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Woodchip BioreactorsOverview, Findings, and Future

Bryan Maxwell, Dr. Francois Birgand

References

Laura Christianson, PhD ; University of Illinois

Richard Cooke, PhD; University of Illinois

Louis Schipper, Phd; University of Waikato (NZ)

Yu Liu (NCSU PhD candidate under Dr. Mohammed Youssef)

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Nitrogen pollution: What are we doing about it?

Cover crops

Management and Treatment Tools

Application rates

Timing

Erosion control

Tillage patterns

Wetlands

Controlled drainage

Riparian buffers

Lagoon spray field

Woodchip bioreactors

Reducing Nitrogen

Woodchip Bioreactors : Why are they installed?Anaerobic conditions

+Organic Material

+Helpful BacteriaNitrogen in Water

NO3

Nitrogen in Gas> 99.9% as N2

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Woodchip Bioreactors : How are they installed?

Woodchip Bioreactors : How are they installed?

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Woodchip Bioreactors : How are they installed?

Woodchip Bioreactors : How are they installed?

Robertson, W. D., and L. C. Merkley. "In-stream bioreactor for agricultural nitrate treatment." Journal of Environmental Quality 38.1 (2009): 230-237.

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Woodchip Bioreactors : Where are they installed?

http://artnsinks.apps.uri.edu/index.html

Artificial N Sinks

Woodchip Bioreactors : ApplicationsFertilizer Runoff from Tile Drainage

http://www.striptillfarmer.com/articles/1438-strip-tilling-as-part-of-a-comprehensive-nutrient-management-strategy

110 feet long

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Woodchip Bioreactors : ApplicationsHydroponic Tomato Greenhouses (NZ)

580 feet long200-300 mg/L NO3

Schipper et al. (2010), Nitrate removal from three different effluents using large-scale denitrification beds

Woodchip Bioreactors : ApplicationsAquaculture Recirculating System

12 feet long35 mg/L NO3

Lepine, Christine, et al. "Optimizing Hydraulic Retention Times in Denitrifying Woodchip Bioreactors Treating Recirculating Aquaculture System Wastewater." Journal of Environmental Quality (2015).

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Woodchip Bioreactors : ApplicationsHog Lagoon Spray Field (Plymouth, NC)

Liu et al (2016, in review). “Using denitrifying bioreactors for nitrogen removal from subsurface drained grassland receiving liquid swine waste”

Woodchip Bioreactors : PerformanceApplication

Mean Water Temp ( F )

Inlet Conc. NO3 (mg/L)

Treatment Eff.(Bioreactor)

Treatment Eff.(Total)

Reference

Corn (Iowa)44 1.2 – 8.5 22 - 74% 22 -74% Christianson et al. (2012)

Corn/Soybean (IA)44 7.7 – 9.6 74 – 76 % 49 - 57 % Christianson et al. (2012)

Corn/Soybean (IA)44 9.6 – 15.2 50 – 68 % 27 - 33% Christianson et al. (2012)

Aquaculture (WV)57 20 – 80 45 – 99% (HRT!) 45 – 99% Lepine et al. (2015)

Corn/Soybean (IL)50 10 – 40 NA 3 - 81 % (HRT!) David et al. (2015)

Tomato Greenhouse (NZ)

66 150 – 350 30 – 79 % 30 – 79 % Schipper et al. (2010)

Lagoon Spray Field Free Drainage(NC) 61 0.5 – 16.8 84 – 95%

20 – 50% (75% < 0.5 mg/L)

Yu Liu et al. (in prep.)

Lagoon Spray Field Contr. Drainage(NC) 61 0.5 – 20.8 74 – 91%

45 – 85% (75% < 1.0 mg/L)

Yu Liu et al. (in prep.)

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Woodchip Bioreactors : Design

Factors affecting removal• HRT ( + )

• 6 - 8 hr HRT at 10-20% of peak flow (Christianson, 2010)• Sizing!!! ( + )• Temperature (+ )• DO at inlet ( - )• Geometry (long and narrow is good)• Inlet/Outlet Design?

Woodchip Bioreactors : Design

Developed by Richard Cooke et al., University of Illinois (available online)

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Woodchip Bioreactors : EconomicsReactor Structure Contractor Woodchips Supplies Total Costs Cost per Area

($/ha drained)

Greene Co. $2,750 $5,250 $1,245 $500 $9,745 $512.35

Hamilton Co. $1,640 Donated $2,400 $350 $4,390 $216.96

Iowa 1 $1,970 $1,800 $3,350 $560 $7,680 $316.30

Iowa 2 $1,270 $1,890 $3,000 $780 $6,940 $428.73

Iowa 3 $1,640 $5,030 $4,650 $500 $11,820 $194.72

Iowa 4 $1,480 $2,710 $2,520 $400 $7,110 $585.64

Christianson, Laura, et al. "Performance evaluation of four field-scale agricultural drainage denitrification bioreactors in Iowa." Transactions of the ASABE 55.6 (2012): 2163-2174.

Woodchip Bioreactors : EconomicsPractice

Mean N Reduction (from literature)(%)

Equal Annual Costs (stand. dev.)$ / kg N removed / year

Controlled Drainage 40.5 % $2.00 ($1.40)

Bioreactors 37.5% $2.10 ($0.90)

Wetlands 42.8% $2.90 ($0.80)

N Rate Reduction 14.5% -$1.60 ($0.00)

Spring N Application 9.3% -$14.00 ($12.00)

Cover Crop 23.1% $55.00 ($48.00)

Christianson, Laura, et al. "Performance evaluation of four field-scale agricultural drainage denitrification bioreactors in Iowa." Transactions of the ASABE 55.6 (2012): 2163-2174.

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Woodchip Bioreactors : Future Research

Phosphorus removal• Biochar• Iron Shavings (Guanghui Hua, SDSU)

Inlet/Outlet Design

Internal flow and kinetics • Prevent short-circuiting

Woodchip Bioreactors : Looking Inside

Lab-scale bioreactor with controlled inflow and network of monitoring wells

Multi-port sampling system with spectrophotometer

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Woodchip Bioreactors : Looking Inside

Woodchip Bioreactors : Looking Inside

Saturated Conditions Rewetting after 3 days drained

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Summary

Woodchip bioreactors are a useful tool for managing regional nitrogen pollution by treating “non-point source” pollution at the source, offering high treatment efficiency and comparable costs to other available technologies.