In addition to the application for ex situ treatment of groundwater in
bioreactors, solid-phase denitrification has been also used for in situ
groundwater remediation by direct treatment of groundwater into the
aquifer without water extraction. In situ denitrification is a very attractive
alternative due to the relative simplicity, low investment and operational
costs, but it is difficult to control. The permeable reactive barrier
is major technique for in situ groundwater treatment. The studies by
Gibert et al. (2008) showed that softwood was the suitable carbon
source for denitrification in a permeable reactive barrier, with a nitrate
removal of more than 98% and a denitrification rate of
0.067 mg N L−1 d−1 gsub
−1.