Grantee Research Project Results
2003 Progress Report: Study of Particle and Pathogen Removal During Bank Filtration of River Waters
EPA Grant Number: R829011Title: Study of Particle and Pathogen Removal During Bank Filtration of River Waters
Investigators: Bouwer, Edward J. , Schwab, Kellogg J. , O'Melia, Charles R. , LeChevallier, Mark W. , Aboytes, Ramon
Institution: The Johns Hopkins University
EPA Project Officer: Page, Angela
Project Period: August 24, 2001 through August 23, 2004 (Extended to August 23, 2005)
Project Period Covered by this Report: August 24, 2002 through August 23, 2003
Project Amount: $536,316
RFA: Drinking Water (2000) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The objectives of this research project are to: (1) evaluate the merits of riverbank filtration (RBF) for removing/controlling pathogens in drinking water supplies; and (2) establish the merits of using the removal of particles and other potential water quality indicator parameters as surrogates for pathogen removal. RBF is a process that subjects river water to ground passage prior to its use as a drinking water source. Experience with RBF in Europe and more recently in the United States has demonstrated significant improvements in raw water quality, including removal of natural organic matter, biodegradable compounds, pesticides, microbes, and other contaminants. Little is known, however, about the extent to which RBF may serve to reliably remove Giardia, Cryptosporidium, and other pathogens (e.g., bacteria and viruses) from river water.
Progress Summary:
This research consists of: (1) field studies to document actual changes in pathogen and particle concentrations from rivers of similar source quality in the context of variations in subsurface travel distances, pumping rates, seasons, porous medium properties, and residence times; and (2) parallel laboratory column studies with aquifer media to evaluate relationships among the pathogens and potential surrogate parameters (including particle counts, turbidity, aerobic and anaerobic bacterial spores, bacteriophage, and other surface water indicators such as algae and plant debris) under various physical/chemical conditions and in both laboratory-prepared and natural river waters.
Field monitoring was completed at three study sites (Indiana-American Water Company on the Ohio River in Jeffersonville, IN; Indiana-American Water Company on the Wabash River in Terre Haute, IN; Missouri-American Water Company on the Missouri River in Parkville, MO) for various micro-organisms and other water quality parameters. Average monthly monitoring results (January 2002-July 2003) indicate greater than or equal to 0.8 log reduction of Bacillus (aerobic spores), greater than 4.6 log reduction of Clostridium (anaerobic spores), greater than 1.1 log reduction of male-specific bacteriophage, and greater than 2.9 log reduction of somatic bacteriophage concentrations in the bank-filtered waters relative to the river waters. Waterborne protozoan parasites Cryptosporidium sp. and Giardia sp. were detected in raw surface water samples from all three rivers, but never in any of the well waters.
Sediment for column studies was collected from the bank of the Potomac River in western Maryland. The sediment then was dried in batches in a low-heat oven (80°F) to minimize the effects of heat on the character of the sediment. When all of the batches were dry, the sediment was sieved to remove fine (< 0.106 µm) and coarse (< 1.7 mm) particles and combined into one large batch. No additional sediment manipulation or cleaning was carried out; thus, organic matter, plant debris, and a coating of very fine material remained on the processed sediment.
Sediment characterization (size distribution and total organic carbon analysis) indicated a fine sand (average d10 and d60 values for the sediment are 0.039 mm and 0.20 mm), with a fraction of organic carbon of approximately 0.4 percent by mass.
Potomac River sediment columns (30 cm long, 2.5 cm diameter) were packed with dry sediment, filled with CO2 to displace air in the pore spaces, and then flushed with pH 7 phosphate buffer for approximately 10 pore volumes before an experiment. Each experiment was conducted with a freshly prepared column. Column experiments with the viruses (bacteriophage MS2 and PRD1 and the human polio virus [PV]) suggest that MS2 may be useful as an indicator for PV. Under two ionic strength conditions, PV was retained to a greater extent than MS2. Escherichia coli and Cryptosporidium also were passed through columns. Retention of these larger (relative to the viruses) micro-organisms, however, was very high, such that neither organism could be detected in the column effluent. Removal of sediment from the column at the end of a run and analysis for presence of the bacterium indicated that E. coli was able to travel approximately 10 cm into the column. Therefore, future column studies will use shorter columns to ensure breakthrough of the E. coli and Cryptosporidium.
Future Activities:
We will continue to study the laboratory riverbank sediment columns that are challenged with mixtures of pathogens and particles. The solutions will be composed of a variety of chemical compositions (e.g., pH, ionic strength, calcium concentration, and total organic carbon content) to study the effect of different porewater chemistries on the relationships among the pathogens and potential surrogates (including latex microspheres, particle counts, bacteriophage, and aerobic and anaerobic bacterial spores). We will vary the flow rate, ionic strength, pH, and pathogen concentrations of the feed solutions to simulate periods of rainfall and increased pumping. We also will evaluate the relationships among the various microorganisms and other potential surrogate parameters by using log removals observed during column experiments.
Journal Articles:
No journal articles submitted with this report: View all 13 publications for this projectSupplemental Keywords:
pump and treat, water treatment, regulations, water quality, micro-organisms, health, waste, water, contaminated sediments, drinking water, environmental microbiology, hydrology, risk assessments, Giardia, aquifer characteristics, Clostridium, contaminated sediment, Cryptosporidium, disinfection byproducts, DBPs, drinking water contaminants, drinking water distribution system, drinking water treatment, ecological risk assessment, exposure, exposure and effects, groundwater disinfection, human exposure, human health risk, microbial contamination, microbial risk management, microbiological organisms, monitoring, particle counts, pathogens, river water, riverbank filtration, RBF, treatment, water quality parameters., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Water, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Environmental Microbiology, Environmental Monitoring, Physical Processes, Drinking Water, clostridium, groundwater disinfection, microbial contamination, pathogens, river water , monitoring, ecological risk assessment, disinfection byproducts, aquifer characteristics, microbiological organisms, water quality parameters, waterborne disease, exposure and effects, disinfection byproducts (DPBs), exposure, cryptosporidium , drinking water distribution system, particle counts, treatment, microbial risk management, human exposure, water quality, drinking water contaminants, drinking water treatment, Giardia, water treatment, riverbank filtrationProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.