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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Water Quality and Ecology Research » Research » Publications at this Location » Publication #413080
Research Project: Enhancing Long-Term Agroecosystem Sustainability of Water and Soil Resources Through Science and Technology

Location: Water Quality and Ecology Research

Title: Removal of microplastics from agricultural runoff using biochar: a column feasibility study

Author
item OLUBUSOYE, BOLUWATIFE - University Of Mississippi
item CIZDZIEL, JAMES - University Of Mississippi
item WONTOR, KENDALL - University Of Mississippi
item HEINEN, EDWARD - University Of Mississippi
item GRANDBERRY, TONY - University Of Mississippi
item BENNETT, ERIN - Trent University
item Moore, Matthew

Submitted to: Frontiers in Environmental Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2024
Publication Date: 6/10/2024
Citation: Olubusoye, B.S., Cizdziel, J.V., Wontor, K., Heinen, E., Grandberry, T., Bennett, E., Moore, M.T. 2024. Removal of microplastics from agricultural runoff using biochar: a column feasibility study. Frontiers in Environmental Science. 12:1388606. https://doi.org/10.3389/fenvs.2024.1388606.
DOI: https://doi.org/10.3389/fenvs.2024.1388606

Interpretive Summary: Microplastics are an emerging environmental contaminant that are causing water quality problems as well as the potential to damage wildlife. Biochar is the black carbon and ash resulting from burning material like wood chips and plant residue with extremely high heat. Biochar has been shown to effectively bind with and filter out many environmental contaminants. A laboratory study was conducted to see how well biochar would bind with microplastics found in runoff water collected from an agricultural field. Biochar bound up and reduced 87-93% of the microplastics in the water. We also determined that more than 90% of the different size microplastics were bound up in the biochar used in this study. The proof-of-concept research shows that farmers may be able to use biochar filters in their drainage ditches to bind microplastics and filter them out of the runoff water.

Technical Abstract: Plastics are extensively used in agriculture, but their weathering and degradation generates microplastics (MPs) that can be carried by runoff into water bodies where they can accumulate and impact wildlife. Due to its physicochemical properties, biochar has shown promise in mitigating contaminants in agricultural runoff. However, few studies have examined its effectiveness at removing MPs. In this study, we (1) assessed MP pollution (>30 µm) in runoff from a farm in the Mississippi Delta using micro-Fourier Transform Infrared (µ-FTIR) microscopy and (2) performed column studies to examine the effectiveness of biochar (pinewood and sugarcane) to remove MPs from aqueous solutions. Farm runoff contained an average of 237 MPs/L (range 27-609), with most particles identified as polyethylene, polyamide, polyvinyl chloride, polyurethane, acrylonitrile butadiene styrene, and polyarylamide. Biochar columns effectively removed MPs from runoff samples with reductions ranging from 86.6% to 92.6%. We also stained different sizes, shapes, and types of MPs with Nile red dye (to facilitate observation by fluorescence) and quantified their downward progress with multiple column volumes of water and wet/dry cycles. Smaller MPs penetrated the columns further, but =90% of MPs were retained in the ~20 cm columns regardless of their shape, size, and type, likely through physical entrapment and hydrophobic and electrostatic interactions. Overall, this proof-of-concept work suggests biochar may serve as a cost-effective approach to remove MPs from runoff, warranting further field studies.