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Cheng X, Xu K. Evaluation of autotrophic process influencing extracellular polymeric substances in aerobic membrane bioreactor with expanded ASM model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172207. [PMID: 38583621 DOI: 10.1016/j.scitotenv.2024.172207] [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: 03/04/2024] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024]
Abstract
A mathematical model was developed to predict the formation of both the autotrophic and heterotrophic extracellular polymeric substances (EPS) in the aerobic membrane bioreactor (MBR). Batch experimental results and 45-day operation data on a pilot MBR at a sludge retention time (SRT) of 20 d were used to calibrate and validate the model. Simulated MBR setup results demonstrated the key role of the influent COD and NH4+-N in governing the composition of heterotrophic and autotrophic EPS in the MBR. These results also revealed that the autotrophic EPS process was non-ignorable in the system. According to the autotrophic EPS simulation in the MBR, the EPS yield increased with increasing influent COD/NH4+-N ratio towards a constant level. The EPS yield was significantly influenced by the SRT, attributed to the autotrophic process's impact on EPS. Simulation results revealed a slight increase in EPS yield with an SRT of up to 5 days, followed by a rapid decrease beyond that threshold.
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Affiliation(s)
- Xiaoqiao Cheng
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Kangning Xu
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
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Ahuja V, Bhatt AK, Banu JR, Kumar V, Kumar G, Yang YH, Bhatia SK. Microbial Exopolysaccharide Composites in Biomedicine and Healthcare: Trends and Advances. Polymers (Basel) 2023; 15:polym15071801. [PMID: 37050415 PMCID: PMC10098801 DOI: 10.3390/polym15071801] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/27/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023] Open
Abstract
Microbial exopolysaccharides (EPSs), e.g., xanthan, dextran, gellan, curdlan, etc., have significant applications in several industries (pharma, food, textiles, petroleum, etc.) due to their biocompatibility, nontoxicity, and functional characteristics. However, biodegradability, poor cell adhesion, mineralization, and lower enzyme activity are some other factors that might hinder commercial applications in healthcare practices. Some EPSs lack biological activities that make them prone to degradation in ex vivo, as well as in vivo environments. The blending of EPSs with other natural and synthetic polymers can improve the structural, functional, and physiological characteristics, and make the composites suitable for a diverse range of applications. In comparison to EPS, composites have more mechanical strength, porosity, and stress-bearing capacity, along with a higher cell adhesion rate, and mineralization that is required for tissue engineering. Composites have a better possibility for biomedical and healthcare applications and are used for 2D and 3D scaffold fabrication, drug carrying and delivery, wound healing, tissue regeneration, and engineering. However, the commercialization of these products still needs in-depth research, considering commercial aspects such as stability within ex vivo and in vivo environments, the presence of biological fluids and enzymes, degradation profile, and interaction within living systems. The opportunities and potential applications are diverse, but more elaborative research is needed to address the challenges. In the current article, efforts have been made to summarize the recent advancements in applications of exopolysaccharide composites with natural and synthetic components, with special consideration of pharma and healthcare applications.
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Affiliation(s)
- Vishal Ahuja
- University Institute of Biotechnology, Chandigarh University, Mohali 140413, Punjab, India
- University Centre for Research & Development, Chandigarh University, Mohali 140413, Punjab, India
| | - Arvind Kumar Bhatt
- Department of Biotechnology, Himachal Pradesh University, Shimla 171005, Himachal Pradesh, India
| | - J. Rajesh Banu
- Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur 610005, Tamil Nadu, India
| | - Vinod Kumar
- Centre for Climate and Environmental Protection, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
| | - Gopalakrishnan Kumar
- Institute of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, P.O. Box 8600 Forus, 4036 Stavanger, Norway
| | - Yung-Hun Yang
- Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 05029, Republic of Korea
- Institute for Ubiquitous Information Technology and Applications, Seoul 05029, Republic of Korea
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 05029, Republic of Korea
- Institute for Ubiquitous Information Technology and Applications, Seoul 05029, Republic of Korea
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Peng S, Wang Z, Yu P, Liao G, Liu R, Wang D, Zhang W. Aggregation and construction mechanisms of microbial extracellular polymeric substances with the presence of different multivalent cations: Molecular dynamic simulation and experimental verification. WATER RESEARCH 2023; 232:119675. [PMID: 36758351 DOI: 10.1016/j.watres.2023.119675] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/07/2023] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Interactions between cations and extracellular polymeric substances (EPS) play an important role in the formation of microbial aggregates and have key effects on the physical properties of activated sludge across wastewater and sludge treatment process. Here, a molecular model of EPS cluster in activated sludge was constructed and simulated by molecular dynamics (MD) to probe the structural properties of EPS and the interaction between EPS and prevalent multivalent cations (Ca2+, Mg2+, Al3+). Then the predicted changes in physical properties were validated against the dynamic light scattering, XAD resin fractionation and rheology test. The binding dynamics and interactions mechanisms between multivalent cations and EPS functional groups were further investigated using MD in combination with spectroscopic analysis. Results suggest that biopolymers are originally aggregated by electrostatic and intermolecular interactions forming dynamic clusters with negatively charged surface functional groups, which induced electrostatic repulsion preventing further agglomeration of biopolymer clusters. In the presence of multivalent cations, surface polar functional groups in biopolymers are connected, causing the rearrangement of EPS molecular conformation that forms larger and denser agglomerates. Reduced solvent accessible surface area, enhanced hydrophobicity, and increased binding free energy lead to a strong gel-like network of EPS. Ca2+ and Al3+ predominantly interact with functional groups in polysaccharides, promoting agglomeration of macromolecules. In contrast, Mg2+ and Al3+ disrupted the secondary structure of proteins, exposing hydrophobic interaction sites. Al3+ can better agglomerate biopolymers with its higher positive charge and shorter coordination distance as compared to Ca2+ and Mg2+, but compromised by the effect of hydration. This work offers a novel approach to explore the construction and molecular aggregation of EPS, enriching the theoretical basis for optimization of wastewater and sludge treatment.
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Affiliation(s)
- Sainan Peng
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Zhiyue Wang
- Department of Civil and Environmental Engineering, University of Hawai'i at Mānoa, USA, Honolulu, HI, USA 96822-2217; Water Resources Research Center, University of Hawai'i at Mānoa, USA, Honolulu, HI, USA 96822-2217.
| | - Pingfeng Yu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Guiying Liao
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Rui Liu
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Dongsheng Wang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Weijun Zhang
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China; National Engineering Laboratory of High Concentration Refractory Organic Wastewater Treatment Technology, Research Center for Eco-Environmental Science, Chinese Academy of Science, Beijing 100085, China.
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Xu R, Fang S, Zhang L, Cheng X, Huang W, Wang F, Fang F, Cao J, Wang D, Luo J. Revealing the intrinsic drawbacks of waste activated sludge for efficient anaerobic digestion and the potential mitigation strategies. BIORESOURCE TECHNOLOGY 2022; 345:126482. [PMID: 34864182 DOI: 10.1016/j.biortech.2021.126482] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 06/13/2023]
Abstract
Anaerobic digestion (AD) is an effective approach for waste activated sludge (WAS) disposal with substantial recovery of valuable substrates. Previous studies have extensively explored the correlations of common operational parameters with AD efficiency, but the impacts of intrinsic characteristics of WAS on the AD processes are generally underestimated. This study focused on disclosing the association of intrinsic drawbacks in WAS with AD performance, and found that the cemented WAS structure, low fraction of biomass and various high levels of inhibitory pollutants (e.g., organic pollutants and heavy metals), as the integral parts of WAS all greatly restricted the AD performance. The main potential strategies and underlying mechanisms to mitigate the restrictions for efficient WAS digestion, including the practical pretreatment methods, bioaugmentation and aided substances addition, were critically analyzed. Also, future directions for the improvement of WAS digestion were proposed from the perspectives of technical, management and economic aspects.
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Affiliation(s)
- Runze Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Shiyu Fang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Le Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Xiaoshi Cheng
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Wenxuan Huang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Feng Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Fang Fang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Jiashun Cao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
| | - Jingyang Luo
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
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Xu RZ, Fang S, Zhang L, Huang W, Shao Q, Fang F, Feng Q, Cao J, Luo J. Distribution patterns of functional microbial community in anaerobic digesters under different operational circumstances: A review. BIORESOURCE TECHNOLOGY 2021; 341:125823. [PMID: 34454239 DOI: 10.1016/j.biortech.2021.125823] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Anaerobic digestion (AD) processes are promising to effectively recover resources from organic wastes or wastewater. As a microbial-driven process, the functional anaerobic species played critical roles in AD. However, the lack of effective understanding of the correlations of varying microbial communities with different operational factors hinders the microbial regulation to improve the AD performance. In this paper, the main anaerobic functional microorganisms involved in different stages of AD processes were first demonstrated. Then, the response of anaerobic microbial community to different operating parameters, exogenous interfering substances and digestion substrates, as well as the digestion efficiency, were discussed. Finally, the research gaps and future directions on the understanding of functional microorganisms in AD were proposed. This review provides insightful knowledge of distribution patterns of functional microbial community in anaerobic digesters, and gives critical guidance to regulate and enrich specific functional microorganisms to accumulate certain AD products.
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Affiliation(s)
- Run-Ze Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Shiyu Fang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Le Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Wenxuan Huang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Qianqi Shao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Fang Fang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Qian Feng
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Jiashun Cao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China
| | - Jingyang Luo
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
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