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Perman E, Karlsson A, Westerholm M, Isaksson S, Schnürer A. High-solid digestion - A comparison of completely stirred and plug-flow reactor systems. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 189:265-275. [PMID: 39217801 DOI: 10.1016/j.wasman.2024.08.025] [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: 05/17/2024] [Revised: 08/17/2024] [Accepted: 08/21/2024] [Indexed: 09/04/2024]
Abstract
High-solid digestion (HSD) for biogas production is a resource-efficient and sustainable method to treat organic wastes with high total solids content and obtain renewable energy and an organic fertiliser, using a lower dilution rate than in the more common wet digestion process. This study examined the effect of reactor type on the performance of an HSD process, comparing plug-flow (PFR) type reactors developed for continuous HSD processes, and completely stirred-tank reactors (CSTRs) commonly used for wet digestion. The HSD process was operated in thermophilic conditions (52 °C), with a mixture of household waste, garden waste and agricultural residues (total solids content 27-28 %). The PFRs showed slightly better performance, with higher specific methane production and nitrogen mineralisation than the CSTRs, while the reduction of volatile solids was the same in both reactor types. Results from 16S rRNA gene sequencing showed a significant difference in the microbial population, potentially related to large differences in stirring speed between the reactor types (1 rpm in PFRs and 70-150 rpm in CSTRs, respectively). The bacterial community was dominated by the genus Defluviitoga in the PFRs and order MBA03 in the CSTRs. For the archaeal community, there was a predominance of the genus Methanoculleus in the PFRs, and of the genera Methanosarcina and Methanothermobacter in the CSTRs. Despite these shifts in microbiology, the results showed that stable digestion of substrates with high total solids content can be achieved in both reactor types, indicating flexibility in the choice of technique for HSD processes.
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Affiliation(s)
- Ebba Perman
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden; Biogas Solutions Research Center, Linköping, Sweden
| | - Anna Karlsson
- Biogas Solutions Research Center, Linköping, Sweden; Biokraft International AB, Kungsbron 1, 111 22 Stockholm, Sweden
| | - Maria Westerholm
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden; Biogas Solutions Research Center, Linköping, Sweden
| | - Simon Isaksson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Anna Schnürer
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden; Biogas Solutions Research Center, Linköping, Sweden.
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Pinela E, Schnürer A, Neubeck A, Moestedt J, Westerholm M. Impact of additives on syntrophic propionate and acetate enrichments under high-ammonia conditions. Appl Microbiol Biotechnol 2024; 108:433. [PMID: 39110235 PMCID: PMC11306274 DOI: 10.1007/s00253-024-13263-7] [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: 04/25/2024] [Revised: 07/17/2024] [Accepted: 07/20/2024] [Indexed: 08/10/2024]
Abstract
High ammonia concentrations in anaerobic degradation systems cause volatile fatty acid accumulation and reduced methane yield, which often derive from restricted activity of syntrophic acid-oxidising bacteria and hydrogenotrophic methanogens. Inclusion of additives that facilitate the electron transfer or increase cell proximity of syntrophic species by flocculation can be a suitable strategy to counteract these problems, but its actual impact on syntrophic interactions has yet to be determined. In this study, microbial cultivation and molecular and microscopic analysis were performed to evaluate the impact of conductive (graphene, iron oxide) and non-conductive (zeolite) additives on the degradation rate of acetate and propionate to methane by highly enriched ammonia-tolerant syntrophic cultures derived from a biogas process. All additives had a low impact on the lag phase but resulted in a higher rate of acetate (except graphene) and propionate degradation. The syntrophic bacteria 'Candidatus Syntrophopropionicum ammoniitolerans', Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen were found in higher relative abundance and higher gene copy numbers in flocculating communities than in planktonic communities in the cultures, indicating benefits to syntrophs of living in close proximity to their cooperating partner. Microscopy and element analysis showed precipitation of phosphates and biofilm formation in all batches except on the graphene batches, possibly enhancing the rate of acetate and propionate degradation. Overall, the concordance of responses observed in both acetate- and propionate-fed cultures highlight the suitability of the addition of iron oxide or zeolites to enhance acid conversion to methane in high-ammonia biogas processes. KEY POINTS: • All additives promoted acetate (except graphene) and propionate degradation. • A preference for floc formation by ammonia-tolerant syntrophs was revealed. • Microbes colonised the surfaces of iron oxide and zeolite, but not graphene.
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Affiliation(s)
- Eduardo Pinela
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden
| | - Anna Schnürer
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden
| | - Anna Neubeck
- Department of Earth Sciences, Uppsala University, 752 36, Uppsala, Sweden
| | - Jan Moestedt
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden
- Department of Biogas R & D, Tekniska Verken I Linköping AB (Publ.), Box 1500, 581 15, Linköping, Sweden
- Department of Thematic Studies - Environmental Change, Linköping University, 581 83, Linköping, Sweden
| | - Maria Westerholm
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden.
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Weng N, Singh A, Ohlsson JA, Dolfing J, Westerholm M. Catabolism and interactions of syntrophic propionate- and acetate oxidizing microorganisms under mesophilic, high-ammonia conditions. Front Microbiol 2024; 15:1389257. [PMID: 38933034 PMCID: PMC11201294 DOI: 10.3389/fmicb.2024.1389257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/23/2024] [Indexed: 06/28/2024] Open
Abstract
Microbial inhibition by high ammonia concentrations is a recurring problem that significantly restricts methane formation from intermediate acids, i.e., propionate and acetate, during anaerobic digestion of protein-rich waste material. Studying the syntrophic communities that perform acid conversion is challenging, due to their relatively low abundance within the microbial communities typically found in biogas processes and disruption of their cooperative behavior in pure cultures. To overcome these limitations, this study examined growth parameters and microbial community dynamics of highly enriched mesophilic and ammonia-tolerant syntrophic propionate and acetate-oxidizing communities and analyzed their metabolic activity and cooperative behavior using metagenomic and metatranscriptomic approaches. Cultivation in batch set-up demonstrated biphasic utilization of propionate, wherein acetate accumulated and underwent oxidation before complete degradation of propionate. Three key species for syntrophic acid degradation were inferred from genomic sequence information and gene expression: a syntrophic propionate-oxidizing bacterium (SPOB) "Candidatus Syntrophopropionicum ammoniitolerans", a syntrophic acetate-oxidizing bacterium (SAOB) Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen, for which we propose the provisional name "Candidatus Methanoculleus ammoniitolerans". The results revealed consistent transcriptional profiles of the SAOB and the methanogen both during propionate and acetate oxidation, regardless of the presence of an active propionate oxidizer. Gene expression indicated versatile capabilities of the two syntrophic bacteria, utilizing both molecular hydrogen and formate as an outlet for reducing equivalents formed during acid oxidation, while conserving energy through build-up of sodium/proton motive force. The methanogen used hydrogen and formate as electron sources. Furthermore, results of the present study provided a framework for future research into ammonia tolerance, mobility, aggregate formation and interspecies cooperation.
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Affiliation(s)
- Nils Weng
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Abhijeet Singh
- Palaeobiology, Department of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - Jonas A. Ohlsson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jan Dolfing
- Faculty of Energy and Environment, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Maria Westerholm
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Zhu Y, Chen Y, An G, Zhang C, Yang J, Yang R, Chen G, Yang Y. Significance of homogeneous operation in light-assisted fixed-bed bioprocess under ammonia stress: Optimization, long-term operation and metagenomic analysis. BIORESOURCE TECHNOLOGY 2024; 399:130568. [PMID: 38467264 DOI: 10.1016/j.biortech.2024.130568] [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: 01/18/2024] [Revised: 03/08/2024] [Accepted: 03/08/2024] [Indexed: 03/13/2024]
Abstract
Activating microbes with light is a promising strategy for addressing ammonia-stressed anaerobic digestion (AD). However, as a critical in-process parameter, homogenous operation, in light-assisted AD amended by bio-fixed bed has received limited attention. This research endeavors to establish a uniform-illuminated biosystem and assess its practical feasibility through a 90-day semi-continuous operation at pilot scale under solar light illumination. With optimal stirring mode (intermittent stirring for 3 min every 15 min), robust methane yields were achieved across various organic loads, reaching 88.7-94.3% of theoretical yield under high ammonium stress (3500 mg/L). The metagenomic analysis unveiled that uniform illumination triggered synergistic effects in AD, fostering a diversified microbial consortium, enhancing carbohydrate and methane metabolism, and facilitating the formation of an electroactive bio-cluster. This study underscores the significance of homogenous illumination in AD systems for efficient waste-to-energy conversion, highlighting the implementation of solar light as a greener approach for scale-up application.
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Affiliation(s)
- Yunxin Zhu
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Yujia Chen
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Guangqi An
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Cheng Zhang
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Jingwei Yang
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Rongyong Yang
- Shanghai High Victory Science and Technology Co., Ltd., 4688 Jinshan Avenue, Shanghai 201512, China
| | - Guoping Chen
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yingnan Yang
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
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Khanthong K, Kadam R, Kim T, Park J. Synergetic effects of anaerobic co-digestion of food waste and algae on biogas production. BIORESOURCE TECHNOLOGY 2023; 382:129208. [PMID: 37217150 DOI: 10.1016/j.biortech.2023.129208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 05/14/2023] [Accepted: 05/17/2023] [Indexed: 05/24/2023]
Abstract
Anaerobic co-digestion of food waste and algae was assessed to offset the drawbacks of anaerobic mono-digestion of each substrate. Batch test results indicated that a food waste and algae mixture ratio of 8:2 facilitated the highest CH4 yield (334 mL CH4/g CODInput). This ratio was applied to the anaerobic co-digestion reactor, resulting in a CH4 yield that was twice that of the anaerobic mono-digestion reactors, thereby facilitating high operational stability. In contrast to the anaerobic mono-digestion, anaerobic co-digestion resulted in stable CH4 production by overcoming volatile fatty acid accumulation and a decreased pH, even under a high organic loading rate (3 kg COD/m3∙d). Furthermore, a comparative metagenomic analysis revealed that the abundance of volatile fatty acid-oxidizing bacteria and hydrogenotrophic and methylotrophic methanogens was significantly increased in the anaerobic co-digestion reactor. These findings indicate that the anaerobic co-digestion of food waste and algae significantly improves CH4 production and process stability.
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Affiliation(s)
- Kamonwan Khanthong
- Department of Advanced Energy Engineering, Chosun University, Gwangju 61457, Republic of Korea
| | - Rahul Kadam
- Department of Advanced Energy Engineering, Chosun University, Gwangju 61457, Republic of Korea
| | - Taeyoung Kim
- Department of Environmental Engineering, Chosun University, Gwangju 61457, Republic of Korea
| | - Jungyu Park
- Department of Advanced Energy Engineering, Chosun University, Gwangju 61457, Republic of Korea.
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Xu Q, Yang G, Liu X, Wong JWC, Zhao J. Hydrochar mediated anaerobic digestion of bio-wastes: Advances, mechanisms and perspectives. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 884:163829. [PMID: 37121315 DOI: 10.1016/j.scitotenv.2023.163829] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/05/2023]
Abstract
Bio-wastes treatment and disposal has become a challenge because of their increasing output. Given the abundant organic matter in bio-wastes, its related resource treatment methods have received more and more attention. As a promising strategy, anaerobic digestion (AD) has been widely used in the treatment of bio-wastes, during which not only methane as energy can be recovered but also their reduction can be achieved. However, AD process is generally disturbed by some internal factors (e.g., low hydrolysis efficiency and accumulated ammonia) and external factors (e.g., input pollutants), resulting in unstable AD operation performance. Recently, hydrochar was wildly found to improve AD performance when added to AD systems. This review comprehensively summarizes the research progress on the performance of hydrochar-mediated AD, such as increased methane yield, improved operation efficiency and digestate dewatering, and reduced heavy metals in digestate. Subsequently, the underlying mechanisms of hydrochar promoting AD were systematically elucidated and discussed, including regulation of electron transfer (ET) mode, microbial community structure, bio-processes involved in AD, and reaction conditions. Moreover, the effects of properties of hydrochar (e.g., feedstock, hydrothermal carbonization (HTC) temperature, HTC time, modification and dosage) on the improvement of AD performance are systematically concluded. Finally, the relevant knowledge gaps and opportunities to be studied are presented to improve the progress and application of the hydrochar-mediated AD technology. This review aims to offer some references and directions for the hydrochar-mediated AD technology in improving bio-wastes resource recovery.
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Affiliation(s)
- Qiuxiang Xu
- Research Center for Eco-Environmental Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, China; College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, PR China
| | - Guojing Yang
- College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, PR China
| | - Xuran Liu
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Jonathan W C Wong
- Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Jun Zhao
- Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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Cardona L, Mazéas L, Chapleur O. Deterministic processes drive the microbial assembly during the recovery of an anaerobic digester after a severe ammonia shock. BIORESOURCE TECHNOLOGY 2022; 347:126432. [PMID: 34838975 DOI: 10.1016/j.biortech.2021.126432] [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: 09/30/2021] [Revised: 11/21/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
Anaerobic digestion allows to produce sustainable energy but the microbial community involved in this process is highly sensitive to perturbations. In this study, a longitudinal experiment was performed in two sets of triplicate bioreactors to evaluate the influence of ammonia addition on AD microbiome and its recovery. Zeolite was added in three reactors to mitigate the inhibition. Microbial dynamics were monitored with 16S rRNA sequencing at 15 time points. Dominant methanogenic pathways were determined with gas isotopic signature analysis. Zeolite addition did not enable to reduce ammonia inhibition or improve the process under the conditions tested. In all the bioreactors, ammonia inhibition sharply decreased the methane production but the process could restart thanks to the increase of hydrogenotrophic archaea and syntrophic bacteria. Interestingly, similar behaviour was observed in the six reactors. Neutral modelling and null model were used and showed that a deterministic process governed the recovery of AD microbiome after failure.
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Affiliation(s)
- Laëtitia Cardona
- Université Paris-Saclay, INRAE, PRocédés biOtechnologiques au Service de l'Environnement, 92761 Antony, France.
| | - Laurent Mazéas
- Université Paris-Saclay, INRAE, PRocédés biOtechnologiques au Service de l'Environnement, 92761 Antony, France.
| | - Olivier Chapleur
- Université Paris-Saclay, INRAE, PRocédés biOtechnologiques au Service de l'Environnement, 92761 Antony, France.
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A biogeographic 16S rRNA survey of bacterial communities of ureolytic biomineralization from California public restrooms. PLoS One 2022; 17:e0262425. [PMID: 35030221 PMCID: PMC8759634 DOI: 10.1371/journal.pone.0262425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 12/24/2021] [Indexed: 11/29/2022] Open
Abstract
In this study, we examined the total bacterial community associated with ureolytic biomineralization from urine drainage systems. Biomineral samples were obtained from 11 California Department of Transportation public restrooms fitted with waterless, low-flow, or conventional urinals in 2019. Following high throughput 16S rRNA Illumina sequences processed using the DADA2 pipeline, the microbial diversity assessment of 169 biomineral and urine samples resulted in 3,869 reference sequences aggregated as 598 operational taxonomic units (OTUs). Using PERMANOVA testing, we found strong, significant differences between biomineral samples grouped by intrasystem sampling location and urinal type. Biomineral microbial community profiles and alpha diversities differed significantly when controlling for sampling season. Observational statistics revealed that biomineral samples obtained from waterless urinals contained the largest ureC/16S gene copy ratios and were the least diverse urinal type in terms of Shannon indices. Waterless urinal biomineral samples were largely dominated by the Bacilli class (86.1%) compared to low-flow (41.3%) and conventional samples (20.5%), and had the fewest genera that account for less than 2.5% relative abundance per OTU. Our findings are useful for future microbial ecology studies of urine source-separation technologies, as we have established a comparative basis using a large sample size and study area.
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Impact of Granular Activated Carbon on Anaerobic Process and Microbial Community Structure during Mesophilic and Thermophilic Anaerobic Digestion of Chicken Manure. SUSTAINABILITY 2022. [DOI: 10.3390/su14010447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this work, the impact of granular activated carbon (GAC) on the mesophilic and thermophilic anaerobic digestion of chicken manure and the structure of microbial communities was investigated. These results demonstrated that GAC supplementation effectively enhanced the consumption of produced organic acids in the mesophilic and thermophilic batch tests, accompanied by faster biomethane production in the presence of GAC than from reactors without GAC. However, since the free ammonia level was 3–6 times higher in the thermophilic reactors, this led to the instability of the anaerobic digestion process of the nitrogen-rich substrate at thermophilic temperatures. Bacteroidia and Clostridia were the two main bacterial classes in the mesophilic reactors, whereas the class Clostridia had a competitive advantage over other groups in the thermophilic systems. The archaeal communities in the mesophilic reactors were mainly represented by representatives of the genera Methanosarcina, Methanobacterium, and Methanotrix, whereas the archaeal communities in the thermophilic reactors were mainly represented by members of the genera Methanosarcina, Methanoculleus, and Methanothermobacter. New data obtained in this research will help control and manage biogas reactors in the presence of GAC at different temperatures.
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Zheng Z, Cai Y, Zhang Y, Zhao Y, Gao Y, Cui Z, Hu Y, Wang X. The effects of C/N (10-25) on the relationship of substrates, metabolites, and microorganisms in "inhibited steady-state" of anaerobic digestion. WATER RESEARCH 2021; 188:116466. [PMID: 33027695 DOI: 10.1016/j.watres.2020.116466] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/04/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
The carbon/nitrogen ratio (C/N) is a key parameter that affects the performance of anaerobic digestion (AD). Recent AD research has focused on optimizing the C/N of feedstock. The so-called "inhibited steady-state" refers to a special state of ammonia inhibition of AD that often occurs at low-C/N (below 25) when degradable nitrogen-rich substrates, such as livestock manure, are used as feedstock. However, the mechanism behind the "inhibited steady-state" is still unknown. In the current study, co-digestion and recirculation were used to create a C/N gradient in the influent to explore the relationship between substrates, metabolites, and microorganisms in the "inhibited steady-state." Data were collected at the macro, microbial, and genetic levels. Three CSTRs were successfully made run into the "inhibited steady-state" using influent C/Ns of 10-12. Digestion performance levels of R10-R12 were low and stable, transitioning from an aceticlastic methane-producing pathway to a hydrogenotrophic pathway as the C/N gradually decreased. As the abundance of the hydrogenophilic methanogens increased, the abundance of syntrophic acetate-oxidizing bacteria (SAOB) also increased. The succession between populations of Methanosaeta and Methanosarcina may be used as a microbiological indicator of ammonia inhibition. Under high-C/Ns, cooperation among bacteria was high, while under low-C/Ns, competition among bacteria was high. These results clarify the processes underlying the "inhibited steady-state," which is a condition often faced in actual large-scale biogas facilities that use degradable nitrogen-rich substrates. Moreover, practical guidelines for evaluating ammonia inhibition are provided, and strategies to alleviate ammonia suppression are developed.
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Affiliation(s)
- Zehui Zheng
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Yafan Cai
- Department of Biochemical conversion, Deutsches Biomassforschungszentrum gemeinnütziges GmbH, Torgauer Straße116, 04347 Leipzig, Germany.
| | - Yue Zhang
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Yubin Zhao
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Youhui Gao
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Zongjun Cui
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Yuegao Hu
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China
| | - Xiaofen Wang
- College of Agronomy and Biotechnology/Biomass Engineering Center, China Agricultural University, Beijing 100193, China.
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Abstract
The microbiome residing in anaerobic digesters drives the anaerobic digestion (AD) process to convert various feedstocks to biogas as a renewable source of energy. This microbiome has been investigated in numerous studies in the last century. The early studies used cultivation-based methods and analysis to identify the four guilds (or functional groups) of microorganisms. Molecular biology techniques overcame the limitations of cultivation-based methods and allowed the identification of unculturable microorganisms, revealing the high diversity of microorganisms involved in AD. In the past decade, omics technologies, including metataxonomics, metagenomics, metatranscriptomics, metaproteomics, and metametabolomics, have been or start to be used in comprehensive analysis and studies of biogas-producing microbiomes. In this chapter, we reviewed the utilities and limitations of these analysis methods, techniques, and technologies when they were used in studies of biogas-producing microbiomes, as well as the new information on diversity, composition, metabolism, and syntrophic interactions of biogas-producing microbiomes. We also discussed the current knowledge gaps and the research needed to further improve AD efficiency and stability.
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