My favourite challenge and experimentation
-Sai Sandeep Yelchuri
CHALLENGE:
How can freshwater (desalinated water) be produced from the sea and distributed to
every household at a minimal cost like electricity?
DESCRIPTION: With
the continuous depletion of groundwater resources, unpredictable rainfall, and
drying up of rivers, it is very important to find a sustainable alternative for
finding freshwater. Having an enormous coastal line of 7516.6 Kms, India has a
wonderful opportunity in the form of seas and an ocean. But, purification or
desalination of this seawater is very costly. Considering the requirement(across
various states) and their financial conditions, it is difficult to go ahead
with the available technology. Even after processing the seawater, distributing
it to every household across the country would be a herculean task. So, the
idea is to look for a solution that can desalinate seawater and distribute it
at a very low cost. For a metaphorical reference, we can look at how
electricity is produced and distributed at a reasonable cost to every household
and industrial facility.
SCOPE
OF EXPERIMENT: As mentioned earlier, we identified two
sub-problems within this challenge,
1. High cost of production
2. Difficulty in distributing across the
country
Due
to the paucity of time, I’ve picked up only the first problem for this
experimentation exercise.
BRIGHT
SPOT: For low-cost production, the main criteria to be
considered are ‘Low cost of setup and maintenance’ and ‘Feasibility in implementation’.
Bright
Spot 1[1]: Initially,
I looked around if someone is doing something similar, at a very low cost. I
came across an experiment performed by an Indian American high school boy,
Chaitanya Karamchedu, who discovered a way to filter out salt from seawater at
a meager cost using an absorbent polymer. Though it is an extraordinary idea
that reduces the cost to a great extent, there is no mention of how to scale
it, as the polymer used is costly and difficult to manufacture.
Bright Spot 2[2]:
After extensive research over the internet, going through various research
papers and news articles, I came across an article published in the ‘Journal
for Water Science & Technology,’ by a few young scientists in Egypt. These
researchers used a process called ‘Pervaporation,’ which is a two-step process
of filtering and vaporizing. The filtering is done using a polymeric membrane,
while the vaporizing, and consequently condensation produces freshwater.
Although
pervaporation as such is not new, it was associated with quite an expensive and
complicated membrane production. This is probably the reason why it has not
been put into full use. But this team of scientists developed a new type of
membrane, which is salt-attracting and is embedded with Cellulose acetate,
aka fibre from wood pulp. This idea of using the Wood pulp as a membrane
appeared to a Bright spot for me, as it is very cheap and easy to make, and
also highly efficient. Though not implemented yet in a larger setup, the second
solution seems to be very promising.
For
more information on the bright spots, refer the Additional Notes section
and References.
SOLUTION (Chosen for experimenting): The solution chosen
for experimenting is based on the second bright spot mentioned above. We use
the Pervaporation method using ‘Wood Pulp’ as a membrane for filtering out salt
from water. Though the cost of the membrane is lowered, the energy required for the
process is still costly and is a limited resource. So, as an alternative to the
traditional energy sources, we plan to use the solar panels for the energy
requirements.
STORYBOARDS:
1-DAY EXPERIMENT:
What hypothesis
will it test: The current solution is aimed at
creating a new process that will desalinate seawater at a low cost. There are
two parts in/ the solution that should be validated:
• Whether the current process works in
producing freshwater from seawater.
• Whether the process we
designed results in lower cost desalination(per Cu. Metre) compared to the
existing industrial processes.
What will we do:
To conduct this experiment, we can follow the process(shown above) given in the research paper published[2].
This is a laboratory experiment
and we just need to procure the required apparatus and chemical (Cellulose
acetate). As per the description given in the research paper, this experiment can be certainly completed in one day.
Important
difference:
In
an actual industrial setup, the source for the electric heater in step 4 and
Leibig condenser in step 7 and 8 is the solar panels installed on the plant.
Cost of experiment:
It is best to approach a
University/research laboratory for conducting this experiment. It will reduce
the costs to only the cost of Chemical required (cellulose acetate) and
rentals.
If we want to conduct the
experiment on our own, as per online sources the following are the costs for
the material required:
Material
|
Price(in
Rs)
|
Cellulose
acetate
|
158
|
Leibig
condensor
|
91
|
Cooling
centrifuge
(You
can use other cooling methods like a small cooling chamber that can reduce
costs to near 1000)
|
1000
|
Air
blower
|
449
|
Thermometer
|
107
|
Total
|
1804
|
*Please refer to the appendix
to find the references for each price[3]
As it is an experiment,
we are considering the costs of energy required is negligible
Measuring the
success: Currently, the success can be measured
on the two-hypothesis mentioned above:
1. Is
the process, producing freshwater from salty seawater? You can use Salinity
sensors[4] available in the market to
detect the change. If the salinity is low, we can confirm that the process is
working and can consider the first part as a success.
2. Is
the process producing 1 Cubic meter of freshwater at a low cost compared to the
traditional desalination processes used in industries? If the cost of
production(per cubic meter) is less than $1, the industry-standard neglecting
energy costs, we can consider the second part as a success.
ADDITIONAL
NOTES:
Bright
Spot 1: The polymer used filters out the 90% of the water
molecules that are not bonded to the salt, as opposed to the existing methods
that tried to break the bonds between Water and salt molecules (that
constituted 10%).
Bright Spot 2: The
new membrane used is not only very cheap to make, but it is also highly
efficient. According to the researchers, it can handle highly concentrated
seawater, and remove contaminants. What is more, it is not only useful in terms
of freshwater production, it can also be used for capturing environmental
pollutants and salt crystals.
REFERENCES
1. Bright Spot1:
https://www.indianeagle.com/travelbeats/portland-indian-chaitanya-karamchedu-makes-saltwater-drinkable
2. Research Paper:
https://pdfs.semanticscholar.org/3bde/7ff2a17fb442ce24a2efba8a315c881c98b2.pdf
3. Costs of materials for experiment:
- https://www.sterlitech.com/cellulose-acetate-membrane-filters.html
- https://www.indiamart.com/proddetail/leibig-condenser-200-mm-15836435988.html
- https://www.amazon.in/dp/B01GFTEV5Y/ref=cm_sw_em_r_mt_dp_U_2XjnDbBEA7MRX
- https://www.moglix.com/aeronox-500w-air-blower-an20/mp/msn2qreqc5takp?gclid=EAIaIQobChMIgNW73sDG4wIVziMrCh0EyAI3EAQYASABEgJPM_D_BwE
- http://tiny.cc/lk709y
4. Salinity Sensor:
https://www.pce-instruments.com/english/measuring-instruments/test-meters/salt-meter-pce-instruments-salt-meter-pce-pwt-10-det_5852847.htm?_list=kat&_listpos=1
