Grantee Research Project Results
Final Report: An Integrated Approach to Characterize and Reduce Microbial Pathogens, Nutrients, and Sediment Transport in Runoff and Drinking Water Source
EPA Grant Number: R827589E03Title: An Integrated Approach to Characterize and Reduce Microbial Pathogens, Nutrients, and Sediment Transport in Runoff and Drinking Water Source
Investigators: Marchin, George L. , Erickson, Larry E. , Mankin, Kyle R. , Graham, David W.
Institution: Kansas State University
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through March 30, 2003
Project Amount: $147,821
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1998) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The objective of this research project was to characterize and reduce the impact of fecal bacteria, nutrients, and sediments on drinking water. Specifically, we evaluated the efficiency of vegetative filter strips in removing fecal bacteria, nitrogen, and phosphorus from feedlot runoff. To determine the overall efficiency, the following specific objectives were defined: (1) evaluate the survival/die-off of indicator fecal bacteria (fecal coliforms [FC], Escherichia coli, fecal streptococci [FS]) in dairy cow manure over a range of environmental temperatures and manure moistures common under field conditions; (2) determine the impact of soil moisture (extremely dry [2 percent water content, wt/wt], field capacity [25 percent water content, wt/wt], and saturated) on E. coli transport through soil columns; (3) develop and verify a model of E. coli transport through sand columns; (4) identify the effect of lag time and residual water saturation on the vertical migration of Cryptosporidium parvum oocysts under transient flow conditions experienced across vegetative filter strips receiving runoff from livestock areas; and (5) determine the effect of vegetative filter strips on fecal bacteria (FC, E. coli, FS), nitrogen, and phosphorus concentrations in feedlot runoff.
Summary/Accomplishments (Outputs/Outcomes):
Survival/Die-Off of Indicator Fecal Bacteria
Populations of FC, E. coli, and FS in fresh dairy manure were monitored with time at 4, 27, and 41°C and 30, 55, and 83 percent moisture content. Populations of almost all of the bacteria at 83 percent moisture increased during the first 3 days. This represents a continuation of bacterial growth dynamics from intestinal conditions and indicates that as-excreted estimates of manure bacterial populations may underestimate populations available for contamination of surface runoff a few days after excretion.
Overall, FS showed no significant die-off for any temperature or moisture
treatment. Temperature significantly affected die-off of E. coli and fecal
coliforms, with the highest rates at 41°C and lowest at 27°C, whereas
moisture content did not significantly affect die-off. These results suggest
that barnyard and feedlot management practices that allow manure temperatures
to elevate within reasonable summer environmental ranges will decrease the
bacterial pollution potential.
First-order kinetics adequately described E. coli die-off during the first
3 weeks, with rate coefficients that increased with temperature. Clearly, more
complex models are necessary to capture the bacterial growth dynamics for longer
periods. However, for a reasonable period after excretion, a simple first-order
model may capture changes in bacterial populations in manure, which would allow
improved population estimates for models describing bacterial transport from
barnyards, feedlots, and rangelands.
Bacteria Transport in Soil Columns
The results obtained at two soil depths (5 cm and 10 cm) showed that a large number of bacteria were removed by soil. The greatest average reduction in log10 number was found by columns at the field capacity (8.40), which was significantly greater than that for saturated columns (6.95). Saturated soil columns contributed the highest percentage of effluent samples that contained E. coli (53 percent), whereas the field-capacity columns had a significantly lower percentage (33 percent). Again, the highest number (log10 9.61) of E. coli recovered was from effluents of saturated soil columns. Removal was similar for the two depths, indicating that the surface soil layer is the most active in removing bacteria from infiltrated water.
The greatest variation and the highest recovered number of bacteria were found at soil depth of 20 cm and 35 percent soil moisture content (saturated condition). However, that was not the case for 10-cm soil columns. The highest average recovered number and the greatest variation was at soil moisture content of 27 percent (field capacity). The dry soil produced the lowest number recovered at the 10-cm soil columns.
Subsurface Bacteria Transport Modeling
The coupled one-dimensional advection-dispersion equation and second-order kinetic sorption equation can be solved properly with a Lax-Wendroff scheme. The discretization scheme was shown to be consistent, and the model ran stably. The decreasing root-mean-square error with refined grids showed the solution approached a particular solution. The mass balance errors were small and near zero. The coupled equations reasonably modeled the downward transport of bacteria in sand with differing fluid velocities and influent cell concentration. The goodness-of-fit measures (model efficiencies) were good in all of the velocities and concentrations.
C. parvum Transport in Sand Columns
The effect of residual moisture conditions and length of the lag period between water applications on C. parvum oocyst travel distance was evaluated in unsaturated sand columns. Column experiments were performed at residual saturation conditions of either 2.9 or 12.6 percent and a lag period of either 4 hours or 48 hours. The median travel distance for oocysts was 8.7 ± 1.1 cm at 12.6 percent residual water saturation versus 6.7 ± 0.8 cm at 2.9 percent residual water saturation. Lag time did not have a statistically significant effect on median travel distance. Carboxylated latex microspheres were moderately viable surrogates for oocysts based on the results of this limited study, but further evaluation is necessary. The study indicates that surface-applied C. parvum oocysts have rather limited mobility through uniform unsaturated sands experiencing high rates of transient water infiltration at 73 cm per hour.
Vegetative Filter Strips
Vegetative filter strips (VFSs), when used together with settling basins, can significantly reduce the quantities of micro-organisms and nutrients that flow into surface water from feedlots. For many rainfall events, there is no outflow from the VFS (i.e., complete infiltration retention of water and pollutants). However, depending on the soil moisture conditions before the storm and the magnitude of the storm, filter strips may not contain all of the runoff. The first 30 m provided most or all of the reductions found within the 150-m VFSs studied. Fecal bacteria removal by the VFSs was on the order of 1-log; on the site being studied, this provided an important level of protection and reduced surface-flow concentrations of fecal coliforms to below the 200 cfu/100 mL water quality standard.
An improvement in the care and management of the VFSs would help improve the pollutant removal efficiency. At Site A, vegetation is sparse and becoming increasingly overtaken by weeds. At Site B, cattle were grazed on the filter, and it was mowed while wet, leaving ruts from the equipment. The sedimentation basin is full of sediments and needs to be cleaned. At Site C, channels formed down the length of the filter. Spreader boards placed at 55-m (180-ft) intervals and connecting the two inlet pipes together with a spreader pipe helped, but after just 1 year, the soil around the spreader boards was eroded. Once eroded gullies were established, it was hard to fill those gullies. These were all possible reasons for a reduction in VFS removal efficiency.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 25 publications | 2 publications in selected types | All 2 journal articles |
---|
Type | Citation | ||
---|---|---|---|
|
Mankin KR, Barnes PL, Harner JP, Kalita PK. Vegetative filter strip effectiveness in reducing fecal bacteria and nutrients from feedlot runoff. Applied Engineering in Agriculture. |
R827589E03 (Final) |
not available |
|
Okoren C, Mankin KR, Kluitenberg G, Wang H. Technical note: a 1-D kinetic model of subsurface bacteria transport in sand. Water Resources Research. |
R827589E03 (Final) |
not available |
Supplemental Keywords:
biolog, carbon source oxidation, antibiotic resistance analysis, fecal streptococci, FS, nonpoint source pollution, NPS, discriminant analysis, Kansas, KS, bacteria, carbon nutrients, contaminant transport, drinking water contaminants, fecal contamination, microbial contamination, microbial pathogens, nutrient transport, runoff, sediment transport., RFA, INTERNATIONAL COOPERATION, Geographic Area, Water, POLLUTANTS/TOXICS, Ground Water, Water & Watershed, State, Water Pollutants, Drinking Water, Microorganisms, Watersheds, nutrient transport, microbial contamination, bacteria, contaminant transport, fecal contamination, runoff, sediment transport, microbial pathogens, Kansas (KS), water quality, watershed assessment, drinking water contaminants, carbon nutrientsProgress 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.