Knowledge Base

Found 51 Results

Miscellaneous

Waste Estimation Support Tool (WEST)

US Environment Protection Agency

2021

DisciplinesMicrobiology, Statistics & Probabilities

Scale1 to 10 m, 10 to 1000 m, greater than 1 km / 1 to 60 min, 1 to 24 hours, 1 to 30 days, 1 to 12 months, greater than 1 year

Non-expert summaryThe US Environment Protection Agency (EPA) has generated a number of management tools related to cleaning and decontamination. The EPA website states that "Management of waste from a radiological dispersal device (RDD) incident would likely constitute a large part of the remediation cost and effort. The U.S. EPA’s RDD Waste Estimation Support Tool (WEST) is a planning tool for estimating the potential volume and radioactivity levels of waste generated by a radiological incident and subsequent decontamination efforts. WEST supports decision makers by generating a first-order estimate of the quantity and characteristics of waste resulting from a radiological incident, and allows the user to evaluate various decontamination/demolition strategies to examine the impact of those strategies on waste generation. "

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Technical report

Bio-Response Operational Testing and Evaluation (BOTE) Project – Phase 1: Decontamination Assessment

US Environment Protection Agency

2013

Institution / OrganisationUS Environment Protection Agency

Keywordsbacteria, cleaning, decontamination

DisciplinesMicrobiology

CategoryField work

Scale1 to 10 m, 10 to 1000 m, greater than 1 km / 1 to 60 min, 1 to 24 hours, 1 to 30 days, 1 to 12 months, greater than 1 year

Non-expert summaryThe US Environment Protection Agency led a multi-agency investigation into the response to a release of a biological agent. The report summary states "The Bio-response Operational Testing and Evaluation (BOTE) Project was a multi-agency effort designed to operationally test and evaluate a response to a biological incident (release of Bacillus anthracis spores, the causative agent for anthrax) from initial public health and law enforcement response through environmental remediation. The BOTE Project consisted of two distinct phases, both using the same non-pathogenic simulant (or surrogate) for these spores. Phase 1 was a field-level decontamination assessment, and Phase 2 was an operational exercise involving key federal agencies responsible for the forensic investigation, public health assessment, and remediation following a biological incident. Phase 1 was designed to address site remediation after the release of a simulant within a facility in an operational setting, drawing upon the recent advances in both biological sampling and decontamination. "

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Technical report

Tabletop exercise report – Sample plan development for biological incidents, large and small – Trade-Off Tool for Sampling (TOTS)

Calfee, W., Boe, T., Mickelsen, L., Johnson, C., James, R.

2020

Institution / OrganisationUS Environment Protection Agency

Keywordsbacteria, cleaning, decontamination

DisciplinesMicrobiology

CategoryReview

Scale1e-3 to 1 m, 1 to 10 m, 10 to 1000 m, greater than 1 km / 1 to 60 min, 1 to 24 hours, 1 to 30 days, 1 to 12 months, greater than 1 year

Non-expert summaryThe Report Executive Summary states: "The Trade-off Tool for Sampling (TOTS) is a tool under development that aids planners, responders, and subject matter experts in developing defensible yet practicable sample collection plans following a biological contamination incident. The U.S. Environmental Protection Agency (EPA) held a table-top exercise (TTX) with two separate groups of people. The purpose of the TTX was to gather critical end-user feedback on the utility of the tool for future revisions of TOTS and to increase collective (responders, planners, and researchers) understanding of challenges during the sampling and analysis plan (SAP) development for biological incidents, all for the goal of strengthening EPA’s capabilities in this area. The first TTX session was held at the 2019 EPA International Decontamination Conference in Norfolk, Virginia (November 18, 2019), and the second TTX session was held at the EPA On-scene Coordinator (OSC) Academy in Chicago, Illinois (February 26, 2020). The ultimate goal is to provide EPA planners and operational personnel (e.g., on-scene coordinators) the tools and resources necessary to effectively and efficiently plan and execute EPA’s response obligations."

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Technical report

A Review of biological agent sampling methods and application to a wide-area incident scenario to characterize time and resource demands

Calfee, W., Lee, S., Boe, T.

2017

Institution / OrganisationUS Environment Protection Agency

Keywordsbacteria, cleaning, decontamination, risk

DisciplinesMicrobiology

CategoriesField work, Review

Scale1e-3 to 1 m, 1 to 10 m, 10 to 1000 m, greater than 1 km / 1 to 60 s, 1 to 60 min, 1 to 24 hours, 1 to 30 days, 1 to 12 months, greater than 1 year

Non-expert summaryThe executive summary of this US EPA report states: "A large-scale aerosol release of a persistent, disease-causing biological agent can result in contamination of a wide area, and may require significant time and resources for recovery depending on the severity of adverse health effects on the exposed population(s). Many unknowns are associated with characterization and clearance sampling during response to a wide-area (including indoor, outdoor, and underground area) biological incident. The biological agent and its characteristics, the release mechanism, amount of contaminant released, and a plethora of environmental and meteorological factors are completely separate, yet interconnected processes that greatly influence the extent and level of contamination. Similarly, decisions related to the sampling strategy (i.e., sample medium, sampling area, spacing, etc.) will affect the cost, time, amount of waste generated, and personnel (i.e., resource demand) required to characterize and clear the contaminated area. The process of understanding how these elements influence one another and contribute to the overall problem is referred to as a systems approach. To what degree sampling and, more specifically, variations in the sampling strategy interact and contribute to overall resource demand, following a wide area biological incident, is still largely unknown. To date, there have been no attempts to model characterization sampling following a wide-area biological incident."

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Modeling of Biofilm Systems: A Review

Horn, H., Lackner, S.

2014Productive Biofilms14653-76

Editor(s)Muffler, K., Ulber, R.

PublisherSpringer

Keywordsbacteria, biofilm

DisciplinesMicrobiology

CategoryReview

Scale1e-6 m, 1e-6 to 1e-3 m

Non-expert summaryThis book chapter is a review of biofilm dynamics, modelling and simulation. The modeling of biochemical processes in biofilms is more complex compared to those in suspended biomass due to the existence of substrate gradients. The review traces the development of modelling approaches from 1-D mass transfer and removal mechanisms to 2D and 3D descriptions including more levels of physical insight.

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Article

A three-dimensional computer model analysis of three hypothetical biofilm detachment mechanisms

Chambless, J.D., Stewart, P.S.

2007Biotechnology and Bioengineering97(6)1573-1584

Keywordsbacteria, biofilm, cleaning, detachment, flow displacement, shear flow

DisciplinesChemical Engineering, Microbiology

CategoryNumerical simulations

Scale1e-6 m, 1e-6 to 1e-3 m, 1e-3 m / 1e-3 to 1 s, 1 to 60 s, 1 to 60 min

Non-expert summaryThe removal of biofilms by sloughing is a natural phenomenon in biofilm dynamics. Three hypothetical mechanisms of detachment were incorporated into a 3D model of biofilm development. The model integrated processes of substrate utilization, substrate diffusion, growth, cell advection, and detachment in a cellular automata framework. The three detachment mechanisms analyzed represented various physical and biological influences hypothesized to affect biofilm detachment; fluid shear removing protruding material; removal linked to local nutrient availability; and erosion. The detachment mechanisms demonstrated diverse behaviors with respect to the four analysis criteria. The results show that detachment is a critical determinant of biofilm structure and of the dynamics of biofilm accumulation and loss.

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Article

A general description of detachment for multidimensional modelling of biofilms

Xavier, J. de B., Picioreanu, C., van Loosdrecht, M.C.M.

2005Biotechnology and Bioengineering91(6)651-669

Keywordsbacteria, biofilm, cleaning, detachment, erosion, shear flow

DisciplinesChemical Engineering, Microbiology

CategoryNumerical simulations

Scale1e-6 m, 1e-6 to 1e-3 m, 1e-3 m / 1e-3 to 1 s, 1 to 60 s, 1 to 60 min

Non-expert summaryThe structure of many biofilms results in a surface layer which does not detach readily and a growing layer that detaches (sloughs) off more readily. The authors present a general method for describing biomass detachment in a multidimensional biofilm modelling framework. Biomass losses from processes acting on the entire surface of the biofilm, such as erosion, are modelled, and discrete detachment events, i.e. sloughing, are implicitly derived from the simulations. This methodology for biomass detachment was integrated with multidimensional (2D and 3D) particle-based multispecies biofilm models by using the level set method. Application of the method is demonstrated by looking at the trends in biofilm structure and activity over time in two case studies: I - a simple model considering uniform biomass; II - a model discriminating biomass composition in heterotrophic active mass, extracellular polymeric substances (EPS) and inert mass.

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Review article

Instabilities in blistering

Juel, A., Pihler-Puzović, D., Heil, M.

2018Annual Review of Fluid Mechanics50691-714

Keywordscavity flow, decontamination, elasticity theory, fingering instabilities, flow displacement, flow-structure interaction, Hele-Shaw flows, interfacial dynamics, lubrication theory, pattern formation

DisciplinesFluid Mechanics, Physics

CategoryReview

Scale1e-9 to 1e-6 m, 1e-6 m, 1e-6 to 1e-3 m / 1e-3 to 1 s, 1 to 60 s

Non-expert summaryThis is a review of the fluid mechanics associated with blistering, which occurs when a thin solid layer locally separates from an underlying substrate through cracking of a bulk material, delamination of a composite material, or peeling of a thin layer (membrane) adhered to the substrate by a thin layer of viscous fluid. The focus of the review is on the latter case, where the expansion of the newly formed blister by fluid injection occurs via a displacement flow, which peels the adhered surfaces apart through a two-way interaction between flow and deformation. These blisters are prone to fluid- and solid-mechanical instabilities. If the injected fluid is less viscous than the fluid already occupying the gap, patterns of short and stubby fingers (fingering) form on the propagating fluid interface. Buckling/wrinkling instabilities of the delaminated layer can arise for sufficiently thin membranes and can interact with the fluid mechanical fingering instability.

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Article

Three-dimensional advective–diffusive boundary layers in open channels with parallel and inclined walls

Etzold, M.A., Landel, J.R., Dalziel, S.B.

2020International Journal of Heat and Mass Transfer153119504

Keywordscleaning, decontamination, drop, heat transfer, mass transfer, narrow channel

DisciplinesChemical Engineering, Fluid Mechanics

CategoriesNumerical simulations, Theoretical modelling

Scale1e-6 to 1e-3 m, 1e-3 m, 1e-3 to 1 m / 1e-3 to 1 s, 1 to 60 s, 1 to 60 min, 1 to 24 hours

Non-expert summaryThe authors consider the steady laminar advective transport of a diffusive component released at the base of a narrow three-dimensional longitudinal open channel with non-absorbing side walls and rectangular or truncated-wedge-shaped cross-sections: the findings are relevant to heat and mass transfer applications in confined U-shaped or V-shaped channels (or trenches) such as might arise in the decontamination and cleaning of narrow gaps, crevices and boundary features on walls or other surfaces, and well as transport processes in chemical or biological microfluidic devices. The fluid flows along the channel in the laminar regime and there is no flux or slip on the side walls. Numerical simulations are conducted for various duct shapes and the rate of mass transfer from the base is calculated: this is used to evaluate the dimensionless mass transfer coefficient, the Sherwood number. The results for 3-D (constant cross section, long in the direction of flow) are compared favourably with results for a simplified, 2-D, calculation.

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Article

Modelling mass casualty decontamination systems informed by field exercise data

Egan, J.R., Amlôt, R.

2012International Journal of Environmental Research and Public Health93685-3710

Keywordschemical warfare agent simulant, decontamination, emergency response, people

DisciplinesStatistics & Probabilities

CategoriesField work, Numerical simulations

Scale1 to 10 m, 10 to 1000 m, greater than 1 km / 1 to 24 hours, 1 to 30 days

Non-expert summaryThe management of decontamination of the population (who were mobile enough to walk through a showering lane) in the event of a large-scale chemical release in the UK was modelled, based on data collected in field trials. The movement of volunteer casualties at two mass decontamination field exercises was monitored using passive Radio Frequency Identification tags and detection mats. The data were used to inform a computer model of the UK fire and rescue service component of the mass decontamination process. This identified bottlenecks in the process and led to recommendations for change, particularly in the re-dressing part of the process.

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Article

Pressure-driven miscible two-fluid channel flow with density gradients

Sahu, K.C., Ding, H., Valluri, P., Matar, O.K.

2009Physics of Fluids21043603

Keywordscleaning, flow displacement, hydrodynamics, miscible liquids, multiphase flow

DisciplinesChemical Engineering, Fluid Mechanics

CategoryNumerical simulations

Non-expert summaryThe displacement of one liquid by another in a channel of constant height occurs in flushing and cleaning operations. The authors study the effect of buoyancy (arising from different fluid densities) on a pressure-driven flow of two miscible fluids in inclined channels using direct numerical simulations DNS). The flow dynamics are governed by the continuity and Navier–Stokes equations, without the Boussinesq approximation for buoyancy, coupled to a convective-diffusion equation for mass transfer between the two liquids. The effect of concentration on viscosity and density is modelled. The effect of varying the density ratio, Froude number, and channel inclination on the flow dynamics is examined, for moderate Reynolds numbers. These detailed simulations give insights into mixing and cleaning behaviour.

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Article

Linear stability analysis and numerical simulation of miscible two-layer channel flow

Sahu, K.C., Ding, H., Valluri, P., Matar, O.K.

2009Physics of Fluids21042104

Keywordscleaning, flow displacement, interfacial dynamics, linear stability analysis, miscible liquids, multiphase flow

DisciplinesChemical Engineering, Fluid Mechanics

CategoriesNumerical simulations, Theoretical modelling

Non-expert summaryWhen one liquid is pumped into a channel containing a second liquid, the behaviour depends on the properties of the two fluids and pressure driving force. This paper considers the stability of a flow of two miscible fluids in a horizontal channel. The flow dynamics are governed by the continuity and Navier–Stokes equations, with mass transfer between the two. An analysis of the flow in the linear regime delineates the presence of convective and absolute instabilities, and shows that vertical gradients of viscosity perturbations (caused by mixing) are the main destabilizing influence of the interface (in agreement with previous work). Previous work in the area is reviewed as well. Transient numerical simulations demonstrate the development of complex dynamics in the nonlinear regime, characterized by roll-up phenomena and intense convective mixing.

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