Formation Of Hydrogen Sulfide Research Articles

The Inactivation of LPS Biosynthesis Genes in E. coli Cells Leads to Oxidative Stress.

Impaired lipopolysaccharide biosynthesis in Gram-negative bacteria results in the “deep rough” phenotype, which is characterized by increased sensitivity of cells to various hydrophobic compounds, including antibiotics novobiocin, actinomycin D, erythromycin, etc. The present study showed that E. coli mutants carrying deletions of the ADP-heptose biosynthesis genes became hypersensitive to a wide range of antibacterial drugs: DNA gyrase inhibitors, protein biosynthesis inhibitors (aminoglycosides, tetracycline), RNA polymerase inhibitors (rifampicin), and β-lactams (carbenicillin). In addition, it was found that inactivation of the gmhA, hldE, rfaD, and waaC genes led to dramatic changes in the redox status of cells: a decrease in the pool of reducing NADPH and ATP equivalents, the concentration of intracellular cysteine, a change in thiol homeostasis, and a deficiency in the formation of hydrogen sulfide. In “deep rough” mutants, intensive formation of reactive oxygen species was observed, which, along with a lack of reducing agents, such as reactive sulfur species or NADPH, leads to oxidative stress and an increase in the number of dead cells in the population. Within the framework of modern ideas about the role of oxidative stress as a universal mechanism of the bactericidal action of antibiotics, inhibition of the enzymes of ADP-heptose biosynthesis is a promising direction for increasing the effectiveness of existing antibiotics and solving the problem of multidrug resistance.

Increasing Drilling Speed by Absorption and Hydraulic Supercharging of Drill String in Formation Containing Hydrogen Sulfide: A Case Study

Increasing drilling speed and shortening the well construction period are the goals of the drilling field. The use of downhole speed-up tools has been noted for its advantages such as no additional cost, no change in drilling equipment and no impact on normal drilling operations. However, conventional downhole speed-up tools cannot meet the needs when the drilled formation contains hydrogen sulfide. Then, the technology test on increasing drilling speed by absorption and hydraulic supercharging of drill string in hydrogen sulfide formation was carried out in well Wanweiye1 (WWY1), Anhui Province, China. The results show that: firstly, the speed-up device by absorption and hydraulic supercharging of drill string can be used in the formation containing hydrogen sulfide, and can still perform normal drilling operations with a hydrogen sulfide concentration of 567 ppm; secondly, the speed-up technology by absorption and hydraulic supercharging of drill string has a significant speed-raising effect in the region containing hydrogen sulfide and can raise the speed by 62.5% to 92.05%; thirdly, the speed-up device by absorption and hydraulic supercharging of drill string can meet the needs of high density killing fluid. Once the well WWY1 suffered an overflow, the device did not affect the killing operation when the killing fluid density reached 2.2 g/cm3 and killing time reached 104.8 h.

Comparative studies of properties of CdSe/POMA hybrid films electrodeposited on HOPG, Au and Pt substrates

A simple deposition method was used to prepare photoactive composites containing cadmium selenide (CdSe) and poly(o-methoxyaniline) (POMA) nanofilms deposited on various substrates: HOPG, Au and Pt. The films were fabricated in a configuration substrate/CdSe/POMA. The deposition conditions were electrode substrate dependent. It was determined that the lowest required energy for initiation of polymer deposition is in the order of HOPG<Au<Pt substrate. The photovoltage and photocurrent of fabricated composites depend on the substrate underneath. The highest photocurrents 1.4 mAcm–2 were observed for Pt/CdSe/POMA, while the highest photovoltage 406 mV and 455 mV was registered for Au/CdSe/POMA and Pt/CdSe composites. The AFM and XPS studies explained the influence of the deposition substrate on the formed hybrid's quality. The photodegradation mechanism of CdSe/POMA hybrid was proposed and the role of POMA layer was explained. It was detected that the recombination process depends on a structure of deposited layers. As determined by AFM, CdSe and POMA films are the most crystalline when deposited on Pt, what enhanced photocurrent comparing to other substrates. The thickness of the electrodeposited POMA films decreases in the order HOPG>Au>Pt substrates as concluded from the XPS spectra. The observed metal/CdSe/POMA electrodes restructuring may be explained as the formation of selenates, selenosulfites and hydrogen sulfide due the sacrifizing role of the polymer.

Heart and kidney H2S production is reduced in hypertensive and older rats

The prevalence of hypertension increases with age, but the mechanisms linking this phenomenon are not well understood. Hydrogen sulfide (H2S) may be involved in this process, as it plays a role in the cardiovascular system, affecting blood pressure and heart and kidney functions. The aim of this study was to evaluate the influence of hypertension and aging on sulfur-containing compounds metabolism in the hearts and kidneys of Wistar Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR) of different age groups. We determined the expression and activity of four enzymes participating in H2S production: cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CTH), 3-mercaptopyruvate sulfurtransferase (MPST), and thiosulfate sulfurtransferase (TST). The levels of reduced/oxidized glutathione, cysteine, cystine, and cystathionine, and the ability of tissues to form hydrogen sulfide were also investigated. Tissues obtained from younger WKY rats produced the highest amounts of H2S. The effect of hypertension on the metabolism of sulfur-containing compounds was manifested by a decrease in sulfane sulfur concentrations in heart homogenates and a decrease in CTH activity in the kidneys. The hearts and kidneys of older WKY rats were characterized by lower MPST or CTH gene expression, respectively, compared to younger animals. Our study demonstrates that hypertension and aging influence cardiac and renal sulfur-containing compounds metabolism and reduce H2S production. Furthermore, we showed that MPST plays a major role in the production of hydrogen sulfide in the heart and CTH in the kidneys of rats.

Characteristics and Rates of Microbial Processes in Clays of Different Mineral and Elemental Composition in Relation to Safety Prediction for ESB Clay Materials

Microbial activity in clay barrier materials during radioactive waste disposal can lead to a violation of important physicochemical properties of the barrier system as a whole, thereby reducing the safety of the storage facility. This work evaluates the activity of the microbial complex of five bentonite and two kaolin clays. All clay materials were found to contain microorganisms, mostly with organotrophic aerobic and anaerobic metabolism capable of forming hydrogen sulfide and transforming basic and impurity clay minerals. The activity of microorganisms can increase with the ingress of degradation products of aluminophosphate matrices and cement barriers, as well as radiolysis products. For all clay the rates of microbial processes were shown to exhibit a direct correlation with the content of organic matter, kaolinite, and potassium feldspar, and an inverse correlation with montmorillonite content. A systematic methodological approach is proposed for clay materials and their susceptibility to microbial processes. The approach makes it possible, based on the content of organic matter, biophilic elements in the samples, parameters of the respiratory activity of the microbial complex, the formation of hydrogen sulfide, and other parameters, to assess in advance the possibility of using them in barriers.

Study on antimony cake as a technogenic raw material for the production of antimony oxides

In the process of hydrometallurgical and pyrometallurgical production of antimony at the Kadamzhai antimony plant of the Kyrgyz Republic, large-tonnage waste was generated: tailing sand, matte, slag, off-balance ore, cakes, furnace fragments, and electrolytes in salt warehouses. The waste cake is poorly studied; accordingly, the elemental and phase compositions of antimony cake have not been established. In this regard, it was noted that antimony in the cake occurs in the form of calcium antimonate and antimony hydroxide. The content of antimony in the mine tailings cakes is from 3.53 to 4.4%, with a high content of iron (27.5%) and sodium (8.86%). Based on the established elemental and phase compositions, a chemical matrix of antimony cake was compiled. The equilibrium compositions were calculated and the concentration distribution of the main elements of the cake (Fe, Na, Si, Sb) and their compounds in the gas phase was found depending on the temperature of the destruction of the solid phase. It was found that condensed antimony oxides are formed in the range of 1098 - 1348 K. Taking into account the range of temperatures for decomposition of the solid phase, a two-stage smelting of antimony cake is proposed (melting and cupellation). The conversion of antimony cake sulfides from the gas phase into a solution was carried out based on a study of the system: antimony sulfide- manganese (IV) dioxide- sulfuric acid - sodium chloride. The pH value and the redox potential (Eh) of the solution were calculated. It is noted that the sulfur compounds of antimony from the cake are converted to antimony oxychloride with the formation of antimony (III) oxide in an alkaline medium. The use of sodium chloride as a chlorinating agent of antimony sulfur compounds does not lead to the formation of toxic phosgene and hydrogen sulfide; in the solid phase, elemental sulfur is released, which is important for minimizing the technogenic load of pollutants on the environment.

The influence of carbon steel chemical composition on the biochemical activity of sessile sulfate-reducing bacteria

The technogenic failure caused by biological corrosion of pipelines and other oilfield equipment is an urgent problem for all oil-producing countries of the world. It has been established that many types of corrosion are initiated by the development of sulfate-reducing bacteria on the inner pipe surfaces. This paper presents the results of model laboratory experiments aimed at assessing the effect of the chemical composition of pipeline steel on the number and biochemical activity of sulfate-reducing bacteria development on its surface. Three chromium-containing corrosion-resistant steels were selected for the experiment, steel samples alloyed with 1% manganese were used as control samples. The bacteria for model experiments, mostly belonging to the genus Desulfovibrio, were taken from the inner surface of the damaged pipe after exploitation at an oil field in the Samara Region. In model experiments a reliable influence of the chemical composition of pipe steel on the quantitative characteristics and biochemical activity of bacteria developing on its surface was established. The biochemical activity of sulfate-reducing bacteria, determined by the stimulation of hydrogen sulfide formation and a change in dehydrogenase activity, significantly depended on the chromium content. An increase in the chromium concentration in the tested steel samples by up to 5% reduced the number of sulfate-reducing bacteria and their biochemical activity. The experiments allow us only to make a conclusion about the influence of the chemical composition of pipe steels on the number and biochemical activity of sulfate-reducing bacteria, but do not reveal its resistance to bacterial corrosion.

Successive H-atom Addition to Solid OCS on Compact Amorphous Solid Water

Abstract Carbonyl sulfide (OCS) is an abundant sulfur (S)-bearing species in the interstellar medium. It is present not only in the gas phase, but also on interstellar grains as a solid; therefore, OCS very likely undergoes physicochemical processes on icy surfaces at very low temperatures. The present study experimentally and computationally investigates the reaction of solid OCS with hydrogen (H) atoms on amorphous solid water at low temperatures. The results show that the addition of H to OCS proceeds via quantum tunneling, and further addition of H leads to the formation of carbon monoxide (CO), hydrogen sulfide (H2S), formaldehyde (H2CO), methanol (CH3OH), and thioformic acid (HC(O)SH). These experimental results are explained by our quantum chemical calculations, which demonstrate that the initial addition of H to the S atom of OCS is the most predominant, leading to the formation of OCS-H radicals. Once the formed OCS-H radical is stabilized on ice, further addition of H to the S atom yields CO and H2S, while that to the C atom yields HC(O)SH. We have also confirmed, in a separate experiment, the HC(O)SH formation by the HCO reactions with the SH radicals. The present results would have an important implication for the recent detection of HC(O)SH toward G+0.693–0.027.

Sulfur transformations during two-stage anaerobic digestion and intermediate thermal hydrolysis

The formation of hydrogen sulfide (H2S) during anaerobic digestion (AD) imposes constraints on the valorisation of biogas. So far, inorganic sulfur compounds -mainly sulfate - have been considered as the main contributors to H2S formation, while the contribution of organic sulfur compounds is mostly neglected. This study investigates the fate of organic and inorganic sulfur compounds during two-stage anaerobic digestion with intermediate thermal hydrolysis for treatment of primary and secondary sludge in a WWTP treating domestic wastewater. The results of a seven-week monitoring campaign showed an overall decrease of organic sulfur compounds in both stages of anaerobic digestion. Further fractionation of organic sulfur revealed a high conversion of the particulate organic fraction during the first digestion stage and of the soluble organic fraction during the second digestion stage. The decrease of soluble organic sulfur during the second digestion stage was attributed to the solubilisation and hydrolysis of sulfur-containing organic compounds during thermal hydrolysis. In both digestion stages, more organic sulfur was taken up than particulate inorganic sulfur (metal sulfide) was produced, indicating the formation of other reduced sulfur forms (e.g. H2S). Further batch experiments confirmed the role of organic sulfur uptake in the formation of H2S during anaerobic digestion as sulfate reduction only partly explained the total sulfide formed (H2S in biogas and precipitated FeS). Overall, the conversion of organic sulfur was demonstrated to play a major role in H2S formation (and thus the biogas quality), especially in case of thermal hydrolysis pretreatment.

JP-8 Desulfurization by CuNa-Y zeolite at elevated temperatures has two distinct stages: Chemisorption followed by surface reactions.

This study evaluates the performance of continuous flow adsorbers for adsorptive desulfurization. JP-8 fuel with 2,230 ppmw of sulfur was treated in a flow-through adsorber packed with CuNa-Y zeolite pellets and operating at 180 °C and 200 psig with liquid hourly space velocities (LHSV) from 0.13 to 3.24 h-1. Our results showed that a flow-through adsorber operating at these conditions can effectively reduce the sulfur content of JP-8 to ultra-low values (1-10 ppmw) over the entire LHSV range tested, although the overall performance of the adsorber declined with increasing flow rates as expected. We also observed that the total sulfur removal exceeded the theoretical adsorption limit of our zeolite adsorbent. Detailed characterization of the treated fuel and spent adsorbent via chromatographic and surface analysis techniques revealed that desulfurization occurs in two stages. Sulfur is initially removed via adsorption (chemisorption) on the CuNa-Y zeolite, an assertion supported by simulations with a transient heterogeneous model. As the adsorbent becomes saturated, however, surface chemical reactions start taking place leading to the formation of hydrogen sulfide and polymerization products, and depositing carbon residue on the zeolite. The spent adsorbent was regenerated by treating it with air at 550 or 600 °C, which restored the adsorption capacity of the material to about 90% of its initial value.

Vertical Distribution of Phosphates in the Black Sea Based on the Expeditionary Data, 2016–2019

Purpose. The purpose of the study is to analyze the features of vertical distribution of phosphates and dissolved organic phosphorus (Porg) in the Black Sea at the present period. Methods and Results. The data obtained by the scientists of Marine Hydrophysical Institute in the Black Sea within the economic zone of Russia in 2016–2019 were used. At more than 200 deep-sea stations, a cassette of 12 bathometers (the Seabird-Electronics STD-instrument) was applied for taking hydrochemical samples at certain isopycnic surfaces, usually at σt = 16.30; 16.25; 16.20; 16.20; 16.15; 16.10; 16.05; 16.00; 15.95; 15.90; 15.80; 15.50, 14.0 kg/m3. At the coastal shallow-water stations, samples were taken at the 10 m intervals. Such a scheme permitted to carry out vertical sampling in the upper mixed layer and in the suboxic zone (including its upper boundary) with possible minimum of phosphates, to determine the depth of hydrogen sulfide formation and the location of the phosphates concentration maximum in the upper part of the anaerobic zone. Conclusions. From the surface to isopycn σt = 14.4 kg/m3, the content of phosphates and Porg does not exceed 0.1 µM; below this isopycnic surface, the phosphates concentration begins to increase, whereas of Porg remains at the same level. At all the profiles of the phosphates vertical distribution, the phosphates concentration minimum was recorded near the isopycnic surface σt = 15.8 kg/m3, and its maximum – near the isopycnic surface σt = 16.2 kg/m3. The minimum content of phosphates varied within 0–1.5 µM; in 2016–2017 the phosphates concentration maximum did not exceed 8 µM; in 2018, in many cases, it was higher than 12 µM, and once, near the Kerch Strait, it exceeded 17 µM. Increase in the magnitude of the maximum phosphates concentration (in the previous studies in 1988–2013, it did not exceed 8 µM) is assumed to be related to installation of the supports for constructing the Kerch Bridge.

Importance of thermodynamics dependent kinetic parameters in nitrate-based souring mitigation studies

Souring is the unwanted formation of hydrogen sulfide (H2S) by sulfate-reducing microorganisms (SRM) in sewer systems and seawater flooded oil reservoirs. Nitrate treatment (NT) is one of the major methods to alleviate souring: The mechanism of souring remediation by NT is stimulation of nitrate reducing microorganisms (NRM) that depending on the nitrate reduction pathway can outcompete SRM for common electron donors, or oxidize sulfide to sulfate. However, some nitrate reduction pathways may challenge the efficacy of NT. Therefore, a precise understanding of souring rate, nitrate reduction rate and pathways is crucial for efficient souring management. Here, we investigate the necessity of incorporating two thermodynamic dependent kinetic parameters, namely, the growth yield (Y), and FT, a parameter related to the minimum catabolic energy production required by cells to utilize a given catabolic reaction. We first show that depending on physiochemical conditions, Y and FT for SRM change significantly in the range of [0-0.4] mole biomass per mole electron donor and [0.0006-0.5], respectively, suggesting that these parameters should not be considered constant and that it is important to couple souring models with thermodynamic models. Then, we highlight this further by showing an experimental dataset that can be modeled very well by considering variable FT. Next, we show that nitrate based lithotrophic sulfide oxidation to sulfate (lNRM3) is the dominant nitrate reduction pathway. Then, arguing that thermodynamics would suggest that S° consumption should proceed faster than S0 production, we infer that the reason for frequently observed S0 accumulation is its low solubility. Last, we suggest that nitrate based souring treatment will suffer less from S0 accumulation if we (i) act early, (ii) increase temperature and (iii) supplement stoichiometrically sufficient nitrate.

Biomonitoring Studies and Preventing the Formation of Biogenic H2S in the Wierzchowice Underground Gas Storage Facility

The article discusses the results of biomonitoring research at the Underground Gas Storage (UGS). Hydrogen sulphide, as one of the products of microbiological reaction and transformation, as well as a product of chemical reactions in rocks, is a subject of interest for global petroleum companies. The materials used in this research work were formation waters and stored natural gas. The biomonitoring of reservoir waters and cyclical analyses of the composition of gas stored at UGS Wierzchowice enabled the assessment of the microbiological condition of the reservoir environment and individual storage wells in subsequent years of operation. Investigations of the formation water from individual wells of the UGS Wierzchowice showed the presence of sulphate reducing bacteria bacteria (SRB), such as Desulfovibrio and Desulfotomaculum genera and bacteria that oxidize sulphur compounds. In the last cycles of UGS Wierzchowice, the content of hydrogen sulphide and sulphides in the reservoir waters ranged from 1.22 to 15.5 mg/dm3. The monitoring of natural gas received from UGS production wells and observation wells, which was carried out in terms of the determination of hydrogen sulphide and organic sulphur compounds, made it possible to observe changes in their content in natural gas in individual storage cycles. In the last cycles of UGS Wierzchowice, the content of hydrogen sulphide in natural gas from production wells ranged from 0.69 to 2.89 mg/dm3, and the content of organic sulphur compounds converted to elemental sulphur ranged from 0.055 to 0.130 mg Sel./Nm3. A higher hydrogen sulphide content was recorded in natural gas from observation wells in the range of 2.02–25.15 mg/Nm3. In order to explain the causes of hydrogen sulphide formation at UGS Wierzchowice, isotopic analyses were performed to determine the isotope composition of δ34SH2S, δ34SSO4, δ18OSO4 in natural gas samples (production and observation wells) and in the deep sample of reservoir water. The results of isotope tests in connection with microbiological tests, chromatographic analyses of sulphur compounds in natural gas collected from UGS Wierzchowice and an analysis of the geological structure of the Wierzchowice deposit allow us to conclude that the dominant processes responsible for the formation of hydrogen sulphide at UGS Wierzchowice are microbiological, consisting of microbial sulphate reduction (MSR). The presented tests allow for the control and maintenance of hydrogen sulphide at a low level in the natural gas received from the Wierzchowice Underground Gas Storage facility.

Vertikal'noye raspredeleniye form fosfora v Chernom more po ekspeditsionnym dannym 2016–2019 godov

Purpose. The purpose of the study is to analyze the features of vertical distribution of phosphates and dissolved organic phosphorus (Porg) in the Black Sea at the present period. Methods and Results. The data obtained by the scientists of Marine Hydrophysical Institute in the Black Sea within the economic zone of Russia in 2016–2019 were used. At more than 200 deep-sea stations, a cassette of 12 bathometers (the Seabird-Electronics STD-instrument) was applied for taking hydrochemical samples at certain isopycnic surfaces, usually at σt = 16.30; 16.25; 16.20; 16.20; 16.15; 16.10; 16.05; 16.00; 15.95; 15.90; 15.80; 15.50, 14.0 kg/m3. At the coastal shallow-water stations, samples were taken at the 10 m intervals. Such a scheme permitted to carry out vertical sampling in the upper mixed layer and in the suboxic zone (including its upper boundary) with possible minimum of phosphates, to determine the depth of hydrogen sulfide formation and the location of the phosphates concentration maximum in the upper part of the anaerobic zone. Conclusions. From the surface to isopycn σt = 14.4 kg/m3, the content of phosphates and Porg does not exceed 0.1 µM; below this isopycnic surface, the phosphates concentration begins to increase, whereas of Porg remains at the same level. At all the profiles of the phosphates vertical distribution, the phosphates concentration minimum was recorded near the isopycnic surface σt = 15.8 kg/m3, and its maximum – near the isopycnic surface σt = 16.2 kg/m3. The minimum content of phosphates varied within 0–1.5 µM; in 2016–2017 the phosphates concentration maximum did not exceed 8 µM; in 2018, in many cases, it was higher than 12 µM, and once, near the Kerch Strait, it exceeded 17 µM. Increase in the magnitude of the maximum phosphates concentration (in the previous studies in 1988– 2013, it did not exceed 8 µM) is assumed to be related to installation of the supports for constructing the Kerch Bridge.

Ferric Oxide-Containing Waterworks Sludge Reduces Emissions of Hydrogen Sulfide in Biogas Plants and the Needs for Virgin Chemicals

Ferric oxide-containing waterworks sludge can be used to reduce the formation of hydrogen sulfide during anaerobic digestion. The ferric compound is reduced biochemically in the digester and forms insoluble pyrite in digester sludge. Virgin ferric chloride is often used to solve the hydrogen sulfide problem. Since 2013, Sydvatten AB has supplied a growing number of digestion plants in Sweden with ferric-containing dewatered waterworks sludge derived from the drinking water treatment plant Ringsjöverket to limit the formation of hydrogen sulfide. At the waterworks, ferric chloride is added to enhance the coagulation of organic matter from the source water. The sludge formed in this process is dewatered and landfilled, but also recycled in biogas production in order to decrease the hydrogen sulfide concentration. In this study, the use of sludge for hydrogen sulfide removal in digesters was technically and economically evaluated via case studies from 13 full-scale digesters in Sweden. Compared with the use of fresh ferric chloride, the operational costs are reduced by up to 50% by using sludge. The quality of the sludge is high and its content in metals is low or very low, especially when compared with the requirements of different certification standards for biosolid reuse applied in Sweden. The addition of waterworks sludge containing iron to a digester for the removal of dissolved hydrogen sulfide is a technically and economically good alternative when producing biogas. It is also one step closer to a circular economy, as replacing the use of virgin chemicals with the by-product waterworks sludge saves energy and materials and reduces the carbon footprint of the waterworks.

An empirical correlation-based model to predict solid-fluid phase equilibria and phase separation of the ternary system CH4-CO2-H2S

To cover the expected increased demand for natural gas, energy industry has to exploit sour gas reserves located around the world. However, acid gases have to be removed before the natural gas produced from these fields could be used. One of the novel concepts in this field is the utilization of solid phase formation of carbon dioxide and/or hydrogen sulfide. The main aim of this study is to develop an empirical correlation model based on Peng-Robinson equation of state (PR EoS), with fugacity expressions, that is able for the first time to describe the solid-fluid phase equilibria for the ternary system of CH4-CO2-H2S at pressures from 5 to 30 bar and over a wide range of temperature (130–200 K). The model was first tested on the binary systems of CH4-CO2, CO2-H2S and CH4-H2S with optimized interaction parameters. When proven to be successful, it was then expanded in a predictive manner to describe the ternary system of CH4-CO2-H2S. The model predictions for the solidification points of 5 different mixtures were within the acceptable error when compared to the experimental data available in the literature. A model based on equilibrium stage separation unit was used to study the separation of three different feed compositions of this ternary system. Overall, it was found that separation of CO2 in solid phase improves when increasing the operating pressure up to 20 bar, and decreases at higher temperatures. Similarly, the separation of H2S in either liquid or solid phase improves at higher pressures and lower temperatures. The recovery of CH4 was high over the entire ranges of operating conditions, expect at high pressure (30 Bar) at temperatures below 190 K. This work provides scientists and engineers with an accurate tool that may be used with confidence for predicting solid-fluid phase equilibria. Consequently, this model eliminates difficulties associated with the need for experiments on ternary system solid-fluid phase equilibria.

მდ. ალაზნის მარცხენა სანაპიროს გოგირდწყალბადიანი მინერალური წყლების წარმოშობის გეოქიმიური პირობები

Based on the description of the geological structure and hydrogeological conditions of the area in question, there is an opinion about the formation of hydrogen sulfide in groundwater. However, this view differs from the classical theory of sulfate reduction. It is substantiated that the production of hydrogen sulfide in groundwater due to the action of sulfate bacteria takes place not only in the recovery environment, but also in the oxidation zone. The validity of this view is confirmed by the analysis of deep hydrogeological wells and field survey data. Existence of hydrogen sulfide mineral springs within Kakheti is related to carbonate flysch. Their formation, circulation, including natural solutions is entirely in the form of carbonate flysch and is probably the origin of the formation of hydrogen sulfide healing waters. In addition to the mineral springs of Kakheti, the wide prospects of practical use of these waters are discussed, which is related to the picturesque nature and excellent climatic conditions of the area, which provides a great opportunity for resort-medical construction in the Kakheti region.

РАЗРАБОТКА СХЕМЫ ВЫДЕЛЕНИЯ И БАКТЕРИОЛОГИЧЕСКОЙ ИДЕНТИФИКАЦИИ БАКТЕРИЙ PSEUDOMONAS SYRINGAE И ЕЕ АПРОБАЦИИ

The article presents results of studies on development of isolation scheme and bacteriological identification of Pseudomonas syringae bacteria and its approbation. The introduction of the article describes the objects of Pseudomonas syringae contamination - fruit trees and shrubs, agricultural plants, which proves the relevance of the research in the field of expanding of laboratory methods for identifying phytopathogenic microorganisms. The author’s bacteriological scheme includes the use of King B Medium (Pseudomonas F Agar; Pronadisa 1532) as a selective medium. Initially, the isolated bacteria are differentiated to Pseudomonas genus, the following paramters are studied: anaerobic fermentation, production of enzymes catalase, lecithinase, lipase; hydrolysis of starch and gelatin; fermentation of glucose and lactose, also, a test for maceration is put. The second stage of the research includes the study of the growth of bacterial cultures on meat-and-peptone agar at 41 ° C and at 5% of NaCl; oxidase production, arginine hydrolase; fermentation of mannose and sorbitol; formation of levan, hydrogen sulfide and indole, esculin, a hypersensitivity reaction is set. The determined parametres allow to type the representatives of the genus to Pseudomonas syringae species within 192 hours. During the research, a collection of 12 strains of Pseudomonas syringae bacteria was formed, isolated from 97 objects of phytosanitary supervision and identified according to the developed technique. The proposed bacteriological scheme allows to differentiate the above microorganisms on the basis of the analysis of 25 parameters. The application of a phage biological product as a diagnosticum (according to the Otto method) expands the spectrum of the analyzed biological properties of the isolated and identified Pseudomonas syringae bacteria.

Complex Alumina-Ferrous Coagulant for Effective Wastewater Purification from Hydrogen Sulfide

The article provides an overview of studies on the causes of the formation of hydrogen sulfide in anaerobic conditions of urban sewage systems and methods for neutralizing toxic reagent sulfur-containing compounds. It is noted that the presence of sulfur compounds and organic components in sewage flow leads to the formation and release of hydrogen sulfide into the atmosphere of settlements. Three main categories of methods for purifying sewage wastewater from hydrogen sulfide are presented. In this work, a complex alumina-ferrous coagulant has been developed from Kazakh raw materials. Based on natural ferruginous diatomite and middlings of sintered alumina, a complex alumina-ferrous coagulant has been synthesized, which is effective in purifying wastewater from hydrogen sulfide, accelerating the processes of sedimentation and clarification of sewage slurries. Experimental results also show that with the supply of increased amounts of coagulant, oil and oil films disappear from the surface of the cylinder, an almost complete purification of effluents from hydrogen sulfide compounds occurs, and the color of the liquid part is greatly reduced. In addition, the advantage of the developed reagent is that it is presented in the form of fine powder and can be easily dosed and added to a canalization pump station to interact with diluted hydrogen sulfide and be transported to sewage fields. Compared to other proposed methods in previous works, the reagent is suitable to be used directly in sewage systems such as sewage waters treatment plants and collectors to prevent hydrogen sulfide emission into the air atmosphere of populated areas, as well as at city sewage water treatment stations after air tanks and before secondary clarifiers to obtain better purified water suitable for watering agricultural plants.

Ferrocene addition for suppression of hydrogen sulfide formation during thermal recovery of oil sand bitumen

The occurrence of H2S during thermal recovery production becomes one of the biggest challenges. While various industrial processes can remove H2S at the surface, to prevent the formation of H2S in reservoir is much less successful. Ferrocene was chosen as the likely target reagent after a review of iron compound volatility and environmental considerations. To evaluate this, closed system gold tube pyrolysis experiments were conducted on an Athabasca oil sand at 350–650 °C to examine gas compositions with and without ferrocene addition. Slightly higher hydrocarbon gas yields have been observed from samples with ferrocene addition likely caused by ferrocene decomposition. Yields of carbon dioxide (CO2) are higher in plain oil sand samples before 550 °C but the trend was reversed afterwards with more CO2 being generated from ferrocene addition ones. H2S yields in samples without ferrocene increase from background value at 350 °C to the highest amount at 450 °C then disappear above 625 °C. Thermal decomposition of organosulfur compounds is supposed to be the main route for the occurrence of H2S in the sulfur-rich bitumen pyrolysis. Ferrocene is proved to be powerful H2S removal reagent as no H2S can be detected from ferrocene addition samples. The reactions of ferrocene with H2S may form iron sulfides, cyclopentadiene and hydrogen. Complete, rapid, and predictable reactions and inert reaction products make ferrocene as an ideal in situ H2S scavenger, while the potential for the deposition of metal sulfides may reduce the permeability. Ferrocene is widely available for industry, however, the unit cost has not been assessed in this study.