Silage Runoff Treatment

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Proceedings available at: http://www.extension.org/67603

Agricultural filter strips are commonly used to treat runoff from agricultural farmstead areas. Many filter strips have been assessed in terms of surface water quality impacts but have failed to determine the fate of pollutants once they have infiltrated the soil subsurface. Two side-by-side filter strips plots were installed to assess the performance of and determine the fate of contaminants in a filter strip system. One of the two plots also contained a pretreatment system to facilitate nitrogen removal in an attempt to reduce nitrate leaching. Both plots were lined with an impermeable membrane to collect subsurface leachate as well as surface runoff. A mass balance could then be determined for these filter strip systems to assess the fate of nutrients and the ability of a low cost pretreatment system to reduce nitrate leaching.

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  • Leachate moisture from within forage, runoff moisture from precip.
  • Silage Runoff Treatment

    1. 1. Treatment of Silage Runoff with Vegetated Filter-strips Michael Holly University of Wisconsin - Madison Dr. Rebecca Larson, Advisor April 3rd, 2013
    2. 2. Introduction Silage  Fermented forage used as animal feed  Corn and alfalfa are commonly used forage for dairy operations Silage Leachate  Liquid by-product from ensiling forage  High nutrient concentration Silage Runoff  Flow of surface excess water over an area containing silage
    3. 3. Introduction Filter-strip is a long narrow buffer strip and are used in agriculture as a BMP  Used to treat agricultural wastewater  Slow the rate of runoff  Organic matter and other pollutants settled out  Commonly used for feedlot and silage runoff
    4. 4. Introduction Benefits  Silage runoff treatment study  Prescriptive loading  Seasonal operation and treatment  Pre-treatment design analysis  Optimized treatment  Protection of watersheds  Reduction in storage volume and hauling Pre-Treatment Design  Increase soil treatment depth  Provide alternating aerobic and anaerobic soil conditions to complete the nitrogen cycle
    5. 5. Methods Experimental Design  Two filter-strips used for silage runoff application  Pre-treatment design with alternating aerobic anaerobic conditions  Conventional design as a control  Reduced scale filter-strips 12’ by 4’  Applied with runoff at a 1:1 filter-strip to bunker pad ratio  25 year – 24 hour and 2 year - 24 hour design storms  3 runs of each design storm for both filter-strips  Application accomplished in October, November, and early December
    6. 6. Filter Treatment Design Top View Aerobic Section Gravel Anaerobi Tank c Section Retentio n Tank Novel Control Design Filter-strip Filter-stripEffluentCollection
    7. 7. Methods – Filter-strip Construction
    8. 8. Methods – Filter-strip Construction
    9. 9. Methods – Filter-strip Construction
    10. 10. Methods – Filter-strip Construction
    11. 11. Results - 25 year – 24 hour Concentrations BOD5 COD SRP TP Pre-Treatment Design Influent 27810 19796 176 239 Surface 16080 29280 153 222Subsurface 9420 13588 8 33 Control Influent 14100 20290 153 218 Surface NA NA NA NASubsurface 6233 9503 8 31Table 1 Influent, Surface, and Subsurface Nutrient Concentrations for 25 year – 24 hour Design
    12. 12. Results - 2 year -24 hour Concentrations BOD5 COD SRP TP Pre-Treatment Design Influent 19890 57360 309 449 Surface 14790 54000 288 397Subsurface 9075 19350 2 49 Control Influent 13890 40680 222 363 Surface 12060 36040 191 269Subsurface 8625 12445 8 56Table 1 Influent, Surface, and Subsurface Nutrient Concentrations for 2 year – 24 hour Design S
    13. 13. Results – Concentrations Influent  Influent to both pre-treatment and control filter-strips had a low pH (around 4) and were high in organic matter  Strength of runoff was greater in the influent applied to the 2-yr, 24-hr storm events Effluent  Subsurface effluent from both filter-strips had an almost neutral pH (around 6.5) and had lowered organic matter concentrations
    14. 14. Results – Concentration Reduction 25 year – 24 hourFigure 1 Average Reduction of Nutrient Concentrations Grouped by Storm and Filter-Stripfor 25 year – 24 hour design storm
    15. 15. Results – Concentration Reduction 25 year – 24 hour TP and SRP had the highest subsurface reduction in concentration for both filter-strips with 95% reduction for SRP and 85% reduction for TP NH3 was the next highest reduction for both filter- strips at 70% Pre-treatment had a BOD5 reduction around 60% and the control had a reduction about half or 30%
    16. 16. Results – Loading Reduction 25 year – 24 hourFigure 2 Average Reduction of Nutrient Loading Grouped by Storm and Filter-Strip for 25year – 24 hour design storm
    17. 17. Results – Loading Reduction 25 year – 24 hour 80% and higher loading reduction for SRP and TP Increase in NO3 concentrations for the pre-treatment design 60% and higher load reduction for all nutrients except NO3
    18. 18. Results Concentration Reduction 2 year – 24 hourFigure 3 Average Reduction of Nutrient Concentrations Grouped by Storm and Filter-Strip for 2year – 24 hour
    19. 19. Results Concentration Reduction 2 year – 24 hour TP and SRP had the highest subsurface reduction in concentration for both filter-strips with 96-97% reduction for SRP and 84-87% reduction for TP Pre-treatment and Control had a NH3 reduction in concentration around 26% Pre-treatment had higher BOD5 reduction in concentration at around 54%
    20. 20. Results - Loading Reduction 2 year – 24 hourFigure 4 Average Reduction of Nutrient Loading Grouped by Storm and Filter-Strip for 2 year – 24hour
    21. 21. Results - Loading Reduction 2 year – 24 hour Pre-treatment filter-strip had lower infiltration and higher surface runoff resulting in lower overall load reduction Load reduction for both designs applied with the 2 year – 24 hour design storm were less than 25 year - 24 hour  2 year – 24 hour applications had more surface runoff than 25 year – 24 hour surface applications Lower temperatures for 2 year – 24 hour applications resulted in higher surface runoff
    22. 22. Conclusions 80% and higher reduction in concentration of SRP and total P for both filter-strips applied with silage runoff 35-65% reduction in concentration of total solids, BOD5 and COD for both filter-strips 60% and greater load reduction for 25 year -24 hour design storm Novel Design  Higher BOD5 reduction  Increase of Nitrate within effluent Application of leachate near freezing can result in lower infiltration
    23. 23. Future Work Design storm loading to both filter-strip designs in spring and summer Expanding hydraulic detention times for aerobic and anaerobic sections within pretreatment Incorporation of a polishing step for increased denitirification in pre-treatment filter-strip design Modeling soil moisture and load reduction for filter- strip applications
    24. 24. Acknowledgements Dr. Rebecca Larson  Advisor Zach Zopp  Lab and Field Tech Shayne Havlovitz  Undergraduate Research Assistant Dr. John Panuska, Dr.  Committee Member Dr. KG Karthikeyan  Committee Member
    25. 25. Questions?

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