Monitoring bioaerosol and odour emissions from composting facilities - WR1121

Government policy requires that valuable resources should be recovered and recycled from biodegradable waste. A successful and growing organics recycling industry delivers this policy with composting being one of the principal technologies deployed to process suitable feedstock such as garden and food waste. Composting inevitably generates bioaerosols – particulate matter comprising cells or cellular components that are released into the air as a result of disturbance of composting feedstock or the processing of final product. Exposure to bioaerosols has the potential to be harmful to human and animal health. The Environment Agency adopts a precautionary and risk-based approach to the regulation of composting facilities which was developed on the basis of research by Wheeler et al. (2001) and which has been updated as new evidence has become available. The Environment Agency also requires site operators to monitor bioaerosols around their facilities using methods specified in a standard protocol which relies upon classical microbiology methods which are tried and tested but which are labour-intensive, slow and offer only a snapshot view of a highly dynamic system. A recent IOM review commissioned by Defra (Searl, 2009) on exposure-response relationships for bioaerosol emissions from waste treatment processes identified significant gaps in knowledge of exposure to bioaerosols and recommended that more research was needed into alternatives to viable microbial monitoring such as priority biomarkers (notably endotoxin) and potential surrogates such as particulate matter. The IOM review also concluded that there is a lack of information to support the development of appropriate stand-off distances. The overall aim of this project was to provide evidence on bioaerosol production, dispersion and potential exposures from composting facilities in support of future developments in policy and regulation of biowaste facilities. The objectives were: (i) to undertake a comprehensive set of standard and novel bioaerosol measurements at representative composting sites to assess comparability between different methods and also to measure spatial and temporal variations; and (ii) to determine the odour emissions and then compare these with bioaerosol emissions to see if odour is a marker of significant bioaerosol exposure. Standard (AfOR, 2009) and novel (CEN filter method, endotoxin, glucan, qPCR, real-time particulates) bioaerosols measurements were taken on a minimum of three to a maximum of six occasions over a twelve month period at four different composting facilities in England. The composting facilities were selected to represent sites of varying sizes (tonnages) and to allow a comparison of bioaerosol concentrations at standard open windrow sites versus a fully-contained site. Additional supporting information was collected including meteorological data at the time of sampling, observation of site operations and measurements of odour at one of the sites. Supporting bioaerosol and odour dispersion modelling was conducted at the site where the odour measurements were made. The spatial trend of bioaerosol concentrations described by Wheeler et al., (1991) and upon which EA regulatory policy is based was broadly corroborated by this dataset. Excursions above the EA acceptable levels at or beyond 250m from source were rare. Bioaerosol concentrations at the enclosed site were generally lower than at the open windrow sites. There was no evidence of a seasonal pattern in bioaerosol concentrations at any of the sites whereas between-sampling day variations were apparent. The cause(s) of these variations were not identified. No consistent relationship was observed between the concentration of bioaerosols measured by the two AfOR standard methods. The two methods displayed certain strengths and weakness in different situations. The IOM sampling device proved to be better suited to situations where high bioaerosol concentrations were encountered (close to source); the Andersen proving to be more effective in the lower concentration range typically found upwind of a site or at distance downwind from source. The higher volume filtration device tested in this project (referred to as the CEN method) produced data that did not consistently match either of the AfOR standard methods. This device demonstrated greater sensitivity than the IOM filter method but suffered drawbacks associated with its weight and a lack of ease of use in the field. Endotoxin concentrations were normally below the level recommended by the Dutch Expert Committee on Occupational Safety but occasional exceedances of this standard were detected at the larger open windrow sites. The majority of glucan measurements were below a widely referred to 10ng/m3 threshold. Significantly elevated concentrations were detected at one of the larger open windrow sites. The dynamic range of the qPCR method is wider (4-5-log) than either of the AfOR and the CEN methods. It is also quicker to carry out and has the potential for automation. The results from the qPCR method are mainly higher than standard AfOR methods, as the method does not distinguish viable and non-viable spores. The spatial distribution of Aspergillus fumigatus spores (by qPCR) along sampling transects, gives similar results compared to AfOR (and CEN) methods. Real time particle detection showed that both TSP and PM10 are correlated to Aspergillus fumigatus spore concentration. No consistent relationship was observed between odour and bioaerosol concentrations (although this was a limited dataset). The envelope of modelled (back-extrapolated) bioaerosol emission rates straddles several orders of magnitude. Distinguishing the influences of meteorological conditions on this variability was not possible. It was not possible to predict bioaerosol or odour emission rates with confidence. This continues to hamper confidence in modelling of odours and bioaerosols from open windrow facilities. The findings of this research have implications for the current standard monitoring protocol which should be reviewed accordingly. The findings of this multi-site survey accord with existing regulatory policy and are supportive of the general trend towards enclosed facilities. Notwithstanding this, continuing research is needed to enhance the database on emission from bioaerosol and odour abatement technologies (e.g. biofilters); to determine the cause(s) of occasional bioaerosol peaks from open facilities; to improve exposure assessments through better modelling protocols; and to link enhanced exposure information to future health impact studies

Scoping study of potential health effects of fortnightly residual waste collection and related changes to domestic waste systems

This report presents a review of international research into waste collections commissioned by WRAP and the Chartered Institution of Wastes Management (CIWM). The report’s findings have confirmed existing advice for councils and householders on avoiding risks to public health. No evidence was found that changing to a fortnightly collection creates risks that cannot be dealt with by following the good practice guidance already available

Towards improved bioaerosol model validation and verification

Bioaerosols, comprised of bacteria, fungi and viruses are ubiquitous in ambient air. Known to adversely affect human health, the impact of bioaerosols on a population often manifests as outbreaks of illnesses such as Legionnaires Disease and Q fever, although the concentrations and environmental conditions in which these impacts occur are not well understood. Bioaerosol concentrations vary from source to source, but specific industrialised human activities such as water treatment, intensive agriculture and open windrow composting facilitate the generation of bioaerosol concentrations many times higher than natural background levels. Bioaerosol sampling is currently undertaken according to the requirements of the Environment Agency’s regulatory framework, in which the collection of bioaerosols and not its long-term measurement is of most importance. As a consequence, sampling devices are often moved around site according to changing wind direction and sampling intervals are invariably short-term. The dispersion modelling of bioaerosols from composting facilities typically relies on proxy pollutant parameters. In addition, the use of short term emission data gathering strategies in which monitors are moved frequently with wind direction, do not provide a robust reliable and repeatable dataset by which to validate any modelling or to verify its performance. New sampling methods such as the Spectral Intensity Bioaerosol Sensor (SIBS) provide an opportunity to address several gaps in bioaerosol model validation and verification. In the context of model validation, this paper sets out the current weaknesses in bioaerosol monitoring from the perspective of robust modelling requirements

Research into the issues associated with people sleeping in waste containers

In 2014, the Chartered Institution of Wastes Management, waste management and recycling company Biffa and StreetLink, the national rough sleeping service, came together to carry out a study into people sleeping in bins following several near misses and, tragically, one fatality. Five years on, this research has been repeated to determine the scale of the issue now, to assess how far the issue has progressed since the first report and to identify whether best practice is being adopted by waste producers and waste management companies. The intention was to also seek to set out a range of recommendations for the industry as a whole - and to determine how everyone involved can work better together to address the issue of people in bins

Scoping studies to establish the capability and utility of a real-time bioaerosol sensor to characterise emissions from environmental sources

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm−3 and 0.48 cm−3, respectively) and the composting site (2.32 cm−3 and 0.46 cm−3, respectively) and the lowest at the dairy farm (1.03 cm−3 and 0.24 cm−3, respectively) and the sewage treatment works (1.03 cm−3 and 0.25 cm−3, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 and λex 370. This finding suggests differences in the molecular composition of emissions at these sites which can help to identify distinct fluorescence signature of different environmental sources. Overall this study demonstrated that SIBS provides additional spectral information compared to existing instruments and capability to resolve spectrally integrated signals from relevant biological fluorophores could improve selectivity and thus enhance discrimination and classification strategies for real-time characterisation of bioaerosols from environmental sources. However, detailed lab-based measurements in conjunction with real-world studies and improved numerical methods are required to optimise and validate these highly resolved spectral signatures with respect to the diverse atmospherically relevant biological fluorophores

Comparing transparency, consistency and burden in UK research assessments between 1986 and 2021

Research assessments have changed over time in the UK through a cycle of consultation, published guidance, pilot work, detailed preparation, assessment and results. The requirement to focus on the immediate challenge ahead can mean that key constituencies can lose perspective of the changing nature of research assessment over time. This paper explores key differences between the Research Selectivity Exercise (1981-1986) and the Research Excellence Framework (2015-2021), using discourse analysis to evaluate the changing nature of research assessments in terms of transparency and fairness, consistency and standardisation, and burden and efficiency. In conclusion, we argue that UK research assessments became fairer and more consistent between 1986 and 2021 because of greater transparency and standardisation, but this has also introduced calls for greater efficiency due to the increased burden on researchers and research institutes

Engaged Career Development in the context of the Research (Engagement and) Impact Agenda

Though the research impact agenda has the potential to drive equitable and impactful public engagement practice, systematic approaches to career development are crucial to achieve this vision. Come explore key vocabulary, map the engaged career development learning landscape, and chart the increasing importance of engagement and impact within national and institutional strategy. Equip yourself to articulate the value of career development as a pathway to impact to funders and senior leaders. Hear how sector initiatives are implemented at an institutional level and what challenges remain to equip staff with the skills and experience to lead impactful engagement

Methane emissions from trees planted on a closed landfill site

Trees have morphological adaptations that allow methane (CH4) generated below ground to bypass oxidation in aerobic surface soils. This natural phenomenon however has not been measured in a landfill context where planted trees may alter the composition and magnitude of CH4 fluxes from the surface. To address this research gap, we measured tree stem and soil greenhouse gas (GHG) emissions (CH4 and CO2) from a closed UK landfill and comparable natural site, using an off-axis integrated cavity output spectroscopy analyser and flux chambers. Analyses showed average CH4 stem fluxes from the landfill and non-landfill sites were 31.8 ± 24.4 µg m–2 h–1 and –0.3 ± 0.2 µg m–2 h–1, respectively. The landfill site showed seasonal patterns in CH4 and CO2 stem emissions, but no significant patterns were observed in CH4 and CO2 fluxes at different stem heights or between tree species. Tree stem emissions accounted for 39% of the total CH4 surface flux (7% of the CO2); a previously unknown contribution that should be included in future carbon assessments

Nitrous oxide emissions from trees planted on a closed landfill site

Trees growing in natural and managed environments have the capacity to act as conduits for the transport of greenhouse gases produced belowground to the atmosphere. Nitrous oxide (N2O) emissions have been observed from tree stems in natural ecosystems but have not yet been measured in the context of forested former landfill sites. This research gap was addressed by an investigation quantifying stem and soil N2O emissions from a closed UK landfill and a comparable natural site. Measurements were made by using flux chambers and gas chromatography over a four-month period. Analyses showed that the average N2O stem fluxes from the landfill and non-landfill sites were 0.63 ± 0.06 μg –2 h–1 and 0.26 ± 0.05 μg m–2 h–1, respectively. The former landfill site showed seasonal patterns in N2O stem emissions and decreasing N2O fluxes with increased stem sampling position above the forest floor. Tree stem emissions accounted for 1% of the total landfill N2O surface flux, which is lower than the contribution of stem fluxes to the total surface flux in dry and flooded boreal forests

The work of waste during COVID-19: logics of public, environmental, and occupational health

Waste has become a pivotal public health and environmental problem during the COVID-19 pandemic. In this interdisciplinary review, we move beyond the ‘coronalitter’ and ‘coronawaste’ discourses, which have come to dominate public imaginaries of waste, to consider less-visible dimensions of waste infrastructures and systems. We demonstrate how waste is coming to matter in new ways that offer opportunities for reconfiguring health research. By examining the literature addressing the impacts of COVID-19 on the geographies of waste, we shed light on how waste is being problematised and researched through logics of public, environmental, and occupational health. We argue that these logics structure understandings and practice, whilst drawing attention to the overlaps and limits that allow links across disciplinary silos and problem domains to be forged. Developing a multi-logics approach, the paper outlines a research agenda for approaching waste as a critical public health problem at a time of intersecting health crises