Browsing by Author "Drew, Gill H."

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    Bioaerosol emissions from open windrow composting facilities : emission characterisation and dispersion modelling improvements
    (Cranfield University, 2013-06) Douglas, Philippa; Drew, Gill H.; Tyrrel, Sean
    Bioaerosol emissions from open windrow composting facilities are becoming of increasing concern due to the negative health effects associated with bioaerosols, and the fact that emissions from open windrow facilities are not contained. Current bioaerosol monitoring techniques provide only a snapshot of bioaerosol concentrations spatially and temporally, whereas dispersion models have the potential to offer a more continual overview of bioaerosol levels, alongside existing sampling methods. However, dispersion models have not been successful at accurately predicting bioaerosol concentrations from open windrow composting facilities, generally under predicting concentrations by at least one order of magnitude. This is predominantly due to a lack of knowledge and data surrounding the complex nature of bioaerosol release and transportation, particularly when the compost is agitated. This study aimed to improve the reliability in the outputs of the ADMS dispersion model, specifically in the open windrow composting scenario, by performing several model tests alongside selected input parameter quantification improvements. This involved completing a sensitivity analysis, and a model calibration and validation specific to this scenario for the first time. Results from the sensitivity analysis showed that the use of wet and dry deposition modules is significant, and the majority of model inputs associated with the representation of the source of the emission are sensitive. These findings helped select the model input parameters for quantification improvements. Novel preliminary measurements of bioaerosol temperature, velocity and concentration at the source of composting agitation activities were completed. These values provided more accurate model inputs. Collectively, these results allowed the model to be successfully calibrated, and consequently, validated for the first time for this specific scenario, resulting in model outputs corresponding to within one order of magnitude to measured data. This has helped to generate an initial set of modelling recommendations, allowing modellers to use the ADMS dispersion model in a reliable manner, when applied to the open windrow composting scenario. Eventually, these improved model outputs may be used to predict bioaerosol exposure levels at sensitive receptors, particularly in conditions where current monitoring methods are not feasible.
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    Characterisation and disersal of bioaerosols emitted from composting facilities
    (Cranfield University, 2009-07) Tamer Vestlund, Asli; Tyrrel, Sean; Drew, Gill H.
    The role of sustainable and natural waste management processes such as composting are increasingly becoming more important in tackling the current environmental challenge of the amount of waste that is being produced. However a potential risk of composting facilities is the release and dispersal of bioaerosols that might result in adverse health effects in sensitive receptors. Therefore, environmental regulators request regulatory risk assessments from composting facilities that are within 250m of sensitive receptors to assess the risk posed by bioaerosols. The prior art in compost related bioaerosol release and dispersal assessment is not extensive and gaps in the understanding of bioaerosols at source, on release from composting facilities and at receptor remain. Therefore, this research was undertaken to address some of these gaps in the current knowledge and to improve the understanding of the characterisation and dispersal of bioaerosols emitted from compost. Therefore firstly two studies were completed in regards to the characterisation of bioaerosols emitted from compost, in particular in improving the understanding of their aggregation and size distribution. In this context, a novel methodology (the compost tumbler) was developed to release and measure bioaerosols in experimental conditions. Data was generated using a combination of culturing and scanning electron microscopy methods to characterise the aggregation and size distribution of bioaerosols emitted from compost. Secondly, site work was conducted to validate the results of these controlled experiments and characterise the aggregation and size distribution of bioaerosols emitted from composting facilities. These controlled experiments and site work showed evidence of aggregation in bioaerosols released from compost. However, the majority of these bioaerosols were in single cell units hence they are more likely to be dispersed for longer distances. Following this, other studies were conducted in regards to the dispersal of bioaerosols emitted from compost, in particular in improving the understanding of bioaerosol concentration prediction by air dispersion modelling. Firstly preliminary air dispersion modelling was completed to assess the ability of a commercial air dispersion model,ADMS 3.3, to predict bioaerosol emissions from composting facilities compared to bioaerosol concentrations measured by on-site downwind bioaerosol sampling. Folowing this, the sensitivities of ADMS 3.3 were analysed and the effect of different modelling parameters on predicted bioaerosol concentrations were assessed. Finally, a final assessment of the potential of ADMS 3.3 to predict bioaerosol emissions from composting facilities was conducted. The overall results from the modelling studies indicated that ADMS 3.3 was not able to consistently predict absolute downwind bioaerosol concentrations at composting facilities. However it was also concluded that ADMS 3.3 can be a useful tool for the initial screening and assessing relative changes of bioaerosols at a compost facility, provided that the detailed assessment of absolute bioaerosol emissions are made in conjunction with measurement of downwind bioaerosol concentrations. The research presented in this thesis makes a significant contribution to knowledge in terms of improving the understanding of the characterisation and dispersal of bioaerosols emitted from composting facilities.
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    The Effect of Green Waste Composting on the Concentration and Composition of Ambient Bioaerosols
    (Cranfield University, 2010-01) Pankhurst, Louise J.; Tyrrel, Sean; Drew, Gill H.
    The emission and dispersal of bioaerosols from commercial composting facilities has become an issue of increasing concern over the past decade, as historical evidence links bioaerosol exposure to negative human health impacts. As a result, recommended concentrations and risk assessment limits were imposed in 2001. However, more recent research has suggested that these limits may be exceeded under certain circumstances. For example, underestimation of bioaerosol concentrations may occur through „snapshot‟ sampling, and the use of methods that may reduce culturability of bioaerosols. This study aimed to address several gaps in knowledge, including quantification of bioaerosol concentrations downwind from sites, analysis of the effect that operational and environmental influences have on emission and downwind concentrations, and investigation of methods for the enumeration of non-culturable bioaerosols. The concentrations of bioaerosols upwind, on-site and downwind from two open-air green waste windrow composting facilities were enumerated in extensive detail, producing the first detailed and validated database of bioaerosol concentrations at green-waste composting facilities. The effects of composting processing activities, season, and meteorological conditions on concentrations were also investigated utilising this dataset. Results from these studies suggested that bioaerosols are able to disperse in elevated concentrations to distances beyond the 250 m risk assessment limit. Downwind peaks in concentration were directly linked to compost processing activities on-site, with the risk of sensitive receptor exposure to bioaerosols during non-operational hours minimal. Further, it was found that patterns in downwind concentrations of bioaerosols are likely to be governed by buoyancy effects, as a second peak in concentrations was found at 100-150m downwind. This finding was further supported through the use of a novel direct counting method. Finally, molecular methods allowed the composition of bioaerosols emitted from composting to be determined and showed that composting significantly alters the aerobiotic community at distances downwind. The methods investigated provide the potential for detailed, continuous measurements of bioaerosols, alongside identification of potentially pathogenic microorganisms, and could ultimately lead to source apportionment of bioaerosols.
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    Evaluation of a novel biosensor for bioaerosol sampling and modelling.
    (2018-10) Jawad, Mohanad Abdulameer; Drew, Gill H.; Tyrrel, Sean
    The identification and quantification of bioaerosols in the atmosphere is a significant subject of study. Bioaerosols emitted from composting sites are released directly to the atmosphere, which can be potentially harmful to human health. Although there are several studies undertaken to improve the risk assessment of bioaerosols from composting facilities, this subject still requires further research. Some studies focused on the direct detection of bioaerosol from the composting facilities, and the others focused on the dispersion modelling of bioaerosol. In both cases, the bioaerosol data detected in the direct measurement or the data used in the modelling were dependant on traditional sampling techniques. These techniques provide limited details about the bioaerosol emitted from the composting facilities. These traditional data provide spatial and temporal snapshots of bioaerosol emissions concentrations, and these concentrations represented particular components of bioaerosol. The SIBS (Spectral Intensity Bioaerosol Sensor) is a new sampling device and can provide significant data about bioaerosols, as it can sample continuously over long periods. These advantages made the SIBS able to provide an important picture of the variation of bioaerosol concentrations with time. Several sampling experiments have been done in different environments to measure the bioaerosol concentrations using the SIBS alongside the filtration sampling technique (IOM/SKC). The collected data from the composting site showed the advantages and disadvantages of each sampling technique, and also increased the knowledge of bioaerosol emissions from composting facilities. These novel data were used to calculate emission rates of bioaerosol from agitation activities to improve the output of the bioaerosol dispersion modelling. The results achieved have presented new visions to the current understanding of the characterisation and dispersal of bioaerosols emitted from composting facilities and would be anticipated to make an important contribution to improve the risk assessment of bioaerosol from composting facilities to meet the increased regulatory requirements by Environment Agency.
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    How to best communicate Bioaerosol Science to different audiences.
    (2021-09) Bailly, Adrien; Drew, Gill H.; Nasar, Zaheer
    Scientific research aims to advance society through its results and discoveries. However scientific discoveries and results are for most people very difficult to access, both from the point of view of pure understanding and the accessibility of science to non-expert audiences. Making scientific knowledge more accessible to wider public is challenging, especially for an interdisciplinary field like bioaerosol science, where effective communication to various stakeholders is facing complex challenges. This study is integrated into the BioAirNet research network, in the theme of public and policy engagement. Here, the focus is on how best to communicate the science of Biological Particulate Matter (BioPM) or airborne micro-organisms (bioaerosols) and associated results. The aim of the research was to develop a framework for communicating bioaerosol science to different stakeholder; the General Public (GP), professionals, from different areas and the regulators. To do this, the research work consisted of analysing the concerns of the stakeholders, conducting a literature review, and carrying out qualitative data analysis (QDA). Then with the result obtained an investigation on the best communication mechanisms and the research on the key message for the stakeholders. The results of the study led to a Framework that is an asset for a better understanding of stakeholder engagement (SE) through effective scientific communication. this research confirms the fact that when the objective is to communicate to a certain audience or stakeholders identified, understanding the audiences and their concerns is crucial for the achievement. This study provides mechanisms through the choice of well-adapted tools for science communication. The framework developed allows reducing as much as possible the uncertainties and the technical/scientific issues inherent to science communication.
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    An investigation into the categorisation of organisations to understand the potential barriers and motivations to certification of an environmental management system: BS EN ISO14001:2004
    (Cranfield University, 2012-11) Stevens, P. A.; Batty, W. J.; Drew, Gill H.
    An investigation has been undertaken to ascertain the extent of the existing knowledge base regarding publically voluntary instruments capable of supporting organisations in developing improvements in environmental management. The multifaceted nature of the organisations seeking certification mean a generic approach to implementation is unlikely to deliver the desired after results or a resource efficient approach. Furthermore, the diversity of opinions recorded in the literature is often based on anecdotal evidence and small scale research projects. There is a lack of verifiable knowledge and understanding of the difficulties and barriers experienced by organisations attempting to secure certification for existing voluntary instruments for environmental management such as ISO 14001. The aim of the Research: ISO 14001 is the fastest growing of the ISO Standards related to Environmental Management Systems; however existing research has been small scale and anecdotal. This research aims to confirm or dispute the present discussions and assumptions surrounding the motivations and barriers to certification to ISO 14001. Through deductive reasoning this research will provide a comprehensive investigation into the barriers and motivations experienced in its implementation. It is proposed that more comprehensive opportunities for organisational categorisation may also be defined. The focus of the research has been to consider:  The potential for integration of these voluntary instruments.  The effects of the detailed requirements of the standard ISO 14001 on its certification and implementation processes.  The perceived and actual barriers to implementation  The opportunities to categorise participating organisations accordingly. An analysis of instruments available to support organisations in improving their environmental management has been undertaken. A complex and diverse array of instruments have been reviewed beyond the most regularly discussed ISO 14001. Considerable overlaps were identified in the requirements of the various instruments, suggesting opportunities for integration and resource efficiencies in implementation which have not previously been investigated. A detailed review of the certification processes of over 850 organisations certified to ISO 14001 was undertaken. This highlighted patterns in the barriers to implementation that have not previously been observed and which, in some cases, contradict existing literature. It has been shown that existing categorisation of originations was often only on the basis of whether an organisation was an SME or NON SME. However, it was proposed that this method lacked discrimination, with SME encompassing 99.8% of private sector businesses in the UK. This research has elicited significant motivations and barriers to EMS implementation and used these to provide an objective basis to categorise organisations. The outcome of this research has been:  A novel assessment of integration opportunities for 13 instruments.  An objective review of the certification and implementation processes for ISO 14001.  The development of taxonomies that encompasses multiple criteria that exhibit significant variability that could provide a method of classification for organisations.
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    Waste management within a public organisation
    (Cranfield University, 2008-09) Dlamini, Delly; Drew, Gill H.
    Through air pollution from landfill, the increase in waste generation poses a local and global threat to the environment. The UK government recognises organisations’ contribution to meeting raised targets for waste recycling. This research therefore, shows that organisational waste, associated with office operations is produced in large quantities and hence, very significant in contributing towards meeting national recycling targets. The paper addresses two key areas in managing organisational office waste for sustainable development within a public organisation. First, office waste recycling logistics were examined and secondly, the link between sustainable waste management practices such as recycling and the dissemination of information to participants about waste schemes and their ultimate success was investigated. Waste policies and implementation strategies were found to be the determinants of waste management program’s effectiveness. Organisational policy and strategy were identified as drivers in mainstreaming effective waste management within an organisation, especially participation in recycling schemes and waste minimisation. Simultaneously, recycling levels and levels of waste awareness within an office showed a positive relationship. The results show that continuous waste awareness promotions are key to translating high awareness levels into action among recycling participants in the organisation. Overall, an expected reduction in waste destined for landfill was reciprocated by an increase in material collected for recycling. The implications for organisational policy making to ensure staff sustainable waste management behaviour in organisations are also explored.