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Chin KJ, Ünal B, Sanderson M, Aboderin F, Nüsslein K. Selective trace elements significantly enhanced methane production in coal bed methane systems by stimulating microbial activity. Microbiol Spectr 2024; 12:e0350823. [PMID: 38236038 PMCID: PMC10846109 DOI: 10.1128/spectrum.03508-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 10/17/2023] [Indexed: 01/19/2024] Open
Abstract
Trace elements are associated with the microbial degradation of organic matter and methanogenesis, as enzymes in metabolic pathways often employ trace elements as essential cofactors. However, only a few studies investigated the effects of trace elements on the metabolic activity of microbial communities associated with biogenic coalbed methane production. We aimed to determine the effects of strategically selected trace elements on structure and function of active bacterial and methanogenic communities to stimulate methane production in subsurface coalbeds. Microcosms were established with produced water and coal from coalbed methane wells located in the Powder River Basin, Wyoming, USA. In initial pilot experiments with eight different trace elements, individual amendments of Co, Cu, and Mo lead to significantly higher methane production. Transcript levels of mcrA, the key marker gene for methanogenesis, positively correlated with increased methane production. Phylogenetic analysis of the mcrA cDNA library demonstrated compositional shifts of the active methanogenic community and increase of their diversity, particularly of hydrogenotrophic methanogens. High-throughput sequencing of cDNA obtained from 16S rRNA demonstrated active and abundant bacterial groups in response to trace element amendments. Active Acetobacterium members increased in response to Co, Cu, and Mo additions. The findings of this study yield new insights into the importance of essential trace elements on the metabolic activity of microbial communities involved in subsurface coalbed methane and provide a better understanding of how microbial community composition is shaped by trace elements.IMPORTANCEMicrobial life in the deep subsurface of coal beds is limited by nutrient replenishment. While coal bed microbial communities are surrounded by carbon sources, we hypothesized that other nutrients such as trace elements needed as cofactors for enzymes are missing. Amendment of selected trace elements resulted in compositional shifts of the active methanogenic and bacterial communities and correlated with higher transcript levels of mcrA. The findings of this study yield new insights to not only identify possible limitations of microbes by replenishment of trace elements within their specific hydrological placement but also into the importance of essential trace elements for the metabolic activity of microbial communities involved in subsurface coalbed methane production and provides a better understanding of how microbial community composition is shaped by trace elements. Furthermore, this finding might help to revive already spent coal bed methane well systems with the ultimate goal to stimulate methane production.
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Affiliation(s)
- Kuk-Jeong Chin
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - Burcu Ünal
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Environmental Engineering, RheinMain University of Applied Sciences, Wiesbaden, Germany
| | - Michael Sanderson
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - Feranmi Aboderin
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - Klaus Nüsslein
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
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Buenaño-Vargas C, Gagliano MC, Paulo LM, Bartle A, Graham A, van Veelen HPJ, O'Flaherty V. Acclimation of microbial communities to low and moderate salinities in anaerobic digestion. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167470. [PMID: 37778560 DOI: 10.1016/j.scitotenv.2023.167470] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/03/2023]
Abstract
In recent years anaerobic digestion (AD) has been investigated as suitable biotechnology to treat wastewater at elevated salinities. However, when starting up AD reactors with inocula that are not adapted to salinity, low concentrations of sodium (Na+) in the influent can already cause disintegration of microbial aggregates and wash-out. This study investigated biomass acclimation to 5 g Na+/L of two different non-adapted inocula in two lab-scale hybrid expanded granular sludge bed (EGSB)-anaerobic filter (AF) reactors fed with synthetic wastewater. After an initial biomass disintegration, new aggregates were formed relatively fast (i.e., after 95 days of operation), indicating microbial community adaptation. The newly formed microbial aggregates accumulated Na+ at the expense of calcium (Ca2+), but this did not hamper biomass retention or process performance. The hybrid reactor configuration, including a pumice stone filter in the upper section, and the low up-flow velocities applied, were key features for retaining the biomass within the system. This reactor configuration can be easily applied and represents a low-cost alternative for acclimating biomass to saline effluents, even in existing digesters. When the acclimated biomass was transferred from EGSB to an up-flow anaerobic sludge blanket (UASB) reactor configuration also fed with saline synthetic wastewater, more dense aggregates in the form of granules were obtained. The performances of the UASB inoculated with the acclimated biomass were comparable to another reactor seeded with saline-adapted granular sludge from a full-scale plant. Regardless of the inoculum origin, a defined core microbiome of Bacteria (Thermovirga, Bacteroidetes vadinHA17, Blvii28 wastewater-sludge group, Mesotoga, and Synergistaceae) and Archaea (Methanosaeta and Methanobacterium) was detected, highlighting the importance of these microbial groups in developing halotolerance and maintaining AD process stability.
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Affiliation(s)
- Claribel Buenaño-Vargas
- Microbial Ecology Laboratory, School of Biological and Chemical Sciences and Ryan Institute, University of Galway, University Road, Ireland
| | - M Cristina Gagliano
- Wetsus - European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911MA Leeuwarden, the Netherlands
| | - Lara M Paulo
- Microbial Ecology Laboratory, School of Biological and Chemical Sciences and Ryan Institute, University of Galway, University Road, Ireland
| | - Andrew Bartle
- Microbial Ecology Laboratory, School of Biological and Chemical Sciences and Ryan Institute, University of Galway, University Road, Ireland
| | - Alison Graham
- Microbial Ecology Laboratory, School of Biological and Chemical Sciences and Ryan Institute, University of Galway, University Road, Ireland
| | - H Pieter J van Veelen
- Wetsus - European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911MA Leeuwarden, the Netherlands
| | - Vincent O'Flaherty
- Microbial Ecology Laboratory, School of Biological and Chemical Sciences and Ryan Institute, University of Galway, University Road, Ireland.
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Afroze N, Nakhla G, Kim M, Yazdanpanah A. Effects of trace elements on digester performance and microbial community response in anaerobic digestion systems. ENVIRONMENTAL TECHNOLOGY 2023; 44:4157-4172. [PMID: 35611656 DOI: 10.1080/09593330.2022.2082324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/05/2022] [Indexed: 06/15/2023]
Abstract
Trace elements (TE), as micronutrients for microorganisms, have a significant impact on the stability of anaerobic digestion (AD). Studies have been conducted on process stability and performance of the AD of food waste (FW) by supplementing TEs. In this study, mesophilic batch biomethane potential (BMP) tests using FW were conducted to investigate the effect of TEs (Fe, Ni, Co, Se, and Mo) as single and mixed ions. In view of their scarcity, correlations between the microbial community and digester performance such as first-order hydrolysis coefficient (Kh), volatile fatty acids (VFA), methane yield, and methane production rate (MPR) have been developed. Ni2+ at 1 and 1.5 mg/L increased the methane yield by 27% and 23% respectively. Similarly, Co2+ at 0.1 and 0.5 mg/L increased the yield by 21% and 23% respectively, compared to control. Although Se4+ at all concentrations enhanced the methane yield, Fe2+ at only 50 mg/L increased methane yield by 22%. For mixed TEs, the combination of Ni2+ [1 mg/L] +Co2+ was the best and increased methane for all Co2+ concentrations (0.1, 0.4 and 0.5 mg/L) by 16%, 14% and 12% respectively. Firmicutes and Methanosaeta were the most abundant phyla among hydrolytic and methanogenic microbial groups, respectively, constituting 42%-61% and 60-80% of their respective microbial groups. The most significant positive correlations were observed between aceto/acidogenic microorganisms and final VFA concentrations with Pearson correlation factors of 0.91.
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Affiliation(s)
- Niema Afroze
- Civil and Environmental Engineering, University of Western Ontario, London, ON, Canada
| | - George Nakhla
- Civil and Environmental Engineering, University of Western Ontario, London, ON, Canada
- Chemical and Biochemical Engineering, University of Western Ontario, London, ON, Canada
| | - Mingu Kim
- Chemical and Biochemical Engineering, University of Western Ontario, London, ON, Canada
| | - Andisheh Yazdanpanah
- Civil and Environmental Engineering, University of Western Ontario, London, ON, Canada
- Black & Veatch, Markham, ON, Canada
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Fernández-Domínguez D, Yekta SS, Hedenström M, Patureau D, Jimenez J. Deciphering the contribution of microbial biomass to the properties of dissolved and particulate organic matter in anaerobic digestates. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162882. [PMID: 36934942 DOI: 10.1016/j.scitotenv.2023.162882] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/28/2023] [Accepted: 03/11/2023] [Indexed: 05/06/2023]
Abstract
The recalcitrant structures either from substrate or microbial biomass contained in digestates after anaerobic digestion (AD) highly influence digestate valorization. To properly assess the microbial biomass contribution to the digested organic matter (OM), a combination of characterization methods and the use of various substrate types in anaerobic continuous reactors was required. The use of totally biodegradable substrates allowed detecting soluble microbial products via fluorescence spectroscopy at emission wavelengths of 420 and 460 nm while the protein-like signature was enhanced by the whey protein. During reactors' operation, a transfer of complex compounds to the dissolved OM from the particulate OM was observed through fluorescence applied on biochemical fractionation. Consequently, the fluorescence complexity index of the dissolved OM increased from 0.59-0.60 to 1.06-1.07, whereas it decreased inversely for the extractable soluble from the particulate OM from 1.16-1.19 to 0.42-0.54. Accordingly, fluorescence regional integration showed differences among reactors based on visual inspection and orthogonal partial latent structures (OPLS) analysis. Similarly, the impact of the substrate type and operation time on the particulate OM was revealed by 13C nuclear magnetic resonance using OPLS, providing a good model (R2X = 0.93 and Q2 = 0.8) with a clear time-trend. A high signal resonated at ∼30 ppm attributed to CH2-groups in the aliphatic chain of lipid-like structure besides carbohydrates intensities at 60-110 ppm distinguished the reactor fed with whey protein from the other, which was mostly biomass related. Indeed, this latter displayed a higher presence of peptidoglycan (δH/C: 1.6-2.0/20-25 ppm) derived from microbial biomass by 1H-13C heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance. Interestingly, the sample distribution obtained by non-metric multidimensional scaling of bacterial communities resembled the attained using 13C NMR properties, opening new research perspectives. Overall, this study discloses the microbial biomass contribution to digestates composition to improve the OM transformation mechanism knowledge.
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Affiliation(s)
| | - Sepehr Shakeri Yekta
- Department of Thematic Studies-Environmental Change and Biogas Research Center, Linköping University, 581 83 Linköping, Sweden
| | | | - Dominique Patureau
- INRAE, Univ. Montpellier, LBE, 102 Avenue des étangs, 11100 Narbonne, France
| | - Julie Jimenez
- INRAE, Univ. Montpellier, LBE, 102 Avenue des étangs, 11100 Narbonne, France
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Li J, Chen Q, Fan Y, Wang F, Meng J. Improved methane production of two-phase anaerobic digestion by cobalt: efficiency and mechanism. BIORESOURCE TECHNOLOGY 2023; 381:129123. [PMID: 37146694 DOI: 10.1016/j.biortech.2023.129123] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/21/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023]
Abstract
Two-phase anaerobic digestion (AD) is a promising technology, but its performance is sensitive to methanogen. In this study, the effect of cobalt (Co) on two-phase AD was investigated and the enhanced mechanism was revealed. Though no obvious effect of Co2+ was observed in acidogenic phase, the activity of methanogens was significantly affected by Co2+ with an optimal Co2+ concentration of 2.0 mg/L. Ethylenediamine-N'-disuccinic acid (EDDS) was the most effective for improving Co bioavailability and increasing methane production. The role of Co-EDDS in improving methanogenic phase was also verified by operating three reactors for two months. The Co-EDDS supplement increased the level of Vitamin B12 (VB12) and coenzyme F420, and enriched Methanofollis and Methanosarcina, thereby successfully improving methane production and accelerating reactor recovery from ammonium and acid wastewater treatment. This study provides a promising approach to improve the efficiency and stability of anaerobic digester.
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Affiliation(s)
- Jianzheng Li
- National Engineering Research Centre for Safe Sludge Disposal and Resource Recovery, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Qiyi Chen
- National Engineering Research Centre for Safe Sludge Disposal and Resource Recovery, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yiyang Fan
- National Engineering Research Centre for Safe Sludge Disposal and Resource Recovery, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Furao Wang
- National Engineering Research Centre for Safe Sludge Disposal and Resource Recovery, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jia Meng
- National Engineering Research Centre for Safe Sludge Disposal and Resource Recovery, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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Rocamora I, Wagland ST, Hassard F, Villa R, Peces M, Simpson EW, Fernández O, Bajón-Fernández Y. Inhibitory mechanisms on dry anaerobic digestion: Ammonia, hydrogen and propionic acid relationship. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 161:29-42. [PMID: 36863208 DOI: 10.1016/j.wasman.2023.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 01/10/2023] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
Inhibitory pathways in dry anaerobic digestion are still understudied and current knowledge on wet processes cannot be easily transferred. This study forced instability in pilot-scale digesters by operating at short retention times (40 and 33 days) in order to understand inhibition pathways over long term operation (145 days). The first sign of inhibition at elevated total ammonia concentrations (8 g/l) was a headspace hydrogen level over the thermodynamic limit for propionic degradation, causing propionic accumulation. The combined inhibitory effect of propionic and ammonia accumulation resulted in further increased hydrogen partial pressures and n-butyric accumulation. The relative abundance of Methanosarcina increased while that of Methanoculleus decreased as digestion deteriorated. It was hypothesized that high ammonia, total solids and organic loading rate inhibited syntrophic acetate oxidisers, increasing their doubling time and resulting in its wash out, which in turn inhibited hydrogenotrophic methanogenesis and shifted the predominant methanogenic pathway towards acetoclastic methanogenesis at free ammonia over 1.5 g/l. C/N increases to 25 and 29 reduced inhibitors accumulation but did not avoid inhibition or the washout of syntrophic acetate oxidising bacteria.
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Affiliation(s)
- Ildefonso Rocamora
- School of Water, Energy and Environment, Cranfield University, Bedford, UK
| | - Stuart T Wagland
- School of Water, Energy and Environment, Cranfield University, Bedford, UK
| | - Francis Hassard
- School of Water, Energy and Environment, Cranfield University, Bedford, UK
| | - Raffaella Villa
- School of Water, Energy and Environment, Cranfield University, Bedford, UK; De Montfort University, School of Engineering and Sustainable Development, UK
| | - Miriam Peces
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, 08028 Barcelona, Spain
| | | | | | - Yadira Bajón-Fernández
- School of Water, Energy and Environment, Cranfield University, Bedford, UK; Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, Florida, South Africa.
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7
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Absence of oxygen effect on microbial structure and methane production during drying and rewetting events. Sci Rep 2022; 12:16570. [PMID: 36195651 PMCID: PMC9532411 DOI: 10.1038/s41598-022-20448-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 09/13/2022] [Indexed: 11/15/2022] Open
Abstract
Natural environments with frequent drainage experience drying and rewetting events that impose fluctuations in water availability and oxygen exposure. These relatively dramatic cycles profoundly impact microbial activity in the environment and subsequent emissions of methane and carbon dioxide. In this study, we mimicked drying and rewetting events by submitting methanogenic communities from strictly anaerobic environments (anaerobic digestors) with different phylogenetic structures to consecutive desiccation events under aerobic (air) and anaerobic (nitrogen) conditions followed by rewetting. We showed that methane production quickly recovered after each rewetting, and surprisingly, no significant difference was observed between the effects of the aerobic or anaerobic desiccation events. There was a slight change in the microbial community structure and a decrease in methane production rates after consecutive drying and rewetting, which can be attributed to a depletion of the pool of available organic matter or the inhibition of the methanogenic communities. These observations indicate that in comparison to the drying and rewetting events or oxygen exposure, the initial phylogenetic structure and the organic matter quantity and quality exhibited a stronger influence on the methanogenic communities and overall microbial community responses. These results change the current paradigm of the sensitivity of strict anaerobic microorganisms to oxygen exposure.
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Hasani Zadeh P, Serrano A, Collins G, Fermoso FG. Interrelating EPS, soluble microbial products and metal solubility in a methanogenic consortium stressed by nickel and cobalt. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 238:113579. [PMID: 35551045 DOI: 10.1016/j.ecoenv.2022.113579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/25/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
The relationships between extracellular polymeric substances (EPS), soluble microbial product production, metal solubility, and methanogenic activity were investigated. The individual, and joint, toxic effects of nickel and cobalt on methanogenic consortia fed with glucose as model substrate were studied using biomethane potential assays. Cobalt was found to be less toxic to methanogens than nickel at each concentration tested, and the combined effects of Ni and Co on methane production in the bimetal experiment was higher than the sum of the effects of each metal alone. The protein content of EPS, and extracellular soluble protein fractions, decreased with increasing concentrations of total metals. Meanwhile, no significant change in response to metal stress was apparent for carbohydrate content of EPS or extracellular soluble carbohydrate. Decreasing protein content of EPS was accompanied by reduced methanogenic activity and an increase in the soluble metal fraction. The strong associations observed between these variables could be due to the critical role of EPS in protecting microbial cells against nickel and cobalt stress, possibly by capturing metal cations through their functional groups, thus reducing metal availability to the microbial cells in the methanogenic consortia underpinning the anaerobic digestion process.
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Affiliation(s)
- Parvin Hasani Zadeh
- Bioprocesses for the Circular Economy Group, Instituto de la Grasa, Spanish National Research Council (CSIC), Seville, Spain; Microbial Communities Laboratory, School of Biological and Chemical Sciences, National University of Ireland Galway, Galway, Ireland
| | - Antonio Serrano
- Institute of Water Research, University of Granada, Granada 18071, Spain; Department of Microbiology, Pharmacy Faculty, University of Granada, Campus de Cartuja s/n, Granada 18071, Spain
| | - Gavin Collins
- Microbial Communities Laboratory, School of Biological and Chemical Sciences, National University of Ireland Galway, Galway, Ireland.
| | - Fernando G Fermoso
- Bioprocesses for the Circular Economy Group, Instituto de la Grasa, Spanish National Research Council (CSIC), Seville, Spain
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Multiple Effects of Different Nickel Concentrations on the Stability of Anaerobic Digestion of Molasses. SUSTAINABILITY 2021. [DOI: 10.3390/su13094971] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Molasses is a highly thick by-product produced after sugarcane crystallization constitutes large amounts of biodegradable organics. These organic compounds can be converted to renewable products through anaerobic digestion. Nevertheless, its anaerobic digestion is limited due to its high chemical oxygen demand (COD) and ion concentration. The effects of nickel (Ni2+) on the stability of anaerobic digestion of molasses were established by studying the degradation of organic matter (COD removal rate), biogas yield, methane content in the biogas, pH, and alkalinity. The results showed that there were no significant effects on the stability of pH and alkalinity. Increased COD removal rate and higher methane content was observed by 2–3% in the digesters receiving 2 and 4 mg/L of Ni2+ in the first phase of the experiment. Ni2+ supplemented to reactors at concentration 2 mg/L enhanced biogas yield. Overall, it is suggested that the addition of Ni2+ has some effects on the enhancement of biogas yield and methane contents but has no obvious effects on the long-lasting stability of the molasses digestion.
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Shakeri Yekta S, Liu T, Mendes Anacleto T, Axelsson Bjerg M, Šafarič L, Goux X, Karlsson A, Björn A, Schnürer A. Effluent solids recirculation to municipal sludge digesters enhances long-chain fatty acids degradation capacity. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:56. [PMID: 33663594 PMCID: PMC7934545 DOI: 10.1186/s13068-021-01913-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 02/21/2021] [Indexed: 06/05/2023]
Abstract
BACKGROUND Slow degradation kinetics of long-chain fatty acids (LCFA) and their accumulation in anaerobic digesters disrupt methanogenic activity and biogas production at high loads of waste lipids. In this study, we evaluated the effect of effluent solids recirculation on microbial LCFA (oleate) degradation capacity in continuous stirred-tank sludge digesters, with the overall aim of providing operating conditions for efficient co-digestion of waste lipids. Furthermore, the impacts of LCFA feeding frequency and sulfide on process performance and microbial community dynamics were investigated, as parameters that were previously shown to be influential on LCFA conversion to biogas. RESULTS Effluent solids recirculation to municipal sludge digesters enabled biogas production of up to 78% of the theoretical potential from 1.0 g oleate l-1 day-1. In digesters without effluent recirculation, comparable conversion efficiency could only be reached at oleate loading rates up to 0.5 g l-1 day-1. Pulse feeding of oleate (supplementation of 2.0 g oleate l-1 every second day instead of 1.0 g oleate l-1 every day) did not have a substantial impact on the degree of oleate conversion to biogas in the digesters that operated with effluent recirculation, while it marginally enhanced oleate conversion to biogas in the digesters without effluent recirculation. Next-generation sequencing of 16S rRNA gene amplicons of bacteria and archaea revealed that pulse feeding resulted in prevalence of fatty acid-degrading Smithella when effluent recirculation was applied, whereas Candidatus Cloacimonas prevailed after pulse feeding of oleate in the digesters without effluent recirculation. Combined oleate pulse feeding and elevated sulfide level contributed to increased relative abundance of LCFA-degrading Syntrophomonas and enhanced conversion efficiency of oleate, but only in the digesters without effluent recirculation. CONCLUSIONS Effluent solids recirculation improves microbial LCFA degradation capacity, providing possibilities for co-digestion of larger amounts of waste lipids with municipal sludge.
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Affiliation(s)
- Sepehr Shakeri Yekta
- Department of Thematic Studies-Environmental Change, Linköping University, 58183, Linköping, Sweden.
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden.
| | - Tong Liu
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala BioCenter, 75007, Uppsala, Sweden
| | - Thuane Mendes Anacleto
- Post Graduate Program in Plant Biotechnology and Bioprocesses, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-901, Brazil
| | - Mette Axelsson Bjerg
- Department of Thematic Studies-Environmental Change, Linköping University, 58183, Linköping, Sweden
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
| | - Luka Šafarič
- Department of Thematic Studies-Environmental Change, Linköping University, 58183, Linköping, Sweden
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
| | - Xavier Goux
- Environmental Research and Innovation Department, Luxembourg Institute of Science and Technology, 4422, Belvaux, Luxembourg
| | - Anna Karlsson
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
- Scandinavian Biogas Fuels AB, 11160, Stockholm, Sweden
| | - Annika Björn
- Department of Thematic Studies-Environmental Change, Linköping University, 58183, Linköping, Sweden
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
| | - Anna Schnürer
- Biogas Research Center, Linköping University, 58183, Linköping, Sweden
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala BioCenter, 75007, Uppsala, Sweden
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