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Bi l i b ildiBio-aerosols in building
drainage and plumbing
tsystems: cross
contamination, monitoring
and prevention.
Dr M...
ContentsContents
 The building drainage system as The building drainage system as
a bioaerosol transmission route
 Tran...
Introduction
Bio-aerosols- what are they?y
Bioaerosols are defined as airborne particles, large
molecules or volatile comp...
Introduction
Relative size of particles
100 microns
10 microns
1 micron
0.01 microns
This is a scale representation of the...
Bio-aerosol generation and
detection
 Bioaerosols, particularly those containing
viruses are particularly difficult to is...
Building drainage system: mechanisms for air
flow and pressure transient generation
direction of air entrainment
flow and ...
Building drainage system: mechanisms for air
flow and pressure transient generationflow and pressure transient generation
...
Pressure transients in system can cause traps to blow
out-
http://www.youtube.com/watch?fea
ture=player detailpage&v=d vNL...
Airflow and pressure transient modelling- AIRNET
and current limitations
 A method of characteristics based numerical
mod...
Building Drainage System modelling
in AIRNET (3)
When
P 
Δt =    Δx  
Δx  A′
B′
C‐
C+
        (u+c)max  
A
R  S 
BC 
  0...
AIRNET modelling
Modelling of complex networks such as the O2
Dome
Thi i th fi t l d d i tThis is the first sealed drainag...
modelling air pressure and flow in large systems
St kSt k
W.c.
Roof line
Stack
termination
W.c.
Roof line
Stack
terminatio...
St kSt k
W.c.
Roof line
Stack
termination
W.c.
Roof line
Stack
termination
Roof line
Stack
terminationRoof line
Stack
term...
Limitations
• Calculations do not include importantp
bioaerosol fluid dynamics such as;
• Brownian Motion
• Gravitation
• ...
Modelling flow rate and direction
6
0
2
4
6
om,-downstack,
nd
-8
-6
-4
-2
nedairflow,+intoroo
litres/secon
Modelling
confi...
The building drainage system
Interconnection- all parts of the building are
interconnectedinterconnected
3F
4F
2F
3F
Waste...
The building drainage system
SARS OutbreakSARS Outbreak
Press Release WHO/70
“droplets originating from virus
26 September...
SARS Outbreak
Transmission routeTransmission route
Bioaerosols carried
to adjacent buildings
by wind current
Bioaerosols t...
The building drainage system
New threatsNew threats
Airborne transmission evidence
Forgotten knowledgeForgotten knowledge
1907: cultured airborne Serratia marcescens (then
te...
Horrocks – In good company
The Royal SocietyThe Royal Society
I N tIsaac Newton
Charles Babbage
James Watt
Horrocks – Other Successes
C fi d th t th f ‘M lt F ’• Confirmed that the cause of ‘Malta Fever’ was
bacteria passed on th...
Pathogen transmission study
Hospital buildingHospital building
Environmental
conditions
Norovirus
Outbreak
3F
4F
2F
3F
Bio...
Pathogen transmission study
Hospital buildingHospital building
Air sampling
Pitot tube measuring 
downward airflow
Collect...
Pathogen transmission study
Real Time Polymerase Chain ReactionReal Time Polymerase Chain Reaction
Samples extracted using...
Pathogen transmission study
RT-PCR ResultsRT PCR Results
T t d tTest date Norovirus GI Norovirus GII
Sewer Stack 1 Stack 2...
Pathogen transmission study
RT-PCR ResultsRT PCR Results
Samples were also tested for Clostridium deficile but was undetec...
CYCLE NUMBER AMOUNT OF DNA
0 1
1 2
2 4
1400000000
1600000000
2 4
3 8
4 16
5 32
6 64
7 128
400000000
600000000
800000000
10...
Pathogen transmission study
Temperature and Humidity
98
100
%)
Temperature and Humidity
94
96
Humidity(%
Average humidity ...
Pathogen transmission study
Airflow results – this proves that the interconnection hypothesis is
validvalid
30
Airflow Up
...
Additonal Domestic system tests
Drainage System Schematic
Roof Level
(height above collection
drain = 10 m
Floor 3
Open pi...
20
Air Flowrate
14
16
18
Note:
Similar
10
12
ow rate (l/s)
AirFlow
Similar
Airflows
to those
4
6
8
Airfl
AirFlow
recorded
...
The DYTEQTA System
Automated monitoring methodAutomated monitoring method
 Defective fixture trap seals increase
risk of ...
Case study BuildingsCase study Buildings
The DYTEQTA System
Case studies
1
60
80
Case studies
Time change detection algorithm
0.5
20
40
rgauge)
0
-20
0
20
0.00 0.0...
The DYTEQTA System
Case studiesCase studies
60
D d (AIRNET)
50
n(m)
Dundee (AIRNET)
Dundee (PROBE)
Arrol (AIRNET)
Arrol (P...
The building drainage system
Transmission of bioaerosolsTransmission of bioaerosols
 The building drainage system
interco...
The building drainage system
Transmission of bioaerosolsTransmission of bioaerosols
 Environmental conditions within theE...
Th k f li t iThank you for listening
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, h...
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Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, hw university

Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention

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Bio aerosols in building drainage and plumbing systems -cross contamination, monitoring and prevention, michael gormley, hw university

  1. 1. Bi l i b ildiBio-aerosols in building drainage and plumbing tsystems: cross contamination, monitoring and prevention. Dr Michael Gormley Drainage Research Group School of the Built Environment Heriot-Watt University Edinburgh
  2. 2. ContentsContents  The building drainage system as The building drainage system as a bioaerosol transmission route  Transmission study of the drainage system of a hospitaldrainage system of a hospital  Monitoring method for minimising Monitoring method for minimising bioaerosol transmission from the drainage systemdrainage system
  3. 3. Introduction Bio-aerosols- what are they?y Bioaerosols are defined as airborne particles, large molecules or volatile compounds that are living, contain living organisms or were released from livingliving organisms or were released from living organisms. The size of a bioaerosol particle may vary from 100 microns to 0.01 micron. The behaviour of bioaerosols is governed by the principles of gravitation, electromagnetism, turbulence and diffusion.
  4. 4. Introduction Relative size of particles 100 microns 10 microns 1 micron 0.01 microns This is a scale representation of the relative size of pollen, pollen spores, bacteria and viruses. The scale of this diagram is roughly 8000:1. Each of the dots on this screen version represent 15 viruses or virions In this diagramdots on this screen version represent 15 viruses, or virions. In this diagram, approximately 100,000 of these virions fit within the 100 micron circle representing the pollen. In actuality, many millions of virions could fit within the cross-section of a pollen.
  5. 5. Bio-aerosol generation and detection  Bioaerosols, particularly those containing viruses are particularly difficult to isolate and identify.  This task is made even more difficult due to the unsteady nature of flows in building d i tdrainage systems.
  6. 6. Building drainage system: mechanisms for air flow and pressure transient generation direction of air entrainment flow and pressure transient generation Discharging Increased entrainedDischarging appliance increases entrained airflow and generates ti t i t entrained airflow negative transients. Trap seal depletion Negative transient depletion Increased water flow.
  7. 7. Building drainage system: mechanisms for air flow and pressure transient generationflow and pressure transient generation operating appliance Positive transient affectsTrap seal all traps Trap seal deflections Airflow reduced due to stack base surchargesurcharge
  8. 8. Pressure transients in system can cause traps to blow out- http://www.youtube.com/watch?fea ture=player detailpage&v=d vNLture player_detailpage&v d_vNL MCZ9jQ video The attached video is anThe attached video is an extreme example – but it is real – most common symptom of smallersymptom of smaller pressure transients is bubbling through a trap, you may have seen this iny y a toilet bowl.
  9. 9. Airflow and pressure transient modelling- AIRNET and current limitations  A method of characteristics based numerical model.  Finite difference scheme  Developed and validated over 30 years at Heriot- Watt University – initiated by, and ti t b i i d b th k f J hcontinues to be inspired by, the work of John Swaffield.
  10. 10. Building Drainage System modelling in AIRNET (3) When P  Δt =    Δx   Δx  A′ B′ C‐ C+         (u+c)max   A R  S  BC    0||4 2    t uufccuu For C+ - Line PR   0 2 ||4 1    D uufccuu RRRRPRP  dx u c  when dt u c    0 2 ||4 1 2      D t uufccuu SSSSPSP  For C- - Line PS Building drainage system boundary conditions cu dt dx  when
  11. 11. AIRNET modelling Modelling of complex networks such as the O2 Dome Thi i th fi t l d d i tThis is the first sealed drainage system ever constructed. It has no penetrations through the roof. As drainage systems go, it is unique. The approach designed by M.Gormley and 50 Storey housing block in Hong Kong Modelling led to novel approaches to preventingpp g y y J.A.Swaffield from Heriot-Watt approaches to preventing excessive positive pressures using P.A.P.A.TM
  12. 12. modelling air pressure and flow in large systems St kSt k W.c. Roof line Stack termination W.c. Roof line Stack termination Roof line Stack terminationRoof line Stack termination Entrained air W.c. W.c. ‘Wet’ stackParallel vent W.c. W.c. ‘Wet’ stackParallel vent W.c. W.c. W.c. W.c. W.c. Roof line Stack termination W.c. Roof line Stack termination air Sewer connection Wet stackParallel vent stack with cross connections Sewer connection Wet stackParallel vent stack with cross connections W.c. Sewer ‘Wet’ stackParallel vent stack with cross connections W.c. Sewer ‘Wet’ stackParallel vent stack with cross connections W c W.c. W c W.c. W.c. Roof line Stack termination W.c. Roof line Stack termination connectionconnection W.c. Sewer connection ‘Wet’ stackParallel vent stack with cross connections W.c. Sewer connection ‘Wet’ stackParallel vent stack with cross connections W.c. W.c. ‘ ’ W.c. W.c. ‘ ’ Combined waste fluids and waste in appliance Sewer connection ‘Wet’ stackParallel vent stack with cross connections Sewer connection ‘Wet’ stackParallel vent stack with cross connections in appliance water flows
  13. 13. St kSt k W.c. Roof line Stack termination W.c. Roof line Stack termination Roof line Stack terminationRoof line Stack termination Potential contaminated air ingress if trap seal lost W.c. W.c. ‘Wet’ stackParallel vent W.c. W.c. ‘Wet’ stackParallel vent W.c. W.c. W.c. W.c. W.c. Roof line Stack termination W.c. Roof line Stack termination p Sewer connection Wet stackParallel vent stack with cross connections Sewer connection Wet stackParallel vent stack with cross connections W.c. Sewer ‘Wet’ stackParallel vent stack with cross connections W.c. Sewer ‘Wet’ stackParallel vent stack with cross connections W c W.c. W c W.c. W.c. Roof line Stack termination W.c. Roof line Stack termination connectionconnection W.c. Sewer connection ‘Wet’ stackParallel vent stack with cross connections W.c. Sewer connection ‘Wet’ stackParallel vent stack with cross connections W.c. W.c. W.c. W.c. Airflow may be drawn from any of the connected sub – section drainage Sewer connection ‘Wet’ stackParallel vent stack with cross connections Sewer connection ‘Wet’ stackParallel vent stack with cross connections sub section drainage systems – total interconnection.
  14. 14. Limitations • Calculations do not include importantp bioaerosol fluid dynamics such as; • Brownian Motion • Gravitation • Electrical Forces • Thermal Gradients & Electromagnetic Radiation • Turbulent Diffusion • Inertial Impaction• Inertial Impaction • Particle Shape However • Flow direction and rate can be calculated – approximations of likely bio-aerosol transport mechanisms can be made.
  15. 15. Modelling flow rate and direction 6 0 2 4 6 om,-downstack, nd -8 -6 -4 -2 nedairflow,+intoroo litres/secon Modelling confirms the establishment of an air exchange between the bathroom and the vertical -12 -10 0 5 10 15 20 Time, seconds. Entrain
  16. 16. The building drainage system Interconnection- all parts of the building are interconnectedinterconnected 3F 4F 2F 3F Waste water  from other  hospital  b ildi i GF 1F buildings i.e.  labs, morgue. GF To main  sewer
  17. 17. The building drainage system SARS OutbreakSARS Outbreak Press Release WHO/70 “droplets originating from virus 26 September 2003: droplets originating from virus- rich excreta…re-entered into residents apartments via sewage and drainage systems where there were strong upwards air flows, inadequate ‘traps’ andflows, inadequate traps and non-functional water seals.”
  18. 18. SARS Outbreak Transmission routeTransmission route Bioaerosols carried to adjacent buildings by wind current Bioaerosols transmittedBioaerosols transmitted to adjacent apartment Infected person introduces virus to drainage system Bioaerosols formed as waste is flushedas waste is flushed
  19. 19. The building drainage system New threatsNew threats
  20. 20. Airborne transmission evidence Forgotten knowledgeForgotten knowledge 1907: cultured airborne Serratia marcescens (then termed Bacillus prodigiosus) from drainage systems and detected airborne transport from one hospital building to another via the sewer drain. Sir William Heaton Horrocks (1859-1941)
  21. 21. Horrocks – In good company The Royal SocietyThe Royal Society I N tIsaac Newton Charles Babbage James Watt
  22. 22. Horrocks – Other Successes C fi d th t th f ‘M lt F ’• Confirmed that the cause of ‘Malta Fever’ was bacteria passed on through goats milk. • Developed methods for testing and purifying drinking water • Published book on bacteriology of water, one of the first of its kindof the first of its kind. Horrocks, William Heaton (1901). An Introduction to the Bacteriological E amination of Waterto the Bacteriological Examination of Water. London: J. & A. Churchill.
  23. 23. Pathogen transmission study Hospital buildingHospital building Environmental conditions Norovirus Outbreak 3F 4F 2F 3F Bioaerosol transmission Waste water  from other  hospital  b ildi i GF 1F buildings i.e.  labs, morgue. GF To main  sewer Wastewater contamination
  24. 24. Pathogen transmission study Hospital buildingHospital building Air sampling Pitot tube measuring  downward airflow Collection swab• Isolation of bioaerosols using collection swab (UTM-RT) Static pressure tube  • Temperature and humidity within drainage stack (USB data logger) • Air flow and direction (pitot tube) Pitot tube measuring  upward airflow USB temperature & relative  humidity data logger Wastewater sampling • Collection of wastewater from main underground drain
  25. 25. Pathogen transmission study Real Time Polymerase Chain ReactionReal Time Polymerase Chain Reaction Samples extracted using NucliSens® easyMAG™ system Ct ≤ 29 St iti tiCt ≤ 29 Strong positive reaction (abundant target nucleic acid) Ct 30-37Positive reaction (moderate amount of target nucleic acid) Amplification, detection and analysis performed in an ABI 7500 RT-PCR system ( g ) Ct 38-40Weak reaction (minimal amounts of target nucleic acid)
  26. 26. Pathogen transmission study RT-PCR ResultsRT PCR Results T t d tTest date Norovirus GI Norovirus GII Sewer Stack 1 Stack 2 Stack 3 Sewer Stack 1 Stack 2 Stack 3 01/03/2011 U U U U U U U U 10/03/2011 U U U U 2 U U U10/03/2011 U U U U 25 U U U 16/03/2011 U U U U 25 U U U 23/03/2011 U U U U 35 U U U 30/03/2011 U U U U 40 U U U30/03/2011 U U U U 40 U U U 05/04/2011* U U U U 37 U U U 26/05/2011 N/A U U U N/A U U U U Undetected Ct ≤ 29 Strong positive reaction (abundant target nucleic acid) Ct 30-37 Positive reaction (moderate amount of target nucleic acid) Ct 38 40 Weak reaction (minimal amounts of target nucleic acid)Ct 38-40 Weak reaction (minimal amounts of target nucleic acid) *a swab of the inside surface of Stack 1 taken on this date also returned undetected for all tests
  27. 27. Pathogen transmission study RT-PCR ResultsRT PCR Results Samples were also tested for Clostridium deficile but was undetected. This was due to the fact that Cdiff produces spores which are not amenable to man of the PCR assa s a ailablemany of the PCR assays available.
  28. 28. CYCLE NUMBER AMOUNT OF DNA 0 1 1 2 2 4 1400000000 1600000000 2 4 3 8 4 16 5 32 6 64 7 128 400000000 600000000 800000000 1000000000 1200000000 AMOUNTOFDNA 8 256 9 512 10 1,024 11 2,048 12 4,096 13 8 192 0 200000000 0 5 10 15 20 25 30 35 PCR CYCLE NUMBER A 13 8,192 14 16,384 15 32,768 16 65,536 17 131,072 18 262,144 100000 1000000 10000000 100000000 1000000000 10000000000 TOFDNA 18 262,144 19 524,288 20 1,048,576 21 2,097,152 22 4,194,304 23 8,388,608 1 10 100 1000 10000 0 5 10 15 20 25 30 35 AMOUNT 24 16,777,216 25 33,554,432 26 67,108,864 27 134,217,728 28 268,435,456 29 536 870 912 31 0 5 10 15 20 25 30 35 PCR CYCLE NUMBER 29 536,870,912 30 1,073,741,824 31 1,400,000,000 32 1,500,000,000 33 1,550,000,000 34 1,580,000,000
  29. 29. Pathogen transmission study Temperature and Humidity 98 100 %) Temperature and Humidity 94 96 Humidity(% Average humidity = 96.6% 90 92 23/03/11 24/03/11 25/03/11 26/03/11 27/03/11 28/03/11 29/03/11 30/03/11 31/03/11 D tDate 26 28 30 re(oC) Average temperature = 24.3% 22 24 26 Temperatu 20 23/03/11 24/03/11 25/03/11 26/03/11 27/03/11 28/03/11 29/03/11 30/03/11 31/03/11 Date
  30. 30. Pathogen transmission study Airflow results – this proves that the interconnection hypothesis is validvalid 30 Airflow Up 20 Airflow Down 0 10 rate (l/s) ‐10 0 0 1 2 3 4 5 6 Airflow r ‐20 ‐30 Time (minutes)
  31. 31. Additonal Domestic system tests Drainage System Schematic Roof Level (height above collection drain = 10 m Floor 3 Open pipe for testing (WC Removed) Simulates open trap Anemometer located here. Bath & sink Floor 2 Kitchen WC To main sewer Floor 1 2 x Bathrooms Utility room 2 x WCs Smoke Pellets To main sewer inserted here Collection drain
  32. 32. 20 Air Flowrate 14 16 18 Note: Similar 10 12 ow rate (l/s) AirFlow Similar Airflows to those 4 6 8 Airfl AirFlow recorded in Amoy Gardens 0 2 4 0 500 1000 1500 2000 2500 3000 3500 40000 500 1000 1500 2000 2500 3000 3500 4000 Time (secs)
  33. 33. The DYTEQTA System Automated monitoring methodAutomated monitoring method  Defective fixture trap seals increase risk of bioaerosol transmission via the building drainage network  Dyteqta is a sonar-like method for establishing the status of each fixture trap seal in a building  Based on reflected wave theory  Using a sinusoidal air pressure a e ens res the test is nonwave ensures the test is non- destructive  System validated by: modelling System validated by: modelling, laboratory investigations and extensive site testing
  34. 34. Case study BuildingsCase study Buildings
  35. 35. The DYTEQTA System Case studies 1 60 80 Case studies Time change detection algorithm 0.5 20 40 rgauge) 0 -20 0 20 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Dt>h re(mmwater -0.5 60 -40 -20 Pressur Defect free baseline -1-80 -60 Time (seconds) Test pressure response Dt > h Is Dt > h over calibration period? NO, trace is reliable. Is Dt > h during test period? YES, at tD = 0.066 seconds. Depleted trap location? T12.
  36. 36. The DYTEQTA System Case studiesCase studies 60 D d (AIRNET) 50 n(m) Dundee (AIRNET) Dundee (PROBE) Arrol (AIRNET) Arrol (PROBE) 30 40 aplocation Arrol (PROBE) Glasgow (AIRNET) Glasgow (PROBE) 20 edictedtra 0 10 Pre 0 0 10 20 30 40 50 60 True trap location (m)
  37. 37. The building drainage system Transmission of bioaerosolsTransmission of bioaerosols  The building drainage system interconnects all parts of a buildingg  Potential cross-transmission route for bio-aerosols.  Every building tested had empty water trap seals.  Healthcare building drains have a distinctly ‘hospital smell’ they do noty y necessarily smell malodorous.  Norovirus GII isolated from t t l d f i d iwastewater sampled from main drain of a hospital building, confirming contamination during an outbreak.
  38. 38. The building drainage system Transmission of bioaerosolsTransmission of bioaerosols  Environmental conditions within theEnvironmental conditions within the drainage system are conducive to bio-aerosol circulation  Current work underway to replicate the Horrocks work reported in the Royal Society proceedings in 1907Royal Society proceedings in 1907 and extend the investigations on the identification of specific pathogens in airflows.  This work has confirmed that bacteria such as psuedomonas spp. Can be carried on airstreams inside a building drainage system.
  39. 39. Th k f li t iThank you for listening

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