Accepted Papers - 3.pdf - UNESCO

when the substrate has high element concentrations,
or have a high net efflux of the element in question,
thus the plant tissue concentration of the element is
low even though the concentration in the substrate
is high (Williams 2002., Wood and Mcatamney
1994, Woulds and Ngwenya 2004, and Ye et al 2001)
CONCLUSIONS :
Surface flow constructed wetlands are being
designed for the treatment of municipal waste waters
in developed nations. Use of constructed wetlands
is spreading rapidly in developed nations how ever,
in tropical nations due to water scarcity and high
surface evapotranspitration the constructed
wetlands for treatment of waste waters is not gaining
significance. Further due to water scarcity wetland
technology is not supported. However, in tropical
contries the mine drainage, agricultural waste waters
and flood water regulation there is considerable
scope due to rich plant diversity.
GLOSSARY FOR SELECTED TERMS
Attenuation
Reduction of peak flow and increased duration of a
flow event.
Balancing pond
A pond designed to attenuate flows by storing runoff
during the peak flow and releasing it at a controlled
rate during and after the peak flow has passed. The
pond always contains water. Also known as wet
detention pond.
Basin
Flow control or water treatment structure that is
normally dry.
Biodegradation
Decomposition of organic matter by microorganisms
and other living things.
Bioretention area
A depressed landscaping area that is allowed to
collect runoff so it percolates through the soil below
the area into an underdrain, thereby promoting
pollutant removal.
Catchment
The area contributing surface water flow to a point
on a drainage or river system. Can be divided into
sub-catchments.
Combined sewer
A sewer designed to carry foul sewage and surface
runoff in the same pipe.
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Controlled waters
Waters defined and protected under the Water
Resources Act 1991. Any relevant territorial waters
that extend seaward for 3 miles from the baselines,
any coastal waters that extend inland from those
baselines to the limit of the highest tide or the
freshwater limit of any river or watercourse, any
enclosed dock that adjoins coastal waters, inland
freshwaters, including rivers, watercourses, and
ponds and lakes with discharges and groundwaters
(waters contained in underground strata).For the full
definition refer to the Water Resources Act 1991.
Detention basin
A vegetated depression, normally is dry except after
storm events constructed to store water temporarily
to attenuate flows. May allow infiltration of water
to the ground.
Diffuse pollution
Pollution arising from land-use activities (urban and
rural) that are dispersed across a catchment, or subcatchment,
and do not arise as a process effluent,
municipal sewage effluent, or an effluent discharge
from farm buildings.
Environmental management
A management agreement for an area or project set
up to plan and make sure the declared management
objectives for the area or project are met.
Environmental Management Plans are often
undertaken as part of an environmental impact
assessment and are set out in several stages with
responsibilities clearly defined and environmental
monitoring procedures in place to show compliance
with the plan.
Evapotranspiration
The process by which the Earth’s surface or soil
loses moisture by evaporation of water and by
uptake and then transpiration from plants.
Extended detention basin
A detention basin in which the runoff is stored
beyond the time normally required for attenuation.
This provides extra time for natural processes to
remove some of the pollutants in the water.
FEH
Flood estimation handbook, produced by Centre for
Ecology and Hydrology, Wallingford (formerly the
Institute of Hydrology)
Filter drain
A linear drain consisting of a trench filled with a
permeable material, often with a perforated pipe in