Transport of Viruses, Bacteria, and Protozoa in Groundwater Joe Ryan Civil, Environmental, and...
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Transcript of Transport of Viruses, Bacteria, and Protozoa in Groundwater Joe Ryan Civil, Environmental, and...
Transport of Viruses, Transport of Viruses, Bacteria, and Protozoa in Bacteria, and Protozoa in
GroundwaterGroundwater
Joe RyanCivil, Environmental, and Architectural Engineering DepartmentUniversity of Colorado, Boulder
Environmental Engineering Seminar October 11, 2000
Acknowledgments
StudentsUniversity of Colorado: Jon Loveland, Jeff Aronheim, Annie Pieper, Becky Ard, Robin Magelky, Jon Larson, Theresa Navigato, Yvonne BogatsuUCLA/Yale University: Jun Long, Ning Sun, Chun-han Ko
CollaboratorsRon Harvey, U.S. Geological SurveyMenachem Elimelech, Yale University
FundingNational Water Research InstituteU.S. Environmental Protection Agency
Laboratory AssistanceChuck Gerba, University of ArizonaJoan Rose, University of South Florida
Field AssistanceDenis LeBlanc & Kathy Hess, U.S. Geological Survey
Public Health Problem
Waterborne Disease Outbreaks estimates for the United States
1 to 6 million illnesses per year1000 to 10,000 deaths per yearonly 630 documented outbreaks 1971-1994
Milwaukee, Wisconsin, 1993Cryptosporidium, the “hidden germ”about 400,000 illnesses, greater than 100 deathsDNA evidence: human, not bovine, origin
Public Health Problem
Waterborne Disease Outbreaks acute gastrointestinal illness
short duration, “self-resolving” for most peoplechronic, severe, fatal for some
infants and elderlypregnant womenimmuno-compromised
more serious illnessesheart disease, meningitis, diabetes (coxsackie virus)liver damage, death (hepatitus virus)
Public Health Problem
Microbial Perpetratorsvirusesbacteriaprotozoa
Where are they coming from?groundwater (58%), surface waterpoint source, non-point source
Viruses
Entericreplicate only in gut
Size20 – 200 nm
Structureprotein capsidRNA or DNA
virushealth effect
coxsackie“hoof and mouth”
echo, adeno
respiratory disease
Norwalk, rota, calici, astro
gastroenteritis
hepatitis Ahepatitis E
jaundice, liver damage, death
Viruses
Life Cycleingestion
drinking water
within the gutadsorptionpenetrationtranscriptionreplicationassemblyhost cell lysis
excretion from gut
Bacteria
Entericgrow in gut (only?)
Size0.5 to 2 m
Structurecell walls
proteinsphospholipids, fatty acids
motililtyflagellaecilia
bacteriumhealth effect
Escherichia coli, Shigella spp., Camplylobacter jejuni, Yersinia spp.
gastroenteritis (arthritis, pneumonia, Guillain-Barre syndrome)
Salmonella spp.
enterocolitis (heart disease, meningitis, arthritis, pneumonia)
Legionella spp.Legionnaire’s disease, Pontiac fever, death
Vibrio cholera diarrhea, vomiting, death
Bacteria
Life Cycleingestion
meat, vegetables, drinking water
within the gutadsorptionpenetrationgrowthrelease of toxins
excretion from gut
Vibrio Cholera adhering to rabbit villus E. coli adhering to calf villus
Protozoa
Entericgrow in gut only
Size3 to 12 m
Cyst Structurerugged protective membranecarries trophozoites
protozoanhealth effect
Cryptosporidium parvum
diarrhea
Giardia lambliachronic diarrhea
Protozoa
Life Cycleingestion
drinking water
within the gutexcystationparasitic growthcyst formation
excretion from gut
Occurrence in Groundwater
Viruses38% positive by PCR7% positive by cell culture
Bacteria40% positive for coliform bacteria50-70% positive for enterococci
Protozoa12% Giardia and/or Cryptosporidium(5% in vertical wells)
Monitoring in Groundwater
Maximum Contaminant Levelcoliform bacteria – 40 per literviruses – 2 per 107 L (proposed, GWDR)
Ground Water Disinfection Rulewill require disinfection unless “proof” of adequate “natural disinfection”viruses nominated as target microbe
Virus Transport Modelspredictions of travel timeattachment and inactivation
Microbe Transport
Microbe Transport
Transport equation2
2b
att det
c c dc sD v k c k s c
t x dx t
dispersion
advection kinetic attachmen
t/release
equilibrium attachmen
t/release
growth or inactivatio
n/“die-off”
Microbe Attachment
Attachmentkinetic
colloid filtrationcollision frequency collision efficiency
releasefirst-order (kdet)
much slower than attachment
equilibriumdistribution coefficientlinear, reversible
time
con
cen
trati
on
tracer
microbe
time
con
cen
trati
on
tracer
microbe
Microbe Attachment
Surface Chemistrycapsids, cell walls
carboxyl – RCOO-
amine – RNH3+
net surface chargeusually negativepHpzc ~3-4
for viruses, pHpzc can be estimated from protein content of capsid
Microbe Attachment
Porous Media Surface Chemistrynegative
quartz, feldspars, etc.clay faces
positiveiron, aluminum oxidesclay edges
electrostatic interactionsfavorable deposition sitesunfavorable deposition sites
Microbe Attachment
Microbe Sizesmall
collisions caused by Brownian motion
largecollisions caused by settling
Microbe DensityRange 1.01 to 1.05 g cm-3
collisions caused by settling
Microbe Attachment
Optimal Size for Transport
about 1-2 mbacteriaviruses collide by diffusionprotozoa collide by settlingprotozoa also removed by straining
1.00E-06
1.00E-04
1.00E-02
1.00E+00
1.00E+02
1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04
particle diameter (m)
co
llis
ion
fre
qu
en
cy
Brow nian
Interception
Settling
Total
Microbe Attachment
Target Organismcollision efficiency
about the same for all microbesvariation in comes from porous media
collision frequencyfavors bacteria
BACTERIA, but…adhesion favored for growthbiofilms
Virus Attachment
Bacteriophage PRD1Cape Cod field experimentssewage-contaminated zoneuncontaminated zone100 L injectionsmulti-level samplers
Virus Attachment
Transport favored in contaminated zonePRD1 attachment sites blocked by sewage organic mattercollision efficiency fraction of favorable deposition sites
0 2 4 6 8 10 12 14
brom
ide
C/C
00.0
0.2
0.4
0.6
0.8
PR
D1
C/C
0
0.00
0.05
0.10
0.15
0.20
Col 21 vs Col 22 Col 21 vs Col 24
time (d)
0 2 4 6 8 10 12 14
PR
D1
C/C
0
brom
ide
C/C
0
0.0
0.2
0.4
0.6
0.8
bromide32P - PRD1
CONTAMINATED
UNCONTAMINATED
Microbe Growth/Inactivation
Growthviruses – no replication outside gutbacteria – growth possible, but unlikelyprotozoa – no growth outside gut
Microbe Growth/Inactivation
Inactivationviruses – mainly temperature-dependent
bacteria – lysis? predation?
protozoa – generally resistant to disinfection, so inactivation is slow?
Virus Inactivation
Virusesinactivation in solution
first-order decay
inactivation on surfaces?effect of strong attachment forces
1 2 3 4
ln C
/Cat
t
-8
-6
-4
poliovirus
aluminum oxide
pfu
3H RNA14C protein
number of extractions (24 h)
1 2 3 4
ln C
/Cat
t
-18
-16
-14
-12
-10
-8
-6
-4
-2aluminum metal
pfu
3H RNA14C protein
Virus Inactivation
Bacteriophage MS2Cape Cod sediment32P DNA35S protein capsidrapid loss of infectivityrelease of radiolabels time (days)
0 5 10 15 20 25 30
C/C
0
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
32P PRD1
35S PRD1
inf PRD1
Summary
Predicting microbe transportless difficult for viruses, protozoa cysts
no growth, inactivation simpler
more difficult for bacteriamotilityadhesion behavior motivated by growth, nutrientsgrowth, die-off more complicated
Bacteria should be target organism (?)least frequent collisions, motilitymay be complicated by longer-term adhesion strategies