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Controlling Microbial Pathogen in Surface
Runoff and Groundwater

Prasanta K. Kalita
Assistant Professor
Department of Agricultural Engineering
(217) 333-0945
Prasanta K. Kalita

Cryptosporidium parvum (C. parvum) and Escherichia coli (E. coli), generally found in dairy or cattle wastes, may impose a human health hazard when acquired directly via the fecal-oral route or indirectly as a waterborne infection.

Very little information is available on the C. parvum oocyst and E. coli survival and transport in surface and near-surface runoff. No information is available on the effects of various environmental factors, such as duration and intensity of precipitation, snowmelt, vegetation and land-use condition, watershed topography, and actual watershed management practices on pathogen loads from dairy/cattle farms to the water supply. Since these factors dominate pathogen transport rates to the environment, it is essential to characterize their roles for developing strategies and designing best management practices (BMP) for source control of microbial pathogens.

Our long-term goal is to control microbial contamination of water resources and provide a safe and sustainable environment for animal production facilities. The overall objective of this study is to understand microbial fate and transport processes, characterize critical environmental factors affecting microbial transport and control in runoff and near-surface runoff, and disseminate information that will prevent transport of microbial pathogens in the water supply. The central hypothesis of this study is that properly designed vegetative filter strips (VFS) can reduce the risk of microbial contamination in runoff from animal production facilities.

Vegetation can increase soil organic content and local microbial population sizes, enhance soil porosity and soil permeability, increase infiltration capacity, slow down near-surface flow velocities, and provide more organic-rich surfaces for microbial adsorption. Most of these factors tend to cause higher levels of immediate adsorption and increase attenuation of organisms in the plant/soil system. The effects of these factors on microbial fate and transport need to be quantified under different soil, climatic, and watershed conditions; only then can a VFS properly be designed with site-specific design criteria for maximum performance. It is also essential that this information be disseminated to interested parties effectively enough for adaptation of design guidelines for understanding and developing best management practices to control microbial pathogen from animal production facilities.

Experiments are being conducted at the University of Illinois in a laboratory set-up under a rainfall simulator. We have completed experiments under two rainfall intensities with three different slopes using one type of soil and vegetation . We have been comparing cryptosporidium recovery data in surface runoff and near-surface flow (subsurface flow at very shallow depth) and those for grassed and bare-ground conditions from a 3.65 m x 1.52 m x 30 cm inclined bed.

So far, we have obtained very encouraging results. For example, data for a 3 percent slope and one-time application of cryptosporidium and recovery after three successive rainfall events of 2.5 cm/hr at one-week intervals (one immediately after the cryptosporidium application and two re-rains) show that the recovery rate from the bare-ground surface was very high (more than 9 percent) with the first rain and more than 3.5 to 4.5 percent from the two successive rain events. However, the recovery from the brome-grassed bed was less than 1 percent from the first rain and none at all from the two successive rains. The recovery from the near-surface flow (30 cm below soil profile) was zero from both beds from all the rains. These results demonstrate very promising effects of vegetation in controlling cryptosporidium transport.

We are also looking at kinetics to understand pathogen transport rates within an event that will help in modeling fate and transport of microbial pathogens in the environment. However, we need to evaluate the effects of a series of rainfall, slope, vegetation, soil, and watershed conditions on pathogen fate and transport before developing design criteria for best management practices and disseminating the information. You can find the results of this study online at the following website: http://www.cvm.uiuc.edu/cryptoweb/.

The research team members are Prasanta Kalita, Jennifer Trask, Mark Kuhlenschmidt, Ted Funk, and Ronald Smith. This project is partly supported by the Illinois Council on Food and Agricultural Research (C-FAR).

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