MXPA00000816A - Method for inhibiting biogenic sulfide generation - Google Patents

Abstract

A non-biocidal method for inhibiting biogenic sulfide generation in a system having an anaerobic biofilm containing active sulfate-reducing bacteria comprising contacting the biofilm with an aqueous solution of anthrahydroquinone compound.

Description

METHOD TO INHIBIT THE GENERATION OF BIOGENIC SULFIDE Field of the Invention The invention is directed to a method for inhibiting the generation of biogenic sulfide. In particular, it addresses a method to inhibit sulfide generation by sulfate-reducing bacteria in aqueous liquid systems and oil reservoirs.

Background of the Invention In the oil industry, the growth and activity of uncontrollable microbes can create several operational, environmental and human security problems. Problems caused or intensified by the growth and activity of microbes include corrosion, production of solids, and generation of hydrogen sulfide (H2S).

The microorganisms that respond primarily by the generation of H2S in a Ref: 032387 anaerobic environment within the oil industry are sulfate-reducing bacteria. These organisms are ubiquitous and can grow in almost any environment. These are routinely found in waters associated with oil production systems and can be found in virtually all industrial aqueous processes, including cooling water systems, paper-making systems, and oil refining.

The requirements for the activity and growth of the sulfate-reducing bacteria include an anaerobic (oxygen-free) aqueous solution containing adequate nutrients, a donor electron, and an acceptor electron. A typical acceptor electron is a sulfide, which produces H2S during reduction. A typical donor electron is a volatile fatty acid (eg, lactic, acetic or propionic acid), although hydrogen can also function as the donor electron. The conditions in a reservoir of oil subject to a seawater inundation are excellent to stabilize the activity of the sulfate-reducing bacteria. Seawater contains a significant concentration of sulphate, although similar, or of native formation, water contains volatile fatty acids and other traces of nutrients (eg, nitrogen and phosphorus). The mixtures of two waters in an oil reservoir provide all the essential conditions for the activity of the sulfate-reducing bacteria. These conditions can result in the generation of sulfur within the reservoir, which is referred to as an acidified reservoir.

Hydrogen sulfide is corrosive and reacts with metal surfaces to form insoluble corrosive iron sulfide products. In addition, the H2S is distributed in the phases of fluid production of water, oil, and natural gas and creates a number of problems. For example, oil and gas containing high levels of H2S have a lower commercial value than oil and gas with low sulfur. The biogenic removal of H2S from an oil and gas source increases the cost of these products. Hydrogen sulfide is an extremely toxic gas and is immediately lethal to humans even in small concentrations. In this way, it is present in the oil field posing a threat to worker safety. The discharge of production waters containing high levels of H2S in aquatic or marine environments is dangerous, since H2S reacts with oxygen and lowers the oxygen levels dissolved in the water.

Waters produced from a reservoir, associated with the production of oil, especially those resulting from a seawater fluid, can typically contain sulfate-reducing bacteria and nutrients required. Conditions in surface facilities (eg pipes, ships, tanks) are usually completely favorable for the activity of the sulfate-reducing bacteria. In addition, these are able to activate and grow in a wide range of temperatures found in the oil field. Reduced surface temperatures facilitate many times of increased microbial growth as compared to elevated temperatures within the reservoir. Oil production operations favor the growth of anaerobic sulfate-reducing bacteria since those environments are usually oxygen-free to avoid oxidative corrosion of steel vessels, pipes, and tanks. However, however, if such systems are aerobic, the localized anaerobic conditions are maintained on the metal surface (the substrate) under the biofilm due to oxygen consumption by the aerobic bacteria.

The activity of the sulfate-reducing bacteria in surface installations is a source of H2S production, which causes corrosion, and results in the production of solid corrosion products, which can cause operational problems such as plugging of injection perforations. of water in injection media. (The waters produced are frequently reinjected into the formation for secondary oil recovery purposes, or they can be disposed by injection in different portions of the reservoir.) Inhibition of the activity of the sulfate-reducing bacteria can reduce H2S production and can interrupt the anaerobic corrosion of the steel surfaces, therefore reducing the formation of solids.

Corrosion (sting) caused by sulfate-reducing bacteria often results in extensive damage. Pipe systems, tank bottoms, and other pieces of petroleum production equipment can quickly be damaged if these are areas where microbial corrosion occurs. If a fault occurs in a pipe or bottom of an oil storage tank, the release of oil can have serious environmental consequences. If a fault occurs in a gas or high pressure water line, the consequences can be injury or death of the workers. Any failure involves replacement costs or substantial repairs.

Potential methods for mitigating the activity of sulfate-reducing bacteria include temperature control, metabolic removal, pH control, Eh control, radiation, filtration, salinity control, chemical control (eg, oxidants, biocides, acids, alkaline), control of solids (for example, control of scraping and control of pitting of the internal surfaces of the pipe), and bacteriological controls (for example, phage bacteria, enzymes, parasitic bacteria, monoclonal antibodies, competitive microflora). Some of these methods can eliminate the sulfate-reducing bacteria, while others stress or cause enough disturbance to inhibit their activity.

Most of the above methods are not practical for implementation in the oil field because of their cost or potential effect on downstream processes. For example, the treatment of large amounts of water by heating to sterilization temperatures, by complete filtration of the microscopic bacteria, or by removal of the nutrient (eg, sulfate) is prohibitively expensive due to the high requirements of equipment and energy. The removal or removal of the bacteria from a current process must be 100% effective if not the exponential growth of the surplus bacteria will recolonize the downstream surfaces. In addition, all downstream surfaces must be sterilized (ie, bacteria-free) prior to the implementation of a sulfate-reducing bacteria mitigation process upstream otherwise the growth of the sulfate-reducing bacteria may continue within the biofilm Two typical control methods for sulfate-reducing bacteria in oil field piping systems are scraping control treatments and biocides. Scraping control is required to remove or alter the biofilm on the surface of the pipe. The scraping control can also remove much of the deposits that can act as cathodes to the corroded anodic areas. While scraping control can be substantially effective where thick biofilms are present, thin biofilms and thin iron sulphide deposits are not appreciably affected by the scraping action of scraping. Subsequently, biocides and treatments of biocidal surfactants are extensively used to control the activity of bacteria in oil field systems. The combination of treatments in conjunction with the scraping control are more effective than chemical treatments alone. Nevertheless, the treatments must be done routinely at a fixed time unless the population of bacteria increases significantly and the control becomes even more difficult. The monitoring of the effectiveness of the treatments may include the sessile bacteria, for the reason that the numbers of bacterial seedlings followed by a biocide treatment may not correlate with the sessile bacteria involved with the corrosion process.

This provides difficulties to eradicate the biofilms from the pipes due to their great resistance to bactericidal agents. The concentration of biocides required to eliminate the bacterium in the sessile phase (in the biofilm) are often much higher than those required for the bacterium in the seedling phase or free from flotation. (Blenkinsopp, S.A., Khoury, A.E. and Costerton, J. W., "Electrical enhancement of biocide efficay against pseudomonas aeruginosabofil s" ("Increased biiocidal efficiency of electricity against pse? Domonas aeruginosa biofilms"), Applied and Environmental Microbiology, 58, No. 11, page 3770, 1992.) This may be due to the role of the abundant exopolysaccharide matrix of the biofilm. This suggests that the diffusion resistance in the growth mode of the biopelicle can be overcome by the imposition of a relatively weak DC electric field so that the biofilm bacterium can be rapidly eliminated by concentrations of biocides only once or twice those that are necessary to eliminate the plant cells of the same organism. While this new technology may be technically effective, it appears to be impractical to apply in a commercial pipeline system 1.

Brief Description of the Invention In a broad aspect, the invention is directed to a non-biocidal method for inhibiting the generation of biogenic sulfide in a system having an anaerobic biofilm containing a sulfate-reducing bacterium comprising contacting the biofilm with a liquid solution of a salt alkali metal of an anthrahydroquinone compound by which the antihydroquinone salt passes through the pores of the biofilm and is dispersed within the biofilm to effect contact with the sulfate-reducing bacteria.

In a second aspect, the invention is directed to a method for inhibiting the generation of biogenic sulfide in pipes through which liquids are transported in turbulent flows, comprising introducing a liquid solution of an alkali metal salt of anthrahydroquinone in the flow liquid as a plug, the volume of which is enough to provide contact with a given point inside the tube for at least one minute.

Brief Description of the Drawings.

The Drawings consist of two figures of which the Figure 1 is a schematic representation of a typical biofilm and Figure 2 is a schematic representation of the valve involved in the use of piping control of the pipes (scraping control).

Detailed description of the invention.

Biopelicula: A biofilm is a heterogeneous accumulation of bacterial colonies bound to a substrate. Although it is characterized as a "biofilm", it is not completely biological, it is not continuous in the conventional sense of the word "film".

Recent studies indicate that a biofilm consists of microcolonies of discrete bacteria immobilized in a submerged substrate in an aqueous medium, the microcolonies being separated by water channels trying to make a connective flow take place. The microbe cells are held together and maintained at the surface of the substrate by extracellular polymeric substances. Within the context of the invention, the medium (also called "the substrate") is an anaerobic liquid, and at least a significant portion of the bacteria in the biofilm are sulfate-reducing. However, the biofilm may contain other species of co-existing bacteria. In addition, the biofilm can contain external material such as exoenzymes, solutes and inorganic inclusions such as corrosion products, sediments and clay particles.

Figure 1 is a schematic representation of a biofilm that is bonded to a metal substrate 1. As shown, a continuous thin layer of bacteria 3 is directly bonded to substrate 1. However, this layer 3 is not always continuously and continuously it does not enter into the efficacy of the invention in this environment. Linked to the thin bacterial layer 3, and / or directly to the substrate 1, as the case may be, is a series of grouped bacterial cells 5 having channels therebetween through which the aqueous medium can flow. Since the porosity of the grouped bacterial cells 5, the aqueous medium 7 and the materials dispersed therein are able to enter the structure and contact the bacterium with the structure. Functionality of Anthrahydroquinone and Applications Although biocides are proposed to eliminate sulfate-reducing bacteria, anthrahydroquinones inhibit their activity. The results of these studies indicate that anthrahydroquinone blocks the production of adenosine triphosphate by the sulfate-reducing bacteria, thereby removing the ability of bacteria to breathe by means of sulfate reduction. Without the reduction of sulfate, H2S is not produced by the bacteria.

Biocides are very reactive, a property that is probably responsible for their limited effectiveness in penetrating biofilms at low doses. The extraordinary efficacy of various forms of anthrahydroquinone lies in its non-reactivity. These products are transported in the biofilm, dispersed through the voids of the biofilm, and then dispersed or transported randomly by Broian movement in the microcolonies of bacteria without reduction in concentration as a consequence of a reaction with the constituents of the bacteria. biofilm These anthrahydroquinone materials are not affected by other bacteria or by the exopolysaccharide matrix present in the biofilm.

Although the solid anthrahydroquinone particles are required to inhibit the activity of the sulfate-reducing bacteria, the anthrahydroquinone can be introduced into the microbe environment in various physical forms. The anthrahydroquinone compound can be introduced as a dispersion of these solid particles while an anionic form (sodium salt) of anthrahydroquinone can allow the anthrahydroquinone to be solubilized in an anaerobic caustic solution with a pH higher than 12 and preferably higher than 13. The salt remains soluble if the pH of the solution is maintained above about 12. The precipitation of solid anthrahydroquinone takes place if the pH is reduced below this value. In the soluble form, or with a light amount of precipitated anthrahydroquinone (typically in colloidal form), the anthrahydroquinone is in ionic form or consists of extremely small particles (sub-micron size). The anthrahydroquinone ions or colloidal particles can then be able to move freely in the biofilm, thereby easily contacting the cells of sulfate-reducing bacteria. The contact of anthrahydroquinone with sulfate-reducing bacteria, and the partition of anthrahydroquinone in the cell membrane, blocks the production of adinosin triphosphate in the body. In addition, the decrease in pH in the biofilm (due to the production of acid from another bacterium in the biofilm or due to the sweep of lower pH fluids through the tube) can precipitate more small particles of anthrahydroquinone from the solution within the biofilm This may expose the sulfate-reducing bacteria within the biofilm to additional anthrahydroquinone particles, promoting the efficacy of the anthrahydroquinone treatment.

The solution of alkali metal hydroxide, for example NaOH solution, (caustic solution) the carrier of the soluble anthrahydroquinone, is also added to the effectiveness of the treatment for its functionality as a surfactant. The caustic solution helps to alter the biofilm and increases the tendency for the biofilm to fall off the wall of the tube. The high pH solution also collides all the bacteria within the biofilm, reducing all activity however in the absence of the anthrahydroquinone. Field studies in a wastewater treatment system have shown that the production of biogenic sulfide mitigated with both caustic treatments and soluble anthrahydroquinone, but the highest degree of inhibition was greater with the treatment of soluble anthrahydroquinone and the restoration of production of sulfur to the original level occurred rapidly with caustic treatment.

The protocol for the implementation of an anthrahydroquinone salt treatment Soluble is relatively simple. The solution typically contains active anthrahydroquinone at a concentration of about 10%. The solution is pumped from a storage tank in the pipeline that transports the water to be treated. Typically a solution dosage core is injected. The solution is injected sufficiently to provide a core in the pipeline at a concentration of about 250 ppm by weight of active anthrahydroquinone for a contact time of about 10 minutes. In some cases the core may need only 50 ppm for 1 minute, while other systems more difficult to treat may require 1000 ppm for 30 minutes to inhibit sulfide production properly. The required dosage core is a function of the composition of the biofilm, thickened, and toughness and also the presence of hydrocarbon constituents associated with the biofilm. The speed of the water stream, the diameter of the tube and the length, and the pH and water damping capacity can also affect the requirements of the soluble anthrahydroquinone. The dispersion of the nucleus while traveling under the pipe tends to reduce the pH of the nucleus in front and behind the nucleus. The dispersion is a function of the diameter of the tube, number of bends in the tube, and the distance that the nucleus has traveled. (Perkins, T.K. and J.A. Euchner, "Safe purging of natural gas pipelines", SPE Production Engineering, page 663, 1988). The core is injected so that the dispersion is minimized and the length of the high pH (that is, the core volume) is sufficient to give at least one minute of contact time for the high pH. High concentrations of anthrahydroquinone by short contact time are typically more effective than low concentrations by long times, but circumstances may dictate that the concentration of the injected core may be limited. One such circumstance is when the treated water contains soluble metals (especially calcium) and a sufficient bicarbonate ion so that the pH of the water increases up to around 9.5 and can cause scale formation. If a very high amount of the soluble anthrahydroquinone salt is introduced into this water, then this may occur. In addition, the scaling process can dampen the pH to a level that can cause the anthrahydroquinone to precipitate out of the solution, the combined scale precipitate and the anthrahydroquinone can reduce the overall efficiency of the treatment. Limiting the amount of soluble high pH solution injected into this water so that the final pH of the water is below about 9.5 can minimize the amount of scale formation while maintaining an adequate solubility of the anthrahydroquinone. If the pH is less than about 9.0, then the scale can not be formed. However, significant anthrahydroquinone can be precipitated due to low pH, thereby reducing the overall effectiveness of the treatment.

The frequency of the anthrahydroquinone core injection is based on the monitored sulfur results. The injection needs to be only frequent enough to keep the sulfide concentration below the predetermined level. Typically, the injection is in a one week interval, however the frequency can be as often as every third day or as not frequent once a month. Low-concentration daily injections are typically necessary for short-length piping systems, such as on an oil production platform, whereas weekly or monthly high-concentration injections are typically necessary for long water transport pipelines.

The effectiveness of the treatment is increased by maintaining a scraping control of the pipe. The control of scraping in the line before the treatments with anthrahydroquinone significantly increases the effectiveness of the anthrahydroquinone due to disturbances of the biofilm, reducing its thickness, and removing deposits of solid iron sulfide.

Treatments with aqueous dispersions of solid anthrahydroquinone particles are typically effective and inexpensive for most applications since anthrahydroquinone is rapidly oxidized in the air to anthraquinone. Due to this property, pure anthrahydroquinone is difficult to process economically. In addition, the solid anthrahydroquinone can be prepared as an aqueous dispersion of extremely small particles (less than about 2 microns) to effect the inhibition of the activity of the sulfate-reducing bacteria. This preparation can be done in an anaerobic environment, otherwise the anthraquinone could be the final product. However, anthraquinone itself is an inhibitor of the generation of biogenic sulfide. PH control is not important in treatments with an aqueous dispersion of anthrahydroquinone. As with soluble materials, treatments with insoluble anthrahydroquinone can be such at a concentration of anthrahydroquinone maintained for a suitable contact time as the core traveling down the pipe.

The preferred, most expensive effective treatment is to inject the water-soluble dialkali metal salt of anthrahydroquinone into the water stream being treated. The precipitation of the molecular anthrahydroquinone (due to the reduction in pH) can be in the form of colloidal particles with a size of typically less than one micrometer. These small particles can then easily penetrate the biofilm, contact the sulfate-reducing bacteria, and effect the inhibition of sulfide production effectively due to their small particle size.

In long pipes with numerous curves and / or in pipes in which the flow is laminar, the dispersion of the core in the water containing the alkali metal salt of the anthrahydroquinone can be significant. This can cause the concentration of anthrahydroquinone in the core to reduce under the tried levels such as the main and lower ends of the core mixed with the water stream. In addition, the low pH of these "tails" can result in a precipitation of anthrahydroquinone and a possible reduction in the effectiveness of the treatment. The main end "tail" can be removed by the scraping of the pipeline immediately before starting the injection of the anthrahydroquinone solution. Scraping can act as a barrier for mixing the anthrahydroquinone and the water core with water however with low Reynolds number of flow and / or numerous curves in the pipe. In addition, scraping helps reduce the thickness of the biofilm with a sting control action, and can remove many of the iron sulfide deposits and other solid deposits. All these factors can help increase the effectiveness of anthrahydroquinone treatment. However, scraping entrains the water-anthrahydroquinone core to the detriment of the treatment, since it can remove the anthrahydroquinone that has penetrated the biofilm.

The increased effectiveness of anthrahydroquinone treatment for some applications may result from the combined use of anthrahydroquinone and a biocide or oxidizer. The biocide / oxidizer may be needed to reduce the amount of biofluid on the surface, while the anthrahydroquinone is responsible for the long-term inhibition of the activity of the sulfur-reducing bacteria. This is especially necessary for applications in which the problem of biofluid or thick biofilm has been established before treatment with anthrahydroquinone. Anthrahydroquinone alone can penetrate the biofilm, starting from the inactive sulfate-reducing bacteria, but other bacteria and their resulting biotic and abiotic products (especially iron sulfide) can still be present in the wall and may possibly contribute to additional problems such as corrosion. A combined application of anthrahydroquinone-biocide, such as alternative materials or periodically treatment with a biocide instead of an anthrahydroquinone treatment, is more effective than the use of these materials separately.

Anthrahydroquinone Formulation and Compounds Although a wide variety of anthrahydroquinone compounds can be used in the method of the invention, it has been found that significantly higher results are obtained from the use of certain 9, 10-anthrahydroquinones and alkali metal salts thereof. In particular, the anthrahydroquinone itself (9,10-dihydroxyanthracene), 9,10-dihydro-9,10-dihydroxy-racene and mixtures thereof. The water-soluble forms of these compounds are alkali metal salts thereof.

More particularly, both the water-insoluble forms and the water-soluble forms can be used. The nonionic compounds are mostly soluble in aqueous systems, while the ionic derivatives are di-alkaline metal salts and are mostly soluble in water. Water soluble forms are stable only in anaerobic fluids with high pH. Low pH fluids (pH less than about 12) can result in the formation of insoluble molecular anthrahydroquinone. Aerobic solutions can cause oxidation of anthrahydroquinones to anthraquinones. In this way, the anthrahydroquinones may not exist for long periods of time in an aerated environment. For these reasons, anthrahydroquinone treatments are usually implemented with the soluble form in a caustic solution. NaOH solutions are preferred over other alkali metals for economic reasons.

The distinct use of the biocides in the treatment of the sulfate-reducing bacteria, the anthrahydroquinone compounds used in the invention do not eliminate the sulfate-reducing bacteria, but merely inhibit the sulfur-producing activity. Interestingly enough, the active species of alkali metal salts of anthrahydroquinone compound are believed to be water-insoluble compounds that apparently modify the electron transfer process of the sulfate-reducing bacteria. In order to make the water-insoluble compounds effective, they can be divided very finely to an extent that they can be dispersed in the biofilm. A reduction in the pH of the alkali metal salt solution can form extremely small particles of biochemically active anthrahydroquinone, which can easily be dispersed in the biofilm and the substrate cover.

Despite the fact that the active species appear to be insoluble forms of the anthrahydroquinone compound, it is nevertheless preferred to use the water-soluble form of anthrahydroquinone since it is distributed in the biofilm and thus contacts the sulfate-reducing bacteria more rapidly. The activity of the anthrahydroquinone ion form appears to derive from the conversion from the ionic form (ie, alkali metal salt) to the nonionic (ie, molecular) form by which it precipitates as very fine particles that bind to the sulfate-reducing bacteria.

If the soluble or insoluble anthrahydroquinone is used, it will be observed that the functional binding of the anthrahydroquinone particles to the bacteria is limited in time by the metabolism of the particles by the sulfate-reducing bacteria. In this way, the application of the treatment medium should be repeated periodically in order to maintain the effectiveness of the inhibition.

The compositions are added to the medium containing the sulfate-reducing bacteria in an amount sufficient to inhibit the production of sulfur. A smallness of 0.1 ppm by weight in the aqueous medium gives a significant inhibition for many uses. In the preferred method the concentration of the active anthrahydroquinone in the medium is at least 1 ppm, preferably 1-50 ppm. Higher concentrations, such as above 1000 ppm, can be used, especially for the treatment of long pipes.

Scraping Control Procedure Figure 2 is a schematic representation of a typical tubing for transporting liquids that facilitates scraping control operations (or pit control). The liquid fluid through the tube is directed through the main pipe 1 through the upstream valve B and the downstream valve G, both of which are opened during the normal pipe operation. The valve V in the starting tube 3 and the valve A in the outlet scraper tube 7 are closed and the valve D in the pressurizing tube 9 is opened during the normal pipe operation.

When it is desired that the scraper be released, the valve C, which connects to the main pipe 1 with an outer scraper barrel 5 by means of a pipe 3, opens slowly to raise the pressure in the launch barrel. containing the scraper, to the full pressure of the pipe. After the launch barrel 5 has fully reached the pipeline pressure, the valve D in the pressurizing tube 9 closes and the scraper outlet valve A in the outlet tube 7 scraper opens. Then, slowly punching down on valve B, the different pressure inside the launch barrel increases and exceeds the friction between the scraper and the launch barrel. The scraper passes slowly through the scraper of the outlet valve A and the sweeper of the outlet pipe 7 into the full flow of the main pipe 1. After the scraper is released, the valve B is completely open and the valves A and C are closed. In addition, the scraper valve F of the return pipe, the valve G of the main pipe and the receiver scraper of the valve H of the pipe is opened. The scraper is then processed through the pipe 1, the scraper of the return pipe 1 and the valve F in the receiving barrel 13.

As the scraper passes through the gasket of the supply pipe 17 and the main pipe 1, the inhibiting feed valve E opens to inject the anthrahydroquinone compound into the main pipe. The valve E is then closed early to choose the quantity of anthrahydroquinone compound that is injected into the main pipe 1.

Then the scraper reaches the receiving barrel 13, the main pipe G on completely open and the valves F and H are closed. During the venting of the pressure inside the receiving barrel 13, this can be opened to remove the scraper.

EXAMPLES Example 1.

Anthrahydroquinone that inhibits the production of sulfur by desulfovibrio desul furicans G100A.

A frozen culture of 1 mL of Des ul fo vibri or des ul ur urins G100A is thawed, injected into a capped septum tube containing 10 mL of modified reduced BTZ-3 medium, and incubated at 30 ° C for three days. (All transfers, additional materials, and samples during this experiment were run in an anaerobic chamber at room temperature (incubation took place outside this chamber). Five ml of this culture were transferred in a bottle of 60 ml capped septum serum containing 50 ml of reduced BTZ-3 medium and incubating overnight at 30 ° C. Three ml of this culture was transferred to 50 ml of modified Postgate B medium in 60 ml serum bottles capped with septum lock. A total of 6 crops were prepared like this. Four were then treated with two duplicate concentrations (100 ppm and 500 ppm) of the anthrahydroquinone salt solution described above by injecting the material with a microliter syringe into the serum bottles and shaking these bottles. Two of the six bottles were removed as untreated controls.

The anthrahydroquinone material tested has been prepared by reacting appropriate quantities of anthraquinone, sodium borohydride, sodium hydroxide, and water at 80 ° C-85 ° C in a nitrogen atmosphere for 6 hours, heating the resulting liquid to 95 ° C. two hours to decompose the unreacted sodium borohydride, and then cooling the solution to room temperature. The resulting bright red solution with a pH > 13 was filtered to remove any unreacted anthraquinone and solid impurities and stored under a nitrogen environment. Nuclear magnetic resonance analysis of the solution indicated that this was a mixture of sodium salts of at least three reduced anthraquinone derivatives: 9,10-dihydroxyanthracene, 9,1 O-dihydroanthrahydroquinone, and oxyanthron. The acidification, filtration, and oxidation of a sample of this solution convert the salts to anthraquinone. The quantitative analysis indicates that the solution contains 10.1% by weight of anthraquinone equivalent.

After the bottles were treated, sulfur measurements at zero time were made in each culture according to the following procedure: 1) A sample of 0.5 mL was removed and injected into a 3 mL vacuum container containing 0.1 mL of HCl IN. 2) The sample in the vacuum container was allowed to stand for 10 minutes and then removed from the anaerobic chamber. Using a gas adjustment syringe, 0.15 ml of the gas phase was removed. This gas was injected slowly into a well covered with paraffin containing 1.8 mL of water with pH 8, the needle was quickly removed through the paraffin, and the cuvette was overcoated with an excess of paraffin initially in place. The cuvette was inverted several times. 3) 0.2 mL of N, N-dimethyl-p-phenylenediamine reagent (DPD) was added to the cuvette. The cuvette was inverted several times and allowed 30 minutes to reveal a blue color. 4) The OD6 was read or in a spectacle ofotometer. A check was made to secure the OD670 within the linear portion of the calibration curve to ensure that the reading is proportional to the sulfur concentration in the test bottle.

After the samples were taken for the zero time sulfur readings, the serum bottles were removed from the anaerobic chamber and placed in an incubator at 30 ° C. Samples were taken from the serum bottles for sulfide analysis at 21, 27, 45, 69 and 131 hours from time zero by the same procedure described above. The results of the sulfide analyzes, given as OD670 readings, are shown in Table I.

The results conclusively show that the anthrahydroquinone salt solution effectively inhibits the generation of sulfur by the Desulfur ovibrio des ul f uri cans G100A.

TABLE 1 Inhibition of Sulfur Generation by the Use of an Anthrahydroquinone Salt Solution.

These data clearly show the inhibition of generation of hydrogen sulfide for 27 hours even though the concentrations of anthrahydroquinone salt solution are less than 100 ppm * by weight and for 69 hours at solution concentrations of 500 ppm **. The data are not unambiguous for 69 and 131 hours primarily due to two factors: (1) because the tests were static, insoluble anthrahydroquinone particles were formed during the test tending to settle and therefore having less contact with the dispersed bacteria within the test medium; and (2) this is some agglomeration of anthraquinone particles that reduces the surface area of the particles. In this way the inhibition was reduced. Despite the variety of the static inhibition test, the data clearly show that the anthrahydroquinone particles effectively inhibit the generation of hydrogen sulfide at extremely low concentrations if an efficiently long contact is maintained. * 100 ppm by weight of the solution concentration is equivalent to 13 ppm of the anthrahydroquinone salt. ** 500 ppm by weight of the solution concentration is equivalent to 65 ppm of the anthrahydroquinone salt Example 2 Anthrahydroquinone that inhibits the production of sulfur by Des ul f or vibri or des ul ur ur can s G100A.

A frozen culture of 1 mL of Des ulf ovibri or des ulf uri can s G100A is thawed, injected into a capped septum tube containing 10 mL of modified reduced BTZ-3 medium, and incubated at 30 ° C for three days. (All transfers, additional materials, and samples during this experiment were run in an anaerobic chamber at room temperature (incubation took place outside this chamber). Five ml of this culture was transferred into a 60 ml capped septum bottle containing 50 ml of the reduced BTZ-3 medium and incubating overnight at 30 ° C. Three ml of this culture was transferred to 50 ml of modified Postgate B medium in 60 ml serum bottles capped with septum lock. A total of 6 crops were prepared like this. Four were then treated with two duplicate concentrations (140 ppm and 700 ppm) of the anthrahydroquinone salt solution described above by injecting the material with a microliter syringe into the serum bottles and shaking these bottles. Two of the six bottles were removed as untreated controls.

The anthrahydroquinone material tested has been prepared by reacting appropriate amounts of anthraquinone, formamidine sulfinic acid, sodium hydroxide, and water at room temperature for more than 24 hours. HPLC analysis of the resulting deep red solution indicates that it contains an equivalent of 7.13% 9,10-anthraquinone. Another solution, which was prepared with the same reagents, was subsequently neutralized with dilute HCl under a nitrogen environment to provide a yellow anthrahydroquinone precipitate. While left over under the nitrogen environment, this thickened mixture was filtered and the cake was washed with deionized water to remove the impurities of water-soluble by-products. After this, the washed solids were resuspended in de-aerated water and reallocated with de-aerated sodium hydroxide solution. This deep red solution was then dried in a rotary evaporator to form a microcrystalline talin solid that was subsequently analyzed by nuclear magnetic resonance. The spectrum showed that the solid was the pure substance of disodium salt 9, 10-dihydroxythi racene.

After the bottles were treated, sulfur measurements at zero time were made in each culture according to the following procedure: 1) A sample of 0.5 mL was removed and injected into a 3 mL vacuum container containing 0.1 mL of HCl IN. 2) The sample in the vacuum container was allowed to stand for 10 minutes and then removed from the anaerobic chamber. Using a gas adjustment syringe, 0.15 ml of the gas phase was removed. This gas was injected slowly into a well covered with paraffin containing 1.8 mL of water with pH 8, the needle was quickly removed through the paraffin, and the cuvette was overcoated with an excess of paraffin initially in place. The cuvette was inverted several times. 3) 0.2 mL of N, -dimethyl-p-phenylenediamine reagent (DPD) was added to the cuvette. The cuvette was inverted several times and allowed 30 minutes to reveal a blue color. 4) The OD6 or a spectrophotometer was read. A check was made to secure the OD670 within the linear portion of the calibration curve to ensure that the reading is proportional to the sulfur concentration in the test bottle.

After the samples were taken for the zero time sulfur readings, the serum bottles were removed from the anaerobic chamber and placed in an incubator at 30 ° C. The samples were taken from the serum bottles for sulfide analysis at 21, 27, 45, 69 and 141 hours from time zero by the same procedure described above. The results of the sulfide analyzes, given as OD670 readings, are shown in Table 2.

The results conclusively show that the anthrahydroquinone salt solution effectively inhibits the generation of sulfur by the Des ulf ovibri or des ul f uri cans G100A.

TABLE 2 Inhibition of Sulfur Generation by the Use of a Disodium Salt Solution of 9,10-Dihydroxyanthracene.

These data clearly show the inhibition of generation of hydrogen sulphide for 27 hours even though the concentrations of anthrahydroquinone salt solution are less than 140 ppm * by weight and for 69 hours at solution concentrations of 700 ppm **. * 140 ppm by weight of the solution concentration is equivalent to 13 ppm of the disodium salt 9, 10-dihydroxyanthracene. ** 700 ppm by weight of the concentration of solution is equivalent to 65 ppm of disodium salt 9, 10-dihydroxyanthracene.

Example 3 Comparison of Two Different Anthrahydroquinone Salt Solutions to Inhibit the Production of Sulfur by Desulfurization or Desulphurin G100A.

A frozen culture of 1 mL of Des ul fo vibri or des ul ur urins G100A is thawed, injected into a capped septum tube containing 10 mL of modified reduced BTZ-3 medium, and incubated at 30 ° C for three days. (All transfers, additional materials, and samples during this experiment were run in an anaerobic chamber at room temperature (incubation took place outside this chamber). Five ml of this culture was transferred into a 60 ml capped septum bottle containing 50 ml of the reduced BTZ-3 medium and incubating overnight at 30 ° C. Three ml of this culture was transferred to 50 ml of modified Postgate B medium in 60 ml serum bottles capped with septum lock. A total of 14 crops were prepared like this. Twelve were then treated with three concentrations in duplicate (5, 10, and 50 mg / L of the 9,10-anthraquinone equivalent) of two different anthrahydroquinone salt solutions described above by injecting the material with a microliter syringe into the serum bottles. and waving these bottles. Two of the fourteen bottles were removed as untreated controls.

One of the tested anthrahydroquinone materials (designated as SSC) was prepared as described in Example 1. The second (designated as SAQ) was obtained from Kawasaki Kasei Chemical Ltd, which specifies the material which is a caustic solution of the salt of Disodium 1,4-dihydro-9, 10-anthracenediol. The biggest difference in these materials is that the SSC is a solution of 9, 10-dihydro-9, 10-anti- racenediol and disodium salts of 9, 10 -antracenediol (plus oxyanthone salt) while the SAQ is a solution of a disodium salt of 1,4-dihydro-9,10-anthracenediol pure. The equivalent 9, 10-anthraquinone contained in each was determined by acidifying a known amount of each with hydrochloric acid, collecting the resulting precipitated anthrahydroquinone by filtration, washing the filtered cake thoroughly with deionized water, drying the washed cake in an aerator oven oxidizing the anthrahydroquinone to 9,10-anthraquinone, and then weighing the resulting dry solid. The content of 9, 10-anthraquinone of the SSC was 10.3% by weight and of the SAQ was 22.7% by weight.

After the bottles were treated, sulfur measurements at zero time were made in each culture according to the following procedure: 1) A sample of 0.5 mL was removed and injected into a 3 mL vacuum container containing 0.1 mL of IN HCl. 2) The sample in the vacuum container was allowed to stand for 10 minutes and then removed from the anaerobic chamber. Using a gas adjustment syringe, 0.15 ml of the gas phase was removed. This gas was injected slowly into a well covered with paraffin containing 1.8 mL of water with pH 8, the needle was quickly removed through the paraffin, and the cuvette was overcoated with an excess of paraffin initially in place. The cuvette was inverted several times. 3) 0.2 L of N, N-dimethyl-p-phenylenediamine reagent (DPD) was added to the cuvette. The cuvette was inverted several times and allowed 30 minutes to reveal a blue color. 4) The OD670 was read in a spectofotómet ro.

After the samples were taken for the zero time sulfur readings, the serum bottles were removed from the anaerobic chamber and placed in an incubator at 30 ° C. The samples were taken from the serum bottles for sulfide analysis at 21, 27 and 45 hours from time zero by the same procedure described above. The results of the sulfide analyzes, given as ODg7o readings, are shown in Table 3.

TABLE 3 Inhibition of Sulfur Generation by the Use of Disodium Salt Solutions, Anthracenediol The results clearly show that, at each equivalent concentration of 9,10-anti- raquinone, the anthrahydroquinone salt solution designated by SAQ (comprised of disodium salt of 1,4-dihydro-9,10-anthracenediol) was lower than the SSC, a mixture of anthrahydroquinone salts that does not contain the substance 1,4-dihydro, to inhibit the generation of sulfur by the Des ul f ovibri or des ul f uri cans G100A.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (13)

Claims

1. A non-biocidal method for inhibiting the generation of biogenic sulfide in a system having an anaerobic biofilm containing a sulfate-reducing bacterium, characterized in that it comprises contacting the biofilm with a liquid dispersion of an anthrahydroquinone compound selected from the group consisting of 9, 10-dihydroxyanthracene, 9,10-dihydro-9, 10-dihydroxyanthracene and mixtures thereof so that the anthrahydroquinone compound passes through the pores of the biofilm and is dispersed within the biofilm to effect contact with the biofilm. sulfate reducing bacteria.

2. The method according to claim 1, characterized in that the anthrahydroquinone compound is in the form of solid particles having an average particle size no greater than 2.5 microns.

3. The method according to claim 1, characterized in that the anthrahydroquinone compound is dissolved in an aqueous solvent.

4. The method according to claim 3, characterized in that the solution of the anthrahydroquinone compound has a pH of at least 12.

5. The method according to claim 1, characterized in that the biofilm is on the surface of the metal in contact with a turbulent liquid stream in which the anthrahydroquinone compound is dispersed.

6. The method according to claim 1, characterized in that the biofilm is on the surface of the metal in contact with a static liquid in which the anthrahydroquinone compound is dispersed.

7. The method according to claim 1, characterized in that the anthrahydroquinone compound is 9,10-dihydroxyanthracene.

8. The method according to claim 1, characterized in that the anthrahydroquinone compound is 9,10-dihydro-9,10-dihydroanthracene.

9. The method according to claim 3, characterized in that the anthrahydroquinone compound is in the form of an alkali metal salt.

10. The method according to claim 5, characterized in that the dispersion of the anthrahydroquinone compound is introduced into the liquid running through a tube as a core whose volume is sufficient to provide a liquid contact with a given point within the pipeline. for at least one minute.

11. The method according to claim 3, characterized in that the core is introduced into the tube immediately following a scraping.

12. The method according to claim 5, characterized in that the aqueous alkaline solution of the anthrahydroquinone compound is added to the liquid flow continuously.

13. The method according to claim 1, characterized in that the anthrahydroquinone compound is metabolized by the sulfate reducing bacteria.