TY - JOUR
T1 - Transport and removal of spores of Bacillus subtilis in an alluvial gravel aquifer at varying flow rates and implications for setback distances
AU - Oudega, Thomas J
AU - Lindner, Gerhard
AU - Sommer, Regina
AU - Farnleitner, Andreas H
AU - Kerber, Georg
AU - Derx, Julia
AU - Stevenson, Margaret E
AU - Blaschke, Alfred P
N1 - Funding Information:
This work was supported by the Vienna Science and Technology Fund (WWTF) (Grant ESR17–070, “Giardy”, and Grant ESR20–013, “Faterisk Aqua”), the Austrian Science Fund (FWF) as part of the DKplus (Vienna Doctoral Program on Water Resource Systems, W1219-N22) and the Austrian Academy of Sciences (Grant JF_2019_15, “Swim City”). M.E.S. received funding from the Austrian Science Fund (FWF) (Grant T970-N29). Additional support came from the Vienna Water Resource Systems Project (ViWa 2020+), a research cooperation between Vienna Water (Municipal Department 31) and the ICC Water & Health.
Funding Information:
Julia Derx, Gerhard Lindner reports financial support was provided by Vienna Science and Technology Fund. A.P. Blaschke reports financial support was provided by Austrian Academy of Sciences. Margaret Stevenson reports financial support was provided by Austrian Science Fund. Thomas Oudega, Gerhard Lindner reports equipment, drugs, or supplies was provided by Vienna Water Resource Systems Project.
Funding Information:
This work was supported by the Vienna Science and Technology Fund (WWTF) (Grant ESR17–070, “Giardy”, and Grant ESR20–013, “Faterisk Aqua”), the Austrian Science Fund (FWF) as part of the DKplus (Vienna Doctoral Program on Water Resource Systems, W1219-N22) and the Austrian Academy of Sciences (Grant JF_2019_15, “Swim City”). M.E.S. received funding from the Austrian Science Fund (FWF) (Grant T970-N29). Additional support came from the Vienna Water Resource Systems Project (ViWa 2020+), a research cooperation between Vienna Water (Municipal Department 31) and the ICC Water & Health.
Publisher Copyright:
© 2022
PY - 2022/12
Y1 - 2022/12
N2 - To guarantee proper protection from fecally transmitted pathogen infections, drinking water wells should have a sufficiently large setback distance from potential sources of contamination, e.g. a nearby river. The aim of this study was to provide insight in regards to microbial contamination of groundwater under different flow velocities, which can vary over time due to changes in river stage, season or pumping rate. The effects of these changes, and how they affect removal parameters, are not completely understood. In this study, field tracer tests were carried out in a sandy gravel aquifer near Vienna, Austria to evaluate the ability of subsurface media to attenuate Bacillus subtilis spores, used as a surrogate for Cryptosporidium and Campylobacter. The hydraulic gradient between injection and extraction was controlled by changing the pumping rate (1, 10 l/s) of a pumping well at the test site, building upon previously published work in which tracer tests with a 5 l/s pumping rate were carried out. Attachment and detachment rate coefficients were determined using a HYDRUS-3D model and ranged from 0.12 to 0.76 and 0-0.0013 h-1, respectively. Setback distances were calculated based on the 60-day travel time, as well as a quantitative microbial risk assessment (QMRA) approach, which showed similar results at this site; around 700 m at the highest pumping rate. Removal rates (λ) in the field tests ranged from 0.2 to 0.3 log/m, with lower pumping rates leading to higher removal. It was shown that scale must be taken into consideration when determining λ for the calculation of safe setback distances.
AB - To guarantee proper protection from fecally transmitted pathogen infections, drinking water wells should have a sufficiently large setback distance from potential sources of contamination, e.g. a nearby river. The aim of this study was to provide insight in regards to microbial contamination of groundwater under different flow velocities, which can vary over time due to changes in river stage, season or pumping rate. The effects of these changes, and how they affect removal parameters, are not completely understood. In this study, field tracer tests were carried out in a sandy gravel aquifer near Vienna, Austria to evaluate the ability of subsurface media to attenuate Bacillus subtilis spores, used as a surrogate for Cryptosporidium and Campylobacter. The hydraulic gradient between injection and extraction was controlled by changing the pumping rate (1, 10 l/s) of a pumping well at the test site, building upon previously published work in which tracer tests with a 5 l/s pumping rate were carried out. Attachment and detachment rate coefficients were determined using a HYDRUS-3D model and ranged from 0.12 to 0.76 and 0-0.0013 h-1, respectively. Setback distances were calculated based on the 60-day travel time, as well as a quantitative microbial risk assessment (QMRA) approach, which showed similar results at this site; around 700 m at the highest pumping rate. Removal rates (λ) in the field tests ranged from 0.2 to 0.3 log/m, with lower pumping rates leading to higher removal. It was shown that scale must be taken into consideration when determining λ for the calculation of safe setback distances.
UR - http://www.scopus.com/inward/record.url?scp=85138821008&partnerID=8YFLogxK
U2 - 10.1016/j.jconhyd.2022.104080
DO - 10.1016/j.jconhyd.2022.104080
M3 - Journal article
C2 - 36179584
SN - 0169-7722
VL - 251
SP - 104080
JO - Journal of Contaminant Hydrology
JF - Journal of Contaminant Hydrology
M1 - 104080
ER -