Solar Technologies for Water
Purification
and Environmental Sustainability
Solar
energy is the largest source of all carbon-neutral energy sources.
Studies show that more energy from sun light strikes the earth in one
hour (4.3*1020 J) than all the energy consumed on the planet in a year
(4.1*1020 J). Thus it is a compelling solution for energy requirement in
India which is projected to double by 2050 and will be more than triple
by the end of the 21st century. Solar power is the abundant, clean,
green, renewable and readily available source of energy and is secure
from controversies raised due to geopolitical tension. It poses no
threat to the environment in terms of pollution and is also freely
available to all.
Technology Innovation and Application
Solar energy can be the solution for the
world's energy demands subject to its
efficient utilisation. The solar
energy conversion to hydrogen generation mediated through photocatalytic
splitting of water appears to be an aspiring positive step towards water
treatment. Applied research in this regard has enriched the database on
the application of various materials with different compositions and
percentages so far. The recent innovation has focused towards
carbon-based nanomaterials, which are well known for their excellent
light absorption and charge transfer characteristics. The carbon-based
nanomaterials either individually or in combination with other
semiconducting materials enhance the hydrogen generation and effective
dispersion of metal nanoparticles by virtue of the photothermal effect.
The recent research interest is driven towards the quest for advanced
materials and it is largely centered on nanotechnology application. When
the particle size of the materials scaled down, it leads to change in
their properties and makes way for their application in various fields.
Development Alternatives along with CSIR-National
Environmental Engineering Research Institute (NEERI) has piloted a
project at Bundelkhand and other rural regions in India on water
purification for drinking and cooking proposes. NEERI has developed six
solar water disinfection products and devices by using patented
materials such as Plasmonic CNP and Titania in form of paints and fabric
for water treatment (bacterial contamination) at the household and
community level for rural and urban slums. The project intervention
includes product demonstration, performance validation and market
research.
During the baseline survey, it was found
that most of the water samples collected from community tube wells at
Punawali Kala, Jhansi district (project intervention site) were
bacterial contaminated and people were using the water for drinking and
cooking. Focus Group Discussions (FGD) and Key Personal Interviews (KPI)
were conducted to understand people’s perceptions and knowledge of water
quality and to create awareness about access to safe drinking water.
Solar pasteuriser with the per day treatment
capacity of 60 litres has been installed by Development Alternatives and
it is operated by the community with the help of local support staff.
5-6 households comprising of 25 members have been using the treated
water for domestic proposes without any operational and quality
problems. The ease of operation and maintenance is very simple and can
be operated by local villagers.
Cost Benefit Analysis
Rural and urban slum communities will be
benefited from this innovative technology since physical and chemical
water purification methods require operation and maintenance cost with
harmful chemical usage and heavy wastage of fresh water (as in the case
of Reverse Osmosis). In the case of solar water purification, there is
no requirement of energy, consumable chemicals and cartridges and no
environmental pollution or health hazards. Thus, solar water
disinfection proves to be both an economically and environmentally
friendly technique in rural areas and urban slums.■
References
•
Mangrulkar et al, Throwing light on platinized carbon nanostructured
composites for hydrogen generation, Energy Environ. Sci, 2014, 7, 4087
•
Edla et al, Solar Water Purifier for Indian villages; A review,
International Journal of Engineering Research and Technology, 2013, 2, 6
•
www.neeri.res.in
•
www.energypedia.info
Pradip Kumar Mishra
pmishra@devalt.org
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