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. "
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. "
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."
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."
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.
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.
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.
Non-expert summaryAn important part of hygienic design is knowledge of the forces imposed on a surface by the flow of a process liquid, and whether those forces are large enough to remove any contaminants. This is a chiefly experimental study investigating the numbers of adhering Bacillus cereus spores before and after cleaning in place of part of a dairy processing line. Non-intrusive flow characterization, of local wall shear stress and velocity profiles, were measured using electrochemical and ultrasonic Doppler velocimetry techniques. The geometries studied inlcuded gradual asymmetric pipe contractions and pipe expansions and bends. The recirculation zone resulting from the flow detachment after the expansion resulted in a large number of adherent spores downstream of this geometrical change. Welding and gasket regions also retained spores, proving difficult to clean despite high-shear stress forces involved. The flow measurements are compared with some theory so the level of modelling is not high but the data sets present important cases for new investigations, e.g. using CFD methods.