Using local woodland resources to unlock the microbiome of bioreactors to improve water quality
Written by Clarisse Siababa
Woodchip bioreactors treat nitrate-laden tile drainage water and improve water quality. These bioreactors use woodchips as carbon substrates for denitrifying microorganisms, which reduce nitrate levels in the water before it is discharged into surface waters. In an anaerobic bioreactor chamber, microorganisms consume carbon released from the woodchips as an energy source to convert nitrate into harmless nitrogen gas. Microbial communities play a significant role in this denitrification process, so understanding the bioreactor microbiome is vital. Besides microbial composition, other factors affecting denitrification in woodchip bioreactors must be identified to enhance nitrate removal efficiency and optimize performance. Selecting different woodchip species as carbon sources can also improve nitrate reduction. In the Midwest, particularly in Iowa, there is an abundant supply of underutilized wood species that could be used as substrates for these bioreactors. Bioreactors provide an economically viable use for wood materials with low market value. However, there is still a gap in understanding how different woodchip species and their extractives affect the denitrification ability of the bioreactor microbiome.
To address this gap, this project aims to integrate research and extension work with Iowa Learning Farms to better understand how carbon and nitrogen are balanced in a bioreactor. This will be achieved by identifying and characterizing individual woodchip species and quantifying wood extractives that can influence bioreactor performance. The project will systematically investigate the physical, chemical, and biological properties of individual wood species, including wood extracts, the wood microbiome, and nitrate removal efficiency to identify the drivers and dynamics of nitrate removal in bioreactors. Ultimately, the goal is to create woodchip blends from high-performing wood species based on N removal, labile carbon availability, and local wood availability and supply. By understanding the shared benefits of woodland management and water quality conservation, the project aims to improve the quality and resilience of integrated agricultural and forest ecosystems.
Collaborators
Michelle Soupir, ISU;
William Beck, ISU;
Jacqueline Comito, ISU
Funding
USDA