|
|
Municipal
sewage treatment
Wetlands,
permanently waterlogged areas populated by hydrophytic plants such as
reeds, comprise a variety of sub-surface micro-habitats of differing
oxygenation and redox potential. Constructed wetland systems are
increasingly being employed for treatment of wastewater, sewage sludges
and industrial effluents as a cost-effective, low energy and robust
alternative to traditional engineered biological treatment such as the
activated sludge process.
The natural ability of
soils to filter
suspended solids mechanically and chemical reactions (precipitation)
with sewage constituents are other forms of cleaning mechanisms, which
interact. Constructed wetlands are classified according to their mode
of operation as free water surface-flow, horizontal flow, vertical
downflow or vertical upflow type. They have been used successfully in
the treatment of domestic sewage,
urban, highway and stormwater runoff, acid mine drainage, agricultural
wastewater and industrial effluents (including landfill leachate). BOD
and solids reduction occurs through microbial activity and removal of
nitrogen and phosphorus through the processes of filtration,
denitrification, plant uptake and sorption.
Constructed Wetlands
|
|
World Map
|
civil
engineering
