Woodchip Bioreactor Research and Consulting

The Freshwater Institute Bioreactor Project

Bioreactor page-David Donohue-150x150At The Conservation Fund Freshwater Institute, we have invested significant effort into research on the engineering-based design of enhanced-denitrification bioreactors, or “woodchip bioreactors”, to reduce point and non-point sources of nitrate from multiple types of agriculture and industry. On the research front, we aim to improve the nitrate-removal ability of woodchip bioreactors, and on the engineering consulting-front, we work with a number of partners on bioreactor installation and monitoring to mitigate nitrate output across the country.

A conventional woodchip bioreactor design consists of an excavation, filled with an organic carbon source, through which nitrate-laden water is routed. The maintenance of saturation precipitates the anoxic (sans oxygen) conditions required by the denitrifying bacteria to convert nitrate in the water to nitrogen gas, thus cleaning the water.

Woodchip Bioreactor

Conventional woodchip bioreactor for treatment of nitrate in subsurface agricultural drainage (From Christianson and Helmers, 2011)

Currently, our bioreactor research involves four “pilot-scale” (test) reactors that allow the comparison of a range of hydraulic retention times for treating aquaculture wastewater. This work also aims to quantify the potential for woodchip clogging due to this specific type of wastewater. This 1:10 ratio pilot-scale work is leading up to the instillation of full-sized woodchip bioreactors at the Freshwater Institute.

FI Denitrification-IA Soybean Association, Joe Murphy-512x339

A bioreactor is filled with woodchips as part of the instillation process


Freshwater Bioreactor

The conceptual design of six full-size woodchip bioreactors planned for instillation at the Freshwater Institute. The strength of this replicated approach facilitates advancement of the design science of woodchip denitrification systems because this method will allow not only replicated evaluation of nearly full-scale systems, but also simultaneous comparison of multiple treatments.


Bioreactor testing

Dr. Laura Christianson and intern Christine Lepine testing monitoring dissolved oxygen in a pilot-scale woodchip bioreactor

For more information about woodchip bioreactors, please visit our publications page or contact Dr. Laura Christianson.