During the past decades, intensification of human activities
along with limited public awareness on environmental management issues, have
resulted in degradation of natural resources.
The principal objective of wastewater treatment is generally
to allow municipal and/or industrial effluents to be disposed of without danger
to human health or unacceptable damage and degradation to the environment. The
management of municipal wastewaters through both treatment and reuse, is a
prerequisite for the protection and sustainable use of water resources. If small
communities are to meet wastewater treatment requirements of the future, they
must have treatment systems that are not only effective and reliable, but also
simple and inexpensive to construct and operate.
At the beginning of the 20th century, a few cities and
industries began to recognize that the discharge of sewage directly into the
streams caused except of health problems, degradation of natural water bodies
and this led to the construction of sewage-treatment facilities. At about the
same time, the septic tank was introduced as a mean of treating domestic sewage
from individual households both in suburban and rural areas. Nevertheless, and
because of sizable social and economic problems and the absence of public
perception on environmental issues, during the first half of the 20th century,
few municipalities and industries provided wastewater treatment.
The summary of technologies using for wastewater treatment,
can be divided into two main categories:
· Natural systems
· Conventional or mechanical systems
Natural treatment systems are available for the treatment
of organic wastewaters such as municipal, and tend to be lower in cost and less
sophisticated in operation and maintenance. In contrast to conventional
treatment systems, natural systems may also provide indirect benefits such as
aesthetic improvement of the landscape, wildlife habitat, and recreational and
educational areas. Additionally, their effluents can be reused for irrigation.
|These man-made constructed systems, treat wastewaters
utilizing physical, chemical and biological processes just like nature does and
without any additional energy or chemical input. Although these processes are
slower comparing with the high-rate processes held in conventional treatment
systems, they treat wastewaters reliably and continuously if properly designed
and not overloaded. Among natural systems, constructed wetlands have been
used widely around the world and a considerable record of experience and design
practice has been documented all over the world.
wetland for EKBY's wastewater treatment
The main advantages of constructed wetlands for
wastewater treatment are in general:
Simplicity. These systems are simple to construct.
Low cost. Constructed wetlands are less expensive
than other wastewater treatment systems, regarding construction and
maintenance. There is no need for high-cost, electromechanical equipment,
or for high consumption of electrical energy.
High efficiency. They provide effective and
reliable wastewater treatment under
fluctuating hydraulic and contaminant loading rates.
They can be aesthetically pleasing and they also
provide habitat for wildlife and human enjoyment.
Cost-effective and environmentally friendly treatment
Reuse of treated wastewater for irrigation and/or other
Disadvantages of constructed wetlands include high land
area requirements (depending on the design, they may require a relatively large
land area compared to a conventional facility), the need for a preliminary
treatment before the wastewaters treated by the system (normally they do not
used to treat raw wastewaters), the need of higher (than a conventional system)
retention time, and that they may cause problems with pests.
Nutrient-rich waters flowing into a water body, may lose some
of their nutrient load when passing through wetland vegetation. Creation of
vegetated wetland buffer zones along rivers has been effective for controlling
non-point source pollution and restoring water quality of rivers. Wetland buffer
zones can reduce the concentration of nutrients, pesticides and sediments in the
surface runoff and thus prevent degradation of water quality in lakes, streams
and rivers. This means that constructed wetlands may and should be integrated
into management plans for conservation of both soil and water resources of a
watershed, or integrated as parts of major restoration projects.