Anaerobic MBBR-A / O biological treatment process for treating ASP flooding oily sewage of oil field

Abstract

The invention relates to an anaerobic MBBR-A / O biological treatment process for treating ASP flooding oily sewage of an oil field, which is applied to the technical field of oil stain treatment and comprises an anaerobic treatment section, namely treating ASP flooding oily sewage through an anaerobic MBBR reactor which is internally provided with domesticated activated sludge and particle suspended filler; a hydrolytic acidification section: treating the sewage subjected to anaerobic treatment through a hydrolytic acidification reactor, wherein domesticated activated sludge is arranged in the reactor; in the aerobic treatment section, the sewage subjected to hydrolytic acidification treatment is subjected to aerobic treatment through a biological contact oxidation reactor, fixed filler is arranged in the reactor, domesticated microbial strains are added, the process aims at the water quality characteristics of the ASP flooding oily sewage, and the anaerobic section can also play a role in intercepting and adsorbing most of inorganic suspended solids; subsequently, further oxidation and interception are carried out through a hydrolytic acidification process, organic matters are continuously degraded, and finally, pollutants are effectively degraded under the action of aerobic microorganisms.

Description

Technical Field

[0001] The present application relates to the technical field of oil pollution treatment, and in particular to an anaerobic MBBR-A / O biological treatment process for treating oily wastewater in oilfield ASP flooding. Background Art

[0002] In the process of oilfield development, the treatment of oily wastewater is a crucial link, especially in the ternary composite flooding oil production process. The water quality characteristics of oily wastewater are extremely complex and difficult to be effectively treated by traditional methods. At present, the treatment of low-permeability reinjection water in oilfields mainly adopts a combination of conventional treatment and deep treatment. Conventional treatment processes are mainly based on physical and chemical methods, usually including steps such as oil removal, flocculation sedimentation or flotation, followed by further treatment by adding chemical agents such as bactericides, corrosion inhibitors, and scale inhibitors. The deep treatment process mostly uses security filtration and microfiltration membrane filtration technology to improve the refinement of water treatment.

[0003] However, with the increasing demand for the treatment of oily wastewater from ASP flooding in oil fields, traditional physical and chemical methods have gradually exposed their limitations in treatment efficiency and cost control. First of all, although physical and chemical methods can effectively remove most suspended solids and oils, they have limited treatment effects in treating complex wastewater components, especially high-concentration organic matter and biodegradable substances. At the same time, the amount of chemical agents required for this type of process is large, resulting in high treatment costs and easy to cause secondary pollution problems. In addition, due to the special water quality characteristics of ASP flooding oily wastewater, the research and application of microbial treatment processes are relatively rare, and existing technologies cannot fully utilize the biodegradation ability of microorganisms to treat this type of wastewater. Summary of the invention

[0004] The purpose of the present invention is to provide an anaerobic MBBR-A / O biological treatment process for treating oilfield ASP flooding oily wastewater to solve the above-mentioned technical problems.

[0005] Technical solution: An anaerobic MBBR-A / O biological treatment process for treating oilfield ASP flooding oily wastewater is provided, and the process comprises the following steps: anaerobic treatment section: treating the ASP flooding oily wastewater through an anaerobic MBBR reactor, wherein the anaerobic reactor is provided with domesticated activated sludge and suspended particle filler; hydrolysis acidification section: treating the anaerobic treated wastewater through a hydrolysis acidification reactor, wherein the reactor is provided with domesticated activated sludge; aerobic treatment section: aerobically treating the hydrolysis acidification treated wastewater through a biological contact oxidation reactor, wherein the reactor is provided with fixed filler and domesticated microbial strains are added.

[0006] In a possible embodiment, the anaerobic MBBR reactor includes a bottom water distribution area, a reaction area, a gas-solid-liquid separation area, a sedimentation area and a water outlet area; wherein the bottom water distribution area is used to uniformly introduce sewage into the reaction area, and activated sludge and suspended fillers are arranged in the reaction area so that the sewage is fully in contact with the activated sludge and suspended fillers in the reaction area; the gas-solid-liquid separation area separates the reaction products by gas stirring, the sedimentation area is used to settle and separate sludge and solid particles, and the water outlet area is used to discharge the treated clean water. The bottom water distribution area includes a plurality of water distribution ports, and the arrangement and opening rate of the water distribution ports are optimized to ensure uniform distribution of sewage in the reaction area, thereby improving the reaction efficiency; the opening rate of the water distribution port is designed to be adjusted according to the geometric shape of the reaction area and the sewage flow rate to avoid dead corners or short-flow phenomena of sewage in the reaction area.

[0007] In a possible implementation, the hydrolysis acidification reactor adopts the form of bottom water inlet and top water outlet, and nutrients are also added in the initial start-up to acclimate the activated sludge.

[0008] In a possible embodiment, the aerobic treatment section is a three-stage biochemical reactor, wherein the sewage is purified step by step through each stage of the biochemical reactor in turn; an aeration release head is provided at the bottom of each stage of the biochemical reactor, and the aeration release head is used to promote the proliferation and metabolism of microorganisms through continuous oxygen supply; the top of each stage of the biochemical reactor is filled with fixed fillers, and the microbial strains are gradually attached to the surface of the filler through aeration to form a biofilm, which is used to efficiently degrade organic pollutants in the sewage.

[0009] In a possible implementation manner, the total hydraulic retention time of the ASP flooding oily wastewater is 40 to 48 hours, and the water temperature is controlled between 30 and 35°C.

[0010] In a possible implementation manner, the reflux ratio of the hydrolysis and acidification section is 50%, and the gas-water ratio of the aerobic section is 20:1.

[0011] In a possible implementation, the sewage is pumped from the anaerobic MBBR reactor to the hydrolysis acidification reactor, and then flows into the aerobic reactor by gravity, and part of the effluent from the aerobic section is pumped to the hydrolysis acidification section by a reflux pump for reflux.

[0012] In a possible implementation, the particle suspended filler added into the anaerobic MBBR reactor accounts for 1 / 3 of the total volume of the reactor.

[0013] In a possible embodiment, the special microbial flora in the biological contact oxidation reactor is domesticated to form a dominant flora, which uses the organic pollutants in the sewage as a nutrient source to perform oxidation, reduction and synthesis, thereby achieving the degradation of organic matter and oils.

[0014] In a possible embodiment, an oilfield ASP flooding oily wastewater treatment system based on the above-mentioned anaerobic MBBR-A / O biological treatment process is provided, comprising an anaerobic MBBR reactor, a hydrolysis acidification reactor, a biological contact oxidation reactor, a lift pump and a control system connected in sequence; wherein the anaerobic MBBR reactor is used to perform anaerobically treatment on the wastewater; the hydrolysis acidification reactor is used to further decompose and acidify the anaerobic treated wastewater; the biological contact oxidation reactor is used to perform aerobic treatment on the hydrolysis acidified wastewater; the lift pump is used to transport the wastewater between the reactors; the control system is used to monitor and adjust the operating parameters of each reactor, including temperature, pH, aeration volume and sludge return ratio, and control the flow path of the wastewater.

[0015] In summary, the present application has the following beneficial technical effects: the present system degrades surfactants and polymers through the water quality characteristics of oily wastewater in ternary composite flooding, sulfate reduction in the anaerobic process, denitrification in the hydrolysis and acidification process, and nitrification, ammoniation, and oxidation in the aerobic process, thereby reducing the emulsification degree of produced water and improving water quality characteristics. The incoming water degrades most of the organic matter through the anaerobic section, and partially degrades some macromolecular substances that are difficult for aerobic microorganisms to use into small molecules; at the same time, the anaerobic section can also serve to intercept and adsorb most of the inorganic suspended solids; the subsequent hydrolysis and acidification process further oxidizes and intercepts, continues to degrade organic matter, and finally, through the action of aerobic microorganisms, the pollutants are effectively degraded. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention;

[0017] Figure 2 It is the water outlet standard table of the present invention;

[0018] Figure 3 The water quality analysis diagram of the test effluent of the present invention;

[0019] Figure 4 It is a comparison chart of the oil content of the inlet and outlet water of the present invention. DETAILED DESCRIPTION

[0020] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0021] Specifically, the anaerobic MBBR-A / O biological treatment process of the present invention is used to treat oilfield ASP flooding oily wastewater, comprising the following steps:

[0022] Step 1 Anaerobic treatment section: The oily wastewater from ASP flooding is treated through an anaerobic MBBR reactor, which is equipped with domesticated activated sludge and suspended particle fillers. The design of the anaerobic MBBR reactor aims to utilize the synergistic effect of activated sludge and suspended fillers to effectively degrade organic matter and oil in the wastewater.

[0023] Step 2: Hydrolysis and acidification: The sewage after anaerobic treatment enters the hydrolysis and acidification reactor, which is equipped with domesticated activated sludge. The purpose of the hydrolysis and acidification stage is to further decompose the complex organic matter in the sewage through the hydrolysis and acidification of the activated sludge, and convert it into small molecular organic matter that is easier to degrade.

[0024] Step 3 Aerobic treatment section: The sewage after hydrolysis and acidification is aerobically treated by a biological contact oxidation reactor, which is equipped with fixed fillers and domesticated microbial strains. The aerobic treatment section promotes the growth and metabolism of microorganisms through aeration, thereby achieving further degradation of organic matter in the sewage. The combination of anaerobic, hydrolysis acidification and aerobic three-stage biological treatment can achieve efficient removal of organic pollutants in ASP flooding oily sewage. In the anaerobic section, activated sludge and suspended fillers degrade macromolecular organic matter in sewage through the anaerobic metabolism of microorganisms. Then, the hydrolysis and acidification section further hydrolyzes macromolecular organic matter into small molecular organic matter and fatty acids through the action of activated sludge. Finally, in the aerobic section, the biological contact oxidation reactor promotes the aerobic metabolism of microorganisms through sufficient aeration to form a biofilm, thereby efficiently removing residual organic matter and oil substances.

[0025] The process improves the treatment efficiency of different types of pollutants through segmented treatment. The anaerobic stage helps to remove most of the organic matter and reduce the load of the subsequent treatment stage; the hydrolysis and acidification stage can convert the refractory organic matter into easily degradable small molecules, enhancing the treatment effect of the aerobic stage; the aerobic stage uses biofilm technology to achieve efficient degradation of residual organic matter in sewage. The overall process has a high treatment efficiency, can meet the strict requirements of oilfield sewage treatment, and has good shock load resistance.

[0026] As a preferred example, the anaerobic MBBR reactor includes a bottom water distribution zone, a reaction zone, a gas-solid-liquid separation zone, a sedimentation zone and a water outlet zone.

[0027] Bottom water distribution area: used to evenly introduce sewage into the reaction area. The water distribution area is designed with multiple water distribution ports, and the arrangement and opening rate of the water distribution ports are optimized to ensure uniform distribution of sewage in the reaction area, avoid short-flow or dead corners, and thus improve reaction efficiency.

[0028] Reaction zone: The reaction zone is equipped with activated sludge and suspended fillers. After the sewage enters the reaction zone, it is fully in contact with the activated sludge and suspended fillers, and anaerobic biodegradation reaction occurs. The suspended fillers are granular and have a large specific surface area, which is conducive to the attachment and growth of microorganisms and enhances the treatment effect.

[0029] Gas-solid-liquid separation zone: Separate the reaction products through gas stirring. The design of this separation zone takes into account the effective separation of sludge, gas and liquid, prevents suspended matter from being discharged with the effluent, and ensures the effluent quality.

[0030] Sedimentation area: used for sedimentation and separation of sludge and solid particles. The design of the sedimentation area can effectively separate the sludge generated during the treatment process from the clean water, ensuring that the sewage is fully purified before discharge.

[0031] Outlet area: used to discharge treated clean water. After being treated in the above-mentioned areas, the sewage is discharged after reaching the standards in the outlet area.

[0032] The anaerobic MBBR reactor introduces sewage evenly into the reaction zone through an optimized water distribution system, avoiding possible dead corners or short-circuit phenomena in the reactor, and ensuring sufficient contact between sewage and activated sludge and suspended fillers. Under anaerobic conditions, microorganisms in the reaction zone degrade organic matter in sewage through metabolism to generate methane and other gases. The generated gas is separated from sewage and sludge by stirring in the gas-solid-liquid separation zone. After entering the sedimentation zone, the sludge and solid particles settle, and the clean water is discharged into the effluent area.

[0033] The anaerobic MBBR reactor effectively improves the sewage treatment efficiency through the design of multiple functional areas. The optimized design of the water distribution area ensures the uniform distribution of sewage, reduces the dead corners and short-circuit phenomena in the sewage treatment process, and thus improves the reaction efficiency. The combined use of suspended fillers and activated sludge increases the attachment area of ​​microorganisms and enhances the anaerobic degradation capacity. The design of the gas-solid-liquid separation and sedimentation area ensures the clarity of the effluent, reduces the risk of sludge loss, and improves the stability and reliability of the entire process.

[0034] Specifically, the hydrolysis and acidification reactor adopts the form of bottom water inlet and upper water outlet, and nutrients are also added in the initial stage of startup to acclimate the activated sludge. The hydrolysis and acidification reactor ensures that the sewage has sufficient residence time and flow path in the reactor through the design of bottom water inlet and upper water outlet to achieve sufficient hydrolysis and acidification reaction. The sewage enters the reactor from the bottom and contacts with the activated sludge at the bottom, promotes the hydrolysis and acidification of organic matter, and converts macromolecular organic matter into small molecular substances that are easy to further process. In the initial stage of startup, an appropriate amount of nutrients is added to the reactor to promote the growth and acclimatization of the activated sludge to ensure that it has good hydrolysis and acidification performance. The design of the present invention enables the sewage to fully contact with the acclimatized activated sludge to ensure that the organic matter in the reactor is effectively decomposed. At the same time, the flow form of bottom water inlet and upper water outlet helps to avoid the short-flow phenomenon of sewage and improve the treatment efficiency of the reactor. The addition of nutrients in the initial stage of startup helps the activated sludge to form quickly and adapt to the working environment in the reactor, shortens the commissioning time of the reactor, and ensures that it quickly enters a stable operating state.

[0035] As a preferred example, the aerobic treatment section is a three-stage biochemical reactor, and the sewage is purified step by step through each stage of the biochemical reactor in turn.

[0036] Three-stage biochemical reactor: The three-stage biochemical reactor is designed as a step-by-step purification method, so that different types of pollutants are gradually removed in each stage of the reactor. The design of each stage of the reactor is optimized to ensure that the organic matter in the sewage is efficiently degraded during the entire aerobic treatment process.

[0037] Aeration release head: Aeration release head is set at the bottom of each biochemical reactor for continuous oxygen supply. The aeration release head ensures that oxygen can be fully dissolved in the sewage through uniform bubble diffusion, promoting the proliferation and metabolism of microorganisms.

[0038] Fixed filler: The top of each biochemical reactor is filled with fixed filler. Under the action of aeration, microbial strains gradually adhere to the surface of the filler to form a biofilm. The presence of the biofilm enhances the microbial adsorption and degradation ability of organic pollutants, thereby improving the efficiency of aerobic treatment.

[0039] The three-stage biochemical reactor of the present invention performs aerobic purification on sewage in sequence by means of graded treatment. In each stage of the reactor, the sewage first contacts the biofilm on the surface of the fixed filler for preliminary degradation. The aeration release head continuously supplies oxygen to ensure sufficient oxygen in the reactor and promote the aerobic metabolism of microorganisms. As the sewage passes through each stage of the reactor in turn, the residual organic pollutants are gradually degraded and eventually meet the emission standards. The design of the three-stage biochemical reactor makes sewage treatment more efficient and stable. Through graded treatment, each stage of the reactor can perform special treatment for different types of organic pollutants, thereby improving the overall purification efficiency. The aeration release head provides a continuous and stable oxygen supply, promotes the growth and activity of microorganisms, and further enhances the sewage treatment effect. The fixed filler provides a stable attachment matrix for microorganisms, helps to form an efficient biofilm, thereby improving the ability to remove organic matter.

[0040] Specifically, the total hydraulic retention time of the ASP flooding oily wastewater is 40 to 48 hours, and the water temperature is controlled between 30 and 35°C. The hydraulic retention time and water temperature control in this embodiment are to optimize the microbial activity and treatment effect of each treatment section. The hydraulic retention time is set to 40 to 48 hours to ensure that the sewage has enough time to fully contact with the microorganisms in the anaerobic, hydrolysis acidification and aerobic treatment sections, so that the organic matter is effectively degraded. The water temperature is controlled between 30 and 35°C to ensure the optimal activity of the microorganisms, because within this temperature range, the metabolic rate of most microorganisms is high, which helps to improve the efficiency of sewage treatment.

[0041] By controlling the hydraulic retention time and water temperature, the process can provide stable operating conditions at each treatment stage, ensuring the activity and metabolic efficiency of microorganisms, thereby improving the treatment effect of sewage. The appropriate hydraulic retention time allows organic pollutants to be fully degraded during the treatment process, reducing the concentration of residual pollutants. The precise control of water temperature avoids the impact of temperature fluctuations on microbial activity, ensuring that the entire treatment process operates under optimal conditions, thereby improving the stability and reliability of the process.

[0042] In the above embodiments, the hydraulic retention time and water temperature can be adjusted according to the actual composition and treatment requirements of the sewage. For example, when treating sewage with low complexity, the hydraulic retention time can be appropriately shortened to improve the treatment efficiency; while when treating high-concentration organic sewage, the retention time can be extended to ensure the treatment effect. The water temperature control range can also be appropriately adjusted according to the actual operating environment and microbial species. For example, in cold areas, insulation measures can be added or the microbial strains can be adjusted to adapt to lower water temperatures.

[0043] Specifically, the reflux ratio of the hydrolysis and acidification section is 50%, and the gas-water ratio of the aerobic section is 20:1. In the hydrolysis and acidification section, the reflux ratio is set to 50%, which means that part of the treated sewage is returned to the hydrolysis and acidification reactor and mixed with the newly entered sewage. Such a design can increase the concentration of organic matter in the reactor, promote the hydrolysis and acidification of organic pollutants by activated sludge, and improve the overall treatment efficiency. In the aerobic section, the gas-water ratio is 20:1, which means that 20 unit volumes of oxygen are required for each unit volume of sewage. By reasonably controlling the gas-water ratio, the oxygen supply demand of microorganisms in the aerobic treatment section is ensured, enabling them to efficiently carry out aerobic metabolism and degrade residual organic matter in the sewage.

[0044] By setting the reflux ratio of the hydrolysis and acidification section to 50%, the degradation efficiency of organic matter in sewage can be significantly improved, the operating state of the reactor can be stabilized, and the load on the subsequent treatment section can be reduced. The gas-water ratio of the aerobic section is 20:1, which ensures sufficient oxygen supply, helps the rapid proliferation and activity maintenance of microorganisms, and further improves the effect of sewage treatment. The optimized design of these parameters enables the process to maintain high efficiency and stability when treating sewage with different loads and pollutant concentrations.

[0045] Specifically, the sewage is transported from the anaerobic MBBR reactor to the hydrolysis acidification reactor by a lifting pump, and then enters the aerobic reactor by gravity, and part of the effluent from the aerobic section is lifted to the hydrolysis acidification section by a reflux pump for reflux. The sewage treatment process is designed by a lifting pump and gravity. After the anaerobic treatment is completed, the sewage is transported to the hydrolysis acidification reactor by a lifting pump. This process ensures the smooth flow of sewage between the various treatment sections. After treatment in the hydrolysis acidification reactor, the sewage enters the aerobic reactor by gravity. The gravity design uses gravity to reduce energy consumption and simplify the operation process. In order to enhance the hydrolysis acidification effect, part of the effluent from the aerobic treatment section is lifted back to the hydrolysis acidification section by a reflux pump for reflux, which can improve the system's decomposition efficiency of organic pollutants and further optimize the overall treatment effect.

[0046] By using lift pumps and gravity flow, the process can effectively transport sewage between treatment sections to ensure the continuity and stability of treatment. The lift pump ensures the smooth transfer of sewage after anaerobic treatment, while the gravity flow method reduces the energy consumption of system operation and simplifies operation and maintenance. By returning part of the effluent from the aerobic section to the hydrolysis and acidification section through a reflux pump, the treatment effect of organic matter in sewage can be improved, especially the further decomposition of some difficult-to-degrade substances, thereby improving the efficiency and quality of overall sewage treatment.

[0047] In the above-mentioned embodiments, the selection and configuration of the lift pump and the return pump can be adjusted according to the scale of the treatment system and the amount of sewage. For example, in a system with a large treatment volume, an energy-efficient pump can be selected to improve the delivery efficiency and reduce energy consumption. For a small-scale treatment system, only a simple lift pump configuration may be required without a complex return system. The return volume can also be adjusted according to actual treatment needs. For example, in the case of a high concentration of organic matter, the return ratio can be increased to enhance the hydrolysis acidification effect. In addition, the automated control of the lift pump and the return pump can be optimized in combination with the real-time monitoring system of the sewage treatment to achieve more accurate flow and treatment effect regulation.

[0048] As a preferred example, the particle suspended filler added into the anaerobic MBBR reactor accounts for 1 / 3 of the total volume of the reactor.

[0049] In the anaerobic MBBR reactor, the particle suspension filler accounts for 1 / 3 of the total volume of the reactor. This filler has a large specific surface area, which is conducive to the attachment and growth of microorganisms. The filler is in a suspended state in the reactor. Through the flow and stirring of sewage, the microorganisms on the surface of the filler can fully contact with the organic pollutants in the sewage, promoting the anaerobic degradation process of organic matter. Since the filler occupies 1 / 3 of the total volume of the reactor, this proportion design can maintain good fluid dynamics in the reactor while ensuring the activity of microorganisms, preventing sludge blockage or excessive accumulation of fillers. The particle suspension filler accounts for 1 / 3 of the total volume of the reactor, providing sufficient attachment area, promoting the growth and reproduction of microorganisms, and thus improving the treatment efficiency of the anaerobic reaction. The right amount of filler maintains a good mixing effect in the reactor, avoids the flow blockage caused by the accumulation of fillers, and ensures full contact between sewage and microorganisms. In addition, the reasonable configuration of the filler helps to maintain the stable operation of the system, reduces the problem of decreased treatment efficiency due to the loss of microorganisms, and improves the reliability and durability of the overall process.

[0050] Specifically, the special microbial flora in the biological contact oxidation reactor forms a dominant flora after domestication, and uses the organic pollutants in the sewage as a nutrient source to perform oxidation, reduction and synthesis, thereby achieving the degradation of organic matter and oils. In the biological contact oxidation reactor, the special microbial flora gradually forms a dominant flora through the domestication process. During the domestication process, these microorganisms adapt to the specific organic pollutants in the sewage, and perform oxidation, reduction and synthesis through metabolic activities. These dominant flora form a biofilm on the surface of the fixed filler, use the organic matter in the sewage as a nutrient source, and degrade complex organic matter into simple inorganic or low-molecular organic matter through metabolism, while decomposing and removing oil substances. The biofilm structure enables microorganisms to more efficiently adsorb, decompose and digest pollutants in sewage, thereby improving the treatment efficiency of the reactor.

[0051] The domesticated special microbial flora can form a stable and efficient dominant flora in the biological contact oxidation reactor, significantly improving the degradation efficiency of organic pollutants and oils in sewage. By forming a biofilm, these microorganisms can stably adhere to the surface of the filler, maintain high activity and high efficiency for a long time, reduce the possibility of microbial loss, and ensure the continuity and stability of the sewage treatment process. In addition, the formation of a dominant flora also makes the system more resistant to shock loads, and can maintain a high treatment effect when the sewage composition or pollutant concentration changes.

[0052] Specifically, the oilfield ASP flooding oily wastewater treatment system includes an anaerobic MBBR reactor, a hydrolysis acidification reactor, a biological contact oxidation reactor, a lift pump and a control system connected in sequence. It is composed of multiple interconnected reactors and treats the oilfield ASP flooding oily wastewater in sequence:

[0053] Anaerobic MBBR reactor: The first step is to introduce sewage into the anaerobic MBBR reactor for anaerobic treatment. The reactor uses anaerobic microorganisms to degrade complex organic matter and oil pollutants in sewage through the combined action of activated sludge and suspended fillers.

[0054] Hydrolysis acidification reactor: The sewage after anaerobic treatment enters the hydrolysis acidification reactor through the lifting pump. The reactor adopts the design of bottom water inlet and top water outlet, and hydrolysis acidification microorganisms decompose complex macromolecular organic matter into small molecular substances that are easier to handle.

[0055] Biological contact oxidation reactor: The sewage then flows into the biological contact oxidation reactor by gravity. In this stage, the domesticated special microbial flora is used to further degrade the remaining organic matter and oil through oxidation, reduction and synthesis. The fixed filler in the reactor provides an attachment surface for the microorganisms to form a biofilm and enhance the treatment effect.

[0056] Lifting pump: Lifting pump is used to transport sewage between various treatment stages to ensure the continuous operation of the system and enhance the treatment effect of each reaction section through backflow control.

[0057] Control system: The system is equipped with an advanced control system for real-time monitoring and adjustment of the operating parameters of each reactor, such as temperature, pH, aeration volume and sludge return ratio. The control system ensures the stability and efficiency of the sewage treatment process, and can automatically adjust various parameters according to the needs of different treatment stages to optimize the treatment effect.

[0058] This treatment system achieves efficient treatment of oily wastewater from ASP flooding in oil fields through a combination of multiple reactors. The three-stage anaerobic, hydrolysis-acidification and aerobic processes in the system design treat different types of pollutants in the wastewater respectively, removing organic matter and oil pollutants in stages. The application of lift pumps and control systems ensures uniform transportation of wastewater during the treatment process and precise control of treatment conditions, thereby significantly improving the overall treatment efficiency and stability of the system. The automatic adjustment function of the control system further reduces the need for manual intervention, reduces operating costs, and improves the reliability of the treatment process.

[0059] As a preferred case, the water quality of the inlet water

[0060] The ternary water of a joint station was treated. The initial oil content of the sewage was 200-300mg / L, the suspended solids were 150-200mg / L; the viscosity was 1.3-2.5mPa·s; the polymer concentration was 600-1000mg / L, the surfactant concentration was 30-40mg / L; the total alkalinity (calculated as calcium carbonate) was 5000-6000mg / L. The "anaerobic-anoxic-aerobic biochemical method" was used, and the initial retention time was set to 72 hours. After 15 days of operation, the volume load rate was increased, and the hydraulic retention time was reduced to 48 hours. The treatment effect of the oil content and suspended solids in the effluent was analyzed.

[0061] Some key indicators of water standards

[0062] Table 1 Designed reinjection water quality

[0063]

[0064] Process Description

[0065] The sewage is pumped into the anaerobic microbial reaction tank, and the domesticated activated sludge and particle suspension filler are added. The activated sludge is added at 20% of the reaction zone volume, and the suspended particle filler is added at a rate of 30%. The activated sludge is added in the hydrolysis and acidification section at 20% of the reaction zone volume. The aerobic section is a biological contact oxidation reactor, which is equipped with primary, secondary and tertiary biochemical tanks, filled with fixed fillers, and domesticated microbial strains are added to the reactor for aeration culture until the microorganisms are fully biofilmed on the filler. Special microorganisms quickly form dominant flora, use organic pollutants in sewage as nutrient sources, and convert complex organic matter into simple inorganic matter through their own oxidation, reduction and synthesis, thereby completing the degradation of organic matter and oil in sewage and achieving the purpose of sewage purification.

[0066] Example 1: Test process and water output data analysis

[0067] Microbial culture stage

[0068] Cycle: 7 days. Add activated sludge into the anaerobic MBBR tank and the hydrolysis acidification tank. Add special microbial flora into the biological contact oxidation tank to control the dissolved oxygen content to be greater than 3 mg / L. Domesticate and cultivate the bacteria. After the biofilm is formed, normal operation can be carried out.

[0069] Normal operation stage

[0070] The sewage retention time is set to 72 hours for the initial 15 days, and the sewage to be treated is pumped into the system through the lifting pump. After stable operation, the volume load is gradually increased and the retention time is adjusted to 60 hours. After a week of stable operation, the retention time is adjusted to 48 hours, and water quality is tested by sampling regularly every day.

[0071] like Figure 3 and Figure 4 The treatment process has a high degradation effect on the oil content in the sewage. The average oil content in the inlet water is 251mg / L, the average suspended solids content in the biochemical pool effluent is 15.6mg / L, and the average total removal rate is 94%. The treatment process has a high degradation effect on the suspended solids content in the sewage. The average suspended solids content in the inlet water is 175mg / L, the average suspended solids content in the biochemical pool effluent is 20mg / L, and the average total removal rate is 88%. The "anaerobic MMBR-hydrolysis acidification-aerobic" treatment process has a good degradation effect on the key indicators of oilfield ternary water.

[0072] Working principle: The process targets the water quality characteristics of oily wastewater from ASP flooding. Through sulfate reduction in the anaerobic process, denitrification in the hydrolysis and acidification process, and nitrification, ammoniation, and oxidation in the aerobic process, surfactants and polymers are degraded to reduce the emulsification degree of produced water and improve water quality characteristics. The incoming water degrades most of the organic matter through the anaerobic section, and partially degrades some macromolecular substances that are difficult for aerobic microorganisms to use into small molecules; at the same time, the anaerobic section can also intercept and adsorb most of the inorganic suspended solids; the subsequent hydrolysis and acidification process further oxidizes and intercepts, continues to degrade organic matter, and finally, through the action of aerobic microorganisms, the pollutants are effectively degraded.

[0073] The anaerobic section is an MBBR reactor, which consists of a bottom water distribution zone reaction zone and a gas, solid, liquid separation zone, a sedimentation zone and an outlet zone. Add activated sludge and granular suspended fillers that have been tamed by ternary composite flooding oily sewage to the MBBR reactor to 1 / 3 of the total volume, inject ternary water through a lifting pump, add nutrients at the initial start, and circulate the activated sludge in the reactor through a circulating pump. The hydrolysis and acidification section selects the form of bottom water inlet and upper water outlet. Add 1 / 3 volume of activated sludge to the reactor, inject ternary water through a lifting pump, add nutrients at the initial start, tame the activated sludge to a stable stage, and operate the reactor. The aerobic section selects a biological contact oxidation reactor. The reactor is divided into three levels of biochemical, with aeration release heads evenly distributed at the bottom of the reactor and fixed fillers filled at the top. Add tamed microbial strains to the reactor and aerate and cultivate until the microorganisms are fully biofilmed on the fillers.

[0074] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An anaerobic MBBR-A / O biological treatment process for treating oilfield ASP flooding oily wastewater, characterized in that: The process includes the following steps: Anaerobic treatment section: The ASP flooding oily wastewater is treated through an anaerobic MBBR reactor, in which domesticated activated sludge and granular suspended fillers are installed; Hydrolysis and acidification section: The anaerobic treated sewage is treated through a hydrolysis and acidification reactor, in which domesticated activated sludge is installed; Aerobic treatment section: The sewage after hydrolysis and acidification treatment is aerobically treated through a biological contact oxidation reactor, in which fixed fillers are provided and domesticated microbial strains are added.

2. The anaerobic MBBR-A / O biological treatment process according to claim 1, characterized in that: The anaerobic MBBR reactor includes a bottom water distribution area, a reaction area, a gas-solid-liquid separation area, a precipitation area and a water outlet area; The bottom water distribution area is used to evenly introduce sewage into the reaction area, and the reaction area is provided with activated sludge and suspended fillers so that the sewage is fully in contact with the activated sludge and suspended fillers in the reaction area; The gas-solid-liquid separation zone separates the reaction products through gas stirring, the sedimentation zone is used to settle and separate the sludge and solid particles, and the effluent zone is used to discharge the treated clean water. The bottom water distribution area includes a plurality of water distribution ports, and the arrangement and opening ratio of the water distribution ports are optimized to ensure uniform distribution of sewage in the reaction area, thereby improving the reaction efficiency; The opening ratio of the water distribution port is designed to be adjusted according to the geometric shape of the reaction zone and the sewage flow rate to avoid dead corners or short-flow phenomena of sewage in the reaction zone.

3. The anaerobic MBBR-A / O biological treatment process according to claim 1 or 2, characterized in that: The hydrolysis acidification reactor adopts the form of bottom water inlet and top water outlet, and nutrients are also added in the initial start-up period to acclimate the activated sludge.

4. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 3, characterized in that: The aerobic treatment section is a three-stage biochemical reactor. Among them, there are three-stage biochemical reactors, and the sewage passes through each stage of biochemical reactor in turn for purification step by step; An aeration release head is provided at the bottom of each stage of the biochemical reactor, and the aeration release head is used to promote the proliferation and metabolism of microorganisms by continuously supplying oxygen; The top of each stage of the biochemical reactor is filled with fixed fillers. Microbial strains gradually adhere to the surface of the fillers through aeration to form a biofilm, which is used to efficiently degrade organic pollutants in sewage.

5. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 4, characterized in that: The total hydraulic retention time of the oily wastewater in the ASP flooding is 40 to 48 hours, and the water temperature is controlled between 30 and 35°C.

6. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 5, characterized in that: The reflux ratio of the hydrolysis and acidification section is 50%, and the gas-water ratio of the aerobic section is 20:

1.

7. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 6, characterized in that: The sewage is pumped from the anaerobic MBBR reactor to the hydrolysis acidification reactor, and then flows into the aerobic reactor by gravity, and part of the effluent from the aerobic section is pumped to the hydrolysis acidification section by a reflux pump for reflux.

8. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 7, characterized in that: The particle suspension filler added into the anaerobic MBBR reactor accounts for 1 / 3 of the total volume of the reactor.

9. The anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 8, characterized in that: The special microbial flora in the biological contact oxidation reactor forms a dominant flora after being domesticated, and uses the organic pollutants in the sewage as a nutrient source to perform oxidation, reduction and synthesis, thereby achieving degradation of organic matter and oils.

10. An oilfield ASP flooding oily wastewater treatment system based on the anaerobic MBBR-A / O biological treatment process according to any one of claims 1 to 9, characterized in that: It includes an anaerobic MBBR reactor, a hydrolysis acidification reactor, a biological contact oxidation reactor, a lifting pump and a control system connected in sequence; in: The anaerobic MBBR reactor is used to perform anaerobic treatment on sewage; The hydrolysis acidification reactor is used to further decompose and acidify the anaerobic treated sewage; The biological contact oxidation reactor is used to aerobically treat the hydrolyzed and acidified sewage; The lift pump is used to transport sewage between various reactors; The control system is used to monitor and adjust the operating parameters of each reactor, including temperature, pH, aeration volume and sludge return ratio, and control the flow path of sewage.

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