silage runoff characterization
DESCRIPTION
Proceedings available at: http://www.extension.org/67602 Silage leachate is a high strength waste which contributes to surface and groundwater contamination of various pollutants from runoff, direct leaching through concrete storage structures, and infiltration of runoff. Feed storage is required for the majority of dairy operations in the country (which are expanding in size and fed storage requirements) leading to widespread potential contamination. Limited data on silage leachate quality and treatment has made management and regulation based solely on observation. This project investigated three bunker silage storage sites to assess the water quality characteristics of silage leachate and runoff from various feed sources and surrounding environmental factors. Surface samples were collected from feed storage structures and analyzed for numerous water quality parameters. Using collected hydrologic data, contaminant loading was analyzed for various storm events and assessed for first flush effects and potential to impact handling and treatment designs. Determination of first flush provides essential data for separation of waste streams (high and low strength) to ease management in terms of operation and cost, reduce loading to treatment systems, and reducing the overall environmental impact.TRANSCRIPT
Silage Runoff Characteristics
Michael HollyUniversity of Wisconsin - Madison
Dr. Rebecca Larson, AdvisorApril 3rd, 2013
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
Introduction Silage Runoff Characteristics
Nutrient concentrations within silage runoff are variable
Dependent on the following factors Event size Seasonality Bunker condition Silage quantity
First-flush Analyzed in studies of urban runoff 80% of the total pollutant mass is transported within the
first 30% of the total volume (Bertrand-Krajewski el al.,1998)
Introduction Impacts Surfacewater
Phosphorus and nitrogen loading of watersheds Oxygen depletion Eutrophication and fish kills Low pH erodes structures and harms vegetation
Groundwater Conversion of organic nitrogen to nitrates Metal leaching Contamination of aquifers
Introduction Benefits of Silage
Runoff Characterization Knowledge of
relationship of loading throughout an event Reduction of
utilized manure storage and hauling
Improved treatment of silage runoff
Standards for
protection of watersheds
Introduction
Characteristic Raw Silage
Leachate
Residential
Wastewater
pH 3.5-5.5 6-9
P (mg/L) 300-600 5-20
Organic N (mg/L) 800-3,700 5-40
NH3 (mg/L) 350-700 10-50
BOD5 (mg/L) 12,000-90,000 100-400
Table 1 Typical Silage Leachate and Residential Wastewater Characteristics (McDonald et. al., 1991 and Burks, et al., 1994)
Introduction Horizontal Bunkers
Common type of silage storage for large dairies
Filled immediately after harvest
Forage is compacted and sealed
High potential for silage runoff
Methods Three Sites Sampled in WI over Spring, Summer
and Fall Arlington Agricultural Research Station (AARS) US Dairy Forage Research Center (DFRC) Private Producer
ISCO Automated Samplers Used for Sampling 2 Samples per bottle, 14 bottles total Flow activated samples Samples refrigerated within sampler
Analysis Completed at UW-Madison Alkalinity, NH3, BOD5, COD, NO2, NO2 + NO3, SRP,
pH, total P and total solids
Methods - AARS 530 head dairy 1.3 acre concrete
silage bunker 0.3 acres pad 1 acre bunker
Separate surface and subsurface collection system
Surface samples collected
Methods - AARS
Methods - DFRC 350 Head
Dairy 0.6 acre
asphalt bunker 0.2 acres
bunker pad 0.4 acres
bunker No subsurface
collection Surface
samples collected for analysis
Methods – DFRC
Methods - Private Producer 3,500 head dairy 1.7 acre bunker
0.5 acres bunker pad
1.2 acres bunker Surface and
subsurface were routed to the same culvert
Surface and subsurface was sampled
Methods – Data Analysis Average Storm
Nutrient Concentrations (mg/L)
Normalized Cumulative Pollution Load Curves
Dimensionless plot of the distribution of
pollutant load with volume
(Tabei et. al., 2004)
AARS – Storm Characteristics
No. Date Depth, inDuration,
h
Max intensity,
in/h
AverageIntensity,
in/h
MaxFlow,
cfs
AverageFlow,
cfs
1 11/2/2011 0.98 14.3 0.36 0.0698 0.639 0.046
2* 11/5/2011 1.5 24.2 0.72 0.0190 n/a n/a
3 4/26/2012 0.52 86.5 0.04 0.0056 0.857 0.085
4 5/30/2012 0.19 7.3 0.12 0.0267 0.699 0.236
5 7/18/2012 1.7 17.7 0.36 0.0972 2.544 0.253
6* 7/24/2012 0.64 7.7 0.92 0.0821 n/a n/a
7* 7/24/2012 0.56 46.9 1.16 0.0119 n/a n/a
8 8/2/2012 0.05 47.6 0.04 0.0010 1.818 0.016
9 8/7/2012 0.18 103.7 0.04 0.0001 3.774 0.230
Table 2 AARS Storm Characteristics
Results - AARS
Figure 1 Normalized Nutrients vs. Normalized Flow for AARS Grouped by Season
0.98’
0.52’
0.05’
1.7’
Results - AARS Maximum average storm nutrient concentrations
for NH3, BOD5 and TP took place during early spring
Minimum concentrations for COD and TP occurred in the summer
Storms three, five and eight illustrated an increase in concentrations with flow and a moderate delayed storm curve
A mild first flush occurred in the fall
DFRC – Storm Characteristics
No. Date Depth, inDuration,
h
Max intesity,
in/h
AverageIntensity,
in/h
MaxFlow,
cfs
AverageFlow,
cfs1 10/23/2011 0.19 7.283333 0.32 0.02375 0.628 0.0488182 11/2/2011 1.04 12.63333 0.48 0.152461 0.766 0.1918013 11/8/2011 1.14 17.33333 0.52 0.12 0.79 0.1467874 4/29/2012 0.76 12.25 0.4 0.057281 1.141 0.1674885 5/30/2012 0.28 6.983333 0.16 0.036894 0.348 0.0592836 7/18/2012 1.26 3.45 3.68 0.33767 0.684 0.1279777 7/24/2012 0.56 41.18333 0.84 0.013363 2.663 0.1943898 8/26/2012 0.38 21.78333 0.08 0.014462 1.536 0.0517889 9/6/2012 0.03 77.91667 0.04 0.00036 0.923 0.019656
10 10/9/2012 0.19 6.466667 0.08 0.026525 0.036 0.00928511 10/13/2012 0.33 12.8 0.08 0.026946 0.171 0.01905412 10/14/2012 0.28 20.21667 0.04 0.0126 0.45 0.03485213 10/25/2012 0.28 9.266667 NA NA 0.13 0.011481
Table 3 DFRC Storm Characteristics
Results - DFRC
Figure 4 Normalized Nutrients vs. Normalized Flow for DFRC for Select Storms
0.56’
1.26’
1.14’
0.52’
0.76’
0.19’
Results - DFRC
Figure 2 BOD5 and COD (mg/L) vs. Cumulative Flow for DFRC Storms One, Three and Ten
DFRC Sample Bottles October Event
Figure 3 Samples Bottles for DFRC Storm Number One
Results - DFRC Maximum average storm concentrations for NH3, BOD5,
COD, SRP, TKN, TP, and TS took place immediately after filling the bunker (large amount of feed on pad)
Minimum average storm concentrations for BOD5, COD, and SRP occurred during the summer with a large storm (high dilution effect)
In the fall runoff indicated strong decay of nutrient concentrations with accumulated flow
In the spring weak first flush
In summer with large storm events with high peak flows resulted in a more delayed nutrient loading
Private Producer – Storm Characteristics
No. Date Depth, inDuration,
h
Max intesity,
in/h
AverageIntensity,
in/h
MaxFlow,
cfs
AverageFlow,
cfs
1 4/29/2012 0.71 10.9 0.36 0.0639 15.412 1.378684
2 5/30/2012 0.53 38.81667 0.36 0.013731 8.433 0.706653
3 7/18/2012 0.82 11.91667 0.92 0.063687 32.945 3.081982
4 7/24/2012 0.75 8.116667 0.92 0.093755 7.472 0.726338
5 7/25/2012 0.49 6.766667 0.72 0.073995 4.864 0.943187
6 8/9/2012 0.44 6.9 0.68 0.065835 9.67 1.459689
7 8/16/2012 0.51 6.616667 0.64 0.079687 7.821 1.513229
8 8/25/2012 0.52 34.7 0.28 0.01508 7.821 0.665683
9 10/13/2012 1.74* 31.21667 NA NA 3.071 0.296152
10 10/17/2012 0.67* 14.95 NA NA 1.681 0.173354
11 10/18/2012 0.78* 145.4333 NA NA 0.894 0.014115
Table 4 Private Producer Storm Characteristics
Results – Private Producer
Figure 5. Normalized Nutrients vs. Normalized Flow for Select Private Producer Storms
0.51’
0.52’
0.53’
0.49’
Results – Private Producer Lag time in sample collection may have missed peak
concentrations
Max flow weighted nutrient concentrations for NH3, COD, TKN, TP, and TS took place during filling
Minimum flow weighted concentrations for NH3, BOD5, SRP, TP and TS were in the spring (a large portion of the feed and all corn silage had been used)
Some summer runoff events displayed a moderate delayed storm curve
Following filling in the fall, data demonstrated a moderate first flush
Conclusions Strongest first flush evidence took place in the fall
while strongest delayed storm curves were documented in the summer
Highest average storm nutrient concentrations were in the fall following filling and sometimes in the spring
Lowest average storm nutrient concentrations were in the summer
Highest concentrations among all sites was for DFRC’s initial samples in the fall (due to collection methods)
Acknowledgements Wisconsin Groundwater Coordinating Council
Funding Dr. Rebecca Larson
Advisor Zach Zopp
Lab and Field Tech Shayne Havlovitz
Undergraduate Research Assistant Dr. John Panuska
Committee Member Dr. KG Karthikeyan
Committee Member
References Burks, B.D. and M.M. Minnis (1994). "Onsite
Wastewater Treatment Systems. " Madison, WI: Hogarth House, Ltd.
McDonald, P., et al. (1991). The Biochemistry of Silage, Scholium International: 340.
Taebi, A. and R. Droste (2004). "First flush pollution load of urban stormwater runoff." Journal of Environmental Engineering and Science 3(4): 301-309.
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