DRUGSTORE COWBOYS INC. PHOSPHATE ESTERS IN CHATTAHOOCHE RIVER FINAL PRESENTATION STATEMENT OF PROBLEM z z 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 z z USGS National Reconnaissance (1999-2000) CDC study at Chattahoochee River (summer 1999) DRUGSTORE COWBOYS INC. USGS study z z z z z 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 z Concentrations collected for over 100 compounds along 50 mile stretch of Chattahoochee River Basin, from Buford, GA to Atlanta, GA z Measurements taken for WWTP discharge and both intake and outflow at drinking water treatment plants (DWTP) Revealed Significant Presence of OCWs z 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 z z z z z 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 z 3 Phosphate Esters: z Tributyl phosphate z Tri (2-butoxyethyl) phosphate z Tri (2-chloroethyl) phosphate Comparable structure and associated properties z Relatively high level of detection in CDC-USGS data z DRUGSTORE COWBOYS INC. Tributyl Phosphate (TBP) z z z z z z 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) z Properties z Formula: z MW (g/mol): 398 n-BuO CH 2 CH 2 Chemical Structure: Uses: Flame Retardant,household product Annual Production:6000 tonnes in 2000 z z z 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) z z z z z z 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 z z z 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 z z z 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 z z 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 z Wastewater discharge only phosphate source considered z Flows based on average January stream gage readings z Average CDC concentrations combined with river flow to determine concentration in river z Allows for estimation of rate of removal from natural sinks DRUGSTORE COWBOYS INC. Estimation of annual loading z 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 z 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 z DRUGSTORE COWBOYS INC. Potential Natural Removal Processes z z z z z z z Sorption Volatilization Photodegradation Hydrolysis Bioaccumulation Biodegradation Time Scale: 1-1.5 days DRUGSTORE COWBOYS INC. Estimates of influence of each process z Our simple calculations provide insight in the removal magnitude DRUGSTORE COWBOYS INC. Discussion of Estimates: What they reveal z z 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 z z z z 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 z Pristine conditions upstream DRUGSTORE COWBOYS INC. A troubled river z The situation near Atlanta is quite different z I AM MISSING PICTURE DRUGSTORE COWBOYS INC. Sampling and Lab work z z z z 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 z z z z z z 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.