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Liu Y, Chen L, Duan Y, Li R, Yang Z, Liu S, Li G. Recent progress and prospects for chain elongation of transforming biomass waste into medium-chain fatty acids. CHEMOSPHERE 2024; 355:141823. [PMID: 38552798 DOI: 10.1016/j.chemosphere.2024.141823] [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: 02/04/2024] [Revised: 03/18/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
Chain elongation technology utilises microorganisms in anaerobic digestion to transform waste biomass into medium-chain fatty acids that have greater economic value. This innovative technology expands upon traditional anaerobic digestion methods, requiring abundant substrates that serve as electron donors and acceptors, and inoculating microorganisms with chain elongation functions. While this process may result in the production of by-products and elicit competitive responses, toxicity suppression of microorganisms by substrates and products remains a significant obstacle to the industrialisation of chain elongation technology. This study provides a comprehensive overview of existing research on widely employed electron donors and their synthetic reactions, competitive reactions, inoculum selection, toxicity inhibition of substrates and products, and increased chain elongation approaches. Additionally, it presents actionable recommendations for future research and development endeavours in this domain, intending to inspire and guide researchers in advancing the frontiers of chain elongation technology.
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Affiliation(s)
- Yuhao Liu
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China.
| | - Long Chen
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Yacong Duan
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Ruihua Li
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Ziyan Yang
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Shuli Liu
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Guoting Li
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
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2
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Almansa X, Starostka R, Raskin L, Zeeman G, De Los Reyes F, Waechter J, Yeh D, Radu T. Anaerobic Digestion as a Core Technology in Addressing the Global Sanitation Crisis: Challenges and Opportunities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:19078-19087. [PMID: 37956995 PMCID: PMC10702437 DOI: 10.1021/acs.est.3c05291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/21/2023]
Abstract
Successfully addressing the complex global sanitation problem is a massive undertaking. Anaerobic digestion (AD), coupled with post-treatment, has been identified as a promising technology to contribute to meeting this goal. It offers multiple benefits to the end users, such as the potential inactivation of pathogenic microorganisms in waste and the recovery of resources, including renewable energy and nutrients. This feature article provides an overview of the most frequently applied AD systems for decentralized communities and low- and lower-middle-income countries with an emphasis on sanitation, including technologies for which pathogen inactivation was considered during the design. Challenges to AD use are then identified, such as experience, economics, knowledge/training of personnel and users, and stakeholder analysis. Finally, accelerators for AD implementation are noted, such as the inclusion of field studies in academic journals, analysis of emerging contaminants, the use of sanitation toolboxes and life cycle assessment in design, incorporation of artificial intelligence in monitoring, and expansion of undergraduate and graduate curricula focused on Water, Sanitation, and Hygiene (WASH).
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Affiliation(s)
| | - Renata Starostka
- Department
of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lutgarde Raskin
- Department
of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Grietje Zeeman
- Wageningen
University & Research, Wageningen, 6708PB, The Netherlands
| | - Francis De Los Reyes
- Department
of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina 27695-7908, United
States
| | | | - Daniel Yeh
- Department
of Civil and Environmental Engineering, University of South Florida, Florida 33620, United States
| | - Tanja Radu
- School
of Architecture, Building and Civil Engineering, Loughborough University, Loughborough LE11 3TU, United
Kingdom
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3
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Lin M, Wang A, Ren L, Qiao W, Wandera SM, Dong R. Challenges of pathogen inactivation in animal manure through anaerobic digestion: a short review. Bioengineered 2022; 13:1149-1161. [PMID: 35258411 PMCID: PMC8805936 DOI: 10.1080/21655979.2021.2017717] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Animal manure is the main source of bioenergy production by anaerobic digestion (AD). However, the pathogenic bacteria in manure may pose a high risk to human health by contaminating the environment if not effectively inactivated during AD. Worldwide, more than 20,000 biogas plants are running for the treatment of animal manure. AD has been playing the important role in establishing a circular economy in the agricultural sector and may contribute to the United Nations sustainable development goal (UN SDG). Nevertheless, whether AD is a reliable approach for pathogens inactivation has been challenged. A comprehensive understanding of the coping mechanisms of pathogens with adverse conditions and the challenges of establishing the AD process to inactivate effectively pathogens are yet to be analyzed. In this review, the diversity and resistance of pathogens in animal manure are summarized. The efficiencies and the difficulties of their inactivations in AD are also analyzed. In particular, three forms of pathogens i.e. sporing-forming pathogens, viable but non-culturable (VBNC) pathogens, and persistent pathogens are discussed. The factors influencing the pathogens’ inactivation and AD efficiencies are analyzed. The trade-off between energy production and pathogens inactivation in an AD system was consequently pointed out. This review concluded that the development of anaerobic processes should meet the goals of high efficient bioenergy production and deep hygienization.
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Affiliation(s)
- Min Lin
- College of Engineering, China Agricultural University, Beijing, China
| | - Aijie Wang
- Key Laboratory of Environmental Biotechnology, Chinese Academy of Sciences, Beijing, China
| | - Lijuan Ren
- College of Engineering, China Agricultural University, Beijing, China
| | - Wei Qiao
- College of Engineering, China Agricultural University, Beijing, China
- Key Laboratory of Environmental Biotechnology, Chinese Academy of Sciences, Beijing, China
| | - Simon Mdondo Wandera
- Department of Civil, Construction & Environmental Engineering, Jomo Kenyatta University of Agriculture & Technology, Nairobi, Kenya
| | - Renjie Dong
- College of Engineering, China Agricultural University, Beijing, China
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4
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Xu J, Bian B, Angenent LT, Saikaly PE. Long-Term Continuous Extraction of Medium-Chain Carboxylates by Pertraction With Submerged Hollow-Fiber Membranes. Front Bioeng Biotechnol 2021; 9:726946. [PMID: 34485261 PMCID: PMC8415110 DOI: 10.3389/fbioe.2021.726946] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/28/2021] [Indexed: 11/13/2022] Open
Abstract
Medium-chain carboxylic acids (MCCAs), which can be generated from organic waste and agro-industrial side streams through microbial chain elongation, are valuable chemicals with numerous industrial applications. Membrane-based liquid-liquid extraction (pertraction) as a downstream separation process to extract MCCAs has been applied successfully. Here, a novel pertraction system with submerged hollow-fiber membranes in the fermentation bioreactor was applied to increase the MCCA extraction rate and reduce the footprint. The highest average surface-corrected MCCA extraction rate of 655.2 ± 86.4 mmol C m−2 d−1 was obtained, which was higher than any other previous reports, albeit the relatively small surface area removed only 11.6% of the introduced carbon via pertraction. This submerged extraction system was able to continuously extract MCCAs with a high extraction rate for more than 8 months. The average extraction rate of MCCA by internal membrane was 3.0- to 4.7-fold higher than the external pertraction (traditional pertraction) in the same bioreactor. A broth upflow velocity of 7.6 m h−1 was more efficient to extract MCCAs when compared to periodic biogas recirculation operation as a means to prevent membrane fouling. An even higher broth upflow velocity of 40.5 m h−1 resulted in a significant increase in methane production, losing more than 30% of carbon conversion to methane due to a loss of H2, and a subsequent drop in the H2 partial pressure. This resulted in the shift from a microbial community with chain elongators as the key functional group to methanogens, because the drop in H2 partial pressure led to thermodynamic conditions that oxidizes ethanol and carboxylic acids to acetate and H2 with methanogens as the syntrophic partner. Thus, operators of chain elongating systems should monitor the H2 partial pressure when changes in operating conditions are made.
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Affiliation(s)
- Jiajie Xu
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Bin Bian
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Largus T Angenent
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Pascal E Saikaly
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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Esquivel-Elizondo S, Bağcı C, Temovska M, Jeon BS, Bessarab I, Williams RBH, Huson DH, Angenent LT. The Isolate Caproiciproducens sp. 7D4C2 Produces n-Caproate at Mildly Acidic Conditions From Hexoses: Genome and rBOX Comparison With Related Strains and Chain-Elongating Bacteria. Front Microbiol 2021; 11:594524. [PMID: 33584563 PMCID: PMC7873966 DOI: 10.3389/fmicb.2020.594524] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/03/2020] [Indexed: 12/13/2022] Open
Abstract
Bulk production of medium-chain carboxylates (MCCs) with 6-12 carbon atoms is of great interest to biotechnology. Open cultures (e.g., reactor microbiomes) have been utilized to generate MCCs in bioreactors. When in-line MCC extraction and prevention of product inhibition is required, the bioreactors have been operated at mildly acidic pH (5.0-5.5). However, model chain-elongating bacteria grow optimally at neutral pH values. Here, we isolated a chain-elongating bacterium (strain 7D4C2) that grows at mildly acidic pH. We studied its metabolism and compared its whole genome and the reverse β-oxidation (rBOX) genes to other bacteria. Strain 7D4C2 produces lactate, acetate, n-butyrate, n-caproate, biomass, and H2/CO2 from hexoses. With only fructose as substrate (pH 5.5), the maximum n-caproate specificity (i.e., products per other carboxylates produced) was 60.9 ± 1.5%. However, this was considerably higher at 83.1 ± 0.44% when both fructose and n-butyrate (electron acceptor) were combined as a substrate. A comparison of 7D4C2 cultures with fructose and n-butyrate with an increasing pH value from 4.5 to 9.0 showed a decreasing n-caproate specificity from ∼92% at mildly acidic pH (pH 4.5-5.0) to ∼24% at alkaline pH (pH 9.0). Moreover, when carboxylates were extracted from the broth (undissociated n-caproic acid was ∼0.3 mM), the n-caproate selectivity (i.e., product per substrate fed) was 42.6 ± 19.0% higher compared to 7D4C2 cultures without extraction. Based on the 16S rRNA gene sequence, strain 7D4C2 is most closely related to the isolates Caproicibacter fermentans (99.5%) and Caproiciproducens galactitolivorans (94.7%), which are chain-elongating bacteria that are also capable of lactate production. Whole-genome analyses indicate that strain 7D4C2, C. fermentans, and C. galactitolivorans belong to the same genus of Caproiciproducens. Their rBOX genes are conserved and located next to each other, forming a gene cluster, which is different than for other chain-elongating bacteria such as Megasphaera spp. In conclusion, Caproiciproducens spp., comprising strain 7D4C2, C. fermentans, C. galactitolivorans, and several unclassified strains, are chain-elongating bacteria that encode a highly conserved rBOX gene cluster. Caproiciproducens sp. 7D4C2 (DSM 110548) was studied here to understand n-caproate production better at mildly acidic pH within microbiomes and has the additional potential as a pure-culture production strain to convert sugars into n-caproate.
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Affiliation(s)
- Sofia Esquivel-Elizondo
- AG Angenent, Max Planck Institute for Developmental Biology, Max Planck Society (MPG), Tübingen, Germany
| | - Caner Bağcı
- Algorithms in Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
- International Max Planck Research School “From Molecules to Organisms”, Max Planck Institute for Developmental Biology, University of Tübingen, Tübingen, Germany
| | - Monika Temovska
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Byoung Seung Jeon
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Irina Bessarab
- Integrative Analysis Unit, Singapore Centre for Environmental Life Sciences Engineering, National University of Singapore, Singapore, Singapore
| | - Rohan B. H. Williams
- Integrative Analysis Unit, Singapore Centre for Environmental Life Sciences Engineering, National University of Singapore, Singapore, Singapore
| | - Daniel H. Huson
- Algorithms in Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
- Integrative Analysis Unit, Singapore Centre for Environmental Life Sciences Engineering, National University of Singapore, Singapore, Singapore
| | - Largus T. Angenent
- AG Angenent, Max Planck Institute for Developmental Biology, Max Planck Society (MPG), Tübingen, Germany
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
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Xu J, Guzman JJL, Angenent LT. Direct Medium-Chain Carboxylic Acid Oil Separation from a Bioreactor by an Electrodialysis/Phase Separation Cell. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:634-644. [PMID: 33347746 DOI: 10.1021/acs.est.0c04939] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Medium-chain carboxylic acids (MCCAs) are valuable platform chemicals and can be produced from waste biomass sources or syngas fermentation effluent through microbial chain elongation. We have previously demonstrated successful approaches to separate >90% purity oil with different MCCAs (MCCA oil) by integrating the anaerobic bioprocess with membrane-based liquid-liquid extraction (pertraction) and membrane electrolysis. However, two-compartment membrane electrolysis unit without pertraction was not able to separate MCCA oil. Therefore, we developed a five-compartment electrodialysis/phase separation cell (ED/PS). First, we tested an ED/PS cell in series with pertraction and achieved a maximum MCCA-oil flux of 1.7 × 103 g d-1 per projected area (m2) (19 mL oil d-1) and MCCA-oil transfer efficiency [100% × moles MCCA-oil moles electrons-1] of 74% at 15 A m-2. This extraction system at 15 A m-2 demonstrated a ∼10 times lower electric-power consumption (1.1 kWh kg-1 MCCA oil) than membrane electrolysis in series with pertraction (9.9 kWh kg-1 MCCA oil). Second, we evaluated our ED/PS as a stand-alone unit when integrated with the anaerobic bioprocess and demonstrated that we can selectively extract and separate MCCA oil directly from chain-elongating bioreactor broth with just an abiotic electrochemical cell. However, the electric-power consumption increased considerably due to the lower MCCA concentrations in the bioreactor broth compared to the pertraction broth.
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Affiliation(s)
- Jiajie Xu
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Juan J L Guzman
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Largus T Angenent
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72076 Tübingen, Germany
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Senecal J, Nordin A, Vinnerås B. Fate of Ascaris at various pH, temperature and moisture levels. JOURNAL OF WATER AND HEALTH 2020; 18:375-382. [PMID: 32589622 DOI: 10.2166/wh.2020.264] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Soil-transmitted helminths (STH) are intestinal worms that infect 24% of the world's population. Stopping the spread of STH is difficult, as the eggs are resilient (can withstand high pH) and persistent (can remain viable in soils for several years). To ensure that new sanitation systems can inactivate STH, a better understanding of their resilience is required. This study assessed the inactivation of Ascaris eggs under various conditions, in terms of moisture content (MC) (<20 to >90%), temperature (20-50 °C) and pH (7-12.5). The results highlight that the exposure of Ascaris eggs to elevated pH (10.5-12.5) at temperatures ≤27.5 °C for >70 days had no effect on egg viability. Compounding effects of alkaline pH (≥10.5) or decreasing MC (<20%) was observed at 35 °C, with pH having more of an effect than decreasing MC. To accelerate the inactivation of STH, an increase in the treatment temperature is more effective than pH increase. Alkaline pH alone did not inactivate the eggs but can enhance the effect of ammonia, which is likely to be present in organic wastes.
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Affiliation(s)
- Jenna Senecal
- Department of Energy and Technology, Swedish University of Agricultural Sciences, P.O. Box 7032, 750 07 Uppsala, Sweden E-mail:
| | - Annika Nordin
- Department of Energy and Technology, Swedish University of Agricultural Sciences, P.O. Box 7032, 750 07 Uppsala, Sweden E-mail:
| | - Björn Vinnerås
- Department of Energy and Technology, Swedish University of Agricultural Sciences, P.O. Box 7032, 750 07 Uppsala, Sweden E-mail:
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8
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Harroff LA, Liotta JL, Bowman DD, Angenent LT. Current time-temperature relationships for thermal inactivation of Ascaris eggs at mesophilic temperatures are too conservative and may hamper development of simple, but effective sanitation. WATER RESEARCH X 2019; 5:100036. [PMID: 31535088 PMCID: PMC6743028 DOI: 10.1016/j.wroa.2019.100036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/19/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
Ascaris eggs are commonly used as indicators for pathogen inactivation during the treatment of fecal sludge and wastewater due to their highly resistant lipid membrane and ability to survive in the environment for long periods of time. Current guidelines suggest that thermal treatment alone cannot inactivate Ascaris eggs at temperatures below 45 °C, although some evidence in the literature suggests this to be incorrect. Here, we performed a controlled experiment to test the effect of mesophilic temperatures on Ascaris inactivation. We exposed Ascaris suum eggs to a temperature gradient between 34°C and 45 °C under anaerobic and aerobic conditions to observe the required exposure times for a 3-log reduction. Indeed, we found that temperatures lower than 45 °C did inactivate these eggs, and the required exposure times were up to two orders of magnitude shorter than suggested by current guidelines. Results from the anaerobic exposures were used to develop a time-temperature relationship that is appropriate for Ascaris inactivation at mesophilic temperatures. Data from the literature demonstrated that our relationship is conservative, with faster inactivation occurring under environmental conditions when Ascaris eggs were suspended in fecal sludge or manure. A specific aerobic relationship was not developed, but we demonstrated that aerobic conditions cause faster inactivation than anaerobic conditions. Therefore, the anaerobic relationship provides a conservative guideline for both conditions. We demonstrate that relatively low temperatures can considerably impact Ascaris viability and suggest that mesophilic temperatures can be used in waste treatment processes to inactivate pathogens. The development of safe, low-input, mesophilic treatment processes is particularly valuable for ensuring universal access to safe sanitation and excreta management.
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Affiliation(s)
- Lauren A. Harroff
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Janice L. Liotta
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Dwight D. Bowman
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Largus T. Angenent
- Center for Applied Geosciences, University of Tübingen, 72074, Tübingen, Germany
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