Biocidal agent (mixture) in a highly saline aqueous system

Abstract

Biocidal agent for controlling hydrogen-utilizing microorganisms during underground storage or transport of hydrogen (H2) and its mixtures, in caverns, pore storage, tanks and pipelines to suppress microbial hydrogen utilization, consisting of a mixture of - zinc salt, preferably zinc chloride, and / or zinc nitrate and / or zinc hydroxide and - highly saline liquids, cavern brines, saline storage waters or process waters where the zinc salt, a zinc salt (ZnX m - ) in dissolved form, where X - an anion chloride (CI - ), Nitrate (NO3 - ), sulfate (SO4 2- ), sulfide (S 2- ), oxide (O 2- ), hydroxide (OH - ), acetate (CH3COO - ) means and where the salt concentration is between 150 g NaCl / l and saturated brine as well as Zinc salts (ZnX- m ) therein be 20 to 1000 ppm / l or zinc chloride (ZnCl2) therein be 20 to 1000 ppm / l, preferably between 20 and 500 ppm / l.

Description

Biocidal agent (mixture) in a highly saline aqueous system and method of using the same.The invention relates to a biocidal composition in a highly saline aqueous system for controlling hydrogen-utilizing microorganisms in the storage and transport of hydrogen and hydrogen gas mixtures thereof in underground storage facilities, tanks and pipelines for avoiding microbial processes thereof and for binding hydrogen sulfide, and to a method for applying the same, in particular in caverns.By converting to a carbon-free energy economy, the industrial storage of hydrogen (in a proportion or in pure form) in underground stores is prepared. Since, unlike hydrocarbons and methane, hydrogen can be metabolized by numerous microorganisms both aerobically and anaerobically (hydrogenotrophy), there is a high risk of storing hydrogen underground in pore reservoirs or caverns. For stable storage of hydrogen in these underground stores, the microbial activity based on hydrogen consumption must be suppressed as much as possible. Due to the large quantities of the liquid to be treated in an underground storage, the extremely high salt content in brine and taking into account high environmental requirements, the use of conventional biocides is almost ruled out from economic, technical and ecological points of view.There is therefore a high interest in an efficient and cost-effective agent which develops a high biocidal effect in highly saline liquids, already occurs naturally and can optionally be separated again from the brine by suitable methods. The agent should be chemically stable, readily soluble even in saturated brine and easy to handle, and not contaminate the hydrogen-containing storage gas.It is known that both pore reservoirs and caverns house a wide variety of microbial communityes which can proliferate under extreme conditions such as oxygen free, high temperatures, high salinity and / or high pressure. Methanogenesis, acetogenesis, sulfate reduction and iron reduction are the essential microbial processes which play a role in the underground storage of hydrogen and mixtures thereof, the sulfide formed by sulfate-reducing prokaryotes being a particular risk for storage operation. Non-bound sulfide can thereby pass into the gas phase in the form of hydrogen sulfide. The hydrogen sulfide is highly toxic and causes considerable technical problems, inter alia as catalyst poison and also as a result of a strong corrosive action on plant parts above the surface.Furthermore, numerous biocidal formulations are known which control microorganisms more or less efficiently (DE69915066T2, EP 0203892A2, WP A 01n / 184 777).In most cases, these are limited to use in waters with a low salt content or are unsuitable for use in underground storage systems for various reasons (foam formation or emulsion formation, precipitation, ecotoxicological non-suitability).The use of zinc salts, for example of microorganisms utilizing zinc chloride for controlling hydrocarbons in the storage of hydrocarbon gases (natural gas, ethylene), for this purpose in a mixture with an aqueous salt solution (DD WP 01n / 193409) is also known.It is an object of the invention to provide a biocidal composition as a mixture for suppressing hydrogenotrophic microorganisms and for eliminating hydrogen sulfide during the storage and transport of hydrogen (H2) and hydrogen gas mixtures. It is intended to be an efficient and cost-effective substance which develops a high biocidal effect in highly saline liquids, already occurs naturally and can optionally be separated again from the brine by suitable methods. The agent should be chemically stable, readily soluble even in saturated brine, and easy to handle, and not contaminate the hydrogen gas and mixtures thereof.According to the invention, the object is achieved as specified by the claims.Studies have shown that a very good biocidal effect of zinc salts, preferably zinc chloride, on hydrogenotrophic microorganisms can be demonstrated, as a result of which it is possible to effectively treat salt-containing liquids, such as, for example, highly saline cavernsols or process waters, by means of zinc chloride and thus to inhibit or completely suppress the microbial activity. It is immaterial in what proportion hydrogen may be added to other gases, such as methane, or is present in pure form.Thus, a biocidal agent against the growth and colonization of hydrogen-utilizing microorganisms in the storage and transport of hydrogen (H2) and mixtures thereof, in caverns, tanks and pipelines for avoiding microbial decomposition processes of hydrogen (H2) and of hydrogen gas mixtures, consists of a mixture ofzinc salt, preferably zinc chloride and / or zinc nitrate and / or zinc hydroxide, andsalt-containing aqueous solutions, such as salt sols and / or process waters or highly salty storage water, wherein the zinc salt is a zinc salt (ZnX m-) in dissolved form, wherein X - is an anion chloride (Cl -), nitrate (NO 3-), sulfate (SO 42-), sulfide (S 2-), oxide (O 2-), hydroxide (OH -), Acetate (CH 3 COO -) and wherein the salt concentration is between 150 g NaCl / l and saturated brine and the concentration of zinc salts (ZnX -m) therein is 20 to 1,000 ppm or zinc chloride (ZnCl 2) therein is 20 to 1,000 ppm, preferably present at a concentration between 20 and 500 ppm and wherein it may contain further active substances which have the ability to kill or inhibit in activity microorganisms such as bacteria, archaea, algae or fungi and wherein it contains further substances for reducing hydrogen sulfide release, such as substances for increasing the pH, namely sodium hydroxide, potassium hydroxide or those which form insoluble compounds with sulfide, as well as metals or metal ions, and wherein these may contain corrosion inhibitors and / or detergents and / or tracers and / or other buffer solutions.The biocidal agent can be formulated such that the zinc salt present can be removed again from the brine, if required, for example by electrolytic zinc deposition.The biocidal agent or the active ingredients thereof can be added directly to the cavern sump in the highly saline cavernensols present there.The biocidal agent or the active ingredients thereof can be effected by injection and / or nebulisation into the cavern gas space and as a result of which the cavern walls receive a biocidal protective film and a biocidal minimum concentration can be achieved in the cavernenol. The naturally present salt concentration in the high saline aqueous system can be artificially increased by adding salt.The good biocidal effect of the biocidal composition according to the invention is advantageous, in particular against hydrogenotrophic microorganisms in salt-containing liquids, in particular highly saline cavernensols in connection with hydrogen and hydrogen mixtures.In addition to the biocidal effect on hydrogen-utilizing microorganisms, microbially formed sulfide is permanently bound and thus the release of extremely harmful hydrogen sulfide into the gas phase of a cavern is significantly reduced. Thus, the release of harmful hydrogen sulfide in its gas phase is reduced by a controlled increase in the pH in the cavern liquid.The invention is explained below using an exemplary embodiment. In a salt cavern for storing hydrogen, the degree of microbial colonization of the saline caverns is first determined on the basis of a sample taken from the cavern bottoms by microbiological and / or molecular biological standard methods. At the same time, an active culture of the microorganisms occurring is enriched from the samples taken in order to determine the actually effective zinc chloride concentration. For this purpose, under sterile conditions, an identical series of sterile, brine-containing nutrient media (for example 15 ml) is each inoculated with the same amount of this test culture (for example 1 ml each). To this series of tests of identical culture batches, a defined amount of zinc chloride is in each case added in such a way that the final concentration of zinc chloride increases with each tube, the first tube without zinc chloride functioning as a positive control (e.g. 0 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, 250 ppm, 500 ppm, 1,000 ppm, etc.). The tubes are sealed gas-tight and covered with a hydrogen atmosphere so that the air is completely displaced and further entry is prevented.The dilution series applied in this way is incubated at 30° C., for example, until clear microbial growth becomes recognizable in the positive control. This can be detectable, for example, by turbidity or black coloration by FeS formation.All tubes are then examined in sequence for microbial growth, optionally by microscopic evaluation. The first dilution step, which does not show any growth, indicates the minimum effective concentration of zinc chloride.Biocide testing with increasing ZnCl 2- concentration (ppm):Row A+++++------Row B+++++------Series C++++++-----The zinc chloride concentration determined in this way should represent, with a certain safety margin, the concentration used for the treatment of the cavernenols. For this purpose, the total volume of the cavern sump must be estimated as possible and the amount of zinc chloride required for a successful treatment must be established. Since zinc chloride is very readily soluble even in saturated NaCl brine, the introduction into the cavern can be effected as a highly concentrated zinc chloride solution, good distribution by, for example, injection or nebulisation being advantageous.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 69915066T2

[0006] EP 0203892A2

[0006]

Claims

Biocidal agent for controlling hydrogen-utilizing microorganisms in the storage of underground or in the transport of hydrogen (H2) and mixtures thereof, in caverns, pore reservoirs, tanks and pipelines for suppressing microbial hydrogen utilization, consisting of a mixture of - zinc salt, preferably zinc chloride, and / or zinc nitrate and / or zinc hydroxide, and - highly saline liquids, cavernsols, saline storage waters or process waters, wherein the zinc salt is a zinc salt (ZnX m-) in dissolved form, in which X - is an anion chloride (Cl -), nitrate (NO 3-), sulfate (SO 42-), Sulfide (S 2-), oxide (O 2-), hydroxide (OH -), acetate (CH 3 COO -) and wherein the salt concentration is between 150 g NaCl / l and saturated brine and zinc salts (ZnX -m) therein are 20 to 1000 ppm / l or zinc chloride (ZnCl 2) therein are 20 to 1000 ppm / l, preferably between 20 and 500 ppm / l.Biocidal agent according to Claim 1, characterized in that it comprises other substances for reducing hydrogen sulfide release, such as substances for increasing the pH, namely sodium hydroxide, potassium hydroxide or those which form insoluble compounds with sulfide, such as metals or metal ions.Biocidal agent according to claims 1 and 2, characterised in that it contains corrosion inhibitors and / or detergents and / or tracers and / or other buffer solutions.Biocidal agent according to one or more of the preceding claims, characterized in that the zinc salt present can be removed again from the brine, if required, for example by electrolytic zinc deposition.Biocidal agent according to one or more of the preceding claims, characterized in that the same or the active ingredients thereof are metered directly into the cavern sump into the highly saline cavernenols present there.Biocidal agent according to one or more of the preceding claims, characterized in that the metering of the same or of the active ingredients thereof takes place by injection and / or nebulisation into the cavern gas space and the cavern walls thereby obtain a biocidal protective film and a biocidal minimum concentration can be achieved in the cavernenol.Biocidal agent according to one or more of the preceding claims, characterized in that the naturally present salt concentration in the high-salt aqueous system can be artificially increased by addition of salt.