70th SWCS International Annual Conference July 26-29, 2015 Greensboro, NC

1. Funded in part by the soybean checkoff
2015 SWCS
Conference
July 28, 2015
Greensboro, North Carolina
Improved Bioreactor Management through
Monitoring of Potential Contaminants
Keegan Kult – Iowa Soybean Association
Mark Dittrich – Minnesota Department of Agriculture
Dr. Robert Hudson – University of Illinois

2. Mr. Irrelevant
• “Mr. Irrelevant” is the title bestowed each year
upon the last pick of the annual National Football
League draft. ~Wikipedia

3. Questions to be answered
• When are contaminants produced?
• How much is being produced?
• How can bioreactors be manage/designed to
prevent production?

4. • Removes nitrate-N from
field tiles
• Divert water through wood
chips
• 30 – 100 acre drainage
areas
• Small footprint
• 10 – 15 year lifespan
Denitrifying Bioreactors
Image from John Petersen

5. Hamilton County
2010 2012 2013 2014 Total
Nitrate-NLoad,kg
0
100
200
300
400
500
600
Performance
LWFC
2012 2013 2014 Total
Nitrate-Nload,kg
0
250
500
750
1000
1250
Potential Load
Actual Load
Greene County
2009 2010 2011 2012 2013 Total
AnnualNitrate-NLoad,kg
0
250
500
750
1000
1250
TotalNitrate-NLoad,kg
0
500
1000
1500
2000
2500
3000
20 – 32% 12 – 76%
35 – 42%

6. • State Nutrient Reduction
Strategies
– Reduce nitrogen export by
45%
– Edge of field practices play
critical role
• ISA has been part of 22
installations
Implementation

7. NRCS Practice Standard
• Must meet 1 of following criteria
– Treat peak flow of 10 yr – 24 hr drain event
– 15% of peak flow from drainage system
– 60% of ave. annual flow
• 3 hour hydraulic retention time
• 30% annual load reduction
• Prevent stagnation

8. • Nitrous oxide (N20)
• Hydrogen sulfide (HS)
• Methylmercury
• Dissolved organic carbon
Potential contaminants

9. Redox ladder

10. Minnesota Testing
• Low flow/high temperature conditions
• 24 hour HRT
• 6 day pump tests
• 4 bioreactors
• Ideal conditions for methylmercury production

11. Minnesota sites
County City Year Installed Source
Contrib.
Area, ac
Bioreactor
dimension, ft
Jackson Windom 2009 Lake 58 75 x 10 x 6
Yellow Med. Granite Falls† 2012 River 20 75 x 10 x 6.5
Mower
Grand
Meadows
2011 Ditch 200 285 x 8 x 5
Stevens Morris‡ 2012 Well 20 60 x 20 x 6
† Four chambered control structure
‡ Treat all – No bypass

12. Methylmercury
Minnesota Bioreactors
Site
GMD GRF MRS WND
Methylmercurygeneratated,ng/L
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0

13. Iowa sites
Bioreactor Year Installed Drainage area, ac Bioreactor dimension,
ft
Greene 2008 47 50 x 25
Hamilton 2009 50 100 x 10
LWFC 2011 45 126 x 31

14. Methylmercury cont.
2012 Iowa Bioreactors
Site
Greene Hamilton LWFC
Methylmercurygenerated,ng/L
0.00
0.05
0.10
0.15
0.20
0.25
20 hr HRT
38 hr HRT
71 hr HRT

15. Illinois sites
Bioreactor Year Installed Drainage area, ac Bioreactor dimension, ft
Deland North Fall 2009 7 56 x 10
Deland South Fall 2007 3 93 x 10
Monticello Fall 2008 15 40 x 10

16. Methylmercury cont.
Illinois Bioreactors
2013
Feb Mar Apr May Jun
Methylmercurygenerated,ng/L
0.000
0.005
0.010
0.015
0.020
0.025
0.030
Deland North
Deland South
Monticello

17. Nitrous oxide
Minnesota Bioreactors
Site
GMD GRF MRS WND
AverageN2Oproduced,mg/L
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04

18. Nitrous oxide
Bioreactor
Measured IC
molarity change
Predicted IC
molarity change
Greene 0.62 0.94
Hamilton 1.03 1.28
LWFC 0.97 0.75
UWFC 0.50 0.67
LEC 2 0.55 0.56
4NO3
- + 5CH2O → 2N2(g) + 4HCO3
- + H+ +2H2O (denitrification)

19. Total organic carbon
Bioreactor Influent TOC, mg/L (n) Effluent TOC, mg/L (n)
Greene 3.1 (23) 6.4 (23)
Hamilton 3.4 (21) 5.7 (21)
LWFC 3.1 (24) 14.0 (23)
UWFC 3.2 (30) 11.4 (29)
LEC 2 3.9 (29) 13.7 (29)

20. • Observed MeHg ≤0.20
ng/L
• Evidence N2O production
possible
• TOC average ranges of 5.7
– 14 mg/L
Summary

21. • Match bioreactors to tiles
with consistent flows
• Periodic monitoring
• High nitrate tiles
• Remove stop logs in late
July
• Manage for at least 3 to 4
hr HRT
Recommendations

22. Recommendations cont.

23. Recommendations cont.

24. Acknowledgements
• Minnesota Department of Agriculture and the University of Minnesota
• University of Illinois with data collected by Dr. Richard Cooke and Todd Oleson
• Farmer partners
This material is based upon work supported by the Natural Resources Conservation Service, U.S.
Department of Agriculture, under number 69-3A75-11-190. Any opinions, finding, and
conclusions or recommendations expressed in this material are those of the authors and do not
necessarily reflect the views of the U.S. Department of Agriculture.

25. Questions?
• kkult@iasoybeans.com @ISA_EPS