Biological treatment method for recycling petroleum wastewater

Abstract

The invention discloses a recycling biological treatment method of petroleum wastewater, which comprises the following steps: screening out functional microorganisms capable of degrading petroleum hydrocarbon organic pollutants, and converting toxic and harmful organic pollutants in the petroleum wastewater into non-toxic and harmless humification products such as humic acid and humic acid; key biological treatment parameters such as the adding amount of microorganisms, the adding amount of nutritive salt and treatment time are determined, biological humification treatment of toxic and harmful organic pollutants in the petroleum wastewater is achieved, and the environmental risk of the petroleum wastewater is remarkably reduced. According to the method, one-time treatment of the petroleum wastewater is achieved, the process is simple, easy to operate, low in cost and environmentally friendly, and harmless, recycling and low-cost treatment of the petroleum wastewater is achieved.

Description

Technical Field

[0001] The present invention discloses a biological treatment method for recycling petroleum wastewater, which is used to treat petroleum wastewater generated in the process of oil and natural gas extraction, storage and transportation, and the process of oil-containing mud and sand disposal in major oil fields, especially toxic and harmful soluble organic pollutants therein, such as phenolic compounds and benzene series. The treatment method includes: screening out petroleum hydrocarbon degradation functional bacteria that can convert organic pollutants in petroleum wastewater into soluble macromolecular organic substances such as humic acid and humic acid, optimizing the technical parameters of biological treatment through biological cultivation methods, and realizing resource-based and harmless treatment of toxic and harmful soluble organic pollutants. The present invention has one-time treatment, simple and easy operation process, low cost, green and friendly, and has great application potential in practical engineering applications. Background Art

[0002] A large amount of oil sludge is produced during the process of crude oil extraction, storage, transportation and refining. The composition is complex and usually contains a large amount of crude oil, asphaltene, wax, colloid, suspended solids, heavy metal salts, benzene, phenol, anthracene and other toxic and harmful substances. After chemical cleaning and hydrothermal carbonization, the crude oil in the oil sludge can be effectively recovered. However, some petroleum wastewater will also be produced during the disposal process, which contains a large amount of difficult-to-degrade organic pollutants, such as phenolic compounds, nitrobenzene and benzene. Organic pollutants such as benzene and nitrobenzene are biologically toxic, carcinogenic and persistent. If they are directly discharged without treatment, they will pollute the environment, destroy the ecology and endanger human health. Therefore, seeking a method for efficiently treating organic pollutants in petroleum wastewater is crucial to solving the problem of environmental pollution in the process of petroleum resource development.

[0003] At present, the methods for treating petroleum wastewater in China mainly include physical and chemical methods and biological methods. Physical and chemical methods mainly include adsorption, advanced oxidation, coagulation and sedimentation, and electroflocculation, which can achieve the adsorption, precipitation or oxidative degradation of difficult-to-degrade organic pollutants and reduce the concentration of toxic and harmful organic pollutants. However, physical and chemical treatment methods have high energy consumption, high investment and operating costs, and cannot completely eliminate petroleum hydrocarbons in wastewater. In addition, biological methods such as the activated sludge method generally use microorganisms with the function of degrading organic pollutants to degrade organic pollutants and convert them into small molecular organic matter and CO2. However, the degradation rate of organic pollutants in biological methods is slow, and additional carbon sources are required to ensure the activity of microorganisms, and the degradation efficiency is low.

[0004] However, in the natural environment, there is a process that is opposite to degradation but can be transformed into the degradation process: the humification process. Organic pollutants produce various intermediates and final products through biodegradation, which can provide precursors for the humification process and then generate humus through coupled polymerization. The humification treatment of organic pollutants can not only achieve carbon fixation of organic components and reduce carbon emissions, but also play a key role in increasing soil fertility. The humification treatment of organic matter is expected to achieve a global green and low-carbon cycle. The organic pollutants in petroleum wastewater usually contain aromatic compounds and benzene series with benzene ring structures, with high CODcr concentration and low biodegradability. However, in the process of biodegradation of aromatic organic pollutants such as polycyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons are easily converted into metabolites with humus-like structures, which have the potential for biological humification. Therefore, petroleum wastewater has the potential for biological humification. Screening out functional microorganisms that can convert organic pollutants in petroleum wastewater into humus-like organic matter and optimizing the method of microbial humification can achieve the harmless and resource-based disposal of petroleum wastewater, significantly reduce the environmental pollution risk of petroleum wastewater, and enhance the value of petroleum wastewater reuse.

[0005] The "a biological treatment method for resource utilization of petroleum wastewater" involved in the present invention uses the aqueous phase petroleum wastewater formed in the hydrothermal carbonization process of oil-containing mud and sand as the main raw material, selects microorganisms with the function of degrading petroleum hydrocarbons, uses petroleum wastewater for cultivation and domestication, and screens functional microorganisms that have the ability to convert organic pollutants into humic acid and humic acid-like organic matter. On this basis, the key biological treatment parameters of biological humification are optimized to achieve biological humification treatment of toxic and harmful organic pollutants in petroleum wastewater, significantly reducing the environmental risks of petroleum wastewater. The entire treatment process is simple and low-cost, and no harmful substances are discharged into nature. In addition, through the promotion and application of this technology, not only can the ecological and environmental problems caused by petroleum wastewater in the oilfield industry and other fields be alleviated, but also a green resource-based approach can be provided for the treatment of wastewater containing organic pollutants such as aromatic compounds and benzene series, and economic benefits can be brought about. Summary of the invention

[0006] The present invention provides a biological treatment method for converting organic pollutants in petroleum wastewater into humic acid and humic acid-like organic matter. By screening and domesticating functional microorganisms and optimizing key biological treatment parameters, biological humification treatment of toxic and harmful organic pollutants in petroleum wastewater is achieved, thereby significantly reducing the environmental risks of petroleum wastewater.

[0007] The biological treatment method for petroleum wastewater resource utilization provided by the present invention is as follows:

[0008] (1) Petroleum wastewater with a TOC concentration of 50 to 100 mg / L was used to domesticate and culture the petroleum hydrocarbon degradation functional bacteria Bacillus subtilis. The culture medium used was LB nutrient salt, the culture temperature was 25 to 35° C., the rotation speed of the shaking culture was 50 to 150 rpm, and the amount of Bacillus subtilis bacterial liquid added was 5% to 25% of the total volume of the domestication solution. The growth curve of Bacillus subtilis was mastered, the optimal growth state of Bacillus subtilis was determined, and the optimal biological treatment time for humification of petroleum wastewater was obtained to be 5 to 15 days.

[0009] (2) Using domesticated Bacillus subtilis as a functional strain, the bioresource treatment is carried out by constant temperature oscillation to convert toxic and harmful organic pollutants such as petroleum hydrocarbons and benzene series in petroleum wastewater into soluble macromolecular organic substances such as humic acid and humic acid. The application amount of Bacillus subtilis in the biological treatment scheme is 0.05% to 5% of the volume of the petroleum wastewater; the TOC of the treated petroleum wastewater is 50 to 100 mg / L; the culture temperature of the bioresource treatment is 25 to 35°C; the oscillation speed is 50 to 150 rpm; and the amount of LB culture medium used is 0.05% to 5% of the volume of the petroleum wastewater.

[0010] (3) By measuring the changes in TOC of petroleum wastewater before and after biological treatment, the changes in organic carbon in petroleum wastewater were analyzed; the organic components of petroleum wastewater before and after biological treatment were tested by three-dimensional fluorescence spectroscopy, the proportion of the five fluorescence regions in the three-dimensional fluorescence spectrum was analyzed, and the changes in the types of organic components in petroleum wastewater were compared; by calculating the absorption spectrum index UV 254 and SUV 254 , respectively evaluate the humification degree and aromatic structural degree of petroleum wastewater after biological treatment. And combine the above data to obtain the optimal technical parameters for humification biological treatment of organic pollutants in petroleum wastewater, and realize low-cost, harmless and resource-based treatment of petroleum wastewater.

[0011] This technical solution can achieve the above-mentioned purpose: a biological treatment method for petroleum wastewater resource utilization, which uses biological transformation to enable organic pollutants to be oxidized, degraded and polymerized by microorganisms to form humus-like organic matter with quinone structures, thereby achieving the harmlessness and resource utilization of organic pollutants in petroleum wastewater.

[0012] The present invention has the following advantages:

[0013] (1) This method uses functional microorganisms to convert toxic and harmful soluble organic pollutants in petroleum wastewater into environmentally friendly organic macromolecules such as humic acid and humic acid, which can significantly reduce the environmental risks of petroleum wastewater and achieve resource reuse.

[0014] (2) The functional bacteria used in this method to degrade petroleum hydrocarbons have been domesticated and screened, and the technical parameters of the biological treatment method are unique, achieving low-cost, harmless, and resource-based treatment of petroleum wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attached Figure 1 It is a three-dimensional fluorescence spectrum of petroleum wastewater before and after biological treatment at different times.

[0016] Attached Figure 2 It is the infrared spectrum of the petroleum wastewater treated by the present invention.

[0017] Attached Figure 3 It is a growth curve of microorganisms in petroleum wastewater during the acclimation process.

[0018] Attached Figure 4 UV of petroleum wastewater in different treatment groups 254 Curve of changes over time.

[0019] Attached Figure 5 SUVA of PetroChina wastewater in different treatment groups 254 Curve of changes over time.

[0020] Attached Figure 6 It is a three-dimensional fluorescence spectrum diagram of petroleum wastewater after biological treatment in different embodiments and comparative examples. DETAILED DESCRIPTION

[0021] Example 1

[0022] (1) Bacillus subtilis was selected as the functional bacteria for petroleum hydrocarbon degradation, and petroleum wastewater with a TOC concentration of 100 mg / L was selected for domestication and cultivation.

[0023] (2) The culture medium used for acclimation was LB nutrient salt, the culture temperature was 30°C, and the shaking culture speed was 100 rpm.

[0024] (3) The amount of Bacillus subtilis bacterial solution added is 10% of the total volume of the acclimation solution, the growth curve of Bacillus subtilis is mastered, and the optimal growth state of Bacillus subtilis is determined.

[0025] (4) The optimal biological treatment time for humification of petroleum wastewater is 10 days, and the domesticated Bacillus subtilis is obtained. After domestication, the Bacillus subtilis has a strong survival and humification ability in petroleum wastewater.

[0026] (5) Based on the domesticated Bacillus subtilis, petroleum wastewater with a TOC concentration of 100 mg / L was selected for bioresource treatment through constant temperature oscillation, and toxic and harmful organic pollutants such as petroleum hydrocarbons and benzene series in the petroleum wastewater were converted into soluble macromolecular organic substances such as humic acid and humic acid.

[0027] (6) On the basis of step (5), domesticated Bacillus subtilis is added to the petroleum wastewater, and the application amount of Bacillus subtilis is 2% of the volume of the petroleum wastewater.

[0028] (7) Based on step (6), a bioresource treatment is performed, wherein the biotreatment temperature is 30° C., the oscillation speed is 100 rpm, and the amount of LB culture medium used is 2% of the volume of the petroleum wastewater.

[0029] (8) On the basis of step (7), the culture was continued for 12 days, and the changes in TOC of the petroleum wastewater before and after biological treatment were measured to analyze the changes in organic carbon in the petroleum wastewater; the organic components of the petroleum wastewater before and after biological treatment were tested by three-dimensional fluorescence spectroscopy, and the proportion of the five fluorescence regions in the three-dimensional fluorescence spectrum was analyzed to compare the changes in the types of organic components in the petroleum wastewater; the absorption spectrum index UV was calculated 254 and SUV 254 , respectively evaluating the humification degree and aromatic structuralization degree of petroleum wastewater after biological treatment.

[0030] Example 2

[0031] The steps are the same as those in Example 1, except that in step (6), the amount of Bacillus subtilis used is 1% of the volume of the petroleum wastewater.

[0032] Example 3

[0033] The steps are the same as those in Example 1, except that the amount of LB culture medium used in step (7) is 0.5% of the volume of the petroleum wastewater.

[0034] Comparative Example

[0035] The steps are the same as those in Example 1, except that the amount of Bacillus subtilis used in step (6) is 0, and the amount of LB culture medium used in step (7) is 0.

[0036] The humification degree and aromatic structure degree of the petroleum wastewater of Examples 1 to 3 and Comparative Examples 1 to 2 were tested in the following manner. The results are as follows: Figure 6 As shown. Based on the above data, the optimal technical parameters for humification biological treatment of organic pollutants in petroleum wastewater are obtained, achieving low-cost, harmless and resource-based treatment of petroleum wastewater. The results of this implementation method are as follows:

[0037] Figure 1 The changes of organic components in petroleum wastewater of different treatment groups indicate that the selected functional bacteria have the ability of biological humification, which makes humic acid and humic acid organic components appear in petroleum wastewater; Figure 2This is the infrared spectrum of the petroleum wastewater treated by the present invention; Figure 3 This is the growth curve of petroleum hydrocarbon degradation functional bacteria in petroleum wastewater, indicating that the selected functional bacteria can be used to treat petroleum wastewater; Figure 4 and Figure 5 The results of the experimental treatment of selecting the most suitable biological treatment conditions for batch experiments showed that under the action of functional bacteria, the concentrations of humus substances and aromatic compounds in petroleum wastewater increased significantly, indicating that the feasibility of biological resource utilization of petroleum wastewater is strong. The selected functional bacteria can effectively improve the biodegradability of petroleum wastewater and reduce the risk of environmental pollution. Figure 6 It is a comparison of the effects of humification in different implementation cases.

[0038] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A biological treatment method for recycling petroleum wastewater, characterized in that: The steps include: Firstly, the petroleum hydrocarbon degrading functional bacteria are screened and domesticated and cultured, which is characterized by: selecting bacteria with the function of degrading petroleum hydrocarbons, adding petroleum wastewater with a total dissolved carbon (TOC) concentration of 50-100 mg / L, culturing in a constant temperature shaking box, and analyzing the growth status of petroleum hydrocarbon degrading bacteria and the changes in organic components in the petroleum wastewater.

2. According to the method for taming and screening petroleum hydrocarbon-degrading functional bacteria according to claim 1, the selected petroleum hydrocarbon-degrading bacteria are Bacillus subtilis, and the conditions for constant temperature shaking culture are controlled as follows: temperature is 25-35°C; shaking speed is 50-150rpm; and the culture medium used is Luria-Bertani (LB) nutrient salt.

3. According to the Bacillus subtilis selected according to claim 2, petroleum wastewater is added to the LB culture medium containing Bacillus subtilis, mixed and shaken, sealed and cultured at a constant temperature and shaking, so that it can convert organic pollutants such as petroleum hydrocarbons into non-toxic and harmless humification products such as humic acid and humic acid, and carry out humification biological treatment.

4. The method for humification biological treatment of petroleum wastewater according to claim 3 is characterized by: The TOC concentration of petroleum wastewater is 50-100 mg / L; the biological treatment method is constant temperature oscillation culture, the culture temperature is 25-35°C, and the oscillation speed is 50-150 rpm; the amount of Bacillus subtilis bacterial solution added is 0.1%-5% of the total volume of the system; the amount of LB nutrient salt added is adjusted to 0.1%-5% of the total volume of the system; and the time of humification biological treatment is adjusted to 5-15 days.

5. The method for humification biological treatment of petroleum wastewater according to claim 3 is characterized by: Humic acid-like and fulvic acid-like humification products were generated in the treated petroleum wastewater, which confirmed that the petroleum wastewater had the potential for biological humification and realized the resource utilization and harmless treatment of petroleum wastewater.

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