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Abstract

Hydrogen sulfide removal from biogas was studied under anoxic conditions in a pilot-scale biotrickling filter operated under counter- and co-current gas-liquid flow patterns. The best performance was found under counter-current conditions (maximum elimination capacity of 140 gS m−3h−1). Nevertheless, switching conditions between co- and counter-current flow lead to a favorable redistribution of biomass and elemental sulfur along the bed height. Moreover, elemental sulfur was oxidized to sulfate when the feeding biogas was disconnected and the supply of nitrate (electron acceptor) was maintained. Removal of elemental sulfur was important to prevent clogging in the packed bed and, thereby, to increase the lifespan of the packed bed between maintenance episodes. The larger elemental sulfur removal rate during shutdowns was 59.1 gS m−3h−1. Tag-encoded FLX amplicon pyrosequencing was used to study the diversity of bacteria under co-current flow pattern with liquid recirculation and counter-current mode with a single-pass flow of the liquid phase. The main desulfurizing bacteria were Sedimenticola while significant role of heterotrophic, opportunistic species was envisaged. Remarkable differences between communities were found when a single-pass flow of industrial water was fed to the biotrickling filter.
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... Most of them have been carried out by Spanish universities (43), followed by institutions from China (15), Brazil (9), Canada (8), and Mexico (8), etc. (Fig. 1b). Most of these studies were conducted on a laboratory scale Cano et al., 2019;Fernández et al., 2013;Khanongnuch et al., 2019a;Xu et al., 2020), although some pilot-scale studies have also been carried out (Almenglo et al., 2016a(Almenglo et al., , 2016b2016c;Gamisans et al., 2021;Zeng et al., 2019). There are a large number of studies using biotrickling filters under anoxic conditions, but it is also possible to find other configurations, such as stirred tank bioreactors (González-Cortés et al., 2021b), gas-lift (González-Cortés et al., 2021a, bubble columns (Deng et al., 2009), horizontal-flow packed bed (de Bello Solcia Guerrero et al., 2020 This review aims to summarize and analyze all the advances achieved from 2008 until the present in anoxic biogas desulfurization. ...
... This simplification has been useful to predict product selectivity. Certain key operational aspects such as reagent consumption, pH control, inhibition by products or the maintenance of the fixed beds are intimately linked to the biological reaction products (Almenglo et al., 2016a;Bayrakdar et al., 2016;Cano et al., 2018Cano et al., , 2019Feng et al., 2021;González-Cortés et al., 2020;Jaber et al., 2017;Lebrero et al., 2016;López et al., 2018). However, more studies are needed addressing its feasibility from an economic and operational point of view. ...
... However, more studies are needed addressing its feasibility from an economic and operational point of view. The influence of the N/S molar ratio on the reaction product has been investigated by several authors (Almenglo et al., 2016a(Almenglo et al., , 2016bBrito et al., 2020Brito et al., , 2018Brito et al., , 2017Cano et al., 2019;Fernández et al., 2014Fernández et al., , 2013López et al., 2018;Soreanu et al., 2008aSoreanu et al., , 2008b, who have found some deviations from the theoretical equations. When total denitrification does not occur, the product selectivity is more complex to estimate as all stoichiometric equations (2)-(7) have to be considered. ...
Article
Recovery of the energy contained in biogas will be essential in coming years to reduce greenhouse gas emissions and our current dependence on fossil fuels. The elimination of H2S is a priority to avoid equipment corrosion, poisoning of catalytic systems and SO2 emissions in combustion engines. This review describes the advances made in this technology using fixed biomass bioreactors (FBB) and suspended growth bioreactors (SGB) since the first studies in this field in 2008. Anoxic desulfurization has been studied mainly in biotrickling filters (BTF). Elimination capacities (EC) up to 287 gS m-3 h-1 have been achieved, with a removal efficiency (RE) of 99%. Both nitrate and nitrite have been successfully used as electron acceptor. SGBs can solve some operational problems present in FBBs, such as clogging or nutrient distribution issues. However, they present greater difficulties in gas-liquid mass transfer, although ECs of up to 194 gS m-3 h-1 have been reported in both gas-lift and stirred tank reactors. One of the major disadvantages of using anoxic biodesulfurization compared to aerobic biodesulfurization is the need to provide reagents (nitrates and/or nitrites), with the consequent increase in operating costs. A solution proposed in this respect is the use of nitrified effluents, some ammonium-rich effluents nitrified include landfill leachate and digested effluent from the anaerobic digester have been tested successfully. Among the microbial diversity found in the bioreactors, the genera Thiobacillus, Sulfurimonas and Sedimenticola play a key role in anoxic removal of H2S. Finally, a summary of future trends in technology is provided.
... On the other hand, in concurrent operation, this condition occurs at the top section. The alternation between these modes allows for a more homogeneous distribution of elemental sulfur along the height of the bed (Almenglo et al., 2016). Once sulfur has accumulated on the bed, there are several methods to remove it being the best approach to stop biogas feeding while maintaining electron acceptor supply or through partial or total replacement of the bed. ...
Chapter
Biogas, a renewable energy source generated by organic matter degradation without oxygen, consists primarily of CH4 (45–75%) and CO2 (20–50%), along with minor components like O2, H2S, N2, NH3, H2, volatile methyl siloxanes (VMSs), and volatile organic compounds (VOCs). While conventional physicochemical methods have been used for biogas purification, biological technologies have emerged due to their cost-effectiveness and eco-friendliness. The chapter provides an overview of biological systems for biogas purification and upgrading. It covers in-situ desulfurization through microaeration and aerobic and anoxic ex-situ desulfurization techniques within different bioreactor configurations such as fixed-bed (biofilters, biotrickling filters) and suspended biomass (CSTR, gas-lift, bubble column, bioscrubber). The chapter also addresses the removal of poorly biodegradable volatile methyl siloxanes (VMSs) and volatile organic compounds (VOCs), known for causing combustion-related deposit formation and emission of toxic compounds during combustion, respectively. Biogas upgrading has gained momentum, producing high CH4 concentration effluent (biomethane) comparable to natural gas. Various upgrading technologies exist, including physical and chemical methods and biological approaches. Among biological options, microalgae and hydrogenotrophic archaea are prominent for biogas upgrading, utilizing photobioreactors for CO2 assimilation and hydrogenotrophic methanogens for CO2 and H2 conversion. The implementation of biological techniques can reduce investment and operational costs compared to physicochemical methods, promoting sustainable integration of upgraded biogas into the energy mix. The chapter concludes by outlining future research directions for biological biogas purification and upgrading.
... Currently, there are technologies for the desulfurization of biogas, which are classified as physical (adsorption, absorption), chemical (addition of iron compounds or iron oxide to the substrate) and/or biological (biodesulfurization) (Almenglo et al., 2016;Dupnock & Deshusses, 2020;Das et al., 2022;Ravishankar et al., 2022). Biodesulfurization technology has advantages when compared to other methods, such as: low implementation and maintenance costs (Almenglo et al., 2023) and high efficiency (Nhut et al., 2020). ...
Article
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The hydrogen sulfide (H2S) present in biogas needs to be removed due to concerns about corrosion during transportation, storage, health and safety. One of the existing removal processes is biological, using a biotrickling filter (BTF). In this study, the performance of full-scale BTF for H2S removal under different operating conditions was evaluated. The BTF system was operated for 300 days, during which two spraying regimes (constant and intermittent) and two sources of nitrate (NO3⁻) as nutrient solution were evaluated (residual effluent from pig farming and synthetic solution prepared with commercial NaNO3). The performance was monitored by the following parameters: removal efficiency (RE), elimination capacity (EC), pH, dissolved oxygen (DO), empty bed residence time (EBRT) and nitrate concentration (NO3⁻). The results showed an REH2S = 36.3% with an EC= 1.95 gH2S m⁻³ d⁻¹ for constant spraying, RE= 99.59% and EC= 4.2 gH2S m⁻³ d⁻¹ for intermittent spraying with residual effluent from pig farming and RE=99.26% and EC= 4.13 gH2S m⁻³ d⁻¹ with synthetic solution prepared with commercial NaNO3 solution. The results indicate that intermittent spraying provides better efficiency in the removal of H2S from biogas regardless of the nitrate source (effluent or synthetic medium). KEYWORDS desulfurization; nitrate; biofilter and biogas
... It's worth mentioning that in sample S2, the phylum Campylobacterota also thrives, with a relative abundance of 11%, as compared to 1.0% and 1.6% in samples S1 and S3, respectively. These phyla have been previously documented in studies related to desulfurization in BTFs and suspended growth bioreactors (Almenglo et al., 2016;González-Cortés et al., 2021a). ...
... The biological oxidation of H 2 S can also be performed under anoxic conditions, using NO x − as an electron acceptor, through which H 2 S is oxidized to elemental sulfur or sulfate (Almenglo et al., 2016). Some representative species in the anoxic desulfurization method are Thiobacillus, Thiomicrospira, and Thiosphaera. ...
Article
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Direct application of high-sulfur fuels and ores can cause environmental pollution (such as air pollution and acid rain) and, in serious cases, endanger human health and contribute to property damage. In the background of preserving the environment, microbial desulfurization technologies for high-sulfur fuels and ores are rapidly developed. This paper aims to reveal the progress of microbial desulfurization research on fuels and ores using bibliometric analysis. 910 publications on microbial desulfurization of fuels and ores from web core databases were collected in this work, spanning 39 years. Through 910 retrieved documents, collaborative networks of authors, institutions and countries were mapped by this work, the sources of highly cited articles and cited documents were statistically analyzed, and keyword development from different perspectives was discussed. The results of the study provide a reference for microbial desulfurization research and benefit environmental protection and energy green applications.
... This indicates that selecting the most effective and efficient biogas desulfurization technique is still challenging for researchers. Several desulfurization techniques that have been proposed include: adsorption and absorption (chemical scrubbing) [11], aerobic and anaerobic bio trickling filters (BTFs) [12], anoxic desulfurization [13], biological bubble column [14], membrane bioscrubble [15], and photocatalytic desulfurizer [16] Using waste as a medium for biogas purification is getting more attention from researchers [17][18][19][20][21][22]. In addition to considering the environmental impact, this is also aimed at obtaining an inexpensive purification medium that can be applied in small-scale desulphurization processes. ...
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p>Abstract— The biogas desulphurization process has a crucial role in the widespread use of biogas due to the toxic and corrosive nature of the element hydrogen sulfide on equipment. This study investigated the potential use of waste welding electrodes as a biogas purification medium. Variables in the form of feed biogas flow rates of 1, 2, and 3 liters/minute were studied for their effects. As a result, the most optimum performance was obtained in the test with a feed biogas flow rate of 1 liter/minute, with an average reduction percentage of hydrogen sulfide content in the biogas of 27.12%. <</script
... The distribution of these phyla in our study concurs well with previously reported distribution models corresponding to other bioreactors used for the anoxic desulfurization of real biogas or biogas mimics. Thus, Almenglo et al. [31] operated a pilot-scale biotrickling filter that was fed with real biogas and wastewater. According to their study, Proteobacteria phylum was markedly predominant at a relative abundance ranging from 64 % and 97 %. ...
Article
Landfill biogas contains certain amounts of H2S that must be removed in order to prevent both equipment corrosion and SO2 emissions to the atmosphere when burnt. Anoxic desulfurization has been proven to be an eco-friendly and cost-efficient method to remove H2S from biogas. Nevertheless, and despite all the reported benefits, the potential consumption of methane (CH4) during the anoxic desulfurization of landfill biogas is a factor that has not yet been thoroughly investigated. The present study evaluates the microbial composition and methane assimilation activity of three microbial samples obtained when feeding different nitrate sources, namely nitrified landfill leachate (M1) or chemical nitrate (M2, M3) with 10 days (M2) and 1.5 days (M3) hydraulic residence times. The samples were characterized by the prevalence of sulfide oxidizing bacteria [Thiomicrospira (11.4–25.5 %), Family Rhodobacteraceae (9.9–14.3 %), Sulfurimonas (0.34–17.9 %), Thioclava (0–23.5 %) and Arcobacter (0–11.5 %)], as well as the presence of methane oxidizing bacteria [Halomonas (0.2–16.0 %), Methylophaga (0–0.2 %) and Methylophilacea (0–0.1 %)] and heterotrophic bacteria [Lentimicrobium (0.1–9.7 %) and Roseovarius (0.1–1.2 %)]. The highest CH4 assimilation levels were reached under anoxic conditions at 34.0 and 50.1 g CH4 m⁻³ h⁻¹ using nitrate and nitrite, respectively. The oxygen present in the landfill biogas itself had a detrimental effect on the anoxic bioreactor nitrate removal efficiency. The presence of organic matter in the nitrified influent gave rise to CH4 inside the anoxic desulfurization bioreactors, which resulted in the offsetting of the CH4 oxidation caused by methane-oxidizing bacteria (MOB).
Article
A cost-efficient, environmentally friendly, and extremely acidic biotrickling filter is essential for desulfurization to recover elemental sulfur and sulfate for extensively remediating H2S. The present study investigated the H2S removal capacity, accumulation of desulfurization products, sulfur balance, microbial community, and the H2S biodegradation kinetics. The results showed that when the empty bed retention time (EBRT) decreased from 180 s to 60 s, the removal efficiency of H2S decreased from 100% to 95.4%, and the elimination capacity increased from 18.0 ± 1.3 to 51.5 ± 3.2 gH2S m–3 h–1. Furthermore, with the increase of EBRT, the proportion of SO42–-S in the biodesulfurization products gradually decreased from 74.83% to 38.71%, whereas that of S⁰-S increased from 16.04% to 53.30%. The content of polysaccharide (PS), protein (PN), and the change of PN/PS values during the H2S removal process were studied. Moreover, 16 S rRNA high-throughput sequencing analysis showed that Acidithiobacillus, Thiobacillus, Sulfuricurvum, and Sulfobacillus were the main genera in the removal of H2S, and their total abundance was higher than 68.00%. In addition, the system viability and robustness were proved by shock loads and starvation regimes.
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The lack of tax incentives for biomethane use requires the optimization of both biogas production and upgrading in order to allow the full exploitation of this renewable energy source. The large number of biomethane contaminants present in biogas (CO2, H2S, H2O, N2, O2, methyl siloxanes, halocarbons) has resulted in complex sequences of upgrading processes based on conventional physical/chemical technologies capable of providing CH4 purities of 88–98 % and H2S, halocarbons and methyl siloxane removals >99 %. Unfortunately, the high consumption of energy and chemicals limits nowadays the environmental and economic sustainability of conventional biogas upgrading technologies. In this context, biotechnologies can offer a low cost and environmentally friendly alternative to physical/chemical biogas upgrading. Thus, biotechnologies such as H2-based chemoautrophic CO2 bioconversion to CH4, microalgae-based CO2 fixation, enzymatic CO2 dissolution, fermentative CO2 reduction and digestion with in situ CO2 desorption have consistently shown CO2 removals of 80–100 % and CH4 purities of 88–100 %, while allowing the conversion of CO2 into valuable bio-products and even a simultaneous H2S removal. Likewise, H2S removals >99 % are typically reported in aerobic and anoxic biotrickling filters, algal-bacterial photobioreactors and digesters under microaerophilic conditions. Even, methyl siloxanes and halocarbons are potentially subject to aerobic and anaerobic biodegradation. However, despite these promising results, most biotechnologies still require further optimization and scale-up in order to compete with their physical/chemical counterparts. This review critically presents and discusses the state of the art of biogas upgrading technologies with special emphasis on biotechnologies for CO2, H2S, siloxane and halocarbon removal.
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We report the closed genome sequence of Sedimenticola thiotaurini strain SIP-G1 and an unnamed plasmid obtained through PacBio sequencing with 100% consensus concordance. The genome contained several distinctive features not found in other published Sedimenticola genomes, including a complete nitrogen fixation pathway, a complete ethanolamine degradation pathway, and an alkane-1-monooxygenase. FOOTNOTES Address correspondence to Beverly E. Flood, beflood{at}umn.edu. ↵* Present address: Daniel S. Jones, University of Minnesota, BioTechnology Institute, St. Paul, Minnesota, USA. Citation Flood BE, Jones DS, Bailey JV. 2015. Complete genome sequence of Sedimenticola thiotaurini strain SIP-G1, a polyphosphate- and polyhydroxyalkanoate-accumulating sulfur-oxidizing gammaproteobacterium isolated from salt marsh sediments. Genome Announc 3(3):e00671-15. doi:10.1128/genomeA.00671-15. Received 18 May 2015. Accepted 19 May 2015. Published 18 June 2015. Copyright © 2015 Flood et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license.
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BACKGROUND Biological oxidation in biotrickling filters of high H2S loads contained in biogas streams still requires further study to reduce elemental sulfur accumulation due to limited gas-liquid oxygen mass transfer inside biotrickling filters bed. Reduction of elemental sulfur accumulation may be improved by regulating the main manipulated variables related to oxygen mass transfer efficiency during biological hydrogen sulfide removal in biotrickling filters.RESULTSTrickling liquid velocity and co-current were selected as the most appropriate variable and flow pattern configuration to manipulate compared to manipulate air supply regulation and counter-current flow pattern in order to improve gas-liquid oxygen mass transfer in abiotic conditions. Then, trickling liquid velocity influence on the performance of a lab-scale biotrickling filter treating high loads of H2S on a biogas mimics and operated in co-current flow at neutral pH and packed with plastic pall rings was investigated.CONCLUSIONS Effect of trickling liquid velocity modulation between 4.4 and 18.9 m h−1 in biotrickling filters performance was compared with operation without trickling liquid velocity regulation. Resulting in an improvement of 10% on the elimination capacity and most importantly, a 9% increase in the product selectivity to sulfate at a loding rate of 283.8 g S-H2S m−3 h−1.Concentration profiles along the biotrickling filter height evidenced that trickling liquid velocity regulation progressively lead to a better dissolved oxygen distribution and, thus, enhanced overall biotrickling filter performance.
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A marine facultative anaerobe, strain SIP-G1T, was isolated from salt marsh sediments, Falmouth, MA, USA. Phylogenic analyses of its 16S rRNA gene indicated that it belongs to an unclassified clade of Gammaproteobacteria that includes numerous sulfide-oxidizing bacteria that are endosymbionts of marine invertebrates endemic to sulfidic habitats. SIP-G1T is a member of the genus Sedimenticola, of which there is one previously-described isolate, Sedimenticola selenatireducens AK4OH1T. S. selenatireducens AK4OH1T was obtained for further characterization and comparison with SIP-G1T. Our study found that both strains are capable of coupling the oxidation of thiosulfate and sulfide with autotrophic growth and they produce sulfur granules as metabolic intermediates. They have varying degrees of O2 sensitivity, but when provided amino acids or peptides as a source of carbon, they appear more tolerant of O2 and exhibit concomitant production of intracellular elemental sulfur granules. The organic substrate preferences and limitations of these two organisms suggest that they possess an oxygen-sensitive carbon fixation pathway(s). Organic acids may be used to produce NADPH through the TCA cycle and are used in the formation of polyhydroxyalkanoates. Cell wall-deficient morphotypes appeared when organics (esp. acetate) are present in excess and reduced sulfur is absent. DNA-DNA hybridization (~47%) and phenotypic characterization indicate that the strain SIP-G1 is a separate species within the Sedimenticola, for which the name Sedimenticola thiotaurini sp. nov. is proposed. The type strain is SIP-G1T (ATCC = BAA-2640T; DSMZ = 28581T). Our results also justify an emended description of the genus Sedimenticola and of S. selenatireducens.
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