denitrifying bioreactor midwestern cornbelt nutrient ...€¦ · change on the basin scale (outlet...

Denitrifying Bioreactor

Exploring N and P Sequestration in Bioreactors

Lu Zhang, Joe Magner, Gary Feyereisen, Rod Venterea, Bruce Wilson, John Nieber

Minnesota Water Resource ConferenceOct. 13th, 2015

N and P effects

http://www.breitbart.com/london/2015/02/09/global-warming-so-dishonest-it-makes-enron-look-like-a-paragon-of-integrity/

http://earthsky.org/earth/2011-gulf-of-mexico-dead-zone-smaller-than-scientists-predicted

http://savethewater.org/2012/07/14/usa-drinking-water-contamination-warning-iowa-perry-issued-a-drinking-water-warning-friday-nitrate-levels-high/

http://www.ecology.com/2011/11/01/paper-plastic-corn/ https://commons.wikimedia.org/wiki/File:Difference_DNA_RNA-EN.svg

Nutrient Reduction Strategy

DenitrificationNO3

− NO2− NO N2O N2

Phosphorus Reduction• Physical

– Filtration, membrane• Chemical

– Precipitation, adsorption• Biological

– EBPR

Bioreactor Advantages• Subsurface flow• Biostimulation• High reduction rate• Space

Bioreactor Locationshttp://artnsinks.apps.uri.edu/Atlas.html

Lab Study Design IDesign Schematic

• The two bioreactors simulatedhorizontal flow in the field with alength to width ratio of 16:1.

• The size of each bioreactor was0.98m (L) * 0.2m (W) * 0.67m (H).

• One had transparent sides toprovide view of the inside. Bothsides were covered with tarp toprevent light effect on microbialgrowth.

• Each chamber had two bafflesinside to guide the flow. Waterentered from the bottom on oneside and comes out from the topon the other side.

Lab Study Design I- continue Design Schematic

• Soil from the field site (mostlyClarion-Storden loams) was usedto cap the top. When water wasrunning, the soil on top wasalways saturated providinganaerobic condition inside.

• Nutrient water was prepared in thestorage tank and pumped into theoverhead tank. Six flow meterswere used to control the flow ratein each chamber.

• PVC containers were used tocatch outflow for nitrate probeuses.

Lab Study Design IIDesign Components

Variables• Alternative C sources: food source for

denitrifying bacteria– Woodchips- mix of hardwood– Biochar- “caramelized woodchips”– Corn cob

• Residence time – 24 and 8-hour

Controlled factors• Nitrate concentration: 21±1 ppm• Phosphorus concentration: 0.35±0.05 ppm• Temperature: around room temperature• Processes competing for available C:

oxygen availability

Biochar• Black carbon• Pyrolysis• Carbon sequestration-

slower cycling form• What we did-

caramelized woodchips

Lab Study MethodResearch Method

• Nutrient removal was evaluated by nitratereduction and phosphorus reduction.Nitrate concentration was measured on adaily-base. Orthophosphateconcentration was measured every threedays.

• Nitrous oxide production was measuredon a weekly base to determine the effecton greenhouse gases emission.

• The in-situ residence time will bedetermined by bromide tracer.

• Residence time was designed to be 24hours (50ml/min flow rate) for the first 3months and 8 hours (150 ml/min) for thenext 2 months.

• ANOVA test and student-t test were usedfor statistical analysis.

Lab Study- 24 hr N Reduction

Lab Study- 8 hr N Reduction

Nitrate-N Removal Summary

Nitrate-N removal rate stats

Nitrate-N removal rate stats cont.

Lab Study- 24 hr P reduction

Lab Study- 8 hr P reduction

Ortho-P removal rate stats

Ortho-P removal rate stats cont.

Lab Study- 24 hr N2O emission

Lab Study- 8 hr N2O emission

Summary• Woodchip: nitrate removal• Biochar: orthophosphate removal, N2O, longevity• Corn Cob: environmental resilience• Suggestion: multi-media treatment, combined

treatment system

AcknowledgementCommittee:• Joe Magner- Advisor• Gary Feyereisen• John Nieber• Bruce Wilson• Rodney Venterea

Funding:Minnesota Corn Growers

Association

Questions

Wetlands and Lakes Reduce Surface Water Nitrogen in Minnesota’s Agricultural Landscapes

Amy Hansen, Christy Dolph, Jacques FinlayUniversity of Minnesota

2015 Minnesota Water Resources Conference

Call for a 45% reduction in nitrogen loading to Mississippi River by 2045.

The Dead ZoneRobertson and Saad, 2011.

Total annual N yield

“Sides line up in Des Moines Water Works' nitrate lawsuit”

Source: Minnesota Pollution Control Agency, June 2013Nitrogen in Minnesota Surface Waters

Image from

microbew

iki.kenyon.edu

Denitrification Assimilation

Primary nitrate removal mechanisms

Can occur anywhere in surface water network. Occur at high rates in wetlands.

Image from

microbew

iki.kenyon.edu

Denitrification

Primary nitrate removal mechanisms

• Nitrate supply• Organic carbon

supply • Temperature• Oxygen status

Project questions

• What factors are limiting denitrification rates? Where? When?

• Does land use predict nitrate concentrations?

Le Sueur BasinJune, 2015

Chippewa, Cottonwood, Le Sueur BasinsJune, 2014

Basin spatial sampling

TDN = total dissolved nitrogen (~90% nitrate)DOC = dissolved organic carbon

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TDN

(mg/

L)

Drainage area (km2)

June 2015, Greater Blue Earth Basin

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DOC

(mg/

L)

Drainage area (km2)

June 2015, Le Sueur River Basin

Variability in ditches and streams

• Avg June tile• (2013-2015, n = 18)

• TDN = 20.6 mg/L• DOC = 3.4 mg/L

• June 2014, 3 basins• 72 sites• Drainage areas:

3 km2 to 5800 km2

• Crop land cover: 30% - 95%

Wetlands and lakes reduce nitrate

y = 19.7e-0.27x

R² = 0.57

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ate

(mg/

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% of drainage area that is lakes + wetlands

75% reduction in nitrate with 5% lakes and wetlands

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Nitr

ate

(mg/

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% cultivated cropland

June 2014, 3 basins

Enhanced nitrate uptake or reduced inputs?

BOTH reduced inputs and enhanced uptake

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ate

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% cultivated cropland

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ate

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% lakes + wetlands

R2 = 0.38p = 0.003

y = 1.83x + 4.5R² = 0.66

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DO

C (m

g/L)

% emergent wetlands (not lakes)

Le Sueur River Basin, June 2015

Emergent wetlands increase DOC

Ditch data

Nitrate over time

Nitr

ate

(mg/

L)

< 5% wetlands/lakes

5% to 20% wetlands/lakes

DOC over timeDO

C (m

g/L)

< 5% wetlands/lakes

5% to 20% wetlands/lakes

More dissolved organic carbon(non saturating) nitrate…

but

denitrification rates were not enhanced downstream of wetlands.

Why not? What, in intensively agricultural setting is limiting denitrification?

(temperature, organic carbon supply or nitrate supply)

Areal denitrification rates

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Area

l den

itirf

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rate

(mg-

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2/hr

)

Nitrate (mg/L)

Upper bound on denitrification was well described as nitrate limited and matched results from USA study of 56 (less disturbed) streams (Mulholland et al 2008, Bohlke et al. 2009)

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l den

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(mg-

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Nitrate (mg/L)

Areal denitrification rates

Spring denitrification rates

(water temperature is a secondary control, after N and C)

R² = 0.25p = 0.01

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DOC (mg/L)

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Nitr

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DOC (mg/L)

Nitrate supply limited DENDOC supply limited DEN

DOC:NO3 = 2 (molar)

Limiting resource switches

Nitrate limitedOrganic carbon limited

Applying limit switching to basin

Conceptualization of changes along reach

Nitrate

DOC

Maximum denitrification

rate

x, distance downstream

No wetland

Conceptualization of changes along reach

Nitrate

DOC

Maximum denitrification

rate

x, distance downstream

No wetlandWetland at x = 0

DOC:NO3 = 2

• Current land use are not resulting in a significant change on the basin scale (outlet concentrations ~ tile outlet concentrations)

• 75% reduction in nitrate concentration with 5% wetland/lake land use

• Denitrification rates are limited by organic carbon supply OR nitrate (limit switching)

• Opportunity to optimize placement of treatment wetlands by considering specific limiting resource

Conclusions

Field and laboratory assistance from:Adam Worm, Ailsa McCulloch, Allison Acosta, Andrea Keeler, Abby Tomasek, Ben Janke, Brent Dalzell, Erika Senjk, Evelyn Boardman, Jon Schwenk, Katie Kemmit, LeAnn Charwood, Maria Roubert, Morgan Andreson, Nick Omodt, Nolan Kleinjan, Sandy Brovold, Shelly Rorer, Vincent Knox

Funding: • NSF grant EAR-1209402 under the Water Sustainability and Climate Program

(WSC): REACH (REsilience under Accelerated CHange)

• NSF grant SEES-1415206 under the Water Sustainability and Climate Program (WSC): SEES Fellows: Leveraging the waterscape to increase agricultural landscape sustainability

Contact:Amy Hansen

hanse782@umn.edu

Contributors and funding

Internal wetland sampling

Lost Marsh Wetland281 acres

Emergent vegetationConstant depth (~ 0.3 m)

Maple River Wetland116 acres

Emergent vegetation/open waterVarying depth (max ~ 1.5 m)

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Nitr

ate

(mg/

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DOC (mg/L)

4 sample events• Inlet streamflow: 6 to 160 L/s• Data from 2 wetlands which

vary in:• Vegetative cover• Water depth• Surface area

• June-July 2015

DOC-NO3- coupling

Tight coupling of N:C suggests resource stoichiometric control of N uptake

Nitrogen Reduction in a Constructed Wetland and Wetland MesocosmsBrad Gordon, Josh Gamble, Chris Lenhart, Dean Current, and Nikol RossUniversity of MinnesotaOctober 13, 2015

Martin County

Overview• Introduction

• Objectives• Location• Design

• Methods• Results

• Nutrient Reduction Efficiency• Water Retention

• Mesocosm Experiment

Objectives• Assess effectiveness of an on-farm, edge-of-field, treatment

wetland in removing nitrogen (nitrate) and phosphorus (total phosphorus and orthophosphorus) from tile drainage water

• Assess biomass production and nutrient uptake of wetland vegetation to determine potential for bioenergy production and contribution to nutrient removal

• Determine the role of ecological components (soil and vegetation) in removing nitrogen from tile drainage water using wetland mesocosms

Location - Blue Earth River Basin

Roberts’ Farm

Constructed Wetland Design

• Three cell design• Separated by berms

• Water supplied from tile drainage

Total wetland: 0.54ac Each treatment cell: 45ft x 87.5ft (0.09ac) Total active treatment

0.27 ac

Soil Properties• All three cells > 40% clay• 2.0-2.77 % TOC

Soil Texture Analysis - Hydrometer Method

Sample ID

Sand(%)

Silt(%)

Clay(%)

TOC( % C )

Total N( % N ) C/N Ratio

Darwin's Wetland - Cell 1 (2013) 9.9/12.6 43.8/41.2 46.3/46.2 2.0-2.77%

Darwin's Wetland - Cell 2 5.0 53.8 41.3 2.0-2.77%

Darwin's Wetland - Cell 3 8.7 45.0 46.3 2.0-2.77%

Darwin's Wetland –Cell 1 (2014) 25.0 28.8 46.3 2.07 0.150 13.77

Corn field

Agri-Drain 1

Agri-Drain 2

Agri-Drain 3/ Outlet

Tile Drainage Inlet

• Level logger

• Level logger

• Area Velocity probe

• Area Velocity probe

Groundwater Well

Groundwater Well• Level logger• barometer

Drainage Area• 25 acres• Land Use History

• Drainage area farmed since before 1930’s

• West half of wetland farmed with row crops since around 1960

• East half has remained natural vegetation

70-acre restored pothole basin, 2004

Size of treatment wetland = 0.5 acre, 2013

Vegetation Biomass & composition

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2013 2014

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100%

Cell 1 Cell 2 Cell 3C4 grasses C3 grassesForbs Reed Canary grassOther weeds

Vegetation Mineral uptake

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N P

Kg H

a-1

2013 Cell 1 2013 Cell 2 2013 Cell 32014 Cell 1 2014 Cell 2 2014 Cell 3

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Kg H

a-1

NP

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Inlet AgriDrain 1 AgriDrain 2 Outlet

Volu

me

(m3 )

2014 Water Volumes

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Inlet AgriDrain 1 AgriDrain 2 Outlet

Volu

me

(m3 )

2013 Water Volumes

2%

74%

6%

18%

2013 Water Volume Outflow Distribution

ET Infiltrated Ponded Outlet

22%

9%69%

2014 Water Volume Outflow Distribution

Surface Outflow ET Infiltration

June 2014 Flood

0123456789

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Out

flow

(m3 /

15 m

inut

es)

2014 Outflow

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2014 Tile Inflow and Rainfall

Tile Inflow Volume(m^3/15 minutes)Daily Rainfall (inches)

Backflow observedduring flood

Reducing Peak Discharge

Lower flow in mid-late summer creates drier conditions than many constructed wetlands

2013 NO3-N removal• Limited vegetation cover• 356.7-377.2 lbs nitrate/nitrite-N

entered the wetland• ~39% (28-40%) Total Reduction (~143 lbs)

23%

38%1%

38%

0%Fate of Nitrogen in Wetland

Surface OutflowSubsurface OutflowSurface RemovalSubsurface RemovalPlant Uptake

2014 NO3-N removal• 379.0-647.6 lbs nitrate/nitrite-N

flowed into the wetland.• ~51% (45-61%) Total Reduction (~240 lbs)

18%

32%17%

32%

1% Fate of Nitrogen in Wetland

Surface OutflowSubsurface OutflowSurface RemovalSubsurface RemovalPlant Uptake

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2.5

2013 2014

Ort

hoph

osph

ate

(lbs.

)

Orthophosphate Reductions

InflowOutflow

76-86%Reduction inSurface flowOrthoP

Can it Reduce Phosphorus Discharge?

Can it Reduce Phosphorus Discharge?

0

0.5

1

1.5

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2.5

3

2013 2014

Tota

l Pho

spho

rus (

lbs.

)Total Phosphorus Reductions

InflowOutflow

68-69%ReductionIn surfaceflow Total P

Groundwater Measurements

Soil, Microbes, and Vegetation

Wetland Mesocosms• Study impacts of soil and vegetation on nitrogen reduction

• 3 wetland soils (remnant, 10-15 years old, 2 years old)• 3 wetland plant species (fringed sedge, cattail, reed canary grass)• DNA analysis of denitrifying microbes

0

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nosZ

Den

sity

(cop

ies/

g so

il)Denitrifying DNA in Various Wetland Soils

2 Years Old 10-15 Years Old Remnant

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DarwinNo Veg

KittlesonNo Veg

KittlesonSedge

KittlesonReed

Canary

Sarita NoVeg

SaritaSedge

SaritaReed

Canary

Perc

ent N

itrog

en R

educ

tion

Wetland Source + Plant Species

Mesocosm Nitrate Reductions

2 Years Old

10-15 Years Old Remnant

Conclusions• Infiltration and subsurface flow may play a large

role in nutrient reduction• Peak discharge to the creek is significantly

reduced during rain events• Surface water reduction of nitrogen improves

after the first growing season (1 to 17%)• These systems may work well in reducing

phosphorus discharged from tile drains• Microbial establishment may take >2 years• Managers must decide whether reed canary

grass is acceptable

Discussion• >50% N reduction is similar to other, larger

constructed wetlands but less than restored.• Can the easier adoption lead to more acres of

treatment wetlands and more reductions in total?• Can multiple reductions of ~240 lbs. N add up?

• Could the vegetation be used for biofuels?• How important is biodiversity in these wetlands?

Acknowledgements• Minnesota Department of Agriculture

• Heidi Peterson & Scott Matteson• Clean Water Fund• Martin Soil and Water Conservation District• Darwin and Sandy Roberts• University of Minnesota Faculty (BBE & Agronomy

departments)• Student assistants