PI: Raymond M. Hozalski
Co-PI and graduate student: David Wunder (Calvin College)
Funding agency: AWWA Research Foundation
Recent evidence indicates the widespread occurrence of numerous pharmaceutical compounds in surface waters around the world. Antibiotics occur in source waters used for drinking water production in the ng/L to µg/L concentration range. The health effects of exposure to low levels of pharmaceutical compounds remains in question, but the thought of unwittingly medicating ourselves simply by drinking tap water is disconcerting. Numerous U.S. water utilities rely on slow-rate biofiltration systems such as slow sand filtration and bank filtration for the treatment of surface waters. The use of these systems is even more pronounced in Europe and the developing world. Slow-rate biofiltration systems may be effective at removing antibiotics from water supplies, but the bacteria that are critical for SRBF treatment of water might be adversely impacted by the presence of antibiotics, alone or as mixtures.
The goals of this research are to elucidate the fate of antibiotics in SRBF processes and to evaluate the impact of antibiotics on biofilm bacteria and on process performance. Specific objectives include the following: (1) assess the impact of antibiotics on the development and activity of SRBF biofilm bacteria, (2) quantify the kinetics and equilibrium of antibiotic sorption onto biofilm, (3) assess the impact of antibiotics on SRBF performance and maturation time, and (4) determine antibiotic removal efficiencies and mechanisms in cores obtained from full-scale SRBF systems. Continuous-flow reactors will be used for the first two objectivesyielding antibiotic/biofilm sorption parameters (rate constants and partitioning coefficients) and data describing antibiotic impacts on: bacterial abundance and activity (substrate removal rate) and microbial diversity. We will scale-up our bench-scale studies to full-scale systems by experimenting with cores from several full-scale systems and by analyzing for antibiotics in water samples from the influents and effluents of those systems.
Illustration of slow sand filtration (left) and riverbank filtration (right) processes.
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