DRUGSTORE COWBOYS INC.
PHOSPHATE ESTERS IN
CHATTAHOOCHE RIVER
FINAL PRESENTATION
STATEMENT OF PROBLEM
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Occurrence and fate of Organic Wastewater
Contaminants (OCWs) in Chattahoochee River
Explore fate and transport in both natural
processes and drinking-water treatment
processes
DRUGSTORE COWBOYS INC.
Existing Studies
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USGS National Reconnaissance (1999-2000)
CDC study at Chattahoochee River (summer
1999)
DRUGSTORE COWBOYS INC.
USGS study
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Sampled 139 streams in 30 states
Sampled for 95 Organic Wastewater Contaminants
OCWs present at ~80% of streams sampled
Very low concentrations (order of ng/l) but
surprisingly high because most are man made
compounds
Persistence in natural environment
DRUGSTORE COWBOYS INC.
CDC study
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Concentrations collected for over 100 compounds along
50 mile stretch of Chattahoochee River Basin, from
Buford, GA to Atlanta, GA
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Measurements taken for WWTP discharge and both
intake and outflow at drinking water treatment plants
(DWTP)
Revealed Significant Presence of OCWs
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DRUGSTORE COWBOYS INC.
Area of Study
Cumming
9
Chattahoochee
River
watershed
1
Cr
ee
k
Buford Dam
Bi
g
Big Creek
watershed
Roswell
4
65
Ch
3
11
10
7
8
Peach
tree
0
0
2
2
2
Croo
ked
Cr
r
Urban land use
Downstream of poultry
processing-plant discharge
1. Kelly Mill Branch
Water pollution control plant
2 Crooked Creek
3 Johns Creek
6 Big Creek
9 City of Cumming
Drinking-water intake and
Creek
4
4
e
che
o
o
h
atta
e
Riv
6 Miles
6 Kilometers
DRUGSTORE COWBOYS INC.
Drinking-water treatment plant
4 and 5 City of Roswell
7 and 8 City of Atlanta
10 and 11 Cobb County
Magnitude of problem
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OCWs are currently present at low concentrations
but their release in the environment is expected to
continue
Unknown effects in human health, potential risk of
long term exposure
Pharmaceutical compounds and their metabolites
gravest fear
Hot current scientific problem
On going research Through-out the world
DRUGSTORE COWBOYS INC.
Selection of Phosphate Esters
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3 Phosphate Esters:
z Tributyl phosphate
z Tri (2-butoxyethyl) phosphate
z Tri (2-chloroethyl) phosphate
Comparable structure and associated properties
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Relatively high level of detection in CDC-USGS data
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DRUGSTORE COWBOYS INC.
Tributyl Phosphate (TBP)
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Properties
Formula:
C12H27O4P
MW (g/mol): 266
Chemical Structure:
Uses: Flame
Retardant,Plastisizer
Annual Production:2500-4000
tonnes in 1985
DRUGSTORE COWBOYS INC.
O
n-BuO
P
OBu-n
OBu-n
Tri (2-butoxyethyl) phosphate
(TBEP)
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Properties
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Formula:
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MW (g/mol): 398
n-BuO
CH 2 CH 2
Chemical Structure:
Uses: Flame
Retardant,household product
Annual Production:6000
tonnes in 2000
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C18H39O7P
DRUGSTORE COWBOYS INC.
O
O
P
O
CH 2
O
CH 2
CH 2
CH 2
OBu-n
OBu-n
Tri (2-chloroethyl) phosphate
(TCEP)
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Properties
Formula:
C8H12PO4Cl3
MW (g/mol): 278
Chemical Structure:
Uses: Flame
Retardant,Plastisizer
Annual Production: <4000
tonnes in 1998
DRUGSTORE COWBOYS INC.
O
ClCH 2
CH 2
O
P
O
CH 2
O
CH 2
CH 2 Cl
CH 2 Cl
CDC data on phosphate esters
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Present at detectable conc’s in most
sampling sites
Significant persistence in the river
environment
Present even after drinking-water treatment
DRUGSTORE COWBOYS INC.
CDC data on phosphate esters
DRUGSTORE COWBOYS INC.
Drugstore Cowboys Inc. initial
approach to the problem
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Create a “black box” mass balance model
Determine the magnitude of each natural
attenuation process occurring
Identify the most promising ones and
research them in depth
DRUGSTORE COWBOYS INC.
Chattahoochee River
Characteristics
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General Description:
z Length of 48 miles from Buford to Atlanta, GA
z Landscape predominantly forestland
z Flow oscillates with power generation schedule at Buford Dam
(550 to 7500 cfs, average 2100 cfs)
Flow Characteristics
z Flow rates determined from USGS stream gages stationed
along Chattahoochee and several tributaries
z WWTP and DWTP flows based on average operation
DRUGSTORE COWBOYS INC.
Black Box Model
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Wastewater discharge only phosphate source
considered
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Flows based on average January stream gage
readings
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Average CDC concentrations combined with river
flow to determine concentration in river
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Allows for estimation of rate of removal from natural
sinks
DRUGSTORE COWBOYS INC.
Estimation of annual loading
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Approximate loading into Chattahoochee River:
z TBP and TCEP in USA: 2000 m3/year
z TBEP in USA: 3000 m3/year
z Population of Atlanta area: 2.8 million
z Population of United States: 280 million
z Thus, 20 - 30 m3/year produced of each chemical
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Average volumetric flow of Chattahoochee River:
20 x 108
m3/year
Conclusion: ~10 - 15 ppb in river
z Actual concentrations are .1 – 2 ppb
z Overestimation due to all production going into streams
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DRUGSTORE COWBOYS INC.
Potential Natural Removal
Processes
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Sorption
Volatilization
Photodegradation
Hydrolysis
Bioaccumulation
Biodegradation
Time Scale: 1-1.5 days
DRUGSTORE COWBOYS INC.
Estimates of influence of each
process
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Our simple calculations provide insight in the removal
magnitude
DRUGSTORE COWBOYS INC.
Discussion of Estimates:
What they reveal
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The only processes that seem to affect the
phosphate esters are biodegradation and
sorption to sediments
Especially for biodegradation great
uncertainty exists and further sampling is
needed. But it is the most promising one
DRUGSTORE COWBOYS INC.
In situ investigation
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A visit to Chattahoochee river was decided that is
needed
Provide Additional sampling tailored to exploring role
of major degradation processes in phosphate
removal
Drinking water treatment plant exploration
Meet with CDC staff to discuss data collection
methods and results from their testing
DRUGSTORE COWBOYS INC.
A troubled River
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Pristine conditions upstream
DRUGSTORE COWBOYS INC.
A troubled river
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The situation near Atlanta is quite different
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I AM MISSING PICTURE
DRUGSTORE COWBOYS INC.
Sampling and Lab work
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Extensive Sampling was done
Carefully chosen sampling locations and
protocol
Sampling done in a way to reveal
biodegradation effects
Significant amount of work done at our “state
of the art” laboratory
DRUGSTORE COWBOYS INC.
Sampling and Lab work
DRUGSTORE COWBOYS INC.
Valuable Experiences
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Nobody realized at first the problems associated
with field work and sampling
Great logistical problems
Countless possible sources of experimental error
The most sophisticated sampling project undertaken
up to now from MEng
Overall highly successful
Without Pete Shanahan’s help it couldn’t have been
done
DRUGSTORE COWBOYS INC.