Promising results for Silverstream denitrification wall trial

Nitrate levels in groundwater have been reduced at the site of an Institute of Environmental and Scientific Research led denitrification wall trial at Silverstream Reserve.

The 25-meter-long wall, which was installed eight weeks ago, is a world-first as denitrification walls haven’t been tested in fast-flowing gravel aquifer systems, like those found in Silverstream.

ESR says the denitrification wall acts as a groundwater filter. Woodchip mixed with gravel removes nitrate from groundwater passing through the wall.

Carbon from the woodchip provides a food source for bacteria within the ground to convert nitrate in groundwater to a harmless di-nitrogen gas (N2), which makes up 80 percent of the air we breathe.