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Abstract A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data. [ABSTRACT FROM AUTHOR]

The biocorrosion of carbon steel poses a risk for ships combining seawater and fuel in metal ballast tanks. Ballast tanks were simulated by duplicate reactors containing carbon steel coupons and either petroleum F76 (petro-F76), Fischer–Tropsch F76 (FT-F76), or a 1:1 mix of both fuels, to investigate whether the alternative fuel FT-F76 influenced this risk. The polycarbonate reactors were inoculated with seawater, and the control reactors did not receive fuel. The reactors were monitored for 400 days, and they all reached a pH and open circuit potential where elemental iron was oxidized, indicating corrosion. The reactors containing petro-76 or fuel mix had higher levels of dissolved iron; one of each replicate had lower concentrations of sulfate than the original seawater, while the sulfate concentration did not decrease in the other incubations. The high sulfate reactors, but not the low sulfate reactors, had a high relative abundance of microaerophilic sulfide-oxidizing bacteria. The FT-F76 and the no-fuel reactors had a high relative abundance of iron-sequestering Magnetovibrio. Although dissolved iron and loss of sulfate under anoxic conditions are associated with biocorrosion, our results suggest that in our reactors these indicators were altered by iron-sequestering and sulfide-oxidizing microbes, which is consistent with the slow diffusion of oxygen across the polycarbonate reactors. [ABSTRACT FROM AUTHOR]

Bacteria are important participants in sulfur cycle of the extremely haloalkaline environment, e.g. soda lake. The effects of physicochemical factors on the composition of sulfide-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) in soda lake have remained elusive. Here, we surveyed the community structure of total bacteria, SOB and SRB based on 16S rRNA, soxB and dsrB gene sequencing, respectively, in five soda lakes with different physicochemical factors. The results showed that the dominant bacteria belonged to the phyla Proteobacteria, Bacteroidetes, Halanaerobiaeota, Firmicutes and Actinobacteria. SOB and SRB were widely distributed in lakes with different physicochemical characteristics, and the community composition were different. In general, salinity and inorganic nitrogen sources (NH4+-N, NO3−-N) were the most significant factors. Specifically, the communities of SOB, mainly including Thioalkalivibrio, Burkholderia, Paracoccus, Bradyrhizobium, and Hydrogenophaga genera, were remarkably influenced by the levels of NH4+-N and salinity. Yet, for SRB communities, including Desulfurivibrio, Candidatus Electrothrix, Desulfonatronospira, Desulfonatronum, Desulfonatronovibrio, Desulfonatronobacter and so on, the most significant determinants were salinity and NO3−-N. Besides, Rhodoplanes played a significant role in the interaction between SOB and SRB. From our results, the knowledge regarding the community structures of SOB and SRB in extremely haloalkaline environment was extended. [ABSTRACT FROM AUTHOR]

The marine subsurface is a reservoir of the greenhouse gas methane. While microorganisms living in water column and seafloor ecosystems are known to be a major sink limiting net methane transport from the marine subsurface to the atmosphere, few studies have assessed the flow of methane-derived carbon through the benthic mat communities that line the seafloor on the continental shelf where methane is emitted. We analyzed the abundance and isotope composition of fatty acids in microbial mats grown in the shallow Coal Oil Point seep field off Santa Barbara, CA, USA, where seep gas is a mixture of methane and CO2. We further used stable isotope probing (SIP) to track methane incorporation into mat biomass. We found evidence that multiple allochthonous substrates supported the rich growth of these mats, with notable contributions from bacterial methanotrophs and sulfur-oxidizers as well as eukaryotic phototrophs. Fatty acids characteristic of methanotrophs were shown to be abundant and 13C-enriched in SIP samples, and DNA-SIP identified members of the methanotrophic family Methylococcaceae as major 13CH4 consumers. Members of Sulfuricurvaceae, Sulfurospirillaceae, and Sulfurovumaceae are implicated in fixation of seep CO2. The mats' autotrophs support a diverse assemblage of co-occurring bacteria and protozoa, with Methylophaga as key consumers of methane-derived organic matter. This study identifies the taxa contributing to the flow of seep-derived carbon through microbial mat biomass, revealing the bacterial and eukaryotic diversity of these remarkable ecosystems.

Deciphering the evolution of ecological interactions among the metabolic types during the early diversification of life on Earth is crucial for our understanding of the ancient biosphere. The stromatolites from the genus Conophyton cylindricus represent a datum for the Proterozoic (Meso to Neoproterozoic) on Earth. Their typical conical shape has been considered a result of a competition between microorganisms for space, light and nutrients. Well-preserved records of this genus from the “Paleontological Site of Cabeludo”, Vazante Group, São Francisco Craton (Southern Brazil) present in situ fossilized biofilms, containing preserved carbonaceous matter. Petrographic and geochemical analyses revealed an alternation between mineral laminae (light grey laminae) and fossilized biofilms (dark grey laminae). The dark grey laminae comprise three different biofilms recording a stratified microstructure of microbial communities. These three biofilms composing the dark grey laminae tend to be organized in a specific pattern that repeats through the stromatolite vertical section. Iron and manganese are distributed differently along the dark and light grey laminae; X-ray absorption and luminescence data showed possible different areas with authigenic iron and iron provided from diagenetic infiltration. Cryptocrystalline apatite in the lowermost biofilms in each dark grey laminae may suggest past metabolic activity of sulfide-oxidizing bacteria. These findings suggest that the microorganisms reached a complex metabolic diversification in order to maintain an equilibrium situation between the three different biofilms along the vertical section of the structures, thus benefiting the whole microbial community. This means that the stromatolites from the Conophyton genus may have formed as a result of a greater complexity of interactions between microorganisms, and not only from competition between photosynthesizers.

Primary gypsum deposits, which accumulated in the Mediterranean Basin during the so‐called Messinian salinity crisis (5.97–5.33 Ma), represent an excellent archive of microbial life. We investigated the molecular fossil inventory and the corresponding compound‐specific δ13C values of bottom‐grown gypsum formed during the first stage of the crisis in four marginal basins across the Mediterranean (Nijar, Spain; Vena del Gesso, Italy; Heraklion, Crete; and Psematismenos, Cyprus). All studied gypsum samples contain intricate networks of filamentous microfossils, whose phylogenetic affiliation has been debated for a long time. Petrographic analysis, molecular fossil inventories (hydrocarbons, alcohols, and carboxylic acids), and carbon stable isotope patterns suggest that the mazes of filamentous fossils represent benthic microbial assemblages dominated by chemotrophic sulfide‐oxidizing bacteria; in some of the samples, the body fossils are accompanied by lipids produced by sulfate‐reducing bacteria. Abundant isoprenoid alcohols including diphytanyl glycerol diethers (DGDs) and glycerol dibiphytanyl glycerol tetraethers (GDGTs), typified by highly variable carbon stable isotope composition with δ13C values spanning from −40 to −14‰, reveal the presence of planktic and benthic archaeal communities dwelling in Messinian paleoenvironments. The compound inventory of archaeal lipids indicates the existence of a stratified water column, with a normal marine to diluted upper water column and more saline deeper waters. This study documents the lipid biomarker inventory of microbial life preserved in ancient gypsum deposits, helping to reconstruct the widely debated conditions under which Messinian gypsum formed. [ABSTRACT FROM AUTHOR]

Biological desulfurization under haloalkaline conditions has been applied worldwide to remove hydrogen sulfide (H 2 S) from sour gas steams. The process relies on sulfide-oxidizing bacteria (SOB) to oxidize H 2 S to elemental sulfur (S 8 ), which can then be recovered and reused. Recently, a dual-reactor biological desulfurization system was implemented where an anaerobic (sulfidic) bioreactor was incorporated as an addition to a micro-oxic bioreactor, allowing for higher S 8 selectivity by limiting by-product formation. The highly sulfidic bioreactor environment enabled the SOB to remove (poly)sulfides (S x 2- ) in the absence of oxygen, with S x 2- speculated as a main substrate in the removal pathway, thus making it vital to understand its role in the process. The SOB are influenced by the oxidation-reduction potential (ORP) set-point of the micro-oxic bioreactor as it is used to control the product of oxidation (S 8 vs. SO 4 2- ), while the uptake of S x 2- by SOB has been qualitatively linked to pH. Therefore, to quantify these effects, this work determined the concentration and speciation of S x 2- in the biological desulfurization process under various pH values and ORP set-points. The total S x 2- concentrations in the sulfidic zone increased at elevated pH (8.9) compared to low pH (< 8.0), with on average 3.3 ± 1.0 mM-S more S x 2- . Chain lengths varied, with S 7 2- only doubling in concentration while S 5 2- increased 9 fold, which is in contrast with observations from abiotic systems. Changes to the ORP set-point of the micro-oxic reactor did not produce substantial changes in S x 2- concentration in the sulfidic zone. This illustrates that the reduction degree of the SOB in the micro-oxic bioreactor does not enhance their ability to interact with S x 2- in the sulfidic bioreactor. This increased understanding of how both pH and ORP affect changes in S x 2- concentration and chain length can lead to improved efficiency and design of the dual-reactor biological desulfurization process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

[Display omitted] • Elemental sulfur (S0) was recovered by oxidation of sulfide in an O 2 -MBfR. • An O 2 /S (g/g) ratio of 0.5 is optimal for efficient sulfide conversion to S0. • The O 2 -MBfR gave S2− oxidation of 98% and a sulfide-to-S0 conversion up to 97%. • Influent composition influenced sulfur genes abundances and biofilm community structure. This work investigated elemental sulfur (S0) biorecovery from Phosphogypsum (PG) using sulfur-oxidizing bacteria in an O 2 -based membrane biofilm reactor (MBfR). The system was first optimized using synthetic sulfide medium (SSM) as influent, then switched to biogenic sulfide medium (BSM) generated by biological reduction of PG alkaline leachate. The results using SSM had high sulfide-oxidation efficiency (98 %), sulfide to S0 conversion (∼90 %), and S0 production rate up to 2.7 g S0/(m2.d), when the O 2 /S ratio was ∼0.5 g O 2 /g S. With the BSM influent, the system maintained high sulfide-to-S0 conversion rate (97 %), and S0-production rate of 1.6 g S0/(m2.d). Metagenomic analysis revealed that Thauera was the dominant genus in SSM and BSM biofilms. Furthermore, influent composition affected the bacterial community structure and abundances of functional microbial sulfur genes, modifying the sulfur-transformation pathways in the biofilms. Overall, this work shows promise for O 2 -MBfR usage in S0 biorecovery from PG-leachate and other sulfidogenic effluents. [ABSTRACT FROM AUTHOR]

Precambrian filamentous microfossils are common and diverse. Nevertheless, their taxonomic assignment can be difficult owing to their overall simple shapes typically lacking in diagnostic features. Here, we report in situ communities of well-preserved, large filamentous impressions from the Ediacaran Itajaí Basin (ca 563 Ma) of Brazil. The filaments are uniserial (unbranched) and can reach up to 200 µm in width and up to 44 mm in length. They occur as both densely packed or sparsely populated surfaces, and typically show a consistent orientation. Although simple in shape, their preferred orientation suggests they were tethered to the seafloor, and their overall flexibility (e.g. bent, folded and twisted) supports a biological (rather than sedimentary) affinity. Biometric comparisons with modern filamentous groups further support their biological affinity, suggesting links with either large sulfide-oxidizing bacteria (SOB) or eukaryotes. Other morphological and palaeoecological characteristics further corroborates their similarities with modern large filamentous SOB. Their widespread occurrence and association with complex Ediacaran macrobiota (e.g. frondose organisms, Palaeopascichnus) suggest that they probably played an important role in the ecological dynamics of these early benthic communities by providing firm substrates for metazoans to inhabit. It is further hypothesized that the dynamic redox condition in the latest Ediacaran, with the noncontinuous rise in oxygen concentration and periods of hypoxia, may have created ideal conditions for SOB to thrive. [ABSTRACT FROM AUTHOR]

The industrial-scale of hydrogen sulfide (H 2 S) removal system using biological process relies on the performance of sulfide-oxidizing bacteria (SOB) to reduce corrosive H 2 S before being used as fuel in an industrial boiler or electric generator. The sulfide-oxidizing bacteria community in the bioscrubber treating H 2 S in biogas from swine farm based on the 16S rRNA gene and Sox gene sequences analysis. Microbial sludge from SPM Feedmill Co., Ltd. (SPM swine farm) were collected from the inlet and outlet sampling ports of the bioscrubber. Sequencing of full-length 16S rRNA gene and next-generation sequencing (NGS) of short-read 16S region were employed to identify the SOB communities. The cultural dependent technique has been applied for isolation of pure SOB strains, including A cinetobacter towneri (MF765755), Enterobacter asburiae (MF765756) and Aeromonas veronii (MK659586). Together with NGS analysis, which showed bacteria belong to the genera Sulfurovum (37%), Sulfuricurvum (17%) and Thiothrix (9%) could play an important role in oxidized H 2 S in biogas. Therefore, these SOB genera: A cinetobacter, Aeromonas, Enterobacter, Sulfurovum, and Sulfuricurvum can be applied as an indicator for efficiency and stability of H 2 S treatment systems in biogas from swine farms. • Sulfide oxidizing bacteria (SOB) community in full scale bioscrubber treating H2S in swine farm biogas was elucidated. • SOB isolated from cultural dependent technique was identified by full length 16S rRNA gene. • Next generation sequencing (NGS) of short read 16S region were employed to identifiy the SOB communities. • SOB plays a key role in a removal efficiency and stability system of hydrogen sulfide in biogas. [ABSTRACT FROM AUTHOR]

The sulfur-bearing limestones interbedded in the upper Miocene diatomaceous sediments (Tripoli Formation) of the Lorca Basin (SE Spain) are typified, as other Mediterranean coeval carbonate and gypsum deposits, by filamentous, circular and rod-shaped microstructures of controversial origin. These features have been interpreted both as fecal pellets of brine shrimps and/or of copepods, remains of algae or cyanobacteria and fossilized sulfide-oxidizing bacteria. To shed light on their origin, a multidisciplinary study including optical, UV and scanning electron microscopy, Raman microspectroscopy, and geochemical (carbon and oxygen stable isotopes) analyses has been carried out on three carbonate beds exposed along the La Serrata ridge. The different composition of the filamentous and circular objects with respect to the rod-shaped microstructures suggest that the former represent remains of bacteria, while the latter fecal pellets of deposit- or suspension-feeder organisms. Size and shape of the filamentous and circular microfossils are consistent with their assignment to colorless sulfide-oxidizing bacteria like Beggiatoa (or Thioploca) and Thiomargarita, which is further supported by the presence, only within the microfossil body, of tiny pyrite grains. These grains possibly result from early diagenetic transformation of original sulfur globules stored by the bacteria, which are a diagnostic feature of this group of prokaryotes. The development of microbial communities dominated by putative sulfide-oxidizing bacteria at Lorca was favored by hydrogen sulfide flows generated through degradation of organic matter by sulfate-reducing bacteria thriving in underlying organic-rich sediments.

Biological sulfide oxidation is an efficient means to recover elemental sulfur (S 0 ) as a valuable resource from sulfide-bearing wastewater. This work evaluated the autotrophic sulfide oxidation to S 0 in the O 2 -based membrane biofilm reactor (O 2 -MBfR). High recovery of S 0 (80-90% of influent S) and high sulfide oxidation (∼100%) were simultaneously achieved when the ratio of O 2 -delivery capacity to sulfide-to S 0 surface loading (SL) (O 2 /S 2- → S 0 ratio) was around 1.5 (g O 2 /m 2 -day/g O 2 /m 2 -day). On average, most of the produced S 0 was recovered in the MBfR effluent, although the biofilm could be a source or sink for S 0 . Shallow metagenomic analysis of the biofilm showed that the top sulfide-oxidizing genera present in all stages were Thauera , Thiomonas , Thauera&#95;A , and Pseudomonas . Thiomonas or Pseudomonas was the most important genus in stages that produced almost only S 0 (i.e., the O 2 /S 2- → S 0 ratio around 1.5 g of the O 2 /m 2 -day/g O 2 /m 2 -day). With a lower sulfide SL, the S 0 -producing genes were sqr and fccAB in Thiomonas . With a higher sulfide SL, the S 0 -producing genes were in the soxABDXYZ system in Pseudomonas . Thus, the biofilm community of the O 2 -MBfR adapted to different sulfide-to-S 0 SLs and corresponding O 2 -delivery capacities. The results illustrate the potential for S 0 recovery using the O 2 -MBfR.

Management of excessive aqueous sulfide is one of the most significant challenges of treating effluent after biological sulfate reduction for metal recovery from hydrometallurgical leachate. The main objective of this study was to characterize and verify the effectiveness of a sulfide-oxidizing bacterial (SOB) consortium isolated from post-mining wastes for sulfide removal from industrial leachate through elemental sulfur production. The isolated SOB has a complete sulfur-oxidizing metabolic system encoded by sox genes and is dominated by the Arcobacter genus. XRD analysis confirmed the presence of elemental sulfur in the collected sediment during cultivation of the SOB in synthetic medium under controlled physicochemical conditions. The growth yield after three days of cultivation reached ~2.34 gprotein/molsulfid, while approximately 84% of sulfide was transformed into elemental sulfur after 5 days of incubation. Verification of isolated SOB on the industrial effluent confirmed that it can be used for effective sulfide concentration reduction (~100% reduced from the initial 75.3 mg/L), but for complete leachate treatment (acceptable for discharged limits), bioaugmentation with other bacteria is required to ensure adequate reduction of chemical oxygen demand (COD).

The sulfur-bearing limestones interbedded in the upper Miocene diatomaceous sediments (Tripoli Formation) of the Lorca Basin (SE Spain) are typified, as other Mediterranean coeval carbonate and gypsum deposits, by filamentous, circular and rod-shaped microstructures of controversial origin. These features have been interpreted both as fecal pellets of brine shrimps and/or of copepods, remains of algae or cyanobacteria and fossilized sulfide-oxidizing bacteria. To shed light on their origin, a multidisciplinary study including optical, UV and scanning electron microscopy, Raman microspectroscopy, and geochemical (carbon and oxygen stable isotopes) analyses has been carried out on three carbonate beds exposed along the La Serrata ridge. The different composition of the filamentous and circular objects with respect to the rod-shaped microstructures suggest that the former represent remains of bacteria, while the latter fecal pellets of deposit- or suspension-feeder organisms. Size and shape of the filamentous and circular microfossils are consistent with their assignment to colorless sulfide-oxidizing bacteria like Beggiatoa (or Thioploca) and Thiomargarita , which is further supported by the presence, only within the microfossil body, of tiny pyrite grains. These grains possibly result from early diagenetic transformation of original sulfur globules stored by the bacteria, which are a diagnostic feature of this group of prokaryotes. The development of microbial communities dominated by putative sulfide-oxidizing bacteria at Lorca was favored by hydrogen sulfide flows generated through degradation of organic matter by sulfate-reducing bacteria thriving in underlying organic-rich sediments. [ABSTRACT FROM AUTHOR]

• Key strategies for in-sewer sulfide and corrosion control critically reviewed. • Fundamental mechanisms involved in sulfide and concrete corrosion control discussed at depth. • Optimal chemical dosing strategies proposed and discussed. • Knowledge gaps, challenges and perspectives of sewer sulfide and corrosion control presented. In sewer systems where anaerobic conditions are present, sulfate-reducing bacteria reduce sulfate to hydrogen sulfide (H 2 S), leading to sewer corrosion and odor emission. Various sulfide/corrosion control strategies have been proposed, demonstrated, and optimized in the past decades. These included (1) chemical addition to sewage to reduce sulfide formation, to remove dissolved sulfide after its formation, or to reduce H 2 S emission from sewage to sewer air, (2) ventilation to reduce the H 2 S and humidity levels in sewer air, and (3) amendments of pipe materials/surfaces to retard corrosion. This work aims to comprehensively review both the commonly used sulfide control measures and the emerging technologies, and to shed light on their underlying mechanisms. The optimal use of the above-stated strategies is also analyzed and discussed in depth. The key knowledge gaps and major challenges associated with these control strategies are identified and strategies dealing with these gaps and challenges are recommended. Finally, we emphasize a holistic approach to sulfide control by managing sewer networks as an integral part of an urban water system. [Display omitted] [ABSTRACT FROM AUTHOR]

Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen- and sulfur cycling in Lake Grevelingen sediments.

Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers, and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen-, and sulfur cycling in Lake Grevelingen sediments. [ABSTRACT FROM AUTHOR]

A novel bioreactor, employing a silicone membrane for microaeration, was studied for partial sulfide oxidation to elemental sulfur. The objective of this study was to assess the feasibility of using an internal silicone membrane reactor (ISMR) to treat dissolved sulfide and to characterize its microbial community. The ISMR is an effective system to eliminate sulfide produced in anaerobic reactors. Sulfide removal efficiencies reached 96 % in a combined anaerobic/microaerobic reactor and significant sulfate production did not occur. The oxygen transfer was strongly influenced by air pressure and flow. Pyrosequencing analysis indicated various sulfide-oxidizing bacteria (SOB) affiliated to the species Acidithiobacillus thiooxidans, Sulfuricurvum kujiense and Pseudomonas stutzeri attached to the membrane and also indicated similarity between the biomass deposited on the membrane wall and the biomass drawn from the material support, supported the establishment of SOB in an anaerobic sludge under microaerobic conditions. Furthermore, these results showed that the reactor configuration can develop SOB under microaerobic conditions and can improve and reestablish the sulfide conversion to elemental sulfur. [ABSTRACT FROM AUTHOR]

Microbially influenced corrosion (MIC) in concrete results in significant cost for infrastructure maintenance. Prior studies have employed molecular techniques to identify microbial community species in corroded concrete, but failed to explore bacterial activity and functionality during deterioration. In this study, biofilms of different sulfur-oxidizing bacteria compositions were developed on the surface of cement paste samples to simulate the natural ecological succession of microbial communities during MIC processes. Noninvasive, self-referencing (SR) microsensors were used to quantify real time changes of oxygen, hydrogen ion and calcium ion flux for the biofilm to provide more information about bacterial behavior during deterioration. Results showed higher transport rates in oxygen consumption, and hydrogen ion at 4 weeks than 2 weeks, indicating increased bacterial activity over time. Samples with five species biofilm had the highest hydrogen ion and calcium ion transport rates, confirming attribution of acidophilic sulfur-oxidizing microorganisms (ASOM). Differences in transport rates between three species samples and two species samples confirmed the diversity between Thiomonas intermedia and Starkeya novella . The limitations of SR sensors in corrosion application could be improved in future studies when combined with molecular techniques to identify the roles of major bacterial species in the deterioration process. [ABSTRACT FROM AUTHOR]

Sulfide generally exists in wastewater, black and odor river, as well as aquaculture water, and give rise to adverse effect on ecological stability and biological safety, due to the toxicity, corrosivity and malodor of sulfide. In the present study, a chemolithotrophic sulfide-oxidizing bacteria (SOB) was isolated and identified as Marinobacter maroccanus strain SDSWS8. And it produced no hemolysin and was susceptible to most antibiotics. There were no accumulation of sulfide, sulfate and thiosulfate during the sulfide removal process. The optimum conditions of sulfide removal were temperature 15–40 °C, initial pH value 4.5–9.5, salinity 10–40‰, C/N ratio 0–20 and sulfide concentration 25–150 mg/L. The key genes of sulfide oxidation, Sox system (sox B, sox X, sox A, sox Z, sox Y, sox D, sox C), dissimilatory sulfur oxidation (dsr A, apr A and sat) and sqr , were successfully amplified and expressed, indicating the three pathways coordinated to complete the sulfide oxidation. Besides, strain SDSWS8 had inhibitory effect on four pathogen Vibrio (V. harveyi, V. parahaemolyticus, V. anguillarum and V. splendidus). Furthermore, efficient removal of sulfide from real aquaculture water and sludge mixture could be accomplished by strain SDSWS8. This study may provide a promising candidate strain for sulfide-rich water treatment. • The sulfide-oxidizing bacteria, Marinobacter sp. SDSWS8 could efficiently remove sulfide. • Strain SDSWS8 could adapt to the fluctuations of temperature and pH. • The sulfide-oxidizing pathway by Sox, rDsr and SQR system was structured. • Sulfide was efficiently removed by strain SDSWS8 from real aquaculture water and sludge. • Strain SDSWS8 was safe and could inhibit pathogen Vibrio. [ABSTRACT FROM AUTHOR]

The basic patterns and mechanisms of adsorption immobilization of sulfide-oxidizing bacteria in the mass of mineral support medium made of phosphogypsum were determined for gas purification system. The advantage of the adsorption method on the granulated support medium of phosphogypsum is that it allows to bind the bacteria in the granules with the bioactive layer formation. Granules based on phosphogypsum are characterized by permeability to Thiobacillus sp. and contain useful minerals for bacteria growth such as calcium, magnesium, phosphorus, etc. Bacterial matrix is closely associated with the support medium matrix. Therefore, its use helps minimize the removal of the sulfide-oxidizing bacteria active mass from biofilter during the process of washing and bio-sulfur removing from the surface granules of phosphogypsum. [ABSTRACT FROM AUTHOR]

Background: On Late Cretaceous Tethyan upwelling sediments from the Mishash/Ghareb Formation (Negev, Israel), bulk geochemical and biomarker analyses were performed to explain the high proportion of phosphates in the lower part and of organic matter (OM) preserved in upper parts of the studied section. The profile is composed of three facies types; the underlying Phosphate Member (PM), the Oil Shale Member (OSM) and the overlying Marl Member (MM). Results: Total organic carbon (TOC) contents are highly variable over the whole profile reaching from 0.6% in the MM, to 24.5% in the OSM. Total iron (TFe) varies from 0.1% in the PM to 3.3% in the OSM. Total sulfur (TS) ranges between 0.1% in the MM and 3.4% in the OSM, resulting in a high C/S ratio of 6.5 in the OSM section. A mean proportion of 11.5% total phosphorus (TP) in the PM changed abruptly with the facies to a mean value of only 0.9% in the OSM and the MM. The TOC/TOCOR ratios argue for a high bacterial sulfate reduction activity and in addition, results from fatty acid analyses indicate that the activity of sulfide-oxidizing activity of bacteria was high during deposition of the PM, while decreasing during the deposition of the OSM. Conclusions: The upwelling conditions effected a high primary productivity and consequently the presence of abundant OM. This, in combination with high sulfate availability in the sediments of the PM resulted in a higher sulfide production due to the activity of sulfate-reducing bacteria. Iron availability was a limiting factor during the deposition of the whole section, affecting the incorporation of S into OM. This resulted in the preservation of a substantial part of OM against microbial degradation due to naturally-occurring sulfurization processes expressed by the high C/S ratio of 6.5 in the OSM. Further, the abundant sulfide in the pore water supported the growth of sulfide-oxidizing bacteria promoting the deposition of P, which amounted to as much as 15% in the PM. These conditions changed drastically from the PM to the OSM, resulting in a significant reduction of the apatite precipitation and a high concentration of reactive S species reacting with the OM. [ABSTRACT FROM AUTHOR]

• Enrichment of electroactive sulfide-oxidizing biofilm from haloalkaline sediments. • Bioelectrochemical sulfide oxidation resulted in sulfate and high current production. • Electrochemical sulfide oxidation resulted in low current and only sulfur production. • Unclassified Desulfobulbaceace genus dominated the sulfide-oxidizing anodic biofilm. Sulfide-oxidizing microorganisms (SOMs) play a vital role in biogeochemical sulfur cycling and are useful for the bioremediation of sulfide-rich wastewaters and environments. The electroactive SOMs remain poorly explored from extreme environments. This study presents the autotrophic electroactive microbial biofilm capable of sulfide oxidation under haloalkaline conditions (pH – 9.5; salinity – 20 g/L). It was obtained through electrochemical microbial enrichment from sub-surface sediments of the haloalkaline Lonar lake at an applied anode potential of -330 mV vs. Ag/AgCl in microbial electrolysis cells (MECs). The sulfide-oxidizing electroactive biofilm achieved a maximum average current density of 315±23 µA/cm2 with 87±10% coulombic efficiency and 34±8% sulfide oxidation to sulfate. The bioelectrocatalytic sulfide oxidation at the anode facilitated 0.16±0.02 mM/day hydrogen production at the cathode of MECs. Low current densities and neither sulfate nor hydrogen production were observed in abiotic electrochemical controls suggesting the bioelectrocatalytic role of anodic microbial biofilm in the sulfide to sulfate oxidation process. The sulfide oxidation process was faster in bioelectrochemical (0.94±0.2 mM/day) than the abiotic reactors (0.49±0.01 mM/day), confirming the microbial role in the enhanced sulfide oxidation bioelectrocatalysis. Sulfur was detected at the anode surface in both abiotic and biotic electrochemical experiments, suggesting the occurrence of electrochemical sulfide oxidation to sulfur process under here-tested conditions. The bio-anode analysis through scanning electron microscopic imaging confirmed the microbial growth at the anode surface, and 16S-rRNA based amplicon sequencing revealed the dominance of unclassified Desulfobulbaceace at a relative sequence abundance of 61.8 ± 9.9% in anodic biofilm. This work on electroactive SOMs from a natural haloalkaline habitat contributes to the limited understanding of extreme electroactive microorganisms and their role in sulfur cycling in such environments. [ABSTRACT FROM AUTHOR]

This work shows the development of a technique for biological removal of barium from production waters. This technology, called stratified microbial associations (SMA), was evaluated at laboratory and bench scale levels. Removal capacity of this metal was demostrated by microcosmos and bioreactor assay. The role of reduced sulfur availability, residence time, flow pattern and bioreactor size were also evaluated. Elemental composition of the solid constituents, localization and nature of the metal deposits in the bioreactor were determined by electron microscopy. This process has an efficiency of 95%-98% of barium removal with concentrations between 8 and 50 gm-3. Metal capture is mainly due to biosorption and the formation of low solubility complexes such as barium sulphate.Se presenta el desarrollo de una técnica para la remoción biológica de bario de aguas de producción. Esta tecnología, denominada Asociaciones Microbianas Estratificadas, AME, se evaluó a nivel de laboratorio y a escala banco. En los ensayos realizados en microcosmos, las AME fueron capaces de inmovilizar el metal, y esta capacidad se incrementó al adicionarse bacterias oxidadoras de azufre. El empleo de biorreactores permitió valorar el efecto de: la concentración de azufre reducido disponible, la longitud del biorreactor, el patrón de flujo y el efecto del tiempo de residencia en la captura del metal. La composición elemental de los constituyentes sólidos, la localización y naturaleza de los depósitos de metal en el biorreactor fueron determinados por microscopía electrónica. Este proceso tiene una eficiencia de remoción del bario entre el 95-98% en concentraciones que van de los 8 a 50 gm-3 . La captura del metal está dada por fenómenos de biosorción y por la formación de complejos de baja solubilidad como es el sulfato de bario.

Highlights: [•] Microaerobic conditions are applied in order to control the H2S content of biogas. [•] The S0-rich deposits found in the HS of two microaerobic reactors are removed. [•] H2S-free biogas is rapidly achieved after cleaning the HS. [•] A cleaning interval of less than 14months ensures minimum micro-oxygenation cost. [•] Moisture level determines the composition, richness and size of the SOB population. [ABSTRACT FROM AUTHOR]

The microbial mats responsible for biological desulfurization from biogas in a full-scale anaerobic digester were characterized in terms of their structure, as well as their chemical and microbial properties. Filament-shaped elemental sulfur 100-500 μm in length was shown to cover the mats, which cover the entire headspace of the digester. This is the first report on filamentous sulfur production in a non-marine environment. The results of the analysis of the mats suggest that the key players in the sulfide oxidation and sulfur production in the bio-desulfurization in the headspace of the digester were likely to be two sulfide-oxidizing bacteria (SOB) species related to Halothiobacillus neapolitanus and Sulfurimonas denitrificans, and that the microbial community, cell density, activity for sulfide oxidation varied according to the environmental conditions at the various locations of the mats. Since the water and nutrients necessary for the SOB were provided by the digested sludge droplets deposited on the mats, and our results show that a higher rate of sulfide oxidation occurred with more frequent digested sludge deposition, the habitat of the SOB needs to be made in the lower part of the headspace near the liquid level of the digested sludge to maintain optimal conditions. [ABSTRACT FROM AUTHOR]

A novel biofiltration system using pure and mixed cultures of sulfide-oxidizing bacteria immobilized on granular activated carbon (GAC) to purify synthetic and real biogas from a sulfate reaction reactor of concentrated latex industry, contaminated by H2S, was studied. Complete H2S removal from synthetic biogas was found in pure and mixed culture reactors at 200 ppm initial H2S concentration, 35 l h−1 of biogas flow rate and 5.83 l h−1 of airflow rate. H2S removal using biofiltration had little effect on the methane content of synthetic biogas. Pure and mixed culture reactors at airflow rates of 0.75–5.83 l h−1 also showed complete H2S removal from real biogas. However, H2S removal efficiency at the airflow rate of 0.53 l h−1 decreased to 99%. Thus, H2S removal using biofiltration had little effect on the methane content of real biogas. The results of this study suggest the feasibility of developing using mixed culture of sulfide-oxidizing bacteria from concentrated latex wastewater for industrial application to remove H2S from biogas through biofiltration. [ABSTRACT FROM PUBLISHER]

This study evaluated the influence of changes in the microbial community structure on reoxidation of reduced uranium during a postbiostimulation period. Effluent groundwater from acetate-stimulated sediment flow-through columns was analyzed over 60 days after acetate amendment was discontinued. Only a small reoxidation of iron or uranium (17%) occurred in the presence of 1–2 mg L−1 O2 influent groundwater for the 2-month period. Most uranium reoxidation occurred during the first 2 weeks after biostimulation with acetate was discontinued. Groundwater and sediment microbial community compositions suggested that two processes played important roles immediately after the cessation of acetate addition. The first process was characterized by a predominance of both sediment-bound and planktonic microorganisms most closely related to Hydrogenophaga sp., Thiobacillus sp., and Gallionella sp., which could oxidize a variety of reduced compounds. The second process was characterized by organisms closely related to Lysobacter sp. and Sterolibacterium sp., with the potential to feed on complex organic compounds from biomass turnover. The presence of these bacteria and the lack of uranium oxidation implied that after acetate addition was stopped, reduced inorganic compounds and dead biomass became electron donors for a microbial community capable of using low ambient oxygen as a terminal electron acceptor, contributing to the preservation, at least temporarily, of biogenic U(IV). [ABSTRACT FROM AUTHOR]

Specimens of Lamellibrachia ( Annelida: Siboglinidae) were recently discovered at cold seeps in the eastern Mediterranean. In this study, we have investigated the phylogeny and function of intracellular bacterial symbionts inhabiting the trophosome of specimens of Lamellibrachia sp. from the Amon mud volcano, as well as the bacterial assemblages associated with their tube. The dominant intracellular symbiont of Lamellibrachia sp. is a gammaproteobacterium closely related to other sulfide-oxidizing tubeworm symbionts. In vivo uptake experiments show that the tubeworm relies on sulfide for its metabolism, and does not utilize methane. Bacterial communities associated with the tube form biofilms and occur from the anterior to the posterior end of the tube. The diversity of 16S rRNA gene phylotypes includes representatives from the same divisions previously identified from the tube of the vent species Riftia pachyptila, and others commonly found at seeps and vents. [ABSTRACT FROM AUTHOR]

Abstract: The feasibility of developing biofilm on exhausted carbon using pre-deposited sulfur compounds as the sole energy source was studied, aiming to re-use them in odor biofiltration. The exhausted carbon with different properties, including surface pH, sulfur content and porosity, was used. A series of off-line trials were conducted to investigate the release of sulfur compounds from the exhausted carbon and the attachment of sulfide-oxidizing bacteria on the exhausted carbon. Without any pre-treatment, a few bacteria attachment on exhausted carbon was observed by SEM, due to possibly the limitation of reduced sulfur compounds release for bacterial growth. The biofilm development was much improved by adding NaOH solution to partially pre-desorb the deposited sulfur into liquid phase, which provided initial energy for bacterial growth. With the attached bacteria, the further significant release of the deposited sulfur was achieved through an additional driving force: biodegradation. The key issues for developing biofilm on exhausted carbon were concluded, which mainly concerned of desorption of pre-deposited reduced sulfur compounds and porosity of carbon. The sulfur-associated reactions occurring in developing biofilm on exhausted carbon was proposed. Bio-regeneration of exhausted carbon in the course of biofilm development was also preliminarily assessed. [Copyright &y& Elsevier]

Sediments of upwelling regions off Namibia, Peru, and Chile contain dense populations of large nitrate-storing sulfide-oxidizing bacteria, Thiomargarita, Beggiatoa, and Thioploca. Increased contents of monounsaturated C16 and C18 fatty acids have been found at all stations studied, especially when a high density of sulfide oxidizers in the sediments was observed. The distribution of lipid biomarkers attributed to sulfate reducers (10MeC16:0 fatty acid, ai-C15:0 fatty acid, and mono-O-alkyl glycerol ethers) compared to the distribution of sulfide oxidizers indicate a close association between these bacteria. As a consequence, the distributions of sulfate reducers in sediments of Namibia, Peru, and Chile are closely related to differences in the motility of the various sulfide oxidizers at the three study sites. Depth profiles of mono-O-alkyl glycerol ethers have been found to correlate best with the occurrence of large sulfide-oxidizing bacteria. This suggests a particularly close link between mono-O-alkyl glycerol ether-synthesizing sulfate reducers and sulfide oxidizers. The interaction between sulfide-oxidizing bacteria and sulfate-reducing bacteria reveals intense sulfur cycling and degradation of organic matter in different sediment depths. [ABSTRACT FROM AUTHOR]

The high turnover of carbon dioxide during bacterial oxidation of sulfides witnessed in cultures of Acidithiobacillus ferrooxidans, Leptospirillum ferroxidans, and even more efficient by Sulfolobus and other thermophile bacteria (e.g., Acidianus brierleyi), and the parallel rapid buildup of bacterial biomass suggests a coupling of these processes to solar energy in order to develop carbon dioxide cycling technologies for sustainable future applications. Synergistic effects can be expected with biometallurgical research and technology which also aims to further increase energy turnover reflected in higher leaching rates. The prospective technology has been investigated by growing bacteria on iron sulfide synthesized from iron sulfate using solar energy. A catalytic process was developed which allows sulfate to sulfide reduction at a carbon electrode at 120 °C. Photovoltaic energy is used to drive the electrochemical reaction and thermal heat for maintaining the operation temperature. H2S is immediately converted in Fe2+-containing solution to iron sulfide which is supplied to bacterial cultures for biological CO2 fixation. It is estimated that solar-powered biohydrometallurgical processes for CO2 fixation may reach efficiencies exceeding biological photosynthesis by one order of magnitude. In addition, they can be operated in infertile environments with very limited water. The bacterial biomass has a high quality and could be used for energy, materials, and even for food production. The perspectives and challenges for coupling biohydrometallurgical processes to regenerative energy utilization are discussed. [Copyright &y& Elsevier]

In the course of pilot industrial testing of a biohydrometallurgical technology for processing gold-arsenic concentrate obtained from the Nezhdaninskoe ore deposit (East Siberia, Sakha (Yakutiya)), a new gram-positive rod-shaped spore-forming moderately thermophilic bacterium (designated as strain N1) oxidizing Fe2+, S0, and sulfide minerals in the presence of yeast extract (0.02%) was isolated from a dense pulp. Physiologically, strain N1 differs from previously described species of the genus Sulfobacillus in having a somewhat higher optimal growth temperature (55°C). Unlike the type strain of S. thermosulfidooxidans, strain N1 could grow on a medium with 1 mM thiosulfate or sodium tetrathionate as a source of energy only within several passages and failed to grow in the absence of an inorganic energy source on media with sucrose, fructose, glucose, reduced glutathione, alanine, cysteine, sorbitol, sodium acetate, or pyruvate. The G+C content of the DNA of strain N1 was 48.2 mol %. The strain showed 42% homology after DNA–DNA hybridization with the type strain of S. thermosulfidooxidans and 10% homology with the type strain of S. acidophilus. The isolate differed from previously studied strains of S. thermosulfidooxidans in the structure of its chromosomal DNA (determined by the method of pulsed-field gel electrophoresis), which remained stable as growth conditions were changed. According to the results of the 16S rRNA gene analysis, the new strain forms a single cluster with the bacteria of the species Sulfobacillus thermosulfidooxidans (sequence similarity of 97.9–98.6%). Based on these genetic and physiological features, strain N1 is described as a new species Sulfobacillus sibiricus sp. nov. [ABSTRACT FROM AUTHOR]

• Sulfide-driven partial denitrification and anammox (SPDA) was verified in long-term. • Anammox contributed up to 87.2% of nitrogen removal in the SPDA system. • The tolerance of anammox to sulfide (IC 50) increased to 9.7 mgS-H 2 S/L in SPDA. • Rapid oxidation toxic S2− to S0 alleviates its inhibitory effect on anammox. • Biologically produced S0 is the favorable electron donor for partial denitrification. Anaerobic ammonia oxidation (anammox) is a well-developed biotechnology for treating high-strength ammonium wastewaters. Recently, partial denitrification has been considered as an alternative to supply anammox with the required nitrite. In this study, a process of sulfide-driven partial denitrification and anammox (SPDA) was developed and operated continuously in an upflow anaerobic sludge blanket (UASB) reactor for 392 days. This reactor was fed with synthetic wastewater containing 100 mgN/L nitrate, 80 mgN/L ammonium and 20–80 mgS/L sulfide. After 160 days of operation, the reactor reached stable performance, and the nitrogen removal efficiency and rate were maintained at 80% and 0.29 kgN/(m³•d), respectively. The estimated nitrogen removal via anammox and sulfide-driven denitrification were 87.2% and 12.8%. Additional batch experiments were conducted to investigate the effects of sulfide on anammox and the mechanisms of nitrogen removal in the SPDA system. The following results were obtained: (1) sulfide had an inhibitory effect on the specific anammox activity with IC 50 of 9.7 mgS-H 2 S/L. (2) The rapid oxidation of sulfide by sulfur-oxidizing bacteria (SOB) could relieve the toxic effects of sulfide on the anammox in the SPDA system. (3) Sulfide bio-oxidation was a two-step reaction with biologically produced elemental sulfur (BPS0) as the intermediate, and the second step using BPS0 as the electron donor, can efficiently produce nitrite via partial denitrification (NO 3 − → NO 2 −) as a supply for anammox. Finally, a high-throughput sequencing analysis identified Thiobacillus and Sulfurimonas as the dominant genera of SOB in the SPDA system, and Candidatus Kuenenia as the dominant anammox bacteria. Overall, this research gives the foundation for the practical application of sulfide-driven partial denitrification and anammox process in the future. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Management of excessive aqueous sulfide is one of the most significant challenges of treating effluent after biological sulfate reduction for metal recovery from hydrometallurgical leachate. The main objective of this study was to characterize and verify the effectiveness of a sulfide-oxidizing bacterial (SOB) consortium isolated from post-mining wastes for sulfide removal from industrial leachate through elemental sulfur production. The isolated SOB has a complete sulfur-oxidizing metabolic system encoded by sox genes and is dominated by the Arcobacter genus. XRD analysis confirmed the presence of elemental sulfur in the collected sediment during cultivation of the SOB in synthetic medium under controlled physicochemical conditions. The growth yield after three days of cultivation reached ~2.34 gprotein/molsulfid, while approximately 84% of sulfide was transformed into elemental sulfur after 5 days of incubation. Verification of isolated SOB on the industrial effluent confirmed that it can be used for effective sulfide concentration reduction (~100% reduced from the initial 75.3 mg/L), but for complete leachate treatment (acceptable for discharged limits), bioaugmentation with other bacteria is required to ensure adequate reduction of chemical oxygen demand (COD). [ABSTRACT FROM AUTHOR]

• Long-term impacts of different salinity (0.7% and 1.0%) on DS-EBPR were studied. • Shock of four levels of salinity (1.0, 1.4, 2.5 and 3.5%) on DS-EBPR was tested. • High salinity decreases/limits the efficiencies of S cycle driven-P removal. • XRD and XPS analysis have been conducted to determine the P precipitates. • The functional bacteria (SRB and SOB) were tolerant to high salinity. DS-EBPR is an alternative to the conventional activated sludge process which face great challenge for treatment of seawater-based highly saline wastewater. This study aims to investigate the impacts of long-term (248 days) 20% and 30% seawater fractions and short-term shock of 30%, 40%, 70% and 100% seawater fractions (corresponding to 1.0, 1.4, 2.5 and 3.5% of salinity) on the DS-EBPR performance, kinetics and microbial community structure. Long-term operation with high fraction (30%) of seawater marginally decreased the sulfur conversion and phosphorus uptake, which correlated well with the microbial dynamics. Temporal salinity shock from 1.0% (30% seawater) to 3.5% (100% seawater) remarkably reduced the phosphorus release/uptake by 36–44%, which was partly due to the decrease in the abundance of functional bacteria and chlorapatite (Ca 5 [PO 4 3 Cl) forming as P precipitates with 70–100% seawater addition. The formed chlorapatite contributed to approximately 8–26% of total P removal estimated by X-ray photoelectron spectroscopy analysis. [ABSTRACT FROM AUTHOR]

Several textile industry processes produce complex organics, azo dyes and sulfide streams that pose a severe challenge to environmental protection. In this work, single-chamber air cathode microbial fuel cells were used to investigate the interaction mechanisms among Congo red decolorization, sulfide oxidation and bioelectricity generation. The results showed that effective removal of sulfide (>98%) and azo dyes (>88%) was achieved at an initial sulfide/dye ratio of 0.9 under neutral conditions, accompanied by a maximum power output of approximately 23.50 mW m−2. In this study, biogenic sulfide played a major role in azo dye decolorization and power generation compared with the chemical sulfide. The results indicated that bulk reduction of sulfide and cell lysis products during biogenic sulfide production by sulfate-reduction bacteria could accelerate the chemical reduction of azo dyes. Moreover, S0, SO 4 2− and S 2 O 3 2− were identified as degradation products, and the intermediates primarily included 3,4-diaminonaphthalene-1-sulfonic acid, sodium 4-aminonaphthalene-1-sulfonate and 4, 4′-diamine biphenyl. Microbial community analysis showed that Proteobacteria (80.7%), Gammaproteobacteria (48.1%), and Dokdonella (29.5%) dominated at the phylum, class, and genus levels, respectively, of the anodic biofilm. This study offers a feasible option for the treatment of recalcitrant organics, azo dyes and sulfide pollutants using single-chamber air cathode MFCs. • Successful bioelectricity production, sulfide and dye removal were achieved. • High dye concentration and low sulfide negatively affected dye decolorization. • Biogenic sulfide was more efficient than chemical sulfide in MFCs. • Proteobacteria (phylum) and Dokdonella (genus) were most abundant at the anode. [ABSTRACT FROM AUTHOR]