1
|
Wang Z, Chen J, Veiga MC, Kennes C. Bioconversion of pure CO 2 to caproic acid with zero valent iron: Optimizing carbon flux distribution in co-cultures of Acetobacterium woodii and Megasphaera hexanoica. BIORESOURCE TECHNOLOGY 2024; 413:131480. [PMID: 39265751 DOI: 10.1016/j.biortech.2024.131480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 08/28/2024] [Accepted: 09/09/2024] [Indexed: 09/14/2024]
Abstract
Acetobacterium woodii and Megasphaera hexanoica were co-cultured for caproic acid (CA) production from lactic acid (LA) and CO2. Also, various concentrations (1 g/L, 3 g/L, 5 g/L, and 10 g/L) of Zero Valent Iron (ZVI) were supplied to study its impact on the co-culture system. In flask experiments, 10 g/L LA and 1.0 bar CO2 produced 0.6 g/L CA with some biomass growth. ZVI increased LA consumption and CA production. Indeed, 3 g/L ZVI boosted CA production by 186 % and biomass accumulation by 103 %, suggesting that ZVI controls the carbon flux. Subsequent automated bioreactor studies showed that 3 g/L ZVI produced 1.842 g/L CA at stable pH, compared to 0.969 g/L without ZVI (control). Further, metabolic activity showed that both bacteria could directly use H2, generated by ZVI (3 g/L), as electron donor. Higher ZVI concentrations (10 g/L) resulted in Fe2+ causing excessive oxidation pressure on M. hexanoica, with its carbon flux flowing preferentially towards biomass. Enzyme assays confirmed that A. woodii preferred 10 g/L ZVI while M. hexanoica preferred 3 g/L for optimal bioconversion.
Collapse
Affiliation(s)
- Zeyu Wang
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - Jun Chen
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain.
| |
Collapse
|
2
|
Wu B, Lin R, Gu J, Yuan H, Murphy JD. Biochar confers significant microbial resistance to ammonia toxicity in n-caproic acid production. WATER RESEARCH 2024; 266:122367. [PMID: 39243461 DOI: 10.1016/j.watres.2024.122367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 08/19/2024] [Accepted: 08/31/2024] [Indexed: 09/09/2024]
Abstract
Microbial chain elongation integrating innovative bioconversion technologies with organic waste utilization can transition current energy-intensive n-caproic acid production to sustainable circular bioeconomy systems. However, ammonia-rich waste streams, despite their suitability, pose inhibitory challenges to these bioconversion processes. Herein, biochar was employed as an additive to enhance the activity of chain elongating microbes under ammonia inhibition conditions, with an objective to detail underlying mechanisms of improvements. Biochar addition significantly improved chain elongation performance even under severe ammonia stress (exceeding 8 g N/L), increasing n-caproic acid yields by 40 % to 158 % and reducing lag times by 51 % to 90 %, compared with the best-performing group without biochar addition. The material contribution to n-caproic production reached up to 94.3 % (at 4 g N/L). These enhancements were mainly attributed to the new electron syntrophy induced by biochar, which improved electron transfer system activity and electrical conductivity of the fermentation system. This is further substantiated by increased relative abundances of the genus Sporanaerobacter, electroactive bacteria, and up-regulated direct electron transfer-related genes including conductive pili and c-type cytochrome. This study demonstrates that biochar can confer robust resilience to ammonia toxicity in functional microbes, paving a way for efficient and sustainable n-caproic acid production.
Collapse
Affiliation(s)
- Benteng Wu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; MaREI Centre, Environmental Research Institute, University College Cork, Cork T23 XE10, Ireland; Guangdong Provincial Key Laboratory of High-Quality Recycling of End-of-Life New Energy Devices, Guangzhou 510640, China
| | - Richen Lin
- MaREI Centre, Environmental Research Institute, University College Cork, Cork T23 XE10, Ireland; Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 211189, China
| | - Jing Gu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of High-Quality Recycling of End-of-Life New Energy Devices, Guangzhou 510640, China
| | - Haoran Yuan
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of High-Quality Recycling of End-of-Life New Energy Devices, Guangzhou 510640, China.
| | - Jerry D Murphy
- MaREI Centre, Environmental Research Institute, University College Cork, Cork T23 XE10, Ireland; Civil, Structural and Environmental Engineering, School of Engineering and Architecture, University College Cork, Cork T12 YN60, Ireland.
| |
Collapse
|
3
|
Bian B, Zhang W, Yu N, Yang W, Xu J, Logan BE, Saikaly PE. Lactate-mediated medium-chain fatty acid production from expired dairy and beverage waste. ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY 2024; 21:100424. [PMID: 38774191 PMCID: PMC11106833 DOI: 10.1016/j.ese.2024.100424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 05/24/2024]
Abstract
Fruits, vegetables, and dairy products are typically the primary sources of household food waste. Currently, anaerobic digestion is the most used bioprocess for the treatment of food waste with concomitant generation of biogas. However, to achieve a circular carbon economy, the organics in food waste should be converted to new chemicals with higher value than energy. Here we demonstrate the feasibility of medium-chain carboxylic acid (MCCA) production from expired dairy and beverage waste via a chain elongation platform mediated by lactate. In a two-stage fermentation process, the first stage with optimized operational conditions, including varying temperatures and organic loading rates, transformed expired dairy and beverage waste into lactate at a concentration higher than 900 mM C at 43 °C. This lactate was then used to produce >500 mM C caproate and >300 mM C butyrate via microbial chain elongation. Predominantly, lactate-producing microbes such as Lactobacillus and Lacticaseibacillus were regulated by temperature and could be highly enriched under mesophilic conditions in the first-stage reactor. In the second-stage chain elongation reactor, the dominating microbes were primarily from the genera Megasphaera and Caproiciproducens, shaped by varying feed and inoculum sources. Co-occurrence network analysis revealed positive correlations among species from the genera Caproiciproducens, Ruminococcus, and CAG-352, as well as Megasphaera, Bacteroides, and Solobacterium, indicating strong microbial interactions that enhance caproate production. These findings suggest that producing MCCAs from expired dairy and beverage waste via lactate-mediated chain elongation is a viable method for sustainable waste management and could serve as a chemical production platform in the context of building a circular bioeconomy.
Collapse
Affiliation(s)
- Bin Bian
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Wenxiang Zhang
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Research Centre of Ecology & Environment for Coastal Area and Deep Sea, Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
| | - Najiaowa Yu
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Wei Yang
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Jiajie Xu
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- School of Marine Science, Ningbo University, Ningbo, 315211, China
| | - Bruce E. Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Pascal E. Saikaly
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Environmental Science and Engineering Program, Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| |
Collapse
|
4
|
Chen Z, Gao S, Zhu S, Yu J, Wen X. Continuous chain elongation process for carbon resource recovery from excess sludge: Enhanced n-caprylate production and specific microbial functionalities. BIORESOURCE TECHNOLOGY 2024; 406:130937. [PMID: 38852892 DOI: 10.1016/j.biortech.2024.130937] [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: 02/03/2024] [Revised: 05/29/2024] [Accepted: 06/06/2024] [Indexed: 06/11/2024]
Abstract
Thermal hydrolyzed sludge (THS) exhibits considerable promise in generating medium-chain fatty acids (MCFAs) through chain elongation (CE) technology. This study developed a novel continuous CE process using THS as the substrate, achieving an optimal ethanol loading rate (5.8 g COD/L/d) and stable MCFA production at 10.9 g COD/L, with a rate of 3.6 g COD/L/d. The MCFAs primarily comprised n-caproate and n-caprylate, representing 41.5 % and 54.3 % of the total MCFAs, respectively. Utilization efficiencies for ethanol and acetate were nearly complete at 100 % and 92.8 %, respectively. Key microbial taxa identified under these optimal conditions included Alcaligenes, SRB2, Sporanaerobacter, and Kurthia, which were instrumental in critical pathways such as the generation of acetyl-CoA, the initial carboxylation of acetyl-CoA, the fatty acid biosynthesis cycle, and energy metabolism. This research provides a theoretical and technical blueprint for converting waste sludge into valuable MCFAs, promoting sustainable waste-to-resource strategies.
Collapse
Affiliation(s)
- Zhan Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Shan Gao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Shihui Zhu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jinlan Yu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xianghua Wen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
5
|
Montecchio D, Gazzola G, Gallipoli A, Gianico A, Braguglia CM. Medium chain Fatty acids production from Food Waste via homolactic fermentation and lactate/ethanol elongation: Electron balance and thermodynamic assessment. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 177:289-297. [PMID: 38359509 DOI: 10.1016/j.wasman.2024.01.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/08/2024] [Accepted: 01/29/2024] [Indexed: 02/17/2024]
Abstract
This study explored the potential of Food Waste (FW) extract as a suitable substrate for Medium Chain Fatty Acids (MCFAs) production, in a single-phase reactor, where both fermentation and Chain Elongation (CE) processes occurred simultaneously. A continuous experiment was conducted with an Organic Loading Rate (OLR) = 20 gCOD L-1 d-1 and was fed in batch mode twice a week with pH = 6. In addition, four batch tests were performed, to assess the effects on the MCFAs production of caproate inhibition, hydrogen partial pressure (PH2) and different lactate/acetate ratios. Thermodynamics and electron flux were calculated to gain insights into the process pathways. Due to the presence of aminoacids, fermentation was mostly homolactic and both lactate and ethanol were produced as Electron Donors (EDs); the average MCFAs production efficiency was ∼ 12 %, although after 4 weeks the elongation process was halted, resulting in EDs accumulation. This occurred regardless of inoculum selection and the presence of caproate as a possible inhibitor, suggesting that EDs accumulation was due to the elongation process kinetics being slower than those of the fermentation step, thus calling for a longer Hydraulic Retention Time (HRT). It's worth noting that lactate was prevalently self-elongated to butyrate, whereas ethanol elongation only took place after lactate depletion, but was more efficient since it required other Electron Acceptors (EAs) such as butyrate, propionate or valerate. Moreover, the selected pH limited the acrylate pathway to a reasonable extent, whereas the high PH2 prevented both ethanol and lactate oxydation to acetate.
Collapse
Affiliation(s)
- Daniele Montecchio
- Istituto di Ricerca sulle Acque-CNR, Area della Ricerca RM1, 00015 Monterotondo, Roma, Italy.
| | - Giulio Gazzola
- Istituto di Ricerca sulle Acque-CNR, Area della Ricerca RM1, 00015 Monterotondo, Roma, Italy.
| | - Agata Gallipoli
- Istituto di Ricerca sulle Acque-CNR, Area della Ricerca RM1, 00015 Monterotondo, Roma, Italy.
| | - Andrea Gianico
- Istituto di Ricerca sulle Acque-CNR, Area della Ricerca RM1, 00015 Monterotondo, Roma, Italy.
| | - Camilla M Braguglia
- Istituto di Ricerca sulle Acque-CNR, Area della Ricerca RM1, 00015 Monterotondo, Roma, Italy.
| |
Collapse
|
6
|
Gao S, Chen Z, Zhu S, Yu J, Wen X. Enhancement of medium-chain fatty acids production from sludge anaerobic fermentation liquid under moderate sulfate reduction. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 354:120459. [PMID: 38402788 DOI: 10.1016/j.jenvman.2024.120459] [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: 09/21/2023] [Revised: 01/10/2024] [Accepted: 02/20/2024] [Indexed: 02/27/2024]
Abstract
In recent years, there has been a marked increase in the production of excess sludge. Chain-elongation (CE) fermentation presents a promising approach for carbon resource recovery from sludge, enabling the transformation of carbon into medium-chain fatty acids (MCFAs). However, the impact of sulfate, commonly presents in sludge, on the CE process remains largely unexplored. In this study, batch tests for CE process of sludge anaerobic fermentation liquid (SAFL) under different SCOD/SO42- ratios were performed. The moderate sulfate reduction under the optimum SCOD/SO42- of 20:1 enhanced the n-caproate production, giving the maximum n-caproate concentration, selectivity and production rate of 5.49 g COD/L, 21.4% and 4.87 g COD/L/d, respectively. The excessive sulfate reduction under SCOD/SO42- ≤ 5 completely inhibited the CE process, resulting in almost no n-caproate generation. The variations in n-caproate production under different conditions of SCOD/SO42- were all well fitted with the modified Gompertz kinetic model. Alcaligenes and Ruminococcaceae_UCG-014 were the dominant genus-level biomarkers under moderate sulfate reduction (SCOD/SO42- = 20), which enhanced the n-caproate production by increasing the generation of acetyl-CoA and the hydrolysis of difficult biodegradable substances in SAFL. The findings presented in this work elucidate a strategy and provide a theoretical framework for the further enhancement of MCFAs production from excess sludge.
Collapse
Affiliation(s)
- Shan Gao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Zhan Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
| | - Shihui Zhu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jinlan Yu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xianghua Wen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
7
|
Mu H, Ding X, Zhu X, Wang L, Zhang Y, Zhao C. Effects of different types of granular activated carbon on methanogenesis of carbohydrate-rich food waste: Performance, microbial communities and optimization. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 895:165173. [PMID: 37385489 DOI: 10.1016/j.scitotenv.2023.165173] [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: 05/02/2023] [Revised: 06/25/2023] [Accepted: 06/25/2023] [Indexed: 07/01/2023]
Abstract
Granular activated carbon (GAC) supplementation is an efficient method for enhancing methane production during the anaerobic digestion of food waste, but it remains unclear which type of GAC is optimal and what potential mechanisms are involved with different types of GAC, particularly for the methanogenic system of carbohydrate-rich food waste. This study selected three commercial GAC (GAC#1, GAC#2, GAC#3) with very distinct physical and chemical properties, and investigated their impacts on the methanogenesis of carbohydrate-rich food waste with an inoculation/substrate ratio of 1. Results indicated that Fe-doped GAC#3 had a lower specific surface area but higher conductivity, yet exhibited superior performance in facilitating methanogenesis compared with GAC#1 and GAC#2, which possessed larger specific surface areas. The addition of 10 g/L GAC#3 enhanced the methane yield by 10-folds through regulating pH levels, alleviating volatile fatty acids-induced stress, enhancing key enzymatic activity, as well as enriching direct interspecies electron transfer-mediated syntrophic partner of Syntrophomonas with Methanosarcina. Furthermore, GAC#1, which had the largest specific surface area but exhibited the poorest performance, was chemically modified to enhance its ability in promoting methanogenesis. The resulting material, named MGAC#1 (Fe3O4-loaded GAC#1), exhibited superior electro-conductivity and high methane production efficiency. The methane yield of 588 mL/g-VS showed a remarkable increase of 468 % compared with GAC#1, and a modest increase of 13 % compared with GAC#3, surpassing most values reported in literature. These findings suggested that the Fe3O4-loaded GAC with lager specific surface area, was the optimal choice for the methanogenesis of sole readily acidogenic waste, providing valuable insights for the preparation of superior-quality GAC for application in biogas industry.
Collapse
Affiliation(s)
- Hui Mu
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China.
| | - Xiaofan Ding
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Xiaoyu Zhu
- Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China; University of Chinese Academy of Sciences, Beijing 100864, China
| | - Liguo Wang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Yongfang Zhang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Chunhui Zhao
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China.
| |
Collapse
|