Environmental Engineering Reference
In-Depth Information
The nexus approach can be extremely useful in developing bioregenerative life-
support systems for terrestrial and extraterrestrial ecosystems.
6 Discussion
There are numerous inter-connected issues with regard to WSW and other nexuses
discussed herein. These issues, with numerous manifestations and rami
cations,
can be appropriately addressed through the nexus approach. All of these consid-
erations are important because if not sustainably managed, ignoring these nexuses
can be a serious threat to the terrestrial-based human civilization (Diamond
2005
).
Improved provisions of food, energy and water necessitate policy interventions
(Baziliana et al.
2011
) to optimize resources and enhance use ef
ciency. As man-
aging the WSW nexus is important, so are energy-water (Hussey and Pittuck
2012
),
soil-water, soil-waste, climate-waste, climate-soil, and soil-water-energy-waste-
climate nexuses. The bottom line is integrating waste recycling and reuse at all
levels of the production chain. Yet, the safe operating space must be clearly de
ned
(Beddington et al.
2012
) because agriculture is a major force affecting the envi-
ronment even beyond the planetary boundaries (Rockstr
รถ
m et al.
2009
).
Rather than using soil as the medium of agricultural production, the nexus
approach is crucial to developing soil-less culture (Fig.
4
). The growing food
demands of 9.6 billion by 2050 and
11 billion by 2100 (UN
2012
) leaves all
options on the table including aquaponics, aeroponics and skyfarming. In this
context, the nutrient-rich grey water from urban centres can play a signi
*
cant role,
for which there exists a strong need for development of appropriate technology (Li
et al.
2008
,
2009a
,
b
). Earthworms are useful organisms to enhance and treat high-
strength wastewater (Charawatchai et al.
2008
), and can be critical to minimizing
the risks of reusing wastewater (Zaidi
2007
), through appropriate technology
(Wendland et al.
2007
). The use of bacterial cultures and synthetic biology (Balmer
and Martin
2008
) are relevant to enhancing environmental security. Potential
challenges of large-scale water storage in surface reservoirs need to be assessed
(Lindstrom et al.
2012
) for site/region speci
c situations. Nanotechnology industry
can be used in managing environmental issues by using the principles of green
chemistry and development of biodegradable goods (Vaseashta
2009
). However,
the nanotechnology itself is generating a new form of waste stream called nano-
waste (Musee
2011
), which may need additional research.
The nexus approach is also crucial in sequestration of atmospheric carbon dioxide
(CO
2
) through either biological measures (soil, trees, wetland, oceans) or engineering
measures (geological sequestration). For example, stable isotropic techniques can be
used to assess leakages in geologic sequestration (Lackner and Brennan
2009
), and in
determining the old vs. new carbon in the soil (Puget et al.
2005
).
There exists a strong link between soil and climate on the one hand, and soil and
ecosystems C on the other. World soils have been a major source of atmospheric
CO
2
since the onset of agriculture, but can be a sink (storehouse) through
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