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Peng G, Li-Xian L, Xi L, Shuang-Fei W, Jian Z. Roles of entrapped bubbles in methanogenic granules under oscillating pressure: Respiration and embolization for intra-granular transport. BIORESOURCE TECHNOLOGY 2024; 395:130356. [PMID: 38262541 DOI: 10.1016/j.biortech.2024.130356] [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: 11/01/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 01/25/2024]
Abstract
Anaerobic granular sludge plays a pivotal role in the treatment of concentrated organic wastewater. However, previous studies on intra- granular transport have generally overlooked lung-like respiration that expedites transport in response to fluctuating pressure. This study explored the activities of calcified and normal granules under simulated hydrostatic pressure oscillations. The results revealed a significant enhancement in the bioactivity of calcified granules under oscillating pressure, contrasting with the comparatively lower bioactivity observed in normal granules. The hypothesis posited that the gas pockets in calcified granules facilitated respiration as the functional structure. The presence of tiny bubbles exhibited a propensity for inducing clogging, thereby diminishing the capillary connectivity essential for substrate diffusion. The proposed respiration and embolization concepts decipher the distinct roles of entrapped bubbles in the granular bioactivity across diverse fluid states. This study offers valuable insights into the impact of fluidization on microscopic transport within granule-based bed reactors.
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Affiliation(s)
- Gan Peng
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China
| | - Lu Li-Xian
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China
| | - Liu Xi
- Guangxi Bossco Environment Co., Ltd, Nanning 530007, China
| | - Wang Shuang-Fei
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China
| | - Zhang Jian
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China.
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2
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Xu D, Cao S, Berry M, Du R, Peng Y. Granulation of partial denitrification sludge: Advances in mechanism understanding, technologies development and perspectives. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166760. [PMID: 37659567 DOI: 10.1016/j.scitotenv.2023.166760] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 08/20/2023] [Accepted: 08/30/2023] [Indexed: 09/04/2023]
Abstract
The high-rate and stably efficient nitrite generation is vital and still challenges the wide application of partial denitrification (PD) and anammox technology. Increasing attention has been drawn to the granulation of PD biomass. However, the knowledge of PD granular sludge is still limited in terms of granules characterization and mechanisms of biomass aggregation for high nitrite accumulation. This work reviewed the performance and granulation of PD biomass for high nitrite accumulation via nitrate reduction, including the system start-up, influential factors, granular characteristics, hypothetical mechanism, challenges and perspectives in future application. The physiochemical characterization and key influential factors were summarized in view of nitrite production, morphology analysis, extracellular polymer substance structure, as well as microbial mechanisms. The PD granules exhibit potential advantages of a high biomass density, good settleability, high hydraulic loading rates, and strong shock resistance. A novel granular sludge-based PD combined with anammox process was proposed to enhance the capability of nitrogen removal. In the future, PD granules utilizing different electron donors is a promising way to broaden the application of anammox technology in both municipal and industrial wastewater treatment.
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Affiliation(s)
- Duanyuan Xu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
| | - Shenbin Cao
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China; College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, PR China
| | - Maxence Berry
- Department of Process Engineering and Bioprocesses, Polytech Nantes, Campus of Gavy, Saint-Nazaire 44603, France
| | - Rui Du
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China; Chair of Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany.
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
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3
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Li YS, Li BB, Tian T, Yu HQ. Quorum sensing unveils the sludge floccule-assisted stabilization of aerobic granules in granule-dominated sequencing batch reactors. Biotechnol Bioeng 2023; 120:444-455. [PMID: 36303067 DOI: 10.1002/bit.28275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 10/19/2022] [Accepted: 10/23/2022] [Indexed: 01/13/2023]
Abstract
Floccules are another major form of microbial aggregates in aerobic granular sludge systems. Previous studies mainly attributed the persistence of floccules to their relatively faster nutrient uptake and higher growth rate over aerobic granules; however, they failed to unravel the underlying mechanism of the long-term coexistence of these two aggregates. In this work, the existence and function of the floccules in an aerobic granule-dominated sequencing batch reactor were investigated from the view of quorum sensing (QS) and quorum quenching (QQ). The results showed that though the floccules were closely associated with the granules in terms of similar community structures (including the QS- and QQ-related ones), they exhibited a relatively higher QQ-related activity but a lower QS-related activity. A compatible proportion of floccules might be helpful to maintain the QS-related activity and keep the granules stable. In addition, the structure difference was demonstrated to diversify the QS- and QQ-related activities of the floccules and the aerobic granules. These findings could broaden our understanding of the interactions between the coexistent floccules and granules in aerobic granule-dominated systems and would be instructive for the development of the aerobic granular sludge process.
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Affiliation(s)
- Yu-Sheng Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei, China
| | - Bing-Bing Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei, China
| | - Tian Tian
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei, China.,Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei, China
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4
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Martinez-Rabert E, van Amstel C, Smith C, Sloan WT, Gonzalez-Cabaleiro R. Environmental and ecological controls of the spatial distribution of microbial populations in aggregates. PLoS Comput Biol 2022; 18:e1010807. [PMID: 36534694 PMCID: PMC9810174 DOI: 10.1371/journal.pcbi.1010807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 01/03/2023] [Accepted: 12/10/2022] [Indexed: 12/23/2022] Open
Abstract
In microbial communities, the ecological interactions between species of different populations are responsible for the spatial distributions observed in aggregates (granules, biofilms or flocs). To explore the underlying mechanisms that control these processes, we have developed a mathematical modelling framework able to describe, label and quantify defined spatial structures that arise from microbial and environmental interactions in communities. An artificial system of three populations collaborating or competing in an aggregate is simulated using individual-based modelling under different environmental conditions. In this study, neutralism, competition, commensalism and concurrence of commensalism and competition have been considered. We were able to identify interspecific segregation of communities that appears in competitive environments (columned stratification), and a layered distribution of populations that emerges in commensal (layered stratification). When different ecological interactions were considered in the same aggregate, the resultant spatial distribution was identified as the one controlled by the most limiting substrate. A theoretical modulus was defined, with which we were able to quantify the effect of environmental conditions and ecological interactions to predict the most probable spatial distribution. The specific microbial patterns observed in our results allowed us to identify the optimal spatial organizations for bacteria to thrive when building a microbial community and how this permitted co-existence of populations at different growth rates. Our model reveals that although ecological relationships between different species dictate the distribution of bacteria, the environment controls the final spatial distribution of the community.
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Affiliation(s)
- Eloi Martinez-Rabert
- James Watt School of Engineering, Infrastructure and Environment Research Division, University of Glasgow, Advanced Research Centre, Glasgow, United Kingdom
- * E-mail:
| | - Chiel van Amstel
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Cindy Smith
- James Watt School of Engineering, Infrastructure and Environment Research Division, University of Glasgow, Advanced Research Centre, Glasgow, United Kingdom
| | - William T. Sloan
- James Watt School of Engineering, Infrastructure and Environment Research Division, University of Glasgow, Advanced Research Centre, Glasgow, United Kingdom
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5
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Burzio C, Ekholm J, Modin O, Falås P, Svahn O, Persson F, van Erp T, Gustavsson DJI, Wilén BM. Removal of organic micropollutants from municipal wastewater by aerobic granular sludge and conventional activated sludge. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129528. [PMID: 35999740 DOI: 10.1016/j.jhazmat.2022.129528] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/02/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Removal performances of organic micropollutants by conventional activated sludge (CAS) and aerobic granular sludge (AGS) were investigated at a full-scale wastewater treatment plant. Lab-scale kinetic experiments were performed to assess the micropollutant transformation rates under oxic and anoxic conditions. Transformation rates were used to model the micropollutant removal in the full-scale processes. Metagenomic sequencing was used to compare the microbial communities and antimicrobial resistance genes of the CAS and AGS systems. Higher transformation ability was observed for CAS compared to AGS for most compounds, both at the full-scale plant and in the complementary batch experiments. Oxic conditions supported the transformation of several micropollutants with faster and/or comparable rates compared to anoxic conditions. The estimated transformation rates from batch experiments adequately predicted the removal for most micropollutants in the full-scale processes. While the compositions in microbial communities differed between AGS and CAS, the full-scale biological reactors shared similar resistome profiles. Even though granular biomass showed lower potential for micropollutant transformation, AGS systems had somewhat higher gene cluster diversity compared to CAS, which could be related to a higher functional diversity. Micropollutant exposure to biomass or mass transfer limitations, therefore played more important roles in the observed differences in OMP removal.
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Affiliation(s)
- Cecilia Burzio
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden.
| | - Jennifer Ekholm
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Oskar Modin
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Per Falås
- Department of Chemical Engineering, Lund University, PO Box 124, Lund 22100, Sweden
| | - Ola Svahn
- Department of Environmental Science and Bioscience, Kristianstad University, Kristianstad 29139, Sweden
| | - Frank Persson
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Tim van Erp
- Strömstad Municipality, Wastewater Treatment Plant Österröd, Strömstad 45233, Sweden
| | | | - Britt-Marie Wilén
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
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6
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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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7
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Soler-Jofra A, Schmidtchen L, Olmo L, van Loosdrecht MCM, Pérez J. Short and long term continuous hydroxylamine feeding in a granular sludge partial nitritation reactor. WATER RESEARCH 2022; 209:117945. [PMID: 34936973 DOI: 10.1016/j.watres.2021.117945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/25/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
Hydroxylamine is a nitrogen intermediate of ammonium oxidizing bacteria (AOB) that can transiently accumulate during nitrification. The impact of hydroxylamine on aerobic ammonium oxidations is still obscure. In the present study the short and long term impact of hydroxylamine on partial nitritation granular sludge was investigated. Dissolved oxygen was the governing factor determining the hydroxylamine impact in short term studies with continuous hydroxylamine feeding. Continuous short term hydroxylamine feeding together with low dissolved oxygen resulted in higher hydroxylamine accumulation, higher N2O production and decreased or maintained ammonium consumption. Instead, high dissolved oxygen reduced hydroxylamine accumulation and N2O production and increased ammonium consumption. Long term continuous hydroxylamine feeding reduced ammonium consumption rate while the constant nitrite production rate indicated that dosed hydroxylamine was mainly transformed to nitrite. This indicates that hydroxylamine was preferred over ammonium as substrate. Nitrosomonas sp. was shown to be predominant during continuous hydroxylamine feeding while the side community shifted.
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Affiliation(s)
- Aina Soler-Jofra
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, the Netherlands
| | - Lisbeth Schmidtchen
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, the Netherlands
| | - Lluc Olmo
- Department of Chemical, Biological and Environmental Engineering, Universitat Autonoma de Barcelona, Cerdanyola del Valles, Spain
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, the Netherlands.
| | - Julio Pérez
- Department of Chemical, Biological and Environmental Engineering, Universitat Autonoma de Barcelona, Cerdanyola del Valles, Spain
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8
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Dockx L, Caluwé M, Dobbeleers T, Dries J. Nitrous oxide formation during simultaneous phosphorus and nitrogen removal in aerobic granular sludge treating different carbon substrates. BIORESOURCE TECHNOLOGY 2022; 345:126542. [PMID: 34906707 DOI: 10.1016/j.biortech.2021.126542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
The impact of different substrates on N2O dynamics and gene expression of marker enzymes (nirS, nirK and nosZ) involved in denitrifying enhanced biological phosphorus removal (d-EBPR) was investigated. Aerobic granular sludge fed with VFAs led to an anoxic P-uptake (27.7 ± 1.2 mg PO43--P.gVSS-1) and N2O emissions up to 80.7 ± 3.4% N2O-N. A decisive role of Accumulibacter in N2O formation was observed. Dosage of amino acids (12.0 ± 1.2 mg PO43--P.gVSS-1) and glucose (1.5 ± 0.9 mg PO43--P.gVSS-1) as sole substrate did not support d-EBPR activity. Presence of NO2- resulted in higher N2O formation in comparison to nitrate and a nosZ/(nirS + nirK) ratio lower than 0.3. A linear correlation (R2 > 0.95) between the nosZ/(nirS + nirK) ratio and the N2O reductase rate was found only when dosing the same type of substrate. This suggests an interplay between the microbial community composition and different polyhydroxyalkanoates derivatives, when dosing different substrates.
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Affiliation(s)
- Lennert Dockx
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium
| | - Michel Caluwé
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium
| | - Thomas Dobbeleers
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium
| | - Jan Dries
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium.
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9
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Dockx L, Caluwé M, De Vleeschauwer F, Dobbeleers T, Dries J. Impact of the substrate composition on enhanced biological phosphorus removal during formation of aerobic granular sludge. BIORESOURCE TECHNOLOGY 2021; 337:125482. [PMID: 34320762 DOI: 10.1016/j.biortech.2021.125482] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
Performance of enhanced biological phosphorus removal (EBPR) is often investigated with simple synthetic wastewater containing volatile fatty acids (VFAs). In this study, various (fermentable) substrates, individually and in mixtures, were examined during the application of a granulation strategy. In addition, the microbial community and N2O formation were monitored. Sludge densification was observed in all systems. Stable EBPR, associated with the presence of Accumulibacter and an anaerobic P-release up to 21.9 mgPO43--P.gVSS-1, was only obtained when VFAs were present as sole substrate or in mixture. Systems fed with VFAs were strongly related to the formation of N2O (maximum of 6.25% relative to the total available nitrogen). A moderate anaerobic dissolved organic carbon (DOC) uptake was observed when amino acids (64.27 ± 3.08%) and glucose (75.39 ± 5.79%) as sole carbon source were applied. The substrate/species-specific enrichment of Burkholderiaceae and Saccharimonadaceae respectively, resulted in unstable EBPR in those systems.
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Affiliation(s)
- Lennert Dockx
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Michel Caluwé
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Flinn De Vleeschauwer
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Thomas Dobbeleers
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Jan Dries
- BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium.
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10
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Zhou JH, Ren Q, Xu XL, Fang JY, Wang T, Wang KM, Wang HY. Enhancing stability of aerobic granules by microbial selection pressure using height-adjustable influent strategy. WATER RESEARCH 2021; 201:117356. [PMID: 34147742 DOI: 10.1016/j.watres.2021.117356] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/15/2021] [Accepted: 06/07/2021] [Indexed: 06/12/2023]
Abstract
Optimizing granules size distribution is critical for both reactor performance and stability. In this research, an optimal size range of 1800 to 3000 μm was proposed regarding mass transfer and granules stability based on granules developed at DO around 8.0 mg L-1 with the feed COD:N:P at 100:5:1. A height-adjustable influent strategy was applied to facilitate the nutrient storage of granules at optimum size range via microbial selective pressure. Results suggested insufficient hydraulic shear stress led to overgrowth of granules size. High abundance of filamentous bacteria (Thiothrix sp.) was observed in oversized granules, which detached and affected the remaining granules, resulting in severe sludge bulking. Strong hydraulic shear stress suppressed uncontrolled growth of granules. However, fewer abundance of simultaneous nitrification and denitrification (SND) bacterium was acquired, which led to unfavored SND effect and total nitrogen (TN) removal efficiency. The height-adjustable influent strategy facilitated the poly-β-hydroxybutyrate (PHB) storage of granules at optimum size range, while limiting the overgrowth of granules size. Additionally, more than 87.51% of total granules situated in optimal sizes range, which led to higher abundance of SND bacterium and higher TN removal efficiency.
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Affiliation(s)
- Jia-Heng Zhou
- College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China.
| | - Qing Ren
- College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
| | - Xiao-Lei Xu
- College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
| | - Jing-Yuan Fang
- College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
| | - Tao Wang
- College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
| | - Kan-Ming Wang
- College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
| | - Hong-Yu Wang
- College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
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