Environmental Engineering Reference
In-Depth Information
15
Sustainab
le Clean Water: Closing the Cycle
Satish Vasu Kailas
1
and Monto Mani
2
1
Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
2
Centre for Sustainable Technologies, Indian Institute of Science, Bangalore, India
Right from the time we wake up in the morning to the time we sleep in the evening, and
even during sleep, we use much more than what we need for survival. All this is done in
the name of comfort. Leaving the tap water running while brushing our teeth, taking long
showers wasting water, and with water hotter than is required, are but some examples of
absolute and avoidable waste. People switch on fans in winter or air conditioners in sum-
mer and use thick blankets to keep themselves warm. All of this waste can be completely
avoided if we accept this as unnecessary. How to control this waste is more of a philosoph-
ical issue. However, why it is that we need to control this urge to use much more is an issue
that is much more important. This chapter seeks to address this issue and on how one can
make living sustainable. This chapter will also address the issue of how the approach of
“closing the cycle” is the answer to sustainable living and sustainable clean water.
The sustenance of humans and their lifestyle depends on the availability of and access
to resources. While the need for resources is satisied through exploitation, and sometimes
destruction of the natural environment, in the context of humans it is also accompanied
with waste generation and environmental pollution. This resource exploitation and con-
sequent waste and pollution is chiely responsible for threatening the sustainability of
both present and future generations, by disrupting nature's ability to maintain resource
availability. Hence, unrestrained resource consumption threatens our own survival and
sustainability.
Resources required for a community's progress include
needs
,
necessities
, and
desires
that
inluence the community's sustainability to varying degrees or levels (Figure 15.1). The
irst level, being basic or fundamental, determines the very survival and healthy existence
of life, and is a prerequisite for other human activities. If air and water supplies are cut off,
life as we know it will cease to exist. In fact, the cycle that sustains this planet is the conver-
sion of oxygen to carbon dioxide and back. This cycle, shown below in Figure 15.2, is made
possible by animals, which convert oxygen to carbon dioxide, and plants, which convert
carbon dioxide to oxygen, with animals and plants being interlinked. This level can be
termed as
basic sustainability
. The second level is essential to support modern civilization
and its lifestyles, where primary education, employment, and primary health care deter-
mine the ability of the community to meet the minimum standards of life (quality of life).
Although not much debate exists on issues of education, health, and individual security,
a lot of debate does exist on issues such as owning individual means of transport (cars),
or televisions, and the like. This level is distinct from the basic sustainability level and
can be termed
essential sustainability
. The third level pertains to resource needs to satisfy a
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