Alternative Treatments to Minimize Water Pollution From Open Animal Feedlots
Iowa State University Extension , 2006
Woerner, B., Lorimor, J.
Current rules for CAFOs will achieve approximately 95% control of open feedlot runoff in most of the U.S. (Anschutz et al., 1979). While complete containment has been the rule for 30 years, livestock producers are interested in utilizing alternative treatment systems, rather than complete containment and land application, in order to minimize capital expense and management requirements. Several systems have been researched since the late 1960s including solids settling, vegetative filter strips, soil infiltration areas, and constructred wetlands. This paper reviews the research literature for each of these alternative treatment technologies. While variabilityis an inherent part of all biological systems, this review shows that piggybacking two or more technologies selected on a site specific basis will provide equivalent pollution reduction to complete containment. Proper construction and management is necessary to achieve the "functional equivalency" desired. Fecal Coliform Removal: More research on FC removal by VFS is needed. Reported values vary greatly and few studies have been conducted on large scale VFS. Fajardo (2001) report FC removal rates between 64% and 87% when using small scale simulated runoff events with stockpiled manure. Lim (1997) found that all fecal coliforms were removed in the first 6.1m of a VFS used to treat runoff from a simulated pasture. Average FC removal in the studies reported here was 76.6%.