Mycorrhizal Inoculated Biochar as an Active Filter of Dairy Wastewater

Jacob KelseyMaster’s candidate

Gund Institute for Ecological Economics and Ecological Design

Rubenstein School for Environment & Natural Resources,

University of Vermont

Felix WaiPhd Student

Rubenstein School for Environment & Natural Resources,

University of Vermont

Objectives:

• To conduct a greenhouse column experiment in order to quantify the ability of biochar and mycorrhizal fungi to uptake phosphorus from a pollutant sample, representative of dairy farm wastewater.

• Results will be used to discern the efficacy of biochar,

compared to other alternative substrates (i.e. steel slag), for incorporation into constructed wetlands.

Eutrophication and Phosphorus Pollution

Eutrophication and Phosphorus Pollution

• Across the United States, eutrophication of freshwater value lost costs approximately $2.2 billion per year

• Vermont Agency of Agriculture says 95% of small scale dairy farms (<200 cows) need to address nutrient leachate problems

• Total costs for Vermont small scale dairy farmers = $30.5 million

• ~$38,000/ small farm

Integrated Constructed Wetlands• Cleanse and manage water flow from farmyards• Integrate the wetland infrastructure into the farm

landscape, enhancing its biodiversity and beauty

Integrated Constructed Wetland Benefits

• Runoff and flood management

• Relative low cost and simplicity of operation

• Odor minimization

• Aesthetically pleasing

• Habitat and biodiversity enhancement

Integrated Constructed Wetland Limitations

• Farm constructed wetlands have a relatively large land requirement

• P uptake, compared to other nutrient treatment is often below desired levels, especially in colder climates

http://www.fairfieldcity.nsw.gov.au/upload/images/SmithfieldWetland3May2006.jpg

Alternative substrates for increasing P uptake/retention in constructed wetlands

http://www.cascadesteel.com/Images/manufacturing_process/02a.jpg

http://www.uvm.edu/~cwrc/Slag%20image.JPG

• Best candidates to date are mostly industrial by products• Of 57 materials tested for P adsorption, Electric Arc Furnace

Steel Slag was found to be the most effective• Vanadium and other heavy metal leaching possible

Biochar P uptake/retention• Physical-Chemical:

– Extremely high surface area– Increased Cation Exchange Capacity– Increased Anion Exchange Capacity

(Lehmann, et al., 2007)

Biochar P uptake/retention, cont.

• Biological:-Beneficial microbe refugia-Mycorrhizal Fungi proliferation-Increased mycorrhizal populations positively correlated with P

uptake

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Biochar P uptake/retention, cont.

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Hypothesis:

Mycorrhizal inoculated biochar mixed in a gravel substrate in a simulated planted constructed wetland will uptake more phosphorus than a control treatment of plants and gravel substrate alone.

Experimental Setup & Methods

Experimental Setup & Methods, cont.Treatment # 1 (control):• Gravel substrate • 20 non-mycorrhizal plants

Treatment # 2: • Gravel substrate• 20 mycorrhizal inoculated plants

Treatment # 4: • 50/50 gravel: biochar substrate • 20 mycorrhizal inoculated plants

Treatment # 3: • 50/50 gravel: biochar substrate• 20 non-mycorrhizal plants

Experimental Setup & Methods, cont.

Experimental Setup & Methods, cont.

Experimental Setup & Methods, cont.

Experimental Setup & Methods, cont.

Hypothesis Revisited

Time

P C

once

ntra

tion

• # 1) control • # 2) +mycorrhizae• # 3) +biochar• # 4) +biochar

+mycorrhizae

Preliminary Data

Phosphate Price Increase

Greenhouse potted plant experiments to test nutrient saturated, microbe inoculated biochar as soil amendment

Future Research

Future Research

Field application of biochar in an active filtering bioswale in combination with an Integrated Constructed Wetland at a small dairy farm in Vermont

Acknowledgments:

John ToddPaul SchabergBrian BibensPaul Stamets