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Mills S, Trego AC, Prevedello M, De Vrieze J, O’Flaherty V, Lens PN, Collins G. Unifying concepts in methanogenic, aerobic, and anammox sludge granulation. ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY 2024; 17:100310. [PMID: 37705860 PMCID: PMC10495608 DOI: 10.1016/j.ese.2023.100310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 06/17/2023] [Accepted: 08/05/2023] [Indexed: 09/15/2023]
Abstract
The retention of dense and well-functioning microbial biomass is crucial for effective pollutant removal in several biological wastewater treatment technologies. High solids retention is often achieved through aggregation of microbial communities into dense, spherical aggregates known as granules, which were initially discovered in the 1980s. These granules have since been widely applied in upflow anaerobic digesters for waste-to-energy conversions. Furthermore, granular biomass has been applied in aerobic wastewater treatment and anaerobic ammonium oxidation (anammox) technologies. The mechanisms underpinning the formation of methanogenic, aerobic, and anammox granules are the subject of ongoing research. Although each granule type has been extensively studied in isolation, there has been a lack of comparative studies among these granulation processes. It is likely that there are some unifying concepts that are shared by all three sludge types. Identifying these unifying concepts could allow a unified theory of granulation to be formed. Here, we review the granulation mechanisms of methanogenic, aerobic, and anammox granular sludge, highlighting several common concepts, such as the role of extracellular polymeric substances, cations, and operational parameters like upflow velocity and shear force. We have then identified some unique features of each granule type, such as different internal structures, microbial compositions, and quorum sensing systems. Finally, we propose that future research should prioritize aspects of microbial ecology, such as community assembly or interspecies interactions in individual granules during their formation and growth.
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Affiliation(s)
- Simon Mills
- Microbial Communities Laboratory, School of Biological and Chemical Sciences, National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland
| | - Anna Christine Trego
- Microbial Ecology Laboratory School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland
| | - Marco Prevedello
- Microbial Communities Laboratory, School of Biological and Chemical Sciences, National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland
| | - Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium
| | - Vincent O’Flaherty
- Microbial Ecology Laboratory School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland
| | - Piet N.L. Lens
- University of Galway, University Road, Galway, H91 TK33, Ireland
| | - Gavin Collins
- Microbial Communities Laboratory, School of Biological and Chemical Sciences, National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland
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Toja Ortega S, van den Berg L, Pronk M, de Kreuk MK. Hydrolysis capacity of different sized granules in a full-scale aerobic granular sludge (AGS) reactor. WATER RESEARCH X 2022; 16:100151. [PMID: 35965888 PMCID: PMC9364025 DOI: 10.1016/j.wroa.2022.100151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/27/2022] [Accepted: 07/30/2022] [Indexed: 06/15/2023]
Abstract
In aerobic granular sludge (AGS) reactors, granules of different sizes coexist in a single reactor. Their differences in settling behaviour cause stratification in the settled granule bed. In combination with substrate concentration gradients over the reactor height during the anaerobic plug-flow feeding regime, this can result in functional differences between granule sizes. In this study, we compared the hydrolytic activity in granules of 4 size ranges (between 0.5 and 4.8 mm diameter) collected from a full-scale AGS installation. Protease and amylase activities were quantified through fluorescent activity assays. To visualise where the hydrolytic active zones were located within the granules, the hydrolysis sites were visualized microscopically after incubating intact and sliced granules with fluorescent casein and starch. The microbial community was studied using fluorescent in situ hybridization (FISH) and sequencing. The results of these assays indicated that hydrolytic capacity was present throughout the granules, but the hydrolysis of bulk substrates was restricted to the outer 100 µm, approximately. Many of the microorganisms studied by FISH, such as polyphosphate and glycogen accumulating organisms (PAO and GAO), were abundant in the vicinity of the hydrolytically active sites. The biomass-specific hydrolysis rate depended mainly on the available granule surface area, suggesting that different sized granules are not differentiated in terms of hydrolytic capacity. Thus, the substrate concentration gradients that are present during the anaerobic feeding in AGS reactors do not seem to affect hydrolytic activity at the granule surfaces. In this paper, we discuss the possible reasons for this and reflect about the implications for AGS technology.
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Key Words
- AGS, aerobic granular sludge
- AS, activated sludge
- Activity staining
- Aerobic granular sludge
- Biomass segregation
- COD, chemical oxygen demand
- EBPR, enhanced biological phosphorus removal
- EPS, extracellular polymeric substances
- FISH, fluorescence in situ hybridization
- GAO, glycogen-accumulating organism
- Hydrolysis
- PAO, polyphosphate-accumulating organism
- Polymeric substrates
- SBR, sequencing batch reactor
- SND, simultaneous nitrification-denitrification
- SRT, solids retention time
- TSS, total suspended solids
- VFA, volatile fatty acid
- VSS, volatile suspended solids
- WWTP, wastewater treatment plant
- Wastewater treatment
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Affiliation(s)
- Sara Toja Ortega
- Section Sanitary Engineering, Department of Water Management, Delft University of Technology, Stevinweg 1, Delft 2628CN, the Netherlands
| | - Lenno van den Berg
- Section Sanitary Engineering, Department of Water Management, Delft University of Technology, Stevinweg 1, Delft 2628CN, the Netherlands
| | - Mario Pronk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, HZ 2629, the Netherlands
- Royal HaskoningDHV, Laan 1914 35, Amersfoort, AL 3800, the Netherlands
| | - Merle K. de Kreuk
- Section Sanitary Engineering, Department of Water Management, Delft University of Technology, Stevinweg 1, Delft 2628CN, the Netherlands
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Ranzinger F, Horn H, Wagner M. Imaging of particle deposition and resulting flow field during flocculation filtration within a granulated activated carbon filter. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ran X, Zhou M, Wang T, Wang W, Kumari S, Wang Y. Multidisciplinary characterization of nitrogen-removal granular sludge: A review of advances and technologies. WATER RESEARCH 2022; 214:118214. [PMID: 35240472 DOI: 10.1016/j.watres.2022.118214] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
Nitrogen-removal granular sludge (NRGS) is a promising technology in wastewater treatment, with advantages of efficient nitrogen removal, less footprint, lower sludge production and energy consumption, and is a way for wastewater treatment plants to achieve carbon-neutrality. Aerobic granular sludge (AGS) and anammox granular sludge (AnGS) are two typical NRGS technologies that have attracted extensive attention. Mounting evidence has shown strong associations between NRGS properties and the status of NRGS systems; however, a holistic view is still missing. The aim of this article is to provide an overview of NRGS with an emphasis on characterization. Specifically, the integrated nitrogen transformation pathways inside NRGS and the performance of NRGS treating various wastewaters are discussed. NRGS properties are categorized as physical-, chemical-, biological- and systematical ones, presenting current advances and corresponding characterization technologies. Finally, the future prospects for furthering the mechanistic understanding and engineering application of NRGS are proposed. Overall, the technological advancements in characterization have greatly contributed to understanding NRGS properties, which are potential factors for optimizing the performance and evaluating the working status of NRGS. This review will provide guidance in characterizing NRGS properties and boost the introduction of novel characterization technologies.
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Affiliation(s)
- Xiaochuan Ran
- State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China
| | - Mingda Zhou
- State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China
| | - Tong Wang
- State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China
| | - Weigang Wang
- State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China
| | - Sheena Kumari
- Institute for Water and Wastewater Technology, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa
| | - Yayi Wang
- State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China.
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Kikuchi J, Yamada S. The exposome paradigm to predict environmental health in terms of systemic homeostasis and resource balance based on NMR data science. RSC Adv 2021; 11:30426-30447. [PMID: 35480260 PMCID: PMC9041152 DOI: 10.1039/d1ra03008f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/31/2021] [Indexed: 12/22/2022] Open
Abstract
The environment, from microbial ecosystems to recycled resources, fluctuates dynamically due to many physical, chemical and biological factors, the profile of which reflects changes in overall state, such as environmental illness caused by a collapse of homeostasis. To evaluate and predict environmental health in terms of systemic homeostasis and resource balance, a comprehensive understanding of these factors requires an approach based on the "exposome paradigm", namely the totality of exposure to all substances. Furthermore, in considering sustainable development to meet global population growth, it is important to gain an understanding of both the circulation of biological resources and waste recycling in human society. From this perspective, natural environment, agriculture, aquaculture, wastewater treatment in industry, biomass degradation and biodegradable materials design are at the forefront of current research. In this respect, nuclear magnetic resonance (NMR) offers tremendous advantages in the analysis of samples of molecular complexity, such as crude bio-extracts, intact cells and tissues, fibres, foods, feeds, fertilizers and environmental samples. Here we outline examples to promote an understanding of recent applications of solution-state, solid-state, time-domain NMR and magnetic resonance imaging (MRI) to the complex evaluation of organisms, materials and the environment. We also describe useful databases and informatics tools, as well as machine learning techniques for NMR analysis, demonstrating that NMR data science can be used to evaluate the exposome in both the natural environment and human society towards a sustainable future.
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Affiliation(s)
- Jun Kikuchi
- Environmental Metabolic Analysis Research Team, RIKEN Center for Sustainable Resource Science 1-7-22 Suehiro-cho, Tsurumi-ku Yokohama 230-0045 Japan
- Graduate School of Bioagricultural Sciences, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
- Graduate School of Medical Life Science, Yokohama City University 1-7-29 Suehiro-cho, Tsurumi-ku Yokohama 230-0045 Japan
| | - Shunji Yamada
- Environmental Metabolic Analysis Research Team, RIKEN Center for Sustainable Resource Science 1-7-22 Suehiro-cho, Tsurumi-ku Yokohama 230-0045 Japan
- Prediction Science Laboratory, RIKEN Cluster for Pioneering Research 7-1-26 Minatojima-minami-machi, Chuo-ku Kobe 650-0047 Japan
- Data Assimilation Research Team, RIKEN Center for Computational Science 7-1-26 Minatojima-minami-machi, Chuo-ku Kobe 650-0047 Japan
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Anaerobic hydrolysis of complex substrates in full-scale aerobic granular sludge: enzymatic activity determined in different sludge fractions. Appl Microbiol Biotechnol 2021; 105:6073-6086. [PMID: 34302200 PMCID: PMC8390406 DOI: 10.1007/s00253-021-11443-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/28/2021] [Accepted: 07/03/2021] [Indexed: 11/17/2022]
Abstract
Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11443-3.
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Layer M, Bock K, Ranzinger F, Horn H, Morgenroth E, Derlon N. Particulate substrate retention in plug-flow and fully-mixed conditions during operation of aerobic granular sludge systems. WATER RESEARCH X 2020; 9:100075. [PMID: 33196033 PMCID: PMC7645637 DOI: 10.1016/j.wroa.2020.100075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/03/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Particulate substrate (XB) is the major organic substrate fraction in most municipal wastewaters. However, the impact of XB on aerobic granular sludge (AGS) systems is not fully understood. This study evaluated the physical retention of XB in AGS sequencing batch reactor (SBR) during anaerobic plug-flow and then aerobic fully-mixed conditions. The influence of different sludge types and operational variables on the extent and mechanisms of XB retention in AGS SBR were evaluated. XB mass-balancing and magnetic resonance imaging (MRI) were applied. During the anaerobic plug-flow feeding, most XB was retained in the first few cm of the settled sludge bed within the interstitial voids, where XB settled and accumulated ultimately resulting in the formation of a filter-cake. Sedimentation and surface filtration were thus the dominant XB retention mechanisms during plug-flow conditions, indicating that contact and attachment of XB to the biomass was limited. XB retention was variable and influenced by the XB influent concentration, sludge bed composition and upflow feeding velocity (vww). XB retention increased with larger XB influent concentrations and lower vww, which demonstrated the importance of sedimentation on XB retention during plug-flow conditions. Hence, large fractions of influent XB likely re-suspended during aerobic fully-mixed conditions, where XB then preferentially and rapidly attached to the flocs. During fully-mixed conditions, increasing floc fractions, longer mixing times and larger XB concentrations increased XB retention. Elevated XB retention was observed after short mixing times < 60 min when flocs were present, and the contribution of flocs towards XB retention was even more pronounced for short mixing times < 5 min. Overall, our results suggest that flocs occupy an environmental niche that results from the availability of XB during aerobic fully-mixed conditions of AGS SBR. Therefore, a complete wash-out of flocs is not desirable in AGS systems treating municipal wastewater.
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Affiliation(s)
- M. Layer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
- ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - K. Bock
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - F. Ranzinger
- Engler-Bunte-Institut, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
| | - H. Horn
- Engler-Bunte-Institut, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
| | - E. Morgenroth
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
- ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - N. Derlon
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
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