 5-15 h, the reaction time of the shallow ion air flotation tank is 3-10 min, the effective hydraulic retention time of the A2O-MBR biochemical treatment system is 18-36 h, the reaction time of the Fenton reactor is 0.5-1 h, the retention time of the neutralization tank is 15-60 min, and the settling time of the inclined plate settling tank is 30-120 min.
The tank capacity of each tank is designed according to the effective hydraulic retention time and the reaction time of each tank, so that the treatment effect of each tank can be ensured, excessive surplus is not generated, the construction cost and the use cost are increased, and the process regulation reaction is slow.
The utility model discloses a sixth technical scheme be the improvement on first technical scheme, the utility model discloses a sixth technical scheme be: the transmembrane pressure difference of the MBR hollow fiber membrane component is 0.1-0.5 bar, and the membrane flux is 10-25 LMH.
By adopting the technical scheme, the membrane bioreactor can retain microorganisms with longer generation period, so that the possibility of deep dephosphorization and denitrification is realized; in addition, the membrane bioreactor can keep high activated sludge concentration, has strong capability of resisting hydraulic impact load, and is stable in system operation and suitable for complex water quality working conditions; the excess sludge amount can be reduced by keeping the sludge load low, and the subsequent sludge disposal cost can be reduced.
The utility model discloses a seventh technical scheme be the improvement on first technical scheme, the utility model discloses a seventh technical scheme be: the aerobic zone is provided with composite filler or porous ring filler and a microporous aeration system.
By adopting the technical scheme, the biochemical treatment effect can be enhanced, and as the high-salinity wastewater sludge particles are unstable and have poor coagulation effect, the filler is used as a microbial carrier and is beneficial to attachment of a biological membrane, so that a relatively stable internal environment for propagation and growth is formed.
To sum up, the utility model provides a based on A2O-MBR method advanced treatment shale gas fracturing returns flowing back system, construction cost and use cost are low, and process flow is compact, and process control is stable, can realize that shale gas fracturing returns up to standard emission of flowing back waste water after handling.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention, based on A2O-MBR method, of a system for deeply treating shale gas fracturing flow-back fluid.
FIG. 2 is a process flow diagram of the system shown in FIG. 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and a preferred embodiment.
Example 1
Referring to fig. 1 and fig. 2, the present embodiment provides a system for deeply treating shale gas fracturing flow-back fluid based on an A2O-MBR method, which includes a homogeneous buffer tank 1, a shallow ion air flotation tank 3, an integrated A2O-MBR biochemical treatment system 4, and a fenton oxidation system, which are connected in sequence.
The homogeneous buffer tank 1 is used for collecting fracturing flow-back fluid and mainly aims at balancing water quantity and water quality. The homogeneous buffer tank adopts a circular tank body with a reinforced concrete structure, and the effective hydraulic retention time of the tank body is preferably 10 h. The fracturing flow-back fluid has high corrosivity, and the construction cost can be reduced by adopting the homogeneous buffer tank with the circular tank body of the reinforced concrete structure.
The effluent of the homogenizing buffer tank 1 is lifted to a shallow ion air floatation tank 2 of an air floatation system through a sewage lifting pump 2.
The shallow ion air floatation tank 3 is provided with a water distribution device and an air floatation device, wastewater uniformly enters through the water distribution device, a dissolved air system of the air floatation device generates 3-7 um micro-bubbles to be adhered with hydrophobic groups, colloidal particles and water vapor particles of various chemical additives in water, and flocs with density smaller than that of the water float to the water surface and are scraped. In order to improve the air floatation effect, PAC or PAM auxiliary agent can be added into the air floatation tank. The air flotation reaction process conditions are as follows: the reaction time is 5 minutes, and the air amount is 0.5-1.6m3The effluent pressure is 0.35-0.45Mpa, and the water inlet pressure is 0.4-0.5 Mpa.
Integration A2O-MBR biochemical treatment system 4 includes rectangular cell body, and 3 exit linkage in cell body import and shallow layer ion air supporting pond, import in the cell body to export set gradually anaerobic zone 41, anoxic zone 42, aerobic zone 43 and membrane area 44, and the volume ratio in anaerobic zone, anoxic zone, aerobic zone is 1: 1: 4, an MBR hollow fiber membrane component 441 is arranged in the membrane area, and the membrane area is respectively connected with the anaerobic area 41, the anoxic area 42 and the aerobic area 43 through a sludge reflux pump 45 and a pipeline.
The effluent of the shallow ion floatation tank 3 automatically flows into the tank body and sequentially flows through the anaerobic zone 41, the anoxic zone 42, the aerobic zone 43 and the membrane zone 44, and the total retention time is 24 h. The MBR membrane device pumps the permeate out of the permeation side of the membrane through a suction pump, the transmembrane pressure difference is 0.1-0.5 bar, and the membrane flux is 10 LMH. The MBR membrane is of a hollow fiber membrane structure, and the nominal diameter of the membrane pores is 0.03 mu m. And (3) respectively refluxing the sludge in the membrane tank to the anaerobic zone, the anoxic zone and the aerobic zone by a sludge reflux pump, wherein the reflux ratio is 100%, 50% and 50%, the sludge concentration in the aerobic zone is 5000mg/L, and the sludge concentration in the membrane zone is 8000 mg/L. The aerobic zone is added with composite filler or porous ring filler, the filler is attached with an active carbon microbial inoculum, and a microporous aeration system is arranged. In order to improve the reaction effect, active carbon can be added into the aerobic zone, the mesh number of the active carbon is 100-200 meshes, and the adding amount is 0.05-0.1%. The specific surface area of the activated carbon microbial inoculum is larger, the activated carbon microbial inoculum is favorable for the attachment growth of microorganisms, the microbial population of an aerobic pool can be enriched, and the synergistic effect of the activated carbon microbial inoculum and the aerobic pool is favorable for resisting the hydraulic impact effect caused by unstable water quality of high-salinity wastewater
To avoidThe nitrite accumulation in the anoxic zone is prevented from influencing the toxic hazard of the microorganisms of the biochemical system, a medicine adding system is arranged above the anoxic zone 42, the medicine adding system comprises a medicine barrel 46 and a medicine pump 47, NaOH or NaCO is added into the anoxic zone through the medicine pump 473And (5) alkaline solution, and adjusting the pH value of the effluent of the anoxic zone to 7.5-8.5. And adding a sodium acetate or glucose carbon source into the anoxic tank through a medicament pump, wherein the adding amount is 50-100 ppm.
The Fenton oxidation system comprises a Fenton reactor 8, a neutralization tank 9, an inclined plate sedimentation tank 10 and a quartz sand filter 12 which are sequentially connected. Purified water separated by the MBR hollow fiber membrane module 441 is pumped into a water production tank 6 through a water production pump 5, and water in the water production tank 6 is lifted to a Fenton reactor 8 through a lifting pump 7.
The Fenton oxidation takes ferrous sulfate pentahydrate as a catalyst and hydrogen peroxide as an oxidant, the reaction pH is 3-5, the adding amount of the hydrogen peroxide is 100mg/L, the mass ratio of the adding amount of the ferrous sulfate pentahydrate to the adding amount of the hydrogen peroxide is 1: 1, and the reaction time is 0.5-1 h. Effluent of the Fenton oxidation device 8 automatically flows into a carbon steel cylindrical neutralization tank 9 for neutralization reaction, NaOH is added into the neutralization tank 9 to control the pH value in the neutralization tank to be 6-8, and the retention time is 30 min. And (9) automatically discharging the effluent to an inclined plate sedimentation tank 10, adding a flocculating agent PAC into the inclined plate sedimentation tank, wherein the adding agent dosage is 5ppm, and the sedimentation time is 30 min. The effluent of the inclined plate sedimentation tank 10 is lifted to a quartz sand filter 12 through a lifting pump 11 for filtration, and macromolecular solid particles and colloid in the water are further intercepted through sand filtration and then are discharged after reaching the standard.
The effect of the treatment system of example 1 on the treatment of shale gas frac flowback fluid is shown in table 1. The quality of the shale gas fracturing flowback fluid is as follows:
pH value: 7-9; COD: 500-1000 mg/L; ammonia nitrogen is 60-100 mg/L; and 15000-20000 mg/L of chloride ions.
TABLE 1 Water quality analysis of wastewater at various stages of treatment
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and the improvements and modifications are also within the protection scope of the present invention.
Claims (6)
1. A deep treatment shale gas fracturing flowback fluid system based on an A2O-MBR method is characterized by comprising the following steps: the homogenizing buffer tank is used for collecting shale gas fracturing flow-back fluid and balancing water quantity and water quality; an inlet of the shallow ion floatation tank is connected with an outlet of the homogenizing buffer tank and is used for forming flocs with density smaller than that of water, floating to the water surface and then scraping; integration A2O-MBR biochemical treatment system, including the cell body, cell body import and shallow layer ion air supporting pond exit linkage, set gradually anaerobic zone, anoxic zone, aerobic zone and membrane zone from the import to the export in the cell body, the volume ratio in anaerobic zone, anoxic zone, aerobic zone is 1: 1: 3-5, arranging an MBR hollow fiber membrane component in the membrane area, and respectively connecting the membrane area with the anaerobic area, the anoxic area and the aerobic area through a sludge reflux pump and a pipeline; the Fenton oxidation system comprises a Fenton reactor, a neutralization tank, an inclined plate sedimentation tank and a quartz sand filter which are sequentially connected, wherein an inlet of the Fenton reactor is connected with a water outlet of the MBR hollow fiber membrane component, and oxidized wastewater is discharged after neutralization, sedimentation and filtration.
2. The advanced treatment shale gas fracturing flow-back fluid system based on the A2O-MBR method of claim 1, wherein the integrated A2O-MBR biochemical treatment system further comprises a medicament tank and a medicament pump, the medicament tank is used for storing alkali liquor and a carbon source, and the alkali liquor and the carbon source are fed into the anoxic zone through the medicament pump to adjust the pH value of water in the anoxic tank and improve the denitrification efficiency.
3. The advanced treatment shale gas fracturing flow-back fluid system based on the A2O-MBR method of claim 2, wherein a water production tank is arranged between the integrated A2O-MBR biochemical treatment system and the Fenton oxidation system, purified water separated from the MBR hollow fiber membrane module is pumped into the water production tank by a water production pump, and water in the water production tank is lifted to the Fenton reactor by a lift pump.
4. The A2O-MBR method-based deep treatment shale gas fracturing flow-back fluid system of claim 3, wherein the effluent of the homogenizing buffer tank is lifted to a shallow ion floatation tank by a lift pump, the effluent of the shallow ion floatation tank flows to the A2O-MBR biochemical treatment system, the effluent of the Fenton reactor flows to a neutralization tank, the effluent of the neutralization tank flows to an inclined plate sedimentation tank, and the clean water separated in the inclined plate sedimentation tank is lifted to a quartz sand filter by the lift pump.
5. The advanced treatment shale gas fracturing flow-back fluid system based on the A2O-MBR method of claim 1, wherein the transmembrane pressure difference of the MBR hollow fiber membrane module is 0.1-0.5 bar, and the membrane flux is 10-25 LMH.
6. The advanced treatment shale gas fracturing flow-back fluid system based on the A2O-MBR method of claim 1, wherein the aerobic zone is provided with composite filler or porous ring filler, and the microporous aeration system is arranged.
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| CN114133095A (en) * | 2021-08-24 | 2022-03-04 | 天津津港基础设施养护运营工程管理有限公司 | Biological enhanced treatment device and process for high-salinity oily wastewater |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114133095A (en) * | 2021-08-24 | 2022-03-04 | 天津津港基础设施养护运营工程管理有限公司 | Biological enhanced treatment device and process for high-salinity oily wastewater |
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