The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
L. J. Niemand - One of the best experts on this subject based on the ideXlab platform.
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cfd simulation of anaerobic Digester with variable sewage sludge rheology
Water Research, 2013Co-Authors: K J Craig, M. N. Nieuwoudt, L. J. NiemandAbstract:Abstract A computational fluid dynamics (CFD) model that evaluates mechanical mixing in a full-scale anaerobic Digester was developed to investigate the influence of sewage sludge rheology on the steady-state Digester performance. Mechanical mixing is provided through an impeller located in a draft tube. Use is made of the Multiple Reference Frame model to incorporate the rotating impeller. The non-Newtonian sludge is modeled using the Hershel–Bulkley law because of the yield stress present in the fluid. Water is also used as modeling fluid to illustrate the significant non-Newtonian effects of sewage sludge on mixing patterns. The variation of the sewage sludge rheology as a result of the digestion process is considered to determine its influence on both the required impeller torque and Digester mixing patterns. It was found that when modeling the fluid with the Hershel–Bulkley law, the high slope of the sewage stress-strain curve at high shear rates causes significant viscous torque on the impeller surface. Although the overall fluid shear stress property is reduced during digestion, this slope is increased with sludge age, causing an increase in impeller torque for digested sludge due to the high strain rates caused by the pumping impeller. Consideration should be given to using the Bingham law to deal with high strain rates. The overall mixing flow patterns of the digested sludge do however improve slightly.
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CFD simulation of anaerobic Digester with variable sewage sludge rheology
Water Research, 2013Co-Authors: K J Craig, M. N. Nieuwoudt, L. J. NiemandAbstract:A computational fluid dynamics (CFD) model that evaluates mechanical mixing in a full-scale anaerobic Digester was developed to investigate the influence of sewage sludge rheology on the steady-state Digester performance. Mechanical mixing is provided through an impeller located in a draft tube. Use is made of the Multiple Reference Frame model to incorporate the rotating impeller. The non-Newtonian sludge is modeled using the Hershel-Bulkley law because of the yield stress present in the fluid. Water is also used as modeling fluid to illustrate the significant non-Newtonian effects of sewage sludge on mixing patterns. The variation of the sewage sludge rheology as a result of the digestion process is considered to determine its influence on both the required impeller torque and Digester mixing patterns. It was found that when modeling the fluid with the Hershel-Bulkley law, the high slope of the sewage stress-strain curve at high shear rates causes significant viscous torque on the impeller surface. Although the overall fluid shear stress property is reduced during digestion, this slope is increased with sludge age, causing an increase in impeller torque for digested sludge due to the high strain rates caused by the pumping impeller. Consideration should be given to using the Bingham law to deal with high strain rates. The overall mixing flow patterns of the digested sludge do however improve slightly. © 2013 Elsevier Ltd.
Per Halkjær Nielsen - One of the best experts on this subject based on the ideXlab platform.
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MiDAS 2.0: An ecosystem-specific taxonomy and online database for the organisms of wastewater treatment systems expanded for anaerobic Digester groups
Database, 2017Co-Authors: Simon Jon Mcilroy, Rasmus Hansen Kirkegaard, Bianca Mcilroy, Marta Nierychlo, Jannie Munk Kristensen, Søren Michael Karst, Mads Albertsen, Per Halkjær NielsenAbstract:Citation details: McIlroy,S.J., Kirkegaard,R.H., McIlroy,B. et al. MiDAS 2.0: an ecosystem-specific taxonomy and online database for the organisms of wastewater treatment systems expanded for anaerobic Digester groups. Abstract Wastewater is increasingly viewed as a resource, with anaerobic Digester technology being routinely implemented for biogas production. Characterising the microbial com-munities involved in wastewater treatment facilities and their anaerobic Digesters is con-sidered key to their optimal design and operation. Amplicon sequencing of the 16S rRNA gene allows high-throughput monitoring of these systems. The MiDAS field guide is a public resource providing amplicon sequencing protocols and an ecosystem-specific taxonomic database optimized for use with wastewater treatment facility samples. The curated taxonomy endeavours to provide a genus-level-classification for abundant phy-lotypes and the online field guide links this identity to published information regarding their ecology, function and distribution. This article describes the expansion of the data-base resources to cover the organisms of the anaerobic Digester systems fed primary sludge and surplus activated sludge. The updated database includes descriptions of the abundant genus-level-taxa in influent wastewater, activated sludge and anaerobic di-gesters. Abundance information is also included to allow assessment of the role of emi-gration in the ecology of each phylotype. MiDAS is intended as a collaborative resource for the progression of research into the ecology of wastewater treatment, by providing a public repository for knowledge that is accessible to all interested in these biotechnologi-cally important systems.
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midas 2 0 an ecosystem specific taxonomy and online database for the organisms of wastewater treatment systems expanded for anaerobic Digester groups
Database, 2017Co-Authors: Simon Jon Mcilroy, Rasmus Hansen Kirkegaard, Bianca Mcilroy, Marta Nierychlo, Jannie Munk Kristensen, Søren Michael Karst, Mads Albertsen, Per Halkjær NielsenAbstract:Wastewater is increasingly viewed as a resource, with anaerobic Digester technology being routinely implemented for biogas production. Characterising the microbial communities involved in wastewater treatment facilities and their anaerobic Digesters is considered key to their optimal design and operation. Amplicon sequencing of the 16S rRNA gene allows high-throughput monitoring of these systems. The MiDAS field guide is a public resource providing amplicon sequencing protocols and an ecosystem-specific taxonomic database optimized for use with wastewater treatment facility samples. The curated taxonomy endeavours to provide a genus-level-classification for abundant phylotypes and the online field guide links this identity to published information regarding their ecology, function and distribution. This article describes the expansion of the database resources to cover the organisms of the anaerobic Digester systems fed primary sludge and surplus activated sludge. The updated database includes descriptions of the abundant genus-level-taxa in influent wastewater, activated sludge and anaerobic Digesters. Abundance information is also included to allow assessment of the role of emigration in the ecology of each phylotype. MiDAS is intended as a collaborative resource for the progression of research into the ecology of wastewater treatment, by providing a public repository for knowledge that is accessible to all interested in these biotechnologically important systems.Database URL : http://www.midasfieldguide.org.
Jules B Van Lier - One of the best experts on this subject based on the ideXlab platform.
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operation driven heterogeneity and overlooked feed associated populations in global anaerobic Digester microbiome
Water Research, 2017Co-Authors: Jules B Van Lier, Masaru K Nobu, Takashi Narihiro, Kyohei Kuroda, Julian Munoz Sierra, Zhuoying Wu, Lin Ye, Michael J McinerneyAbstract:Anaerobic Digester (AD) microbiomes harbor complex, interacting microbial populations to achieve biomass reduction and biogas production, however how they are influenced by operating conditions and feed sludge microorganisms remain unclear. These were addressed by analyzing the microbial communities of 90 full-scale Digesters at 51 municipal wastewater treatment plants from five countries. Heterogeneity detected in community structures suggested that no single AD microbiome could be defined. Instead, the AD microbiomes were classified into eight clusters driven by operating conditions (e.g., pretreatment, temperature range, and salinity), whereas geographic location of the Digesters did not have significant impacts. Comparing Digesters populations with those present in the corresponding feed sludge led to the identification of a hitherto overlooked feed-associated microbial group (i.e., the residue populations). They accounted for up to 21.4% of total sequences in ADs operated at low temperature, presumably due to ineffective digestion, and as low as 0.8% in ADs with pretreatment. Within each cluster, a core microbiome was defined, including methanogens, syntrophic metabolizers, fermenters, and the newly described residue populations. Our work provides insights into the key factors shaping full-scale AD microbiomes in a global scale, and draws attentions to the overlooked residue populations.
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Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage
Water Research, 2015Co-Authors: Dara S.m. Ghasimi, Merle De Kreuk, Marcel H. Zandvoort, Ben Abbas, Jules B Van LierAbstract:Abstract This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) Digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10–14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic Digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10–25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two Digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic Digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved Digester performances, particularly with regard to the thermophilic Digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic Digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature.
Dara S.m. Ghasimi - One of the best experts on this subject based on the ideXlab platform.
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Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage
Water Research, 2015Co-Authors: Dara S.m. Ghasimi, Merle De Kreuk, Marcel H. Zandvoort, Ben Abbas, Jules B Van LierAbstract:Abstract This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) Digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10–14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic Digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10–25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two Digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic Digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved Digester performances, particularly with regard to the thermophilic Digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic Digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature.
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Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage
Water Research, 2015Co-Authors: Dara S.m. Ghasimi, Merle De Kreuk, Marcel H. Zandvoort, Ben Abbas, Yu Tao, Jules B. Van LierAbstract:This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) Digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10e14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic Digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10e25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two Digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic Digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved Digester performances, particularly with regard to the thermophilic Digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic Digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature.
K J Craig - One of the best experts on this subject based on the ideXlab platform.
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cfd simulation of anaerobic Digester with variable sewage sludge rheology
Water Research, 2013Co-Authors: K J Craig, M. N. Nieuwoudt, L. J. NiemandAbstract:Abstract A computational fluid dynamics (CFD) model that evaluates mechanical mixing in a full-scale anaerobic Digester was developed to investigate the influence of sewage sludge rheology on the steady-state Digester performance. Mechanical mixing is provided through an impeller located in a draft tube. Use is made of the Multiple Reference Frame model to incorporate the rotating impeller. The non-Newtonian sludge is modeled using the Hershel–Bulkley law because of the yield stress present in the fluid. Water is also used as modeling fluid to illustrate the significant non-Newtonian effects of sewage sludge on mixing patterns. The variation of the sewage sludge rheology as a result of the digestion process is considered to determine its influence on both the required impeller torque and Digester mixing patterns. It was found that when modeling the fluid with the Hershel–Bulkley law, the high slope of the sewage stress-strain curve at high shear rates causes significant viscous torque on the impeller surface. Although the overall fluid shear stress property is reduced during digestion, this slope is increased with sludge age, causing an increase in impeller torque for digested sludge due to the high strain rates caused by the pumping impeller. Consideration should be given to using the Bingham law to deal with high strain rates. The overall mixing flow patterns of the digested sludge do however improve slightly.
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CFD simulation of anaerobic Digester with variable sewage sludge rheology
Water Research, 2013Co-Authors: K J Craig, M. N. Nieuwoudt, L. J. NiemandAbstract:A computational fluid dynamics (CFD) model that evaluates mechanical mixing in a full-scale anaerobic Digester was developed to investigate the influence of sewage sludge rheology on the steady-state Digester performance. Mechanical mixing is provided through an impeller located in a draft tube. Use is made of the Multiple Reference Frame model to incorporate the rotating impeller. The non-Newtonian sludge is modeled using the Hershel-Bulkley law because of the yield stress present in the fluid. Water is also used as modeling fluid to illustrate the significant non-Newtonian effects of sewage sludge on mixing patterns. The variation of the sewage sludge rheology as a result of the digestion process is considered to determine its influence on both the required impeller torque and Digester mixing patterns. It was found that when modeling the fluid with the Hershel-Bulkley law, the high slope of the sewage stress-strain curve at high shear rates causes significant viscous torque on the impeller surface. Although the overall fluid shear stress property is reduced during digestion, this slope is increased with sludge age, causing an increase in impeller torque for digested sludge due to the high strain rates caused by the pumping impeller. Consideration should be given to using the Bingham law to deal with high strain rates. The overall mixing flow patterns of the digested sludge do however improve slightly. © 2013 Elsevier Ltd.