Formation Of Hydrogen Sulfide Research Articles

Sulfur adsorption and release properties of bimetallic Pd–Ni supported catalysts

The formation of hydrogen sulfide in car exhaust is undesirable due to unpleasant odor and toxicity of H2S gas. H2S release can be suppressed by the addition of a NiO scavenger to a three-way catalyst (TWC). In this work, Pd–Ni bimetallic catalysts were prepared by the co-addition of Pd and Ni to γ-Al2O3 or Al2O3-La2O3 support, by the impregnation method. Different concentrations of a propionic acid aqueous solution were used as the impregnation solvent. The structure of prepared catalysts was characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature-programmed reduction (TPR) techniques. Catalyst poisoning by SO2 was simulated under lean conditions and H2S release under rich conditions. XRD and TPR measurements revealed the effect of the impregnation solvent concentration on the ratio between NiO and NiAl2O4 spinel species and the reducibility of Ni species. Co-addition of Pd with Ni was proven to be beneficial for H2S suppression. Prepared bimetallic catalysts released considerably less H2S compared to physical mixtures of Pd/Al2O3 with NiO. The presence of bulk and well dispersed NiO on Pd–Ni catalysts assisted in sulfur release in the form of sulfur oxides rather than H2S. Bimetallic catalysts supported on Al2O3-La2O3 were found to release more H2S compared to catalysts on γ-Al2O3. The use of diluted solvent in bimetallic catalysts preparation decreased H2S release from Pd–Ni catalysts.

Pediatric Cystic Fibrosis Sputum Can Be Chemically Dynamic, Anoxic, and Extremely Reduced Due to Hydrogen Sulfide Formation.

ABSTRACTSevere and persistent bacterial lung infections characterize cystic fibrosis (CF). While several studies have documented the microbial diversity within CF lung mucus, we know much less about the inorganic chemistry that constrains microbial metabolic processes and their distribution. We hypothesized that sputum is chemically heterogeneous both within and between patients. To test this, we measured microprofiles of oxygen and sulfide concentrations as well as pH and oxidation-reduction potentials in 48 sputum samples from 22 pediatric patients with CF. Inorganic ions were measured in 20 samples from 12 patients. In all cases, oxygen was depleted within the first few millimeters below the sputum-air interface. Apart from this steep oxycline, anoxia dominated the sputum environment. Different sputum samples exhibited a broad range of redox conditions, with either oxidizing (16 mV to 355 mV) or reducing (−300 to −107 mV) potentials. The majority of reduced samples contained hydrogen sulfide and had a low pH (2.9 to 6.5). Sulfide concentrations increased at a rate of 0.30 µM H2S/min. Nitrous oxide was detected in only one sample that also contained sulfide. Microenvironmental variability was observed both within a single patient over time and between patients. Modeling oxygen dynamics within CF mucus plugs indicates that anoxic zones vary as a function of bacterial load and mucus thickness and can occupy a significant portion of the mucus volume. Thus, aerobic respiration accounts only partially for pathogen survival in CF sputum, motivating research to identify mechanisms of survival under conditions that span fluctuating redox states, including sulfidic environments.

Hydrogen sulfide formation characteristics of pulverized coal combustion – Evaluation of blended combustion of two bituminous coals

Abstract This paper presents the characteristics of sulfur release during pyrolysis and hydrogen sulfide (H2S) formation for the pulverized coal combustion of blends of two bituminous coals in a pulverized coal combustion test furnace. The amount of sulfur released during pyrolysis is affected by the total sulfur content and the form of sulfur. Organic sulfur is more readily released to the gaseous phase than pyritic sulfur and sulfate sulfur. When blends of two bituminous coals releasing different amounts of sulfur are fired, the H2S concentrations are between those for the combustion of the single coals. The peak H2S concentration in the near-burner region in the blended combustion coincides with the value estimated from the blending ratio, which means that there is no interaction between the sulfur releases of the two coals during pyrolysis. The reaction behavior of H2S and SO2 after the release of sulfur during the blended combustion is the same as that in the combustion of each single coal.

Estradiol of various saturation and its influence on hydrogen sulfide formation in the myocardium of female rats.

Hydrogen sulfide is signalling molecule that regulates vascular tone and myocardial contractility. Role of estradiol in hydrogen sulfide production in cardiovascular system of rats remains unclear and this becames research objective. Effect of estradiol on hydrogen sulfide level, cystathionine-γ -lyase activity and its kinetic parameters - Michaelis constant (Km) and maximum rate (Vmax) in rats’ heart was estimated. Experiments were conducted on 45 white nonlinear female rats. Deficit of sex hormones level in females was modulated by castration - ovariectomy and hormone replacement therapy with estradiol. It is shown that the production of hydrogen sulfide in the myocardium is determined by the level of estradiol: castration of females causes a significant decrease in myocardial hydrogen sulfide content, cystathionine-γ-lyase activity, maximum rate of hydrogen sulfide formation from cysteine in participation of cystathionine-γ-lyase, as well as increase in Michaelis constant of this enzyme in comparison with the controls. Hormone replacement therapy with estradiol brings nearer hydrogen sulfide level, cystathionine-γ-lyase activity and kinetic parameters of cysteine desulfuration reaction in the rats’ myocardium to the levels of the control group. Thus, estradiol is involved in regulation of hydrogen sulfide production in cardiovascular system of rats, namely it increases cystathionine-γ-lyase activity and its affinity to cysteine.

Dissimilatory sulfate reduction in bacteria Desulfovibrio desulfuricans ІМV К-6 upon influence of Uragan and Raundup herbicides

Objects of the study were sulfate-reducing bacteria Desulfovibrio desulfuricans ІМV К-6, isolated from Yavorivske lakе. This strain is kept in the collection of microorganisms at the Department of Microbiology of Ivan Franko National University. Bacteria were grown in the Kravtsov-Sorokin’s liquid medium with the following composition (g/l): Na2SO4 × 10H2O – 0.5, NaH2PO4 – 0.3, K2HPO4 – 0.5, (NH4)2SO4 – 0.2, MgSO4 × 7H2O – 0.1, C3H5O3Na – 2.0. The bacteria were grown for 10 days at 30 °C under anaerobic conditions. In order to study the sensitivity of the sulfate reducing bacteria to action of Uragan and Raundup herbicides, the cells of D. desulfuricans ІМV К-6 were grown at the concentrations of herbicides as follows: 0,28 mМ, 2,8 mМ (concentration recommended for use) and 5,6 mM. Biomass was determined by photometric method. Concentration of hydrogen sulfide in the culture medium was determined by photo-colorimetric method. Concentration of sulfate-ions in the medium was determined by turbidimetric method. Capacity of sulfate reducing bacteria D. desulfuricans ІМV K-6 to grow, reducing sulfates to hydrogen sulfide upon influence of Uragan and Raundup herbicides was studied. Accumulation of bacterial biomass in the control and upon influence of herbicides was the highest on the fourth-sixth day of cultivation, and after that the stationary growth phase began. It was shown that sulfate reducing bacteria upon influence of herbicides grew more intensively compared with the control. It was discovered that the level of biomass changed depending on the increasing concentration of Uragan or Raundup herbicides in the medium. Sulfate reducing bacteria D. desulfuricans ІМV K-6 could reduce sulfates to hydrogen sulfide in the presence of sulfates and organic compounds in the medium (dissimilatory sulfate reduction). Stimulatory influence of Uragan and Raundup on the dissimilatory sulfate reduction process of D. desulfuricans ІМВ К-6 has been discovered. The formation of hydrogen sulfide correlates with the usage of sulfatе ions. The capacity of sulfate reducing bacteria D. desulfuricans ІМV K-6 to grow, reducing sulfate ions to hydrogen sulfide upon influence of Uragan and Raundup may be caused by presence of inert components (sulfates) in these herbicides that can be used by microorganisms as electron acceptors during sulfate respiration.

Impact of water management practice scenarios on wastewater flow and contaminant concentration

Due to frequent droughts and rapid population growth in urban areas, the adoption of practices to reduce the usage of fresh water is on the rise. Reduction in usage of fresh water can be achieved through various local water management practices (WMP) such as Water Demand Management (WDM) and use of alternative water sources such as Greywater Recycling (GR) and Rainwater Harvesting (RH). While the positive effects of WMPs have been widely acknowledged, the implementation of WMPs is also likely to lower the wastewater flow and increase the concentration of contaminants in sewage. These in turn can lead to increases in sewer problems such as odour and corrosion. This paper analyses impacts of various WMP scenarios on wastewater flow and contaminant load. The Urban Volume and Quality (UVQ) model was used to simulate wastewater flow and the associated wastewater contaminants from different WMP scenarios. The wastewater parameters investigated were those which influence odour and corrosion problems in sewerage networks due to the formation of hydrogen sulphide. These parameters are: chemical oxygen demand (COD), nitrate (NO3−), sulphate (SO42−), sulphide (S2−) and iron (Fe) that were contributed by the households (not including the biochemical process in sewer pipe). The results will help to quantify the impact of WMP scenarios on odour and corrosion in sewerage pipe networks. Results show that the implementation of a combination of WDM and GR had highly increased the concentration of all selected contaminant that triggered the formation of hydrogen sulphide, namely COD, sulphate and sulphide. On the other hand, the RH scenario had the least increase in the concentration of the contaminants, except iron concentrations. The increase in iron concentrations is actually beneficial because it inhibits the formation of hydrogen sulphide.

Cetia pacifica gen. nov., sp. nov., a chemolithoautotrophic, thermophilic, nitrate-ammonifying bacterium from a deep-sea hydrothermal vent

A thermophilic, anaerobic, chemolithoautotrophic bacterium, strain TB-6(T), was isolated from a deep-sea hydrothermal vent located on the East Pacific Rise at 9° N. The cells were Gram-staining-negative and rod-shaped with one or more polar flagella. Cell size was approximately 1-1.5 µm in length and 0.5 µm in width. Strain TB-6(T) grew between 45 and 70 °C (optimum 55-60 °C), 0 and 35 g NaCl l(-1) (optimum 20-30 g l(-1)) and pH 4.5 and 7.5 (optimum pH 5.5-6.0). Generation time under optimal conditions was 2 h. Growth of strain TB-6(T) occurred with H2 as the energy source, CO2 as the carbon source and nitrate or sulfur as electron acceptors, with formation of ammonium or hydrogen sulfide, respectively. Acetate, (+)-d-glucose, Casamino acids, sucrose and yeast extract were not used as carbon and energy sources. Inhibition of growth occurred in the presence of lactate, peptone and tryptone under a H2/CO2 (80 : 20; 200 kPa) gas phase. Thiosulfate, sulfite, arsenate, selenate and oxygen were not used as electron acceptors. The G+C content of the genomic DNA was 36.8 mol%. Phylogenetic analysis of the 16S rRNA gene of strain TB-6(T) showed that this organism branched separately from the three most closely related genera, Caminibacter , Nautilia and Lebetimonas , within the family Nautiliaceae . Strain TB-6(T) contained several unique fatty acids in comparison with other members of the family Nautiliaceae . Based on experimental evidence, it is proposed that the organism represents a novel species and genus within the family Nautiliaceae , Cetia pacifica, gen. nov., sp. nov. The type strain is TB-6(T) ( = DSM 27783(T) = JCM 19563(T)).

Enamel surface changes caused by hydrogen sulfide.

Background:Volatile sulfur compounds (VSCs) produced inside the mouth are a well-known cause of halitosis. Recent studies have suggested that VSCs modify the pathology of periodontitis by encouraging the migration of bacterial toxins associated with increased permeability of gingival epithelia, and enhancing the production of matrix metalloproteinases in gingival connective tissue. Nonetheless, the effects on the enamel of direct exposure to VSCs within the oral cavity remain unclear.In the present study, we observed the effects of VSCs in the form of hydrogen sulfide (H2S) on enamel surfaces and determined their effects on restorations.Materials and Methods:Extracted human tooth and bovine tooth samples were divided into the H2S experimental side and the control side. We observed the effects of H2S on enamel surfaces using electron microscopy and conducted a shear test.Results:We found that exposure to H2S obscured the enamel surface's crystal structure. The surface also exhibited coarseness and reticular changes. Shear testing did not reveal any differences in bond strength.Conclusions:Our findings suggested that H2S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations.

Redox regulation of mammalian 3-mercaptopyruvate sulfurtransferase.

A cystine-catabolizing enzyme, 3-mercaptopyruvate sulfurtransferase catalyzes the trans-sulfuration reaction of mercaptopyruvate or thiosulfate to thiol-containing compounds or cyanide. During the catalytic process, persulfide is formed at the catalytic site cysteine residue and a sulfur-acceptor substrate donates the outer sulfur of the persulfide to form a new persulfide molecule. Subsequently, the molecule can be reduced by thioredoxin to form hydrogen sulfide. The enzyme is regulated by redox changes via two redox-sensing molecular switches consisting redox-sensitive cysteine residues. One switch is the catalytic cysteine in itself, which is oxidized to form a cysteine-sulfenate resulting in inhibition of catalytic activity. The sulfenate can be reduced by thioredoxin resulting in restoration of the activity. The redox potential of sulfenate is lower than that of glutathione and greater than that of thioredoxin. The other switch involves cysteine residues positioned on the surface of the enzyme. The oxidation the intermolecular disulfide linkage at these cysteine residues, leading to dimer formation, inhibits enzyme activity. On the other hand, reduction-associated monomer formation increases catalytic activity. Thioredoxin reduces the disulfide bond more effectively than dithiothreitol, although the specificity mechanism has not been identified. Congenital defects in this enzyme result in, mercaptolactate-cysteine disulfiduria associated with or without mental retardation. However, the pathogenesis has not been identified. Because 3-mercaptopyruvate sulfurtransferase serves as a cellular antioxidative protein, the other biological functions related to the inhabitant disease are being investigated.

Iron flocculation stimulates biogas production in Microthrix parvicella-spiked wastewater sludge

Municipal wastewater sludge has been used for fertiliser and biogas production for several decades. Chemical compounds such as iron and aluminium are common coagulants used in wastewater treatment plants to remove suspended solids, phosphorus and micro-organisms. This laboratory study explores whether ferric chloride (FeCl3 as PIX-111) or aluminium chloride (AlCl3 as PAX-18) flocculation could stimulate biogas production in wastewater sludge contaminated with Microthrix parvicella. In a fermentation process run in three replicates, cumulative methane production was in average about 25 % higher using the iron flocculated sludge than using the aluminium flocculated sludge; this difference was statistically significant (P < 0.05) in the subsequent runs of the semi-continuous process. In all runs, the iron flocculated sludge produced less (P < 0.05) hydrogen sulphide in the biogas than the aluminium flocculated sludge. The numbers of M. parvicella stayed at the similar levels throughout the process. It is concluded that biogas production is higher and more stable with iron coagulant in comparison with aluminium coagulant, presumably due to the reduced formation of hydrogen sulphide. Thus, iron coagulants seem to be better than aluminium coagulants to stimulate the methane production process. Both coagulants significantly suppressed multiplication of M. parvicella in the biogas reactor, i.e. they did not evoke foaming in this experiment.

Formation of hydrogen sulfide from cysteine in Saccharomyces cerevisiae BY4742: genome wide screen reveals a central role of the vacuole.

Discoveries on the toxic effects of cysteine accumulation and, particularly, recent findings on the many physiological roles of one of the products of cysteine catabolism, hydrogen sulfide (H2S), are highlighting the importance of this amino acid and sulfur metabolism in a range of cellular activities. It is also highlighting how little we know about this critical part of cellular metabolism. In the work described here, a genome-wide screen using a deletion collection of Saccharomyces cerevisiae revealed a surprising set of genes associated with this process. In addition, the yeast vacuole, not previously associated with cysteine catabolism, emerged as an important compartment for cysteine degradation. Most prominent among the vacuole-related mutants were those involved in vacuole acidification; we identified each of the eight subunits of a vacuole acidification sub-complex (V1 of the yeast V-ATPase) as essential for cysteine degradation. Other functions identified included translation, RNA processing, folate-derived one-carbon metabolism, and mitochondrial iron-sulfur homeostasis. This work identified for the first time cellular factors affecting the fundamental process of cysteine catabolism. Results obtained significantly contribute to the understanding of this process and may provide insight into the underlying cause of cysteine accumulation and H2S generation in eukaryotes.

Formation of molecular nitrogen and hydrogen sulfide during high‐temperature pyrolysis of coals

AbstractNitrogen and sulfur release from eleven coals during pyrolysis at high temperatures (≥1000 °C) was studied in both fixed‐bed and free‐fall quartz reactors. Yields of N2, char‐N and H2S were found to depend strongly on the pyrolysis conditions, such that N2 and H2S yields increased with increasing pyrolysis temperature and coal particle residence time, whereas char‐N decreased. There was also a strong inverse correlation between N2 and char‐N yields, suggesting that the majority of N2 is produced from char‐N through solid‐phase reactions. H2S formation had no clear relationship with the carbon and sulfur contents of the parent coal. Demineralization with HCl washing was observed to remove primarily Ca2+ cations from four low rank coals examined and to increase the char‐N and H2S yields but decrease N2 generation. In contrast, the addition of 3 wt% Ca to the four coals drastically enhanced N2 formation and suppressed the formation of char‐N and H2S. The X‐ray diffraction analysis of the chars derived from Ca‐loaded coals revealed that the Ca was present primarily as CaO with an average crystallite size of 15–45 nm, and that the presence of the Ca promoted carbon crystallization. Small diffraction peaks due to CaS were also observed. Fine particles of CaO may not only promote N2 formation through solid phase reactions of char‐N but undergo sulfur capture reactions. A mechanism for the Ca‐catalyzed N2 formation was discussed in terms of solid–solid reactions between CaO particles and char‐N. © 2014 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Sulfide elimination by intermittent nitrate dosing in sewer sediments

The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards, and requires expensive programs for its prevention. The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments. The study was carried out based on lab-scale experiments and batch tests using real sewer sediments. The intermittent nitrate dosing mode and the optimal control condition were investigated. The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment. The oxidation–reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S (nitrate/sulfide) ratio with slight excess nitrate is necessary for optimal conditions of efficient sulfide control with lower carbon source loss. The optimal control condition is feasible for the sulfide elimination in sewer systems.

Mechanistic Study of a Complementary Reaction System that Easily Affords Quinazoline and Perimidine Derivatives

AbstractA new reaction between 2‐aminobenzophenone and thiourea in dimethyl sulfoxide (DMSO) has been developed that primarily affords 4‐phenylquinazoline as a single product. This reaction is also applicable, in general, to the reactions between thiourea and conformation‐restricted β‐amino ketones, such as 1‐aminoanthracene‐9,10‐dione and 1‐amino‐9H‐fluoren‐9‐one, to prepare perimidine derivatives. Experimental data is consistent with our computational study on the thermal decomposition of thiourea to form hydrogen sulfide and carbodiimide. This reaction involves a coupling between 2‐aminobenzophenone and carbodiimide generated in situ from thiourea to form 4‐phenylquinazolin‐2(1H)‐imine intermediate, and the generation of sulfur‐containing reducing agent from hydrogen sulfide and DMSO, which reduces 4‐phenylquinazolin‐2(1H)‐imine to 4‐phenyl‐1,2‐dihydroquinazolin‐2‐amine. Elimination of ammonia from the latter yields 4‐phenylquinazoline.

Quantification and Characterization of Sulfate-Reducing Bacteria from Groundwater from the Mogollon Rim, Arizona

Abstract Naturally occurring sulfates are common contaminants of groundwater. Dissolved sulfates are used by sulfate reducing bacteria which release hydrogen sulfide. Sulfate reducing bacteria are common in anaerobic environments such as deep wells. This results in production of hydrogen sulfide, a corrosive gas. Monitoring and control of sulfate reducing bacteria may be used to control the formation of hydrogen sulfide. To this end, the present study examined the prevalence of sulfate-reducing bacteria from five groundwater sources on the Mogollon Rim in central Arizona. The five samples were negative by both assays. Results serve as a basis for future study of ground-water microbiology and sulfate-reducing geochemistry in the Mogollon Rim.

Persistence of Elemental Sulfur Spray Residue on Grapes during Ripening and Vinification

Elemental sulfur (S⁰) is commonly used to control powdery mildew in vineyards, but S⁰ residues in musts have been correlated with increased hydrogen sulfide (H₂S) and sulfurous off-aroma formation during fermentation. As a consequence, S⁰ is often used sparingly late in the season, but defining appropriate preharvest intervals for S⁰ sprays has been challenging due to limited data on S⁰ persistence in vineyards and during prefermentation operations. Using a new quantification method, S⁰ residues were monitored in the vineyard over three years of field studies. Treatments varied in commercial formulation, application rate, and timing of the last application before harvest, all of which affected S⁰ concentrations on the fruit at harvest. Residue concentrations generally were lower for a wettable powder versus a micronized formulation applied at the same rate and timing and increased proportionally to the application rate when timing and formulation were constant. In all years, ceasing application ≥35 days prior to harvest resulted in S⁰ residues below the 10 μg/g concentration associated with increased H₂S production in several previous studies. S⁰ residues &gt;1 μg/g correlated with increased H₂S production in our current work and were observed on all fruit sprayed within 56 days of harvest. However, clarification decreased S⁰ in must by &gt;95% prior to fermentation in all treatments. Furthermore, fermentation on treated skins increased H₂S formation nearly 3-fold over fermentations without skin contact. Collectively, these results indicate that S⁰ residues are likely of low concern in white winemaking, whereas residue concentrations in red fermentations can exceed those associated with increased H₂S production when some S⁰ sprays are applied within eight weeks of harvest.

Field experiments on remediation of coastal sediments using granulated coal ash

Field experiments were carried out to evaluate the effect of Granulated Coal Ash (GCA) on remediation of coastal sediments in terms of removing phosphates and hydrogen sulfide. Phosphate concentrations in the sediment were kept below 0.2mg/l after the application of GCA, whereas those in the control sites increased up to 1.0mg/l. The concentration of hydrogen sulfide in the sediment was maintained at almost zero in the experimental sites (GCA application sites) for over one year, whereas it ranged 0.1–2.4mgSL−1 in control sites. Meanwhile, individual number of benthos increased in the experimental sites by several orders of magnitude compared to the control sites. The major process involved in hydrogen sulfide removal by GCA was thought to be the increase in pH, which suppresses hydrogen sulfide formation. From our findings, we concluded that GCA is an effective material for remediating organically enriched coastal sediment.

STREPTOMYCETES BIOLOGICAL PROPERTIES AND TAXONOMICAL STRUCTURE FROM NATURAL SOILS AND TECHNOZEMS OF KRYVYI RIG AREA

Aim to select the streptomycetes from technogenic-disturbed and natural soils of Kryvyi Rig area, to establish their taxonomical structure, to carry out their identification and to assess the structure of the streptomycetes community. Methods. Allocation of streptomycetes pure culture performed on starch-ammonia agar. Identification of streptomycetes isolates was performed by 36 diagnostic signs using H.F. Hauze guidelines actinomycetes determinant, the description of the genus Streptomyces and computer program of their identification StmId, developed by the employees of Institute of Microbiology and Virology, National Academy of Sciences of Ukraine. Results. There were carried out the identification of bacterial strains based on morphological, cultural and physiological-biochemical properties. According to the morphology of spores 63.8% of surveyed cultures with smooth surface of spores, 24.1% – with thorns, 8.6% – with hillocks. The most streptomycetes isolated from soil have direct sporophores located monopodial. On the scale of colors of A.S. Bondartsev there were established that on mineral agar of Gauze-1 the amount of isolates with white and grey air mycelium made on 29%. For substrate mycelium of many isolates the shades of brown color are characteristic. Among the selected strains of microorganisms of 40% are capable to formation of soluble pigments 64% – melanoid. It is established that practically all isolates well grow on medium with glucose and sucrose. The least suitable for bacterial growth is medium with xylose. It is determined that the process of desamination of amino acids to form ammonia carry 64% of the studied cultures, and the cleavage of sulfur-containing amino acids to form hydrogen sulfide are able 57% of isolates. All studied cultures exhibit amylolytic, cellulolytic and proteolytic activity with varying intensity. Conclusions. The specific structure of streptomycetes community from technogenic-disturbed and natural soils of Kryvyi Rig area is established. It is determined that S. violaceomaculatus, S. sporoherbeus, S. aerionidulus, S. enduracidicus and S. grisinus prevailed in streptomycetes cenosis of natural soils whereas in the technozems – S. dayalbaghensis, S. sporostellatus, S. conganensis, S. violobrunneus and S. albocrustosus.

Effect of Anaerobic Azo Dye Reduction on Continuous Sludge Digestion

Effect of continuous feeding of a reactive azo dye, reactive orange 107, and its hydrolyzed form (HRO107), on a conventional anaerobic digester was investigated in this study together with observation of change in microbial community. Laboratory‐scale digesters were fed with waste activated sludge and azo dye for 575 days continuously. The influent concentrations of reactive azo dye were between 200 and 3200 mg/L. The digester performance was not adversely affected by azo dye and its reduction metabolites throughout the study. A HRO107 concentration with 3200 mg/L was not inhibitory for the digester performance after prolonged exposure. The dye removal efficiencies were between 95 and 99% most of the time of operation implying that dye removal efficiency was not affected by variations in organic loading rate or influent dye concentration. Sulfate‐reducing bacteria may increase in the digester but did not cause any toxicity due to hydrogen sulfide formation after prolonged feeding.

The impact of sulfur contamination on the performance of La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen transport membranes

An oxygen transport membrane made from La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 − δ (LSCF6428) has been tested for air separation by oxygen permeation at 900 °C with the introduction of sulfur in the form of hydrogen sulfide. 200 ppm of hydrogen sulfide was fed either in the sweep-side (argon-side) or the air-side. The membrane was exposed to hydrogen sulfide for 100 h. Results show that the presence of hydrogen sulfide negatively influenced the oxygen permeation due to the formation of strontium sulfate blocking the oxygen permeation pathway. When the hydrogen sulfide was removed from the system, the oxygen permeation was partially restored in the case of argon-side contamination, while being fully restored in the case of air-side contamination. • Sulfur was introduced to an LSCF6428 membrane in the form of hydrogen sulfide. • Hydrogen sulfide was fed either in the argon-side or the air-side. • Oxygen permeation sharply decreased during hydrogen sulfide introduction. • Segregation of strontium to the air-side increased strontium sulfate formation. • In case of argon-side contamination, the oxygen permeation could not be restored. • In case of air-side contamination, the oxygen permeation was fully restored.