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Sorption of Escherichia coli in Agricultural Soils Influenced by Swine Manure Constituents
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: Transactions of the ASABE. 55(1): 61-71. (doi: 10.13031/2013.41255) @2012
Authors: J. A. Guzman, G. A. Fox, C. J. Penn
Keywords: Attached bacteria, Bacteria transport, Escherichia coli, Fecal bacteria, Sorption, Swine effluents
Sorption of fecal bacteria in soils treated with swine effluents as a fertilizer involves complex mechanisms that are functions of the effluent constituents, soil colloid properties, and fecal bacteria population. Swine effluents contribute significant solutes and organic compounds during application and potentially increase the soil solution pH and ionic strength when in contact with soils. The objective of this research was to investigate sorption of fecal bacteria on soils treated with swine effluents and to derive a fecal bacteria sorption model based on soil properties. Sorption of Escherichia coli was investigated using a series of artificial and natural soils treated with swine effluent at varying dilution ratios (i.e., manure effluent concentrations). Note that this research conducted sorption tests based on multiple strains of the E. coli population in the manure effluent, as opposed to a specific E. coli strain. Fecal bacteria in swine effluents mainly consisted of attached bacteria as opposed to free cells in suspension (i.e., planktonic form). Sorption of surface-bonded E. coli appeared to be controlled by processes occurring in the substrate (i.e., surfaces to which the bacteria attached) as a function of the soil solution pH and ion exchange. For soils up to 30% clay content and 3.0% total carbon content, nonlinear equations characterized the sorption of E. coli in the artificial and natural soils. For soils with percent clay less than or equal to 11%, total carbon played a primary role in the estimated sorption of fecal bacteria. For soils with clay percentages larger than 11% and lower than 30%, sorption of fecal bacteria was directly correlated to amorphous aluminum and iron concentrations, percent clay, and total carbon. In addition, dispersion resulting from alkalinity buildup due to adding effluent to the soils in the presence of soil organic matter decreased observed sorption of E. coli in some cases, especially at higher effluent ratios. Experimental data indicated that predictions based exclusively on the percent clay content overestimated sorption of E. coli on soils treated with swine effluent in most soils. Manure effluent concentration, the presence of attached bacteria, and soil dispersion under high effluent concentrations should be considered when modeling fecal bacteria transport in soils. Future environmental research should be conducted with actual manure sources and multiple strains of an E. coli population.(Download PDF) (Export to EndNotes)