Constructed Wetland: An Ecotechnology for Wastewater Treatment and Conservation of Ganga Water Quality - Environmental Sustainability: Role of Green Technologies - page 238

Constructed Wetland:
An Ecotechnology for Wastewater
Treatment and Conservation
of Ganga Water Quality

U.N. Rai, A.K. Upadhyay, and N.K. Singh

1 Introduction

The Ganga basin, the largest river basin of the
country, houses about 40 % of the population of
India. During the course of the journey, municipal
sewage, industrial effluents and wastes from
several other nonpoint sources are discharged
into the river Ganga resulting in its pollution.
Total wastewater generation on the Ganga basin
is about 8,248 MLD (CPCB 2003 ), out of which
2,637.7 MLD and 122 MLD municipal wastes
were generated from class I and class II city situ-
ated along the river Ganga, respectively. In a
report of CPCB ( 2010 ), it was estimated that only
1,117.4 MLD and 16.4 MLD municipal wastes
from class I and class II cities were treated and
remained without any kind of treatment. The
main sources of pollution along the stretch of the
river are urban liquid waste (sewage/sullage),
industrial liquid waste and large-scale bathing of
cattle, throwing of dead bodies in the river,
surface run-off from solid waste landfills and
dumpsites and surface run-off from industrial
solid waste landfills. Industrial wastewater is also
discharged by a number of industries situated in
this riparian zone. In ecosystem terms, the join-
ing of tributaries into the main stream gives the
Ganga both pollution and power. They gain tox-
ins and bacteria harmful to humans but also take
in the water velocity and volume needed to
degrade them and wash them away. Generally,
scientists cite the loss of velocity as the more
serious factor contributing to the rise in levels of
pollution since without adequate flow, toxins and
bacteria cannot be flushed and degraded.

The rapid growth of water consumption within
the urban area due to industrial development, an
increase of the urban population, and an improve-
ment of sanitary conditions is accompanied by
the equally rapid increase of industrial and
domestic wastes polluting all the components of
the natural environment: the atmosphere, water
bodies, soils and subsoils.
Rapid expansion of urban areas and industrial
development are often responsible for the degra-
dation of receiving water bodies such as lakes,
rivers and streams. Aquatic sediments are reposi-
tories of physical and biological debris and act as
sinks for a wide variety of organic and inorganic
pollutants (Zoumis et al. 2001 ). With substantial
wastewater generation requires extensive treat-
ment prior to environmental disposal. For the
maximisation of the health and environmental
benefits associated with the use and discharge of
wastewater, several legislations and guidelines
have been developed, both at international and
national levels. Such treatment of wastewater (to
discharge criteria) can be carried out using natu-
ral or conventional steel-and-concrete treatment
technologies (Haberl 1999 ).

U.N. Rai ( * ) • A.K. Upadhyay • N.K. Singh
Plant Ecology and Environmental Science Division,
CSIR-National Botanical Research Institute,
Lucknow 226 001, India
e-mail: [e-mail]