CN109160603B

CN109160603B - Denitrifying bacterium enrichment method for development of oilfield reinjection water anticorrosive bactericide

Info

Publication number: CN109160603B
Application number: CN201811202422.1A
Authority: CN
Inventors: 吴伟林; 杨帆; 孟章进; 姚峰; 姜桂英; 汪泽龙
Original assignee: China Petroleum and Chemical Corp; Sinopec Jiangsu Oilfield Co
Current assignee: China Petroleum and Chemical Corp; Sinopec Jiangsu Oilfield Co
Priority date: 2018-10-16
Filing date: 2018-10-16
Publication date: 2021-09-07
Anticipated expiration: 2038-10-16
Also published as: CN109160603A

Abstract

The invention discloses a denitrifying bacteria enrichment method for developing an anticorrosive microbial inoculum of oilfield reinjection water, belonging to the technical field of biological corrosion control of oilfield wastewater. Adopting a three-electrode device comprising three parts of a lower cathode, a middle anode and an upper cathode to form a surrounding type electrode placement; the bottom cathode is used for quickly removing high dissolved oxygen to realize the anaerobic reaction protection of the middle anode and the upper cathode; the microorganism of the anode converts organic matter into bioelectronic by oxidation and metabolism under anaerobic condition, and simultaneously supplies the bioelectronic to the two cathodes for different reduction reaction processes; and under the microbial anaerobic condition of the upper cathode, the biological electrons react with nitrate in the solution to supply rapid growth of denitrifying bacteria. The method can quickly and effectively enrich the denitrification mixed flora, and can directly adopt the oil field wastewater to realize the long-term stable proliferation and enrichment of the denitrification flora after the rapid enrichment and domestication.

Description

Denitrifying bacterium enrichment method for development of oilfield reinjection water anticorrosive bactericide

Technical Field

The invention belongs to the technical field of biological corrosion control of oil field wastewater, and relates to a denitrifying bacteria enrichment method for development of an oil field reinjection water anti-corrosive microbial agent.

Background

In recent years, aiming at the hazards of equipment corrosion, pipeline blockage, filter material pollution and the like caused by sulfides in an oil field system, an air desulfurizing tower with high treatment efficiency, low running cost and convenient operation can be adopted to remove the sulfides, but the air desulfurizing tower also brings a new problem of higher dissolved oxygen when removing the sulfides. In addition to chemical corrosion by dissolved oxygen, the microbiological corrosion process that accompanies the reaction is more detrimental. The main production operation of domestic oil fields shows that more than 60% of corrosion of the oil fields is caused by SRB (sulfate reducing bacteria), and perforation, scaling, blockage and even spontaneous combustion explosion of pipeline storage tanks are caused along with the corrosion process. In 2011, the production loss of Jiangsu oil fields caused by biological corrosion reaches 5000 ten thousand yuan.

The mechanism of microbial control of SRB corrosion is that the replacement bacteria used are very similar to sulfate-reducing bacteria in terms of life habit, growth environment, etc., except that they do not produce H₂S, and other products harmless to the oil field are generated or H is generated₂S is converted, thereby reducing corrosion of SRB. The most widely used is the inhibition of sulfate reduction by nitrate reducing bacteria or denitrification. The introduction of a low concentration of nitrate/nitrite component into the formation will more readily and positively replace sulfate as an electron acceptor, which may promote rapid proliferation of nitrate-reducing bacteria naturally present in the reservoir and the preferential use of the substrate in the reservoir by nitrate-reducing bacteria in competition with sulfate-reducing bacteria for living space and substrate, thereby preventing sulfate-reducing bacteria from obtaining the required nutrients and thereby controlling their metabolic activity. However, due to practical factors such as lack of electron donors (low nitrate content) and dissolved oxygen inhibition (too high dissolved oxygen can inhibit colonization of anaerobic denitrifying bacteria) for forming nitrate reducing bacteria in the actual oilfield wastewater, the formation process of obligate denitrifying bacteria is slow, and specific nitrate reducing bacteria need to be continuously added due to bacteria loss, and the like.

Disclosure of Invention

The invention provides a denitrifying bacteria enrichment method for developing an anticorrosive microbial agent for oilfield reinjection water, aiming at solving the problem that denitrifying microorganisms for reducing biological corrosion by means of acclimatization in oilfield reinjection water and sulfate reducing bacteria competition are difficult to enrich quickly, stably and efficiently. Based on the principle of a microbial electrochemical system, the invention constructs a bioelectrochemical system for efficiently enriching the nitrate reduction functional flora through microbial extracellular electron transfer regulation and control, and realizes effective enrichment of the nitrate reduction flora of the biological cathode planted for a long time in the oil field wastewater. The bioelectrochemistry combination mode can realize rapid oxygen consumption at the cathode, so that the method can be used as a treatment means of high dissolved oxygen wastewater in an oil field, can reduce corrosion of oxygen in reinjection water to a pipeline, can reduce the addition of additional denitrifying bacteria, and reduces the cost.

Microbial electrochemical system (BES) refers to an electrochemical system in which a microbial catalyst undergoes oxidation (anode) and/or reduction (cathode) reactions at an electrode. The functional microbe with electrochemical activity, in which the biocatalyst in the microbial electrochemical system performs oxidation and/or reduction reaction on the electrode, can directly or indirectly perform electron transfer and metabolic reaction with the electrode. BES has become a new environmentally engineered biological treatment technology because BES can treat refractory wastewater (waste) through sustainable microbial metabolic reactions using the anode as an electron acceptor. The cathode can realize the utilization of various electron acceptors through a rapid and efficient electron reduction process, and the biocathode is a novel sustainable anaerobic biocatalysis and anaerobic organism growth process.

The invention takes an upflow reactor as a design basis, mainly improves the distribution and the type of electrodes, forms the basic electrode distribution of an upper cathode, a lower cathode and a middle anode, and simultaneously forms a surrounding electrode placing mode. Aiming at the characteristic of multi-factor corrosion factors of oxygen and sulfate in the oil field wastewater, the rapid removal of high dissolved oxygen is realized through the bottom cathode, and the anaerobic reaction protection of the middle anode and the upper cathode is realized. After the dissolved oxygen of the first cathode is reduced, the microorganisms of the anode effectively oxidize and metabolize organic matters into biological electrons under the anaerobic condition, and simultaneously supply the biological electrons to the two cathodes for different reduction reaction processes. Under the anaerobic condition, the upper cathode microorganism utilizes the bioelectronic reaction with the nitrate in the solution to supply the rapid growth of the denitrifying bacteria. By regulating and controlling the auxiliary voltage and increasing the rapid enrichment method of different nitrate and nitrite contents, the consumption and utilization of the microorganism on oxygen are enhanced by adopting a three-electrode system, most of microbial communities formed on the anode and mainly comprising bacteria with an extracellular electron transfer function are facultative bacteria, oxygen can be effectively consumed, the cathode mainly comprises functional bacteria capable of carrying out oxygen reduction, the functional bacteria can be used as a main oxygen removal working area, and the rapid enrichment of the cathode on denitrifying flora capable of competing with sulfate reducing bacteria is realized.

According to the invention, an extracellular electron transfer microorganism reinforced domestication reactor is adopted, rapid enrichment of flora with denitrification function in a cathode biomembrane is realized under the condition of auxiliary external voltage, actual oilfield wastewater can be directly adopted for continuous proliferation after successful domestication, and a long-term continuous denitrifying flora domestication method is provided for the oilfield wastewater treatment process.

The bioelectrochemistry deoxygenation reactor is a three-electrode domestication system, and aims at the situation that the actual oil field wastewater can be rapidly reduced to be within 2mg/L after passing through a first bottom cathode and reduced to be 1mg/L after passing through an anode when the dissolved oxygen of inlet water approaches to the level of 5mg/L, so that effective anaerobic domestication conditions are provided for an upper cathode. In order to maintain high-efficiency domestication efficiency, rapid enrichment of denitrifying flora is realized by using a domestication culture medium, and domestication is carried out for 3 days at 30 ℃ while acetate or volatile acid meeting the requirement of 1000mg/L and nitrate of 150mg/L in a domestication period.

Has the advantages that: aiming at the requirement of enrichment and domestication of the oil field wastewater on the denitrifying flora which can compete with sulfate reducing bacteria, the method can quickly and effectively enrich the denitrifying mixed flora, and can directly adopt the oil field wastewater to realize the long-term stable proliferation and enrichment of the denitrifying flora after the rapid enrichment and domestication.

Drawings

FIG. 1 is a diagram of the start-up and electron transfer monitoring of a three-electrode upflow oilfield wastewater microbial electrocatalysis reactor.

FIG. 2 is a diagram of three-electrode-upflow oilfield sewage electrode microbial acclimation potential monitoring.

FIG. 3 is a three-electrode-upflow oilfield wastewater microbial electrocatalysis biocathode acclimation electrode potential monitoring.

FIG. 4 is an analysis of the nitrate consumption of influent water; wherein A: the inlet water concentration is 45 mg/L; b: the feed water concentration was 136 mg/L.

FIG. 5 is a graph showing the effect of different nitrate and nitrite levels on sulfate-reducing bacteria.

FIG. 6 is a graph of the change in microbial community structure under different nitrite conditions.

Detailed Description

The present invention will be described in detail below with reference to the drawings and examples, but the practice of the invention is not limited thereto.

Aiming at the characteristics of high salinity and high dissolved oxygen in the target oil field wastewater, a microbial electrochemical deoxygenation process with auxiliary voltage regulation is designed, and a carbon brush bioelectrode with a large surface area is adopted to domesticate functional floras with extracellular electron transfer. By optimizing key parameters such as the space arrangement of the biological electrode, the combination proportion of the cathode and the anode and the like, the optimization of the catalytic performance of the electrode, the functional differentiation of the cathode and the anode, the mutual promotion of the cathode and the anode reaction and the mutual promotion of the denitrification biological cathode and the anaerobic process are realized. The method for constructing the high-activity biological cathode is preferably selected by discussing the influence rule of factors such as cathode potential, electrode materials and the like on the electrochemical activity of the biological cathode.

Four groups of three-electrode-upflow oilfield sewage microbial electrocatalysis deoxygenation reactors are constructed and started to operate, the current change condition is monitored in real time by adopting an automatic data recorder after the reactor operates for more than 2 months, and the change condition of the current can reflect the microbial electrocatalysis working state in real time. According to the monitoring result, when the reactor is operated under the sequencing batch condition, the current is stabilized at about 7mA under the condition that the substrate concentration is rich or the degradable COD is more than 1000mg/L in the initial stage of water inlet, and the current is limited by the substrate concentration and is reduced after a period of time of consumption. After using continuous flow, the average current for the four groups of reactors was able to stabilize above 6mA (fig. 1). The results indicate that the reactor has a stable baseline and performs well in both start-up and run modes.

The potential of the anode reflects the capability of the microorganism to carry out extracellular electron transfer to the anode, the activity of the microorganism can be monitored more directly, according to the real-time monitoring result, the potential of the anode is mainly stabilized at about-400 mV (Ag/AgCl is taken as a reference electrode) (figure 2), the activity of the anode microorganism is the highest under the potential, and the organic matter can be effectively oxidized to carry out extracellular electron transfer; the cathode was in a reduced state at-500 mV during start-up (fig. 3), and this potential also indicated that the mediator environment near the anode had little dissolved oxygen present.

In order to quickly enrich nitrate reducing bacteria and form a biological cathode community with denitrifying bacteria as a main part, the concentration of nitrate in the initial water inlet is low, the concentration of the water inlet is 45mg/L, and as can be seen from FIG. 4A, the reduction of the concentration of the nitrate is not obvious in the initial days, and the concentration of the nitrate in each day is reduced between 10 and 20 mg/L. After a period of acclimation, the concentration of the nitrate is further increased to 136mg/L, the increase of the denitrification rate can be obviously seen from the change situation of the concentration of the nitrate in FIG. 4B, and after 2 hours, the concentration of the nitrate is rapidly reduced to the level of about 20 mg/L.

There was a significant decrease in the reduction in nitrate concentration over a two hour period, depending on the change in nitrate concentration. The result shows that the growth of the denitrifying bacteria can be maintained within HRT <4h under the condition of maintaining the nitrate concentration of the inlet water at 45mg/L, but the denitrifying rate is slower, which means that the growth rate of the denitrifying bacteria is slower. When the concentration of the nitrate is higher, the reactor tends to be stable in denitrification function, and the denitrification efficiency of the reactor is higher at the moment. The result shows that when the nitrate concentration is further increased to be more than 100mg/L, the rapid denitrification can be obtained within the reaction time of maintaining HRT <2h, which means that the growth rate of the electrode denitrifying bacteria is accelerated, but long running period tests show that the activity of the rapidly-growing denitrifying bacteria biofilm is reduced due to insufficient carbon source and the shedding of the denitrifying bacteria biofilm is seriously influenced because the carbon source consumption rate is accelerated.

The result analysis shows that the nitrate concentration in the water can be maintained at 40-80mg/L, and the continuous growth of the denitrifying bacteria under the condition that the COD concentration in the sewage is about 300mg/L is realized. Under the condition of supplementing nitrate in the wastewater, the flora structure tends to grow dominantly by denitrifying bacteria, and the growth probability of corrosive flora is reduced. The abundance of sulfate-reducing bacteria was significantly reduced (fig. 5). The denitrifying bacteria with significant growth included Azosprillum, Alischewanella, Brevundimonas, Halomonas, Hyphomonas (FIG. 6).

Example 1

The bioelectrocatalysis domestication device is a three-electrode system and comprises three parts, namely a lower cathode, a middle anode and an upper cathode, wherein the three parts comprise:

the anode of the embodiment adopts the carbon brush, the size of the carbon brush adopts phi 50mm and the length of the carbon brush is 50mm, the whole length of the carbon brush is 15cm, the carbon fiber is fixed by two titanium wires, the using amount of the carbon fiber on each carbon brush is controlled by weight, the weight of the carbon fiber on a single carbon brush is 4.215g, the anode is placed in the middle of the reactor, the titanium wires are used as wires to be connected with the titanium wires at the top of the carbon brush, and the carbon fiber has a good specific surface area, can enrich a large number of microorganisms and has good conductivity. The anode region is connected to the other regions by flanges.

The cathode in this embodiment adopts foamed nickel as the cathode, and the foamed nickel has a thickness of 0.5mm, a length of 17.2cm and a width of 11.5 cm. The foam nickel is physically connected with the titanium wire with the diameter of 0.8mm of the electrode, has higher specific surface area and lower price, and can play a better role in catalysis. Meanwhile, the bending and folding form is selected in the structure, so that the specific surface area in unit volume can be effectively improved. The foamed nickel is connected with the cathode titanium wire and is connected with the anode area by a flange.

The auxiliary voltage of the anode and cathode sections is 0.9V.

Example 2

The bioelectrochemical acclimation device of the present invention operates as follows:

starting domestication conditions:

(1) the effective volume of the reactor is 1.8L, and the height-diameter ratio is 15: 1.

(2) the water intake formula is as follows:

the concentration of the acetate is 0.8-1.3 g/L; 1ml/L of vitamin solution, 1ml/L of trace element solution and 30-60 mM of phosphoric acid buffer solution (pH 7.0);

main vitamin components and concentrations: 0.1-0.3 g/L of vitamin H, 0.1-0.3 g/L of folic acid, 60.8-1.2 g/L of vitamin B, 0.3-0.7 g/L of riboflavin, 10.3-0.6 g/L of vitamin B, 0.3-0.6 g/L of nicotinic acid, 0.4-0.6 g/L of pantothenic acid, 0.78-0.03 g/L of B-120.01, 0.4-0.6 g/L of P-aminobenzoic acid and 0.3-0.6 g/L of lipoic acid.

Main components and concentrations of trace elements: MgSO (MgSO)₄ 2～4g/L，MnSO₄·H₂O 0.3～0.6g/L，NaCl0.8～1.1g/L，FeSO₄·7H₂O 0.08～0.12g/L，CaCl₂·2H₂O 0.08～0.2g/L，CoCl₂·6H₂O 0.08～0.12g/L，ZnCl₂0.1～0.15g/L，CuSO₄·5H₂O 0.01～0.02g/L，AlK(SO₄)₂·12H₂O 0.01～0.02g/L，H₃BO₃ 0.008～0.012g/L，Na₂MoO₄ 0.015～0.028g/L，NiCl₂·6H₂O 0.02～0.03g/L，Na₂WO₄·2H₂O 0.02～0.03g/L。

Phosphoric acid buffer solution (pH 7.0) main component concentration: 10-12 g/L disodium hydrogen phosphate dodecahydrate, 2-4 g/L sodium dihydrogen phosphate dihydrate, 0.2-0.4 g/L ammonium chloride, and 0.05-0.03 g/L potassium chloride).

(3) And (3) inoculation source:

the method comprises the following steps of (1) discharging water from a residual activated sludge + microbial electrolysis tank, wherein the residual activated sludge is obtained from residual sludge in a secondary sedimentation tank of a sewage treatment plant, the discharged water from the microbial electrolysis tank is obtained from periodical discharged water of the microbial electrolysis tank which runs stably, and the mixing ratio is 1: 1, the inoculation ratio is 50%.

Example 3

The enrichment and domestication operation of the electrode denitrifying bacteria colony is as follows:

the method is operated at room temperature, the room temperature is 25 +/-5 ℃, the wastewater adopted in the experimental process is taken from reinjection water of Jiangsu oil fields, and nitrate is added to keep the concentration of 100-200 mg/L. In the experimental process, a peristaltic pump is adopted to control the hydraulic retention time to be 0.5h, and the concentration of dissolved oxygen in the inlet water is controlled to be about 4-5 mg/L. The external voltage is controlled to be 0.9V during the operation.

The anode carbon brush needs to be used after pretreatment, a new carbon brush is soaked in acetone for 24 hours, taken out and then placed in a muffle furnace to be burned for 30min at the temperature of 450 ℃, and then taken out and cooled to room temperature. The nickel foam may be cut to the size of the embodiment without a pretreatment, and then used.

In the embodiment, under the external voltage of 0.9V, the rapid growth of the electrode biofilm is realized by 0.8-1.3 g/L acetate phosphate buffer solution, and after 2-3 days, the stable denitrification flora proliferation is obtained by adding nitrate into the actual oil field wastewater and continuously operating. The result analysis shows that the concentration of the nitrate in the water can be maintained at 40-80mg/L, and the continuous growth of the denitrifying bacteria under the condition that the COD concentration in the sewage is about 300mg/L is realized. The denitrifying bacteria with significant growth include Azosprillum, Alischewanella, Brevundimonas, Halomonas, Hyphomonas.

While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit of the invention, and the scope of the appended claims is to be accorded the full range of equivalents.

Claims

1. A denitrifying bacteria enrichment method for developing an anticorrosive microbial inoculum of oilfield reinjection water is characterized in that a bioelectrical catalysis domestication device is adopted, and the device is a three-electrode system and comprises a lower cathode, a middle anode and an upper cathode, so that a surrounding type electrode placement is formed; the lower cathode is used for quickly removing high dissolved oxygen to realize the anaerobic reaction protection of the middle anode and the upper cathode; the microorganism of the anode converts organic matter into bioelectronic by oxidation and metabolism under anaerobic condition, and simultaneously supplies the bioelectronic to the two cathodes for different reduction reaction processes; under the anaerobic condition of the microorganism with the upper cathode, the rapid growth of denitrifying bacteria is supplied by the reaction of biological electrons and nitrate in the solution;

the method comprises the following steps:

(1) under the external voltage of 0.9-1.1V, the phosphate buffer solution of acetate realizes the rapid growth of the electrode biomembrane; the formulation of the acetate phosphate buffer is as follows: acetate with the concentration of 0.8-1.3 g/L, vitamin liquid with the concentration of 1ml/L, trace element liquid with the concentration of 1ml/L and phosphoric acid buffer solution with the concentration of 30-60 mM;

(2) and after 2-3 days, introducing reinjection water of the oil field, adding nitrate into the water, keeping the concentration of the nitrate to be 100-200 mg/L, controlling the hydraulic retention time to be 0.5h by adopting a peristaltic pump, controlling the concentration of dissolved oxygen in the inflow water to be 4-5 mg/L, and controlling the external voltage to be 0.9-1.1V in the operation process.

2. The method for enriching denitrifying bacteria used for developing the anticorrosive microbial inoculum for oilfield reinjection water as defined in claim 1, comprising the steps of adopting an extracellular electron transfer microorganism to strengthen an acclimatization reactor, realizing the rapid enrichment of the flora with the denitrifying function in a cathode biomembrane under the condition of auxiliary applied voltage, and continuously proliferating after the acclimatization is successful.

3. The method for enriching denitrifying bacteria for developing the anti-corrosive microbial agents for oilfield reinjection water according to claim 1, wherein an anode of the domestication device adopts a carbon brush, the carbon fiber of the carbon brush is fixed by two titanium wires, and an anode area is connected with other areas by a flange; the upper cathode and the lower cathode are made of foamed nickel and are bent and folded, the foamed nickel is connected with a cathode titanium wire, and meanwhile, the cathode area is connected with the anode area through a flange; the auxiliary voltage of the anode and the cathode is 0.9-1.1V.