Hydraulic evaluation of wood chip media constructed wetlands for denitrification.

摘要

Passive denitrification wetland systems using wood chips have been found to remove nitrate effectively. Wood chip media subsurface wetlands, in which wood chips replace gravel, were characterized based on the system hydraulics (conductivities, actual retention times, and levels of dispersion) and compared to gravel subsurface wetlands through permeameter and tracer testing. The hydraulic conductivities of the wood chip wetlands ranged from 0.13 to 0.54 m/s; these values are comparable to the medium sized gravel (media) used commonly in wetlands (Reed et al., 1996, Crites et al., 2006). Nutrient gradients within the wood chip wetland systems caused plant growth to be thicker at the inlets and thinner at the outlets corresponding to where nutrient removal was taking place within the wetland. Wood chip porosity diminished as a result of treatment within the wetlands.