Drainage Contractor

Wood chips could help with denitrification

February 9, 2017  By Otago Daily Times

Untreated pine woodchips could be an affordable, low-tech solution in reducing nitrate levels in waterways.

Brandon Goeller, a PhD student at the School of Biological Sciences, the University of Canterbury in New Zealand, is testing the possibility that untreated pine woodchips will reduce nitrate levels as well as improve habitats for stream dwellers.   

As part of a three-year project, he has constructed woodchip-filled trenches called denitrification bioreactors and placed small string bags of the woodchips alongside, in or under waterways.

Woodchips could be beneficial in two ways: by providing the energy for microbes, which could remove nitrate, and by improving the habitat for in-stream invertebrates and fish.


Water chemistry is monitored upstream, in the woodchip area and downstream, measuring changes in nutrients, carbon and invertebrate and fish abundance.

Experimental results from North America and Europe indicate that the woodchips could remove up to 70% of the nitrate, Goeller says.


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