Silage Leachate: Waste Quality Assessment and Treatment

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7/1/2011 - 6/30/2013

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  • Rebecca Larson, UW-Madison
  • John Panuska, UW-Madison

Silage leachate is a high strength waste which contributes to groundwater contamination of various pollutants, including arsenic and nitrates, by direct leaching through concrete storage structures and infiltration of runoff. Feed storage is required for the majority of livestock operations in the state and country, leading to widespread contamination. Limited data on silage leachate quality and treatment has made management and regulation based solely on observation. The proposed project will assess the water quality characteristics of silage leachate from various feed sources and surrounding environmental factors. Surface and subsurface sample collection from feed storage structures will be analyzed for a number of parameters to assess water quality. Data analysis will have direct implications to current management and treatment of silage leachate, and control of parameters that have a direct effect on production and movement to waterways. Hydrologic data in combination with pollutant concentrations will provide the data needed to develop models for predictive tools which aid in management and treatment design. Direct management applications include determination of first flush volumes required for separation of waste streams to ease management in terms of operation and cost, reduce loading to treatment systems, and reducing the overall environmental impact. Finally, current filter strip treatment designs result in leaching of nitrates (lack of denitrifying or anaerobic zone) and metals (anaerobic soil conditions) as determined from recent research, indicating a need for a multi-step treatment system. An innovative proof of concept deign is to be evaluated with a multiple cell design to increase depth of treatment, and decrease nitrate and metal leaching. Assessment of surface and subsurface performance of the modified agricultural filter strip treatment system will provide additional information for future designs, and have the potential to apply a cost effective solution directly to current treatment practices. This would have a direct impact of groundwater and surface water contamination. In addition, the research proposed falls in line with continuing research for all land applied waste, having a larger impact on ground and surface water contamination through increased application.

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