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Southwell RV, Hilton SL, Pearson JM, Hand LH, Bending GD. Water flow plays a key role in determining chemical biodegradation in water-sediment systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 880:163282. [PMID: 37023820 DOI: 10.1016/j.scitotenv.2023.163282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/31/2023] [Accepted: 03/31/2023] [Indexed: 04/14/2023]
Abstract
Before agrochemicals can be registered and sold, the chemical industry is required to perform regulatory tests to assess their environmental persistence, using defined guidelines. Aquatic fate tests (e.g. OECD 308) lack environmental realism as they are conducted under dark conditions and in small-scale static systems, which can affect microbial diversity and functionality. In this study, water-sediment microflumes were used to investigate the impact of these deficiencies in environmental realism on the fate of the fungicide, isopyrazam. Although on a large-scale, these systems aimed to retain the key aspects of OECD 308 tests. Tests were carried out under both a non-UV light-dark cycle and continuous darkness and under both static and flowing water conditions, to investigate how light and water flow affect isopyrazam biodegradation pathways. In static systems, light treatment played a significant role, with faster dissipation in illuminated compared to dark microflumes (DT50s = 20.6 vs. 47.7 days). In flowing systems (DT50s = 16.8 and 15.3 days), light did not play a significant role in dissipation, which was comparable between the two light treatments, and faster than in dark static microflumes. Microbial phototroph biomass was significantly reduced by water flow in the illuminated systems, thereby reducing their contribution to dissipation. Comprehensive analysis of bacterial and eukaryotic community composition identified treatment specific changes following incubation, with light promoting relative abundance of Cyanobacteria and eukaryotic algae, and flow increasing relative abundance of fungi. We conclude that both water velocity and non-UV light increased isopyrazam dissipation, but the contribution of light depended on the flow conditions. These differences may have resulted from impacts on microbial communities and via mixing processes, particularly hyporheic exchange. Inclusion of both light and flow in studies could improve the extent they mimic natural environments and predict chemical environmental persistence, thus bridging the gap between laboratory and field studies.
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Affiliation(s)
- Rebecca V Southwell
- School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry CV4 7AL, UK; Product Safety, Jealott's Hill International Research Centre, Syngenta, Bracknell, Berkshire RG4 6EY, UK.
| | - Sally L Hilton
- School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry CV4 7AL, UK
| | - Jonathan M Pearson
- School of Engineering, Library Road, University of Warwick, Coventry CV4 7AL, UK
| | - Laurence H Hand
- Product Safety, Jealott's Hill International Research Centre, Syngenta, Bracknell, Berkshire RG4 6EY, UK
| | - Gary D Bending
- School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry CV4 7AL, UK
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2
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Jimenez-Martinez J, Nguyen J, Or D. Controlling pore-scale processes to tame subsurface biomineralization. RE/VIEWS IN ENVIRONMENTAL SCIENCE AND BIO/TECHNOLOGY 2022; 21:27-52. [PMID: 35221831 PMCID: PMC8831379 DOI: 10.1007/s11157-021-09603-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Microorganisms capable of biomineralization can catalyze mineral precipitation by modifying local physical and chemical conditions. In porous media, such as soil and rock, these microorganisms live and function in highly heterogeneous physical, chemical and ecological microenvironments, with strong local gradients created by both microbial activity and the pore-scale structure of the subsurface. Here, we focus on extracellular bacterial biomineralization, which is sensitive to external heterogeneity, and review the pore-scale processes controlling microbial biomineralization in natural and engineered porous media. We discuss how individual physical, chemical and ecological factors integrate to affect the spatial and temporal control of biomineralization, and how each of these factors contributes to a quantitative understanding of biomineralization in porous media. We find that an improved understanding of microbial behavior in heterogeneous microenvironments would promote understanding of natural systems and output in diverse technological applications, including improved representation and control of fluid mixing from pore to field scales. We suggest a range of directions by which future work can build from existing tools to advance each of these areas to improve understanding and predictability of biomineralization science and technology.
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Affiliation(s)
- Joaquin Jimenez-Martinez
- Department of Water Resources and Drinking Water, Eawag, Dübendorf, Switzerland
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zürich, Switzerland
| | - Jen Nguyen
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Dani Or
- Division of Hydrologic Sciences, Desert Research Institute, Reno, NV USA
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3
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Influence of Particle Size of River Sand on the Decontamination Process in the Slow Sand Filter Treatment of Micro-Polluted Water. WATER 2022. [DOI: 10.3390/w14010100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Slow sand filters (SSFs) have been widely used in the construction of water plants in rural areas. It is necessary to find river sand of suitable particle size to improve SSF treatment of micro-polluted water so as to ensure the effective and long-term operation of these plants. In this study, SSF1# (particle size of 0.1–0.5 mm), SSF2# (particle size of 0.5–1 mm), and SSF3# (particle size of 1–1.5 mm) were selected. The physical absorption, CODMn and NH4+-N removal effect, and microbial community were analyzed. According to Langmuir and Freundlich adsorption model fitting, the smaller the particle size of the river sand, the more pollutants are adsorbed under the same conditions. SSF1# has the shortest membrane-forming time, highest CODMn and NH4+-N removal rate, and highest Shannon estimator, indicating that there are more abundant microbial species in the biofilm. Mesorhizobium, Pannonibacter, Pseudoxanthomonas, Aquabacterium, Devosia, and other bacteria have different proportions in each system, each forming its own stable biological chain system. The effluent quality of the three SSFs can meet drinking water standards. However, river sand with a particle size range of 0.1–0.5 mm is easily blocked, and thus the recommended size range for SSF is 0.5–1 mm.
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Scheidweiler D, Peter H, Pramateftaki P, de Anna P, Battin TJ. Unraveling the biophysical underpinnings to the success of multispecies biofilms in porous environments. ISME JOURNAL 2019; 13:1700-1710. [PMID: 30833685 PMCID: PMC6776110 DOI: 10.1038/s41396-019-0381-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 02/07/2019] [Accepted: 02/17/2019] [Indexed: 11/23/2022]
Abstract
Biofilms regulate critical processes in porous ecosystems. However, the biophysical underpinnings of the ecological success of these biofilms are poorly understood. Combining experiments with fluidic devices, sequencing and modeling, we reveal that architectural plasticity enhances space exploitation by multispecies biofilms in porous environments. Biofilms consistently differentiated into an annular base biofilm coating the grains and into streamers protruding from the grains into the pore space. Although different flow-related processes governed the differentiation of these architectures, both BB and streamers were composed of similar bacterial assemblages. This is evidence for architectural plasticity. Architectural plasticity allowed for complementary use of the space provided by the grain–pore complexes, which increased biofilm carrying capacity at the larger scale of the porous system. This increase comes potentially at the cost of a tradeoff. Contrasting time scales of oxygen replenishment and consumption, we show that streamers locally inhibit the growth of the BB downstream from the grains. Our study provides first insights into the biophysical underpinnings to the success of multispecies biofilms in porous environments.
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Affiliation(s)
- David Scheidweiler
- Stream Biofilm and Ecosystem Research Laboratory, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Hannes Peter
- Stream Biofilm and Ecosystem Research Laboratory, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Paraskevi Pramateftaki
- Stream Biofilm and Ecosystem Research Laboratory, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Pietro de Anna
- Institute of Earth Sciences, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Tom J Battin
- Stream Biofilm and Ecosystem Research Laboratory, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
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5
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Carrel M, Morales VL, Dentz M, Derlon N, Morgenroth E, Holzner M. Pore-Scale Hydrodynamics in a Progressively Bioclogged Three-Dimensional Porous Medium: 3-D Particle Tracking Experiments and Stochastic Transport Modeling. WATER RESOURCES RESEARCH 2018; 54:2183-2198. [PMID: 29780184 PMCID: PMC5947749 DOI: 10.1002/2017wr021726] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 02/25/2018] [Indexed: 05/30/2023]
Abstract
Biofilms are ubiquitous bacterial communities that grow in various porous media including soils, trickling, and sand filters. In these environments, they play a central role in services ranging from degradation of pollutants to water purification. Biofilms dynamically change the pore structure of the medium through selective clogging of pores, a process known as bioclogging. This affects how solutes are transported and spread through the porous matrix, but the temporal changes to transport behavior during bioclogging are not well understood. To address this uncertainty, we experimentally study the hydrodynamic changes of a transparent 3-D porous medium as it experiences progressive bioclogging. Statistical analyses of the system's hydrodynamics at four time points of bioclogging (0, 24, 36, and 48 h in the exponential growth phase) reveal exponential increases in both average and variance of the flow velocity, as well as its correlation length. Measurements for spreading, as mean-squared displacements, are found to be non-Fickian and more intensely superdiffusive with progressive bioclogging, indicating the formation of preferential flow pathways and stagnation zones. A gamma distribution describes well the Lagrangian velocity distributions and provides parameters that quantify changes to the flow, which evolves from a parallel pore arrangement under unclogged conditions, toward a more serial arrangement with increasing clogging. Exponentially evolving hydrodynamic metrics agree with an exponential bacterial growth phase and are used to parameterize a correlated continuous time random walk model with a stochastic velocity relaxation. The model accurately reproduces transport observations and can be used to resolve transport behavior at intermediate time points within the exponential growth phase considered.
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Affiliation(s)
- M. Carrel
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic EngineeringETH ZurichZurichSwitzerland
| | - V. L. Morales
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic EngineeringETH ZurichZurichSwitzerland
- Department of Civil and Environmental EngineeringUniversity of California, DavisDavisCAUSA
| | - M. Dentz
- Spanish National Research Council (IDAEA‐CSIC)BarcelonaSpain
| | - N. Derlon
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic EngineeringETH ZurichZurichSwitzerland
- EAWAGDübendorfSwitzerland
| | - E. Morgenroth
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic EngineeringETH ZurichZurichSwitzerland
- EAWAGDübendorfSwitzerland
| | - M. Holzner
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic EngineeringETH ZurichZurichSwitzerland
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6
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Grace MA, Healy MG, Clifford E. Performance and surface clogging in intermittently loaded and slow sand filters containing novel media. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 180:102-10. [PMID: 27213863 DOI: 10.1016/j.jenvman.2016.05.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 05/06/2016] [Accepted: 05/09/2016] [Indexed: 05/27/2023]
Abstract
Slow sand filers are commonly used in water purification processes. However, with the emergence of new contaminants and concern over removing precursors to disinfection by-products, as well as traditional contaminants, there has recently been a focus on technology improvements to result in more effective and targeted filtration systems. The use of new media has attracted attention in terms of contaminant removal, but there have been limited investigations on the key issue of clogging. The filters constructed for this study contained stratified layers comprising combinations of Bayer residue, zeolite, fly ash, granular activated carbon, or sand, dosed with a variety of contaminants (total organic carbon (TOC), aluminium (Al), ammonium (NH4(+)-N), nitrate (NO3(-)-N) and turbidity). Their performance and clogging mechanisms were compared to sand filters, which were also operated under two different loading regimes (continuous and intermittently loaded). The study showed that the novel filter configurations achieved up to 97% Al removal, 71% TOC removal, and 88% NH4(+)-N removal in the best-performing configuration, although they were not as effective as sand in terms of permeability. Deconstruction of the filters revealed that the main clogging mechanism was organic matter build-up at the uppermost layer of the filters. The clogging layer formed more quickly on the surface of the novel media when compared to the sand filters, but extended further into the sand filters, the extent dependent on the loading regime. The study shows the potential for an alternative filtration configuration, harnessing the adsorption potential of industrial waste products and natural media.
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Affiliation(s)
- Maebh A Grace
- Civil Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Mark G Healy
- Civil Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland.
| | - Eoghan Clifford
- Civil Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
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Hofmann R, Grösbacher M, Griebler C. Mini Sediment Columns and Two-Dimensional Sediment Flow-Through Microcosms: Versatile Experimental Systems for Studying Biodegradation of Organic Contaminants in Groundwater Ecosystems. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/8623_2016_210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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8
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Kim M, Or D. Individual-Based Model of Microbial Life on Hydrated Rough Soil Surfaces. PLoS One 2016; 11:e0147394. [PMID: 26807803 PMCID: PMC4726620 DOI: 10.1371/journal.pone.0147394] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 01/04/2016] [Indexed: 12/02/2022] Open
Abstract
Microbial life in soil is perceived as one of the most interesting ecological systems, with microbial communities exhibiting remarkable adaptability to vast dynamic environmental conditions. At the same time, it is a notoriously challenging system to understand due to its complexity including physical, chemical, and biological factors in synchrony. This study presents a spatially-resolved model of microbial dynamics on idealised rough soil surfaces represented as patches with different (roughness) properties that preserve the salient hydration physics of real surfaces. Cell level microbial interactions are considered within an individual-based formulation including dispersion and various forms of trophic dependencies (competition, mutualism). The model provides new insights into mechanisms affecting microbial community dynamics and gives rise to spontaneous formation of microbial community spatial patterns. The framework is capable of representing many interacting species and provides diversity metrics reflecting surface conditions and their evolution over time. A key feature of the model is its spatial scalability that permits representation of microbial processes from cell-level (micro-metric scales) to soil representative volumes at sub-metre scales. Several illustrative examples of microbial trophic interactions and population dynamics highlight the potential of the proposed modelling framework to quantitatively study soil microbial processes. The model is highly applicable in a wide range spanning from quantifying spatial organisation of multiple species under various hydration conditions to predicting microbial diversity residing in different soils.
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Affiliation(s)
- Minsu Kim
- Soil and Terrestrial Environmental Physics (STEP), Department of Environmental Systems Sciences (USYS), ETH Zürich, 8092 Zürich, Switzerland
| | - Dani Or
- Soil and Terrestrial Environmental Physics (STEP), Department of Environmental Systems Sciences (USYS), ETH Zürich, 8092 Zürich, Switzerland
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9
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Dissolved Organic Carbon Mobilisation in a Groundwater System Stressed by Pumping. Sci Rep 2015; 5:18487. [PMID: 26691238 PMCID: PMC4686979 DOI: 10.1038/srep18487] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/19/2015] [Indexed: 11/09/2022] Open
Abstract
The concentration and flux of organic carbon in aquifers is influenced by recharge and abstraction, and surface and subsurface processing. In this study groundwater was abstracted from a shallow fractured rock aquifer and dissolved organic carbon (DOC) was measured in observation bores at different distances from the abstraction bore. Groundwater abstraction at rates exceeding the aquifers yield resulted in increased DOC concentration up to 3,500 percent of initial concentrations. Potential sources of this increased DOC were determined using optical fluorescence and absorbance analysis. Groundwater fluorescent dissolved organic material (FDOM) were found to be a combination of terrestrial-derived humic material and microbial or protein sourced material. Relative molecular weight of FDOM within four metres of the abstraction well increased during the experiment, while the relative molecular weight of FDOM between four and ten metres from the abstraction well decreased. When the aquifer is not being pumped, DOC mobilisation in the aquifer is low. We hypothesise that the physical shear stress on aquifer materials caused by intense abstraction significantly increases the temporary release of DOC from sloughing of biofilms and release of otherwise bound colloidal and sedimentary organic carbon (SOC).
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10
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Roth EJ, Gilbert B, Mays DC. Colloid Deposit Morphology and Clogging in Porous Media: Fundamental Insights Through Investigation of Deposit Fractal Dimension. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:12263-12270. [PMID: 26412205 DOI: 10.1021/acs.est.5b03212] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Experiments reveal a wide discrepancy between the permeability of porous media containing colloid deposits and the available predictive equations. Evidence suggests that this discrepancy results, in part, from the predictive equations failing to account for colloid deposit morphology. This article reports a series of experiments using static light scattering (SLS) to characterize colloid deposit morphology within refractive index matched (RIM) porous media during flow through a column. Real time measurements of permeability, specific deposit, deposit fractal dimension, and deposit radius of gyration, at different vertical positions, were conducted with initially clean porous media at various ionic strengths and fluid velocities. Decreased permeability (i.e., increased clogging) corresponded with higher specific deposit, lower fractal dimension, and smaller radius of gyration. During deposition, fractal dimension, radius of gyration, and permeability decreased with increasing specific deposit. During flushing with colloid-free fluid, these trends reversed, with increased fractal dimension, radius of gyration, and permeability. These observations suggest a deposition scenario in which large and uniform aggregates become deposits, which reduce porosity, lead to higher fluid shear forces, which then decompose the deposits, filling the pore space with small and dendritic fragments of aggregate.
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Affiliation(s)
- Eric J Roth
- University of Colorado Denver , Department of Civil Engineering, Campus Box 113, PO Box 173364, Denver, Colorado 80217-3364, United States
| | - Benjamin Gilbert
- Lawrence Berkeley National Laboratory , Earth Sciences Division, Mail Stop 74R316C, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - David C Mays
- University of Colorado Denver , Department of Civil Engineering, Campus Box 113, PO Box 173364, Denver, Colorado 80217-3364, United States
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11
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Fridjonsson E, Vogt S, Vrouwenvelder J, Johns M. Early non-destructive biofouling detection in spiral wound RO membranes using a mobile earth׳s field NMR. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2015.03.088] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Poonoosamy J, Kosakowski G, Van Loon LR, Mäder U. Dissolution-precipitation processes in tank experiments for testing numerical models for reactive transport calculations: Experiments and modelling. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 177-178:1-17. [PMID: 25805363 DOI: 10.1016/j.jconhyd.2015.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/19/2015] [Accepted: 02/25/2015] [Indexed: 06/04/2023]
Abstract
In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time.
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Affiliation(s)
- Jenna Poonoosamy
- Laboratory for Waste Management, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | - Georg Kosakowski
- Laboratory for Waste Management, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Luc R Van Loon
- Laboratory for Waste Management, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Urs Mäder
- Rock Water Interaction, Institute of Geological Sciences, University of Bern, Baltzerstrasse 3, CH-3012 Bern, Switzerland
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13
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Ballarini E, Beyer C, Bauer RD, Griebler C, Bauer S. Model based evaluation of a contaminant plume development under aerobic and anaerobic conditions in 2D bench-scale tank experiments. Biodegradation 2014; 25:351-71. [PMID: 24122285 DOI: 10.1007/s10532-013-9665-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 10/04/2013] [Indexed: 10/26/2022]
Abstract
The influence of transverse mixing on competitive aerobic and anaerobic biodegradation of a hydrocarbon plume was investigated using a two-dimensional, bench-scale flow-through laboratory tank experiment. In the first part of the experiment aerobic degradation of increasing toluene concentrations was carried out by the aerobic strain Pseudomonas putida F1. Successively, ethylbenzene (injected as a mixture of unlabeled and fully deuterium-labeled isotopologues) substituted toluene; nitrate was added as additional electron acceptor and the anaerobic denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic /anaerobic conditions. The spatial distribution of anaerobic degradation was resolved by measurements of compound-specific stable isotope fractionation induced by the anaerobic strain as well as compound concentrations. A fully transient numerical reactive transport model was employed and calibrated using measurements of electron donors, acceptors and isotope fractionation. The aerobic phases of the experiment were successfully reproduced using a double Monod kinetic growth model and assuming an initial homogeneous distribution of P. putida F1. Investigation of the competitive degradation phase shows that the observed isotopic pattern cannot be explained by transverse mixing driven biodegradation only, but also depends on the inoculation process of the anaerobic strain. Transient concentrations of electron acceptors and donors are well reproduced by the model, showing its ability to simulate transient competitive biodegradation.
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14
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Bradford SA, Wang Y, Kim H, Torkzaban S, Šimůnek J. Modeling microorganism transport and survival in the subsurface. JOURNAL OF ENVIRONMENTAL QUALITY 2014; 43:421-440. [PMID: 25602644 DOI: 10.2134/jeq2013.05.0212] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An understanding of microbial transport and survival in the subsurface is needed for public health, environmental applications, and industrial processes. Much research has therefore been directed to quantify mechanisms influencing microbial fate, and the results demonstrate a complex coupling among many physical, chemical, and biological factors. Mathematical models can be used to help understand and predict the complexities of microbial transport and survival in the subsurface under given assumptions and conditions. This review highlights existing model formulations that can be used for this purpose. In particular, we discuss models based on the advection-dispersion equation, with terms for kinetic retention to solid-water and/or air-water interfaces; blocking and ripening; release that is dependent on the resident time, diffusion, and transients in solution chemistry, water velocity, and water saturation; and microbial decay (first-order and Weibull) and growth (logistic and Monod) that is dependent on temperature, nutrient concentration, and/or microbial concentration. We highlight a two-region model to account for microbe migration in the vicinity of a solid phase and use it to simulate the coupled transport and survival of species under a variety of environmentally relevant scenarios. This review identifies challenges and limitations of models to describe and predict microbial transport and survival. In particular, many model parameters have to be optimized to simulate a diversity of observed transport, retention, and survival behavior at the laboratory scale. Improved theory and models are needed to predict the fate of microorganisms in natural subsurface systems that are highly dynamic and heterogeneous.
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15
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Yoon H, Leibeling S, Zhang C, Müller RH, Werth CJ, Zilles JL. Adaptation of Delftia acidovorans for degradation of 2,4-dichlorophenoxyacetate in a microfluidic porous medium. Biodegradation 2014; 25:595-604. [DOI: 10.1007/s10532-014-9684-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 01/29/2014] [Indexed: 11/28/2022]
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16
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Rolle M, Chiogna G, Hochstetler DL, Kitanidis PK. On the importance of diffusion and compound-specific mixing for groundwater transport: an investigation from pore to field scale. JOURNAL OF CONTAMINANT HYDROLOGY 2013; 153:51-68. [PMID: 23994908 DOI: 10.1016/j.jconhyd.2013.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/12/2013] [Accepted: 07/23/2013] [Indexed: 06/02/2023]
Abstract
Mixing processes significantly affect and limit contaminant transport and transformation rates in the subsurface. The correct quantification of mixing in groundwater systems must account for diffusion, local-scale dispersion and the flow variability in heterogeneous flow fields (e.g., flow-focusing in high-conductivity and de-focusing in low-conductivity zones). Recent results of multitracer laboratory experiments revealed the significant effect of compound-specific diffusive properties on the physical displacement of dissolved species across a representative range of groundwater flow velocities. The goal of this study is to investigate the role of diffusion and compound-specific mixing for solute transport across a range of scales including: (i) pore-scale (~10⁻² m), (ii) laboratory bench-scale (~10⁰ m) and (iii) field-scale (~10² m). We investigate both conservative and mixing-controlled reactive transport using pore-scale modeling, flow-through laboratory experiments and simulations, and field-scale numerical modeling of complex heterogeneous hydraulic conductivity fields with statistical properties similar to the ones reported for the extensively investigated Borden aquifer (Ontario, Canada) and Columbus aquifer (Mississippi, USA, also known as MADE site). We consider different steady-state and transient transport scenarios. For the conservative cases we use as a metric of mixing the exponential of the Shannon entropy to quantify solute dilution either in a given volume (dilution index) or in a given solute flux (flux-related dilution index). The decrease in the mass and the mass-flux of the contaminant plumes is evaluated to quantify reactive mixing. The results show that diffusive processes, occurring at the small-scale of a pore channel, strongly affect conservative and reactive solute transport at larger macroscopic scales. The outcomes of our study illustrate the need to consider and properly account for compound-specific diffusion and mixing limitations in order to accurately describe and predict conservative and reactive transport in porous media.
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Affiliation(s)
- Massimo Rolle
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, 94305 Stanford, CA, USA; Center for Applied Geosciences, University of Tübingen, Hoelderlinstrasse 12, D-72074 Tübingen, Germany.
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The Effect of Microbial Activity on Biodegradation of 2,4,6-Tribromophenol and Flow in Naturally Fractured Chalk Cores. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/162gm18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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18
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Seifert D, Engesgaard P. Sand box experiments with bioclogging of porous media: hydraulic conductivity reductions. JOURNAL OF CONTAMINANT HYDROLOGY 2012; 136-137:1-9. [PMID: 22647500 DOI: 10.1016/j.jconhyd.2012.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 04/20/2012] [Accepted: 04/26/2012] [Indexed: 06/01/2023]
Abstract
Tracer experiments during clogging and de-clogging experiments in a 2D sand box were via an image analysis used to establish a data set on the relation between changes in hydraulic conductivity (K) and relative porosity (β). Clogging appears to create a finger-like tracer transport, which could be caused by an initial heterogeneous distribution of biomass in the sand box. De-clogging occurs at a slower rate possibly due to the presence of inert biomass that is not affected by the starvation conditions by sudden removal of the substrate source. The tracer front was observed to get disturbed closer and closer to the substrate source during the experiments suggesting that the zone of clogging moved upstream. Three clogging models, K(β), from the literature were tested for their ability to describe the temporal changes in clogging at the scale of the sand box; the model of Clement et al. (1996) that makes no assumption on biomass distribution, the plug formation model of Thullner et al. (2002a), and the biofilm-plug formation model of Vandevivere (1995). The plug formation and biofilm-plug formation models both match the observed changes between the hydraulic conductivity of the sand box and the relative porosity. Unfortunately our experiments did not reach low relative porosities where the two models predict different behaviors. The model by Clement et al. (1996) underestimates clogging.
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Affiliation(s)
- Dorte Seifert
- DTU Environment, Technical University of Denmark, Denmark
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19
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Bozorg A, Gates ID, Sen A. Real time monitoring of biofilm development under flow conditions in porous media. BIOFOULING 2012; 28:937-951. [PMID: 22963147 DOI: 10.1080/08927014.2012.723204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Biofilm growth can impact the effectiveness of industrial processes that involve porous media. To better understand and characterize how biofilms develop and affect hydraulic properties in porous media, both spatial and temporal development of biofilms under flow conditions was investigated in a translucent porous medium by using Pseudomonas fluorescens HK44, a bacterial strain genetically engineered to luminesce in the presence of an induction agent. Real-time visualization of luminescent biofilm growth patterns under constant pressure conditions was captured using a CCD camera. Images obtained over 8 days revealed that variations in bioluminescence intensity could be correlated to biofilm cell density and hydraulic conductivity. These results were used to develop a real-time imaging method to study the dynamic behavior of biofilm evolution in a porous medium, thereby providing a new tool to investigate the impact of biological fouling in porous media under flow conditions.
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Affiliation(s)
- Ali Bozorg
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada
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Bozorg A, Sen A, Gates ID. A new approach to model the spatiotemporal development of biofilm phase in porous media. Environ Microbiol 2011; 13:3010-23. [DOI: 10.1111/j.1462-2920.2011.02578.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Ezeuko CC, Sen A, Grigoryan A, Gates ID. Pore-network modeling of biofilm evolution in porous media. Biotechnol Bioeng 2011; 108:2413-23. [PMID: 21520022 DOI: 10.1002/bit.23183] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 03/28/2011] [Accepted: 04/04/2011] [Indexed: 11/11/2022]
Abstract
The influence of bacterial biomass on hydraulic properties of porous media (bioclogging) has been explored as a viable means for optimizing subsurface bioremediation and microbial enhanced oil recovery. In this study, we present a pore network simulator for modeling biofilm evolution in porous media including hydrodynamics and nutrient transport based on coupling of advection transport with Fickian diffusion and a reaction term to account for nutrient consumption. Biofilm has non-zero permeability permitting liquid flow and transport through the biofilm itself. To handle simultaneous mass transfer in both liquid and biofilm in a pore element, a dual-diffusion mass transfer model is introduced. The influence of nutrient limitation on predicted results is explored. Nutrient concentration in the network is affected by diffusion coefficient for nutrient transfer across biofilm (compared to water/water diffusion coefficient) under advection dominated transport, represented by mass transport Péclet number >1. The model correctly predicts a dependence of rate of biomass accumulation on inlet concentration. Poor network connectivity shows a significantly large reduction of permeability, for a small biomass pore volume.
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Affiliation(s)
- C C Ezeuko
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4; telephone: 1-403-479-1254; fax: 1-403-284-4852.
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22
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Investigation of hydrodynamic/biomass growth coupling in a pilot scale granular bioreactor at low pore Reynolds number. Chem Eng Sci 2011. [DOI: 10.1016/j.ces.2011.01.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Haest PJ, Philips J, Springael D, Smolders E. The reactive transport of trichloroethene is influenced by residence time and microbial numbers. JOURNAL OF CONTAMINANT HYDROLOGY 2011; 119:89-98. [PMID: 20952091 DOI: 10.1016/j.jconhyd.2010.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 08/31/2010] [Accepted: 09/21/2010] [Indexed: 05/30/2023]
Abstract
The dechlorination rate in a flow-through porous matrix can be described by the species specific dechlorination rate observed in a liquid batch unless mass transport limitations prevail. This hypothesis was examined by comparing dechlorination rates in liquid batch with that in column experiments at various flow rates (3-9-12 cm day(-1)). Columns were loaded with an inoculated sand and eluted with a medium containing 1mM trichloroethene (TCE) for 247 days. Dechlorination in the column treatments increased with decreasing flow rate, illustrating the effect of the longer residence time. Zeroth order TCE or cis-DCE degradation rates were 4-7 folds larger in columns than in corresponding batch systems which could be explained by the higher measured Geobacter and Dehalococcoides numbers per unit pore volume in the columns. The microbial numbers also explained the variability in dechlorination rate among flow rate treatments marked by a large elution of the dechlorinating species' yield as flow increased. Stop flow events did not reveal mass transport limitations for dechlorination. We conclude that flow rate effects on reactive transport of TCE in this coarse sand are explained by residence time and by microbial transport and that mass transport limitations in this porous matrix are limited.
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Affiliation(s)
- P J Haest
- Division Soil and Water Management, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
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24
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Rolle M, Chiogna G, Bauer R, Griebler C, Grathwohl P. Isotopic fractionation by transverse dispersion: flow-through microcosms and reactive transport modeling study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:6167-73. [PMID: 20704214 DOI: 10.1021/es101179f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Flow-through experiments were carried out to investigate the role of transverse dispersion on the isotopic behavior of an organic compound during conservative and bioreactive transport in a homogeneous porous medium. Ethylbenzene was selected as model contaminant and a mixture of labeled (perdeuterated) and light isotopologues was continuously injected in a quasi two-dimensional flow-through system. We observed a significant fractionation of ethylbenzene isotopologues during conservative transport at steady state. This effect was particularly pronounced at the plume fringe and contrasted with the common assumption that physical processes only provide a negligible contribution to isotope fractionation. Under the experimental steady state conditions, transverse hydrodynamic dispersion was the only process that could have caused the observed fractionation. Therefore, the measured isotope ratios at the outlet ports were interpreted with different parameterizations of the transverse dispersion coefficient. A nonlinear compound-specific parameterization showed the best agreement with the experimental data. Successively, bioreactive experiments were performed in two subsequent stages: a first oxic phase, involving a single strain of ethylbenzene degraders and a second phase with aerobic and anaerobic (i.e., ethylbenzene oxidation coupled to nitrate reduction) degradation. Significant fractionation through biodegradation occurred exclusively due to the metabolic activity of the anaerobic degraders. We performed analytical and numerical reactive transport simulations of the different experimental phases which confirmed that both the effects of physical processes (diffusion and dispersion) and microbially mediated reactions have to be considered to match the observed isotopic fractionation behavior.
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Affiliation(s)
- Massimo Rolle
- Center for Applied Geosciences, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany.
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25
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Zhang C, Kang Q, Wang X, Zilles JL, Müller RH, Werth CJ. Effects of pore-scale heterogeneity and transverse mixing on bacterial growth in porous media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:3085-3092. [PMID: 20192171 DOI: 10.1021/es903396h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Microbial degradation of contaminants in the subsurface requires the availability of nutrients; this is impacted by porous media heterogeneity and the degree of transverse mixing. Two types of microfluidic pore structures etched into silicon wafers (i.e., micromodels), (i) a homogeneous distribution of cylindrical posts and (ii) aggregates of large and small cylindrical posts, were used to evaluate the impact of heterogeneity on growth of a pure culture (Delftia acidovorans) that degrades (R)-2-(2,4-dichlorophenoxy)propionate (R-2,4-DP). Following inoculation, dissolved O2 and R-2,4-DP were introduced as two parallel streams that mixed transverse to the direction of flow. In the homogeneous micromodel, biomass growth was uniform in pore bodies along the center mixing line, while in the aggregate micromodel, preferential growth occurred between aggregates and slower less dense growth occurred throughout aggregates along the center mixing line. The homogeneous micromodel had more rapid growth overall (2 times) and more R-2,4-DP degradation (9.5%) than the aggregate pore structure (5.7%). Simulation results from a pore-scale reactive transport model indicate mass transfer limitations within aggregates along the center mixing line decreased overall reaction; hence, slower biomass growth rates relative to the homogeneous micromodel are expected. Results from this study contribute to a better understanding of the coupling between mass transfer, reaction rates, and biomass growth in complex porous media and suggest successful implementation and analysis of bioremediation systems requires knowledge of subsurface heterogeneity.
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Affiliation(s)
- Changyong Zhang
- Chemical and Materials Sciences Division, Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
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27
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Werth CJ, Zhang C, Brusseau ML, Oostrom M, Baumann T. A review of non-invasive imaging methods and applications in contaminant hydrogeology research. JOURNAL OF CONTAMINANT HYDROLOGY 2010; 113:1-24. [PMID: 20163885 PMCID: PMC3864598 DOI: 10.1016/j.jconhyd.2010.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 01/17/2010] [Accepted: 01/19/2010] [Indexed: 05/04/2023]
Abstract
Contaminant hydrogeological processes occurring in porous media are typically not amenable to direct observation. As a result, indirect measurements (e.g., contaminant breakthrough at a fixed location) are often used to infer processes occurring at different scales, locations, or times. To overcome this limitation, non-invasive imaging methods are increasingly being used in contaminant hydrogeology research. Four of the most common methods, and the subjects of this review, are optical imaging using UV or visible light, dual-energy gamma radiation, X-ray microtomography, and magnetic resonance imaging (MRI). Non-invasive imaging techniques have provided valuable insights into a variety of complex systems and processes, including porous media characterization, multiphase fluid distribution, fluid flow, solute transport and mixing, colloidal transport and deposition, and reactions. In this paper we review the theory underlying these methods, applications of these methods to contaminant hydrogeology research, and methods' advantages and disadvantages. As expected, there is no perfect method or tool for non-invasive imaging. However, optical methods generally present the least expensive and easiest options for imaging fluid distribution, solute and fluid flow, colloid transport, and reactions in artificial two-dimensional (2D) porous media. Gamma radiation methods present the best opportunity for characterization of fluid distributions in 2D at the Darcy scale. X-ray methods present the highest resolution and flexibility for three-dimensional (3D) natural porous media characterization, and 3D characterization of fluid distributions in natural porous media. And MRI presents the best option for 3D characterization of fluid distribution, fluid flow, colloid transport, and reaction in artificial porous media. Obvious deficiencies ripe for method development are the ability to image transient processes such as fluid flow and colloid transport in natural porous media in three dimensions, the ability to image many reactions of environmental interest in artificial and natural porous media, and the ability to image selected processes over a range of scales in artificial and natural porous media.
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Affiliation(s)
- Charles J Werth
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801, USA.
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28
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Englert A, Hubbard SS, Williams KH, Li L, Steefel CI. Feedbacks between hydrological heterogeneity and bioremediation induced biogeochemical transformations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:5197-5204. [PMID: 19708341 DOI: 10.1021/es803367n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
For guiding optimal design and interpretation of in situ treatments that strongly perturb subsurface systems, knowledge about the spatial and temporal patterns of mass transport and reaction intensities are important. Here, a procedure was developed and applied to time-lapse concentrations of a conservative tracer (bromide), an injected amendment (acetate) and reactive species (iron(II), uranium(VI) and sulfate) associated with two field scale biostimulation experiments, which were conducted successively at the same field location over two years. The procedure is based on a temporal moment analysis approach that relies on a streamtube approximation. The study shows that biostimulated reactions can be considerably influenced by subsurface hydrological and geochemical heterogeneities: the delivery of bromide and acetate and the intensity of the sulfate reduction is interpreted to be predominantly driven by the hydrological heterogeneity, while the intensity of the iron reduction is interpreted to be primarily controlled by the geochemical heterogeneity. The intensity of the uranium(VI) reduction appears to be impacted by both the hydrological and geochemical heterogeneity. Finally, the study documents the existence of feedbacks between hydrological heterogeneity and remediation-induced biogeochemical transformations at the field scale, particularly the development of precipitates that may cause clogging end flow rerouting.
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Affiliation(s)
- A Englert
- Earth Sciences Division, Lawrence Berkeley National Laboratory, USA.
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29
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Bauer RD, Rolle M, Bauer S, Eberhardt C, Grathwohl P, Kolditz O, Meckenstock RU, Griebler C. Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes. JOURNAL OF CONTAMINANT HYDROLOGY 2009; 105:56-68. [PMID: 19095328 DOI: 10.1016/j.jconhyd.2008.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 10/20/2008] [Accepted: 11/04/2008] [Indexed: 05/27/2023]
Abstract
In case of dissolved electron donors and acceptors, natural attenuation of organic contaminant plumes in aquifers is governed by hydrodynamic mixing and microbial activity. Main objectives of this work were (i) to determine whether aerobic and anaerobic biodegradation in porous sediments is controlled by transverse dispersion, (ii) to elucidate the effect of sediment heterogeneity on mixing and biodegradation, and (iii) to search for degradation-limiting factors. Comparative experiments were conducted in two-dimensional sediment microcosms. Aerobic toluene and later ethylbenzene degradation by Pseudomonas putida strain F1 was initially followed in a plume developing from oxic to anoxic conditions and later under steady-state mixing-controlled conditions. Competitive anaerobic degradation was then initiated by introduction of the denitrifying strain Aromatoleum aromaticum EbN1. In homogeneous sand, aerobic toluene degradation was clearly controlled by dispersive mixing. Similarly, under denitrifying conditions, microbial activity was located at the plume's fringes. Sediment heterogeneity caused flow focusing and improved the mixing of reactants. Independent from the electron accepting process, net biodegradation was always higher in the heterogeneous setting with a calculated efficiency plus of 23-100% as compared to the homogeneous setup. Flow and reactive transport model simulations were performed in order to interpret and evaluate the experimental results.
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Affiliation(s)
- Robert D Bauer
- Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Institute of Groundwater Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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30
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Bauer RD, Maloszewski P, Zhang Y, Meckenstock RU, Griebler C. Mixing-controlled biodegradation in a toluene plume--results from two-dimensional laboratory experiments. JOURNAL OF CONTAMINANT HYDROLOGY 2008; 96:150-68. [PMID: 18083271 DOI: 10.1016/j.jconhyd.2007.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 10/25/2007] [Accepted: 10/26/2007] [Indexed: 05/12/2023]
Abstract
Various abiotic and biotic processes such as sorption, dilution, and degradation are known to affect the fate of organic contaminants, such as petroleum hydrocarbons in saturated porous media. Reactive transport modeling of such plumes indicates that the biodegradation of organic pollutants is, in many cases, controlled by mixing and therefore occurs locally at the plume's fringes, where electron donors and electron-acceptors mix. Herein, we aim to test whether this hypothesis can be verified by experimental results obtained from aerobic and anaerobic degradation experiments in two-dimensional sediment microcosms. Toluene was selected as a model compound for oxidizable contaminants. The two-dimensional microcosm was filled with quartz sand and operated under controlled flow conditions simulating a contaminant plume in otherwise uncontaminated groundwater. Aerobic degradation of toluene by Pseudomonas putida mt-2 reduced a continuous 8.7 mg L(-1) toluene concentration by 35% over a transport distance of 78 cm in 15.5 h. In comparison, under similar conditions Aromatoleum aromaticum strain EbN1 degraded 98% of the toluene infiltrated using nitrate (68.5+/-6.2 mg L(-1)) as electron acceptor. A major part of the biodegradation activity was located at the plume fringes and the slope of the electron-acceptor gradient was steeper during periods of active biodegradation. The distribution of toluene and the significant overlap of nitrate at the plume's fringe indicate that biokinetic and/or microscale transport processes may constitute additional limiting factors. Experimental data is corroborated with results from a reactive transport model using double Monod kinetics. The outcome of the study shows that in order to simulate degradation in contaminant plumes, detailed data sets are required to test the applicability of models. These will have to deal with the incorporation of existing parameters coding for substrate conversion kinetics and microbial growth.
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Affiliation(s)
- Robert D Bauer
- Helmholtz Center Munich, German Research Center for Environmental Health, Institute of Groundwater Ecology, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
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Vogt C, Gödeke S, Treutler HC, Weiss H, Schirmer M, Richnow HH. Benzene oxidation under sulfate-reducing conditions in columns simulating in situ conditions. Biodegradation 2006; 18:625-36. [PMID: 17160546 DOI: 10.1007/s10532-006-9095-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
The oxidation of benzene under sulfate-reducing conditions was examined in column and batch experiments under close to in situ conditions. Mass balances and degradation rates for benzene oxidation were determined in four sand and four lava granules filled columns percolated with groundwater from an anoxic benzene-contaminated aquifer. The stoichiometry of oxidized benzene, produced hydrogen carbonate and reduced sulfate correlated well with the theoretical equation for mineralization of benzene with sulfate as electron acceptor. Mean retention times of water in four columns were determined using radon ((222)Rn) as tracer. The retention times were used to calculate average benzene oxidation rates of 8-36 microM benzene day(-1). Benzene-degrading, sulfide-producing microcosms were successfully established from sand material of all sand filled columns, strongly indicating that the columns were colonized by anoxic benzene-degrading microorganisms. In general, these data indicate a high potential for Natural Attenuation of benzene under sulfate-reducing conditions at the field site Zeitz. In spite of this existing potential to degrade benzene with sulfate as electron acceptor, the benzene plume at the field site is much longer than expected if benzene would be degraded at the rates observed in the column experiment, indicating that benzene oxidation under sulfate-reducing conditions is limited in situ.
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Affiliation(s)
- Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.
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Maier U, Grathwohl P. Numerical experiments and field results on the size of steady state plumes. JOURNAL OF CONTAMINANT HYDROLOGY 2006; 85:33-52. [PMID: 16500721 DOI: 10.1016/j.jconhyd.2005.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 12/06/2005] [Accepted: 12/20/2005] [Indexed: 05/06/2023]
Abstract
Contaminated groundwater poses a serious risk for drinking water supplies. Under certain conditions, however, groundwater contamination remains restricted to a tolerable extent because of natural attenuation processes. We present an innovative approach to evaluate the size of these so-called steady-state plumes by 2-D and 1-D modelling in homogeneous aquifers. If longitudinal mixing is negligible, scenarios can be modelled in a simplified way using a 1-D domain vertical to the direction of flow. We analysed the sensitivity of the plume length with respect to biodegradation kinetics, flow velocity, transverse vertical dispersivity alphat, the source and aquifer geometry and reaction stoichiometry. Our findings indicate that for many readily biodegradable compounds transverse-dispersive mixing rather than reaction kinetics is the limiting factor for natural attenuation. Therefore, if alphat, aquifer and source geometry and concentrations of electron acceptors and donors are known, the length of the steady state contaminant plume can be predicted. The approach is validated under field conditions for an ammonium plume at a former landfill site in SW Germany.
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Affiliation(s)
- U Maier
- University of Tübingen, Center for Applied Geoscience, Sigwartstr. 10, 72076 Tübingen, Germany.
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Cirpka OA, Olsson A, Ju Q, Rahman MA, Grathwohl P. Determination of transverse dispersion coefficients from reactive plume lengths. GROUND WATER 2006; 44:212-21. [PMID: 16556203 DOI: 10.1111/j.1745-6584.2005.00124.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
With most existing methods, transverse dispersion coefficients are difficult to determine. We present a new, simple, and robust approach based on steady-state transport of a reacting agent, introduced over a certain height into the porous medium of interest. The agent reacts with compounds in the ambient water. In our application, we use an alkaline solution injected into acidic ambient water. Threshold values of pH are visualized by adding standard pH indicators. Since aqueous-phase acid-base reactions can be considered practically instantaneous and the only process leading to mixing of the reactants is transverse dispersion, the length of the plume is controlled by the ratio of transverse dispersion to advection. We use existing closed-form expressions for multidimensional steady-state transport of conservative compounds in order to evaluate the concentration distributions of the reacting compounds. Based on these results, we derive an easy-to-use expression for the length of the reactive plume; it is proportional to the injection height squared, times the velocity, and inversely proportional to the transverse dispersion coefficient. Solving this expression for the transverse dispersion coefficient, we can estimate its value from the length of the alkaline plume. We apply the method to two experimental setups of different dimension. The computed transverse dispersion coefficients are rather small. We conclude that at slow but realistic ground water velocities, the contribution of effective molecular diffusion to transverse dispersion cannot be neglected. This results in plume lengths that increase with increasing velocity.
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Affiliation(s)
- Olaf A Cirpka
- Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Uberlandstr. 133, CH-8600 Dübendorf, Switzerland.
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Arnon S, Ronen Z, Adar E, Yakirevich A, Nativ R. Two-dimensional distribution of microbial activity and flow patterns within naturally fractured chalk. JOURNAL OF CONTAMINANT HYDROLOGY 2005; 79:165-86. [PMID: 16099071 DOI: 10.1016/j.jconhyd.2005.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 06/16/2005] [Accepted: 06/17/2005] [Indexed: 05/04/2023]
Abstract
The two-dimensional distribution of flow patterns and their dynamic change due to microbial activity were investigated in naturally fractured chalk cores. Long-term biodegradation experiments were conducted in two cores ( approximately 20 cm diameter, 31 and 44 cm long), intersected by a natural fracture. 2,4,6-tribromophenol (TBP) was used as a model contaminant and as the sole carbon source for aerobic microbial activity. The transmissivity of the fractures was continuously reduced due to biomass accumulation in the fracture concurrent with TBP biodegradation. From multi-tracer experiments conducted prior to and following the microbial activity, it was found that biomass accumulation causes redistribution of the preferential flow channels. Zones of slow flow near the fracture inlet were clogged, thus further diverting the flow through zones of fast flow, which were also partially clogged. Quantitative evaluation of biodegradation and bacterial counts supported the results of the multi-tracer tests, indicating that most of the bacterial activity occurs close to the inlet. The changing flow patterns, which control the nutrient supply, resulted in variations in the concentrations of the chemical constituents (TBP, bromide and oxygen), used as indicators of biodegradation.
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Affiliation(s)
- Shai Arnon
- Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer Campus 84990, Israel.
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35
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Cirpka OA. Effects of sorption on transverse mixing in transient flows. JOURNAL OF CONTAMINANT HYDROLOGY 2005; 78:207-29. [PMID: 16006008 DOI: 10.1016/j.jconhyd.2005.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 03/18/2005] [Accepted: 05/04/2005] [Indexed: 05/03/2023]
Abstract
Transverse mixing has been identified as a potentially limiting factor for natural attenuation of plumes originating from continuously emitting sources. Under steady-state flow conditions, dispersion is the only process leading to lateral mixing. This process is very slow and cannot explain the lateral spread of plumes observed in the field. When the flow direction fluctuates with time, transverse dispersion is slightly enhanced, but not very pronounced. Under these flow conditions, however, sorption can contribute to mixing into the mean transverse direction. If the reacting compounds differ in their strength of sorption, chromatographic mixing and separation alternate in time-periodic flows. For instantaneous sorption, the plumes may overlap within a stripe of fixed width. In contrast to sorption in local equilibrium, kinetic sorption contributes to mixing also for compounds with identical sorption strength. I derive an analytical expression for the equivalent transverse dispersion coefficient of a kinetically sorbing compound in a spatially uniform flow field undergoing sinusoidal fluctuations in time. This expression may be used for reactive transport calculations in an equivalent domain with constant flow. The effects are the strongest for compounds with a dimensionless partitioning coefficient of about unity, slow sorption kinetics, and slowly fluctuating velocities. For realistic parameters, kinetic sorption contributes to transverse mixing in the same range as heterogeneity.
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Affiliation(s)
- Olaf A Cirpka
- Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Uberlandstr. 133, CH-8600 Dübendorf, Switzerland.
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Arnon S, Adar E, Ronen Z, Yakirevich A, Nativ R. Impact of microbial activity on the hydraulic properties of fractured chalk. JOURNAL OF CONTAMINANT HYDROLOGY 2005; 76:315-336. [PMID: 15683886 DOI: 10.1016/j.jconhyd.2004.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2004] [Revised: 11/15/2004] [Accepted: 11/26/2004] [Indexed: 05/24/2023]
Abstract
The impact of microbial activity on fractured chalk transmissivity was investigated on a laboratory scale. Long-term experiments were conducted on six fractured chalk cores (20 cm diameter, 23-44 cm long) containing a single natural fracture embedded in a porous matrix. Biodegradation experiments were conducted under various conditions, including several substrate and oxygen concentrations and flow rates. 2,4,6-Tribromophenol (TBP) was used as a model contaminant (substrate). TBP biodegradation efficiency depended mainly on the amount of oxygen. However, under constant oxygen concentration at the core inlet, elevating the flow rates increased the removal rate of TBP. Transmissivity reduction was clearly related to TBP removal rate, following an initial slow decline and a further sharp decrease with time. The fracture's transmissivity was reduced by as much as 97% relative to the initial value, with no leveling off of the clogging process. For the most extreme cases, reductions of 262 and 157 microm in the equivalent hydraulic apertures were recorded for fractures with initial apertures of 495 and 207 microm, respectively. The reductions in fracture transmissivity occurred primarily because of clogging by bacterial cells and extracellular polymeric substances (EPS) produced by the bacteria. Most of the biodegradation activity was concentrated near the fracture inlet, where the most suitable biodegradation conditions (nutrients and oxygen) prevailed, suggesting that the clogging had occurred in that vicinity. The clogging must have changed the structure of the fracture void, thereby reducing the active volume participating in flow and transport processes. This phenomenon caused accelerated transport of non-reactive tracers and doubled the fracture's dispersivity under constant flow rates.
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Affiliation(s)
- Shai Arnon
- Department of Environmental Hydrology & Microbiology, Zuckerberg Institute for Water Research, J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer 84990, Israel.
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Thullner M, Schroth MH, Zeyer J, Kinzelbach W. Modeling of a microbial growth experiment with bioclogging in a two-dimensional saturated porous media flow field. JOURNAL OF CONTAMINANT HYDROLOGY 2004; 70:37-62. [PMID: 15068868 DOI: 10.1016/j.jconhyd.2003.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2002] [Accepted: 08/19/2003] [Indexed: 05/24/2023]
Abstract
A model was developed simulating reactive transport in groundwater including bioclogging. Results from a bioclogging experiment in a flow cell with a two-dimensional flow field were used as a data base to verify the simulation results of the model. Simulations were performed using three different hydraulic conductivity vs. porosity relations published in literature; two relations derived from pore network simulations assuming the biomass to grow in discrete colonies and as a biofilm, respectively, and a third relation, which did not include pore connectivity in more than one dimension. Best agreement with the experimental data was achieved using a hydraulic conductivity vs. porosity relation derived from pore network simulation assuming the biomass to grow in colonies. The relation derived from pore network simulations assuming biomass to grow as a biofilm was unable to reproduce the experimental data when realistic parameter values were employed. With the third relation the clogging ability of the biomass was strongly underestimated. These findings indicate that the porous medium needs to be treated as a multi-dimensional medium already on the pore scale, and that biomass growth different than in a biofilm must be considered to get an appropriate description of bioclogging.
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Affiliation(s)
- Martin Thullner
- Institute of Terrestrial Ecology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
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Dunsmore BC, Bass CJ, Lappin-Scott HM. A novel approach to investigate biofilm accumulation and bacterial transport in porous matrices. Environ Microbiol 2003; 6:183-7. [PMID: 14756882 DOI: 10.1046/j.1462-2920.2003.00546.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Knowledge of bacterial transport through, and biofilm growth in, porous media is vitally important in numerous natural and engineered environments. Despite this, porous media systems are generally oversimplified and the local complexity of cell transport, biofilm formation and the effect of biofilm accumulation on flow patterns is lost. In this study, cells of the sulphate-reducing bacterium, Desulfovibrio sp. EX265, accumulated primarily on the leading faces of obstructions and developed into biofilm, which grew to narrow and block pore throats (at a rate of 12 micro m h(-1) in one instance). This pore blocking corresponded to a decrease in permeability from 9.9 to 4.9 Darcy. Biofilm processes were observed in detail and quantitative data were used to describe the rate of biofilm accumulation temporally and spatially. Accumulation in the inlet zone of the micromodel was 10% higher than in the outlet zone and a mean biofilm height of 28.4 micro m was measured in a micromodel with an average pore height of 34.9 microm. Backflow (flow reversal) of fluid was implemented on micromodels blocked with biofilm growth. Although biofilm surface area cover did immediately decrease (approximately 5%), the biofilm quickly re-established and permeability was not significantly affected (9.4 Darcy). These results demonstrate that the glass micromodel used here is an effective tool for in situ analysis and quantification of bacteria in porous media.
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Affiliation(s)
- Braden C Dunsmore
- Oil Plus Ltd, Hambridge Road, Newbury, Berkshire, RG14 5TR, UK. B.Dunsmore@oilplus
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Nambi IM, Werth CJ, Sanford RA, Valocchi AJ. Pore-scale analysis of anaerobic halorespiring bacterial growth along the transverse mixing zone of an etched silicon pore network. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2003; 37:5617-5624. [PMID: 14717172 DOI: 10.1021/es034271w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The anaerobic halorespiring microorganism, Sulfurospirillum multivorans, was observed in the pore structure of an etched silicon wafer to determine how flow hydrodynamics and mass transfer limitations along a transverse mixing zone affect biomass growth. Tetrachloroethene (PCE, an electron acceptor, 0.2 mM) and lactate (an electron donor, 2 mM) were introduced as two separate and parallel streams that mixed along a reaction line in the pore structure. The first visible biomass occupied a single line of pores in the direction of flow, a few pore bodies from the micromodel centerline. This growth was initially present as small aggregates; over time, these grew and fused to form finger-like structures with one end attached to downgradient ends of the silicon posts and the other end extending into pore bodies in the direction of flow. Biomass did not grow in pore throats as expected, presumably because shear forces were not favorable. Over the next few weeks, the line of growth migrated upward into the PCE zone and extended over a width of up to five pore spaces. When the PCE concentration was increased to 0.5 mM, the microbial biomass increased and growth migrated down toward the lactate side of the micromodel. A new analytical model was developed and used to demonstrate that transverse hydrodynamic dispersion likely caused the biomass to move in the direction observed when the PCE concentration was changed. The model was unable, however, to explain why growth migrated upward when the PCE concentration was initially constant. We postulate that this occurred because PCE, not lactate, sorbed to biofilm components and that biomass on the lactate side of the micromodel was limited in PCE. A fluorescent tracer experiment showed that biomass growth changed the water flow paths, creating a higher velocity zone in the PCE half of the micromodel. These results contribute to our understanding of biofilm growth and will help in the development of new models to describe this complex process.
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Affiliation(s)
- Indumathi M Nambi
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, USA
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