Bioaerosols in Waste Management Facilities Dr Ikpe Ibanga I.E.Ibanga@greenwich.ac.uk 05 August 2020
Outline • Background • The Sniffer Project • Research Aim & Objectives • Methods – Biofilter construction, bioaerosol sampling • Results • Conclusions • References • Acknowledgements
What are bioaerosols? • Aerosols, aeroallergens, or particulate matter of microbiological, plant or animal origin (Defra, 2009). • Can interact with living systems through infective, allergenic and/or toxic mechanisms. • Aerosolised as clumps, aggregates and attached to larger mineral particles. • Weather conditions and process parameters can affect generation and aerosolisation. • Viability can deteriorate according to temperature, humidity and sunlight. • Die off is generally exponential, although non-viable microorganisms may still be able to cause health effects e.g. allergenic/toxic effects in sufficient concentrations
Why are we interested in bioaerosols? • Increase in composting activities • They have received increased media attention over the past few years • The risk of exposure to bioaerosols is a growing research area • Increasing number of complaints regarding health effects and odour problems from residents living close to composting facilities • July 2009 – waste workers warned of the potential health impacts of bioaerosols – Dr Alison Searl – Institute of Occupational Health “Time bomb of major respiratory health problems in the future” • July 2009 – Waste and Resources Action Programme (WRAP) said the issue required more investigation – relating to a study done on the impact of fortnightly bin collection.
Bioaerosols from waste Bacteria facilities Mycotoxins Fungi Bioaerosols Peptidoglycans Viruses Endotoxins Spores
Viable and non- viable Bioaerosols from waste Bacteria facilities Mycotoxins Fungi Bioaerosols Peptidoglycans Viruses Endotoxins Spores
Bioaerosols from waste Bacteria facilities Mycotoxins Fungi Bioaerosols Peptidoglycans Viruses Endotoxins Spores Pathogenic or non- pathogenic
Bioaerosols from waste Bacteria facilities Mycotoxins Fungi Bioaerosols Peptidoglycans Viruses Cell wall components with toxicological properties Endotoxins Spores
Bioaerosols from waste Bacteria facilities Mycotoxins Fungi Secondary metabolites Bioaerosols Peptidoglycans Viruses Endotoxins Spores
Bioaerosols from waste Bacteria facilities Mycotoxins Fungi May also find algal fragments, protozoa and Bioaerosols nematodes but these are not routinely encountered Peptidoglycans Viruses in emissions at waste management sites Endotoxins Spores
What are the potential health effects? Direct health effects – little research carried out to establish: • Safe levels • Dose-response relationships Why? • Many different species of viable bioaerosols • Many components (glycans, endotoxins, mycotoxins) • Whole range of potential health effects that may have other unconnected causes • Human response - varied and complex
Mucous membrane irritation Skin irritation Allergic type reactions Asthma Respiratory complaints Chronic bronchitis Invasive aspergillosis Headaches Organic Dust Toxic Syndrome Systemic Toxic Effects Fever Chills Excessive tiredness Flu-like symptoms
Aspergillus us f fum umigatus us A rapid growing mould which survives over a wide range of conditions. Propagated via airborne spores 2-3mm in diameter. Opportunist pathogen – spores can enter the lungs very easily – spores may be inhaled frequently but infection is uncommon. Wide spectrum of human illness ranging from mild respiratory tract irritation, colonisation of the bronchial tree through to rapidly invasive and disseminated disease. Of particular concern regarding IC individuals such as bone marrow transplant, heart and lung transplants and cystic fibrosis patents. Healthy individuals - spores are dealt with by the innate defences of the URT or if they penetrate the LRT by macrophages which ingest and kill the spores before they can go on to cause infection.
Aspergillus us f fum umigatus us One of the prime concerns in composting and waste management generally. Survives over a wide range of temperature, moisture content, pH, oxygen concentrations and on a range of substrates. Optimum conditions are temperatures between 37 – 43 o C and substrates with high carbon content. Spores are very small and can be carried long distances – from a few 100m up to several km.
How and why are bioaerosols generated? Raw wastes contain high concentrations of microorganisms Microorganism growth is associated with the breakdown of organic matter Some are potentially pathogenic and can be released as bioaerosols: • Handling of waste materials on site – shredding, turning, screening • Storage and movement of waste • Material characteristics – source material, moisture content • Meteorological conditions – rain, wind, humidity
Current Guidelines • Workers in the vicinity of an activity involving material agitation – should be at least 30m away • 250m trigger limit – Environment Agency – Wheeler et al (2001) based on dispersal monitoring in 1999-2000 – found background concentrations were reached within 200m • Site specific bioaerosol risk assessment (SSBRA) must be carried out if there are sensitive receptors within that distance from the site • Environment Agency Acceptable Limits at 250m or Sensitive receptors: 500 cfu m -3 for A. fumigatus o 1000 cfu m -3 for Total bacteria o 300 cfu m -3 for Gram negative bacteria o
Odour & Bioaerosols concerns
Measures for Odour Control • Incineration • Adsorption • Misting and deodorisers • Biofilters
What are biofilters? Mechanism for odour control
This research project was commissioned by Sniffer on behalf of the UK environmental agencies and was carried out by a team from the University of Leeds and Odournet UK.
Odour up to 94% Removal (200 – 5000 OU E m -3 ) Key Findings Bioaerosols - performance variable with time and site; and removal mechanism not same for odour To determine the criticality of design and operating parameters on biofilter performance
Study Aim & Objectives Biofilter Performance Assessment for Bioaerosols control • Evaluation of the removal efficiencies. • Evaluation of the net bioaerosol-emitting potential of biofilters. • Assessment of the impact on bioaerosol particle size distribution between inlet and outlet samples.
Methods
Methods
Operating Parameter Value Media type Wood chips Media porosity 61% Methods 225 Kg/m 3 Media density Media conductivity 248 µ S/cm Media moisture content 40 – 70% Media height 0.5 m Surface loading 149 m 3 /m 2 /hr 298 m 3 /m 3 /hr Volumetric loading Inlet air temperature 15 – 30°C Outlet air temperature 15 – 30°C Inlet air relative humidity 70 - 95% Media pH 5.5 - 8 Gas residence time 9 – 109 s Air distribution Through a plenum, up-flow configuration
Methods MRF – 2 nd in odour complaints with ~ 5000 reports between 10/13 – 10/15 (Environment Agency, 2016)
Methods
Methods
Methods
Methods
Methods - surrogate indicator species Aspergillus Total mesophilic Gram negative fumigatus bacteria bacteria 500 cfu m -3 1000 cfu m -3 300 cfu m -3
Methods - Concentration of bioaerosols in the process air reported in literature & current study System Waste Bioaerosols Concentration Authors (cfu m -3 ) 10 2 – 10 5 Various Various A. fumigatus Sanchez-Monedero et al. 10 3 – 10 5 Mesophilic bacteria (2003) 10 5 - 10 6 - - Mesophilic bacteria Fischer et al. (2008) 10 2 – 10 5 - - A. fumigatus Kummer and Thiel (2008) 10 3 – 10 5 Various GW/FW Bacteria Frederickson et al. (2013) 10 4 – 10 5 Gram negative bacteria Fungi 0 – 10 4 Various Various A. fumigatus 9 – 10 3 Fletcher et al. (2014) 10 3 – 10 4 Total bacteria 10 2 – 10 3 Gram negative bacteria 10 3 – 10 4 MRF MSW A. fumigatus This study 10 3 – 10 4 Total fungi 10 3 – 10 5 Total mesophilic bacteria 10 3 – 10 5 Gram negative bacteria FW – Food waste, GW – Green waste, MSW – Municipal Solid Waste
Results – Operated inside the waste hall Background concentration Inlet concentration Outlet concentration Aspergillus fumigatus concentration (cfu m -3 ) 1E+06 1E+06 100 100 97 96 88 86 85 85 50 Total fungi concentration (cfu m -3 ) 50 78 77 78 76 72 72 65 60 61 59 53 49 1E+05 1E+05 35 35 0 0 70% (35 – 97%) 71% (35 – 94%) Removal Efficiency (%) Removal Efficiency (%) -50 -50 1E+04 1E+04 -100 -100 -150 -150 1E+03 1E+03 -200 -200 -250 -250 1E+02 1E+02 -300 -300 -350 -350 1E+01 -400 1E+01 -400 1 2 3 4 5 6 13 14 15 16 1 2 3 4 5 6 13 14 15 16 Visits Visits (b)
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