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.