Mentor’s Comment

• Mention Water Crisis in major cities.
• Explain Desalinisation.
• Give benefits and challenges in the use of technology.
• Conclude suggesting some reforms.

Answer:

The NITI Aayog report on Composite Water Management Index(CWMI) said that India is facing its ‘worst’ water crisis in history. Taps in Shimla went dry in summer of 2018, posing an unprecedented water crisis in the hill town. According to a forecast by the Asian Development Bank, India will have a water deficit of 50% by 2030. Recent studies also ranked Chennai and Delhi at the top of the 27 most vulnerable Asian cities in terms of low per-day water availability Mumbai and Kolkata follow close. In this scenario, some experts have opined that de-salination can help in solving the urban water crisis.

Current water crisis in India:
India has only 4% of the planet’s fresh-water for 16% of its population.
The annual per capita availability of water continues to decline sharply from about 5,177 cubic metres in 1951 to about 1,720 cubic metres in 2019.
The NITI Aayog in its report on Composite Water Management Index (2018) has underlined that currently 600 million people face high to extreme water stress.
Twenty-one cities, including Delhi, Bengaluru, Chennai and Hyderabad will run out of groundwater by 2020, affecting 100 million people.
The rate of groundwater extraction is so severe that NASA’s findings suggest that India’s water table is declining alarmingly at a rate of about 0.3 metres per year. At this rate of depletion, India will have only 22 per cent of the present daily per capita water available in 2050, possibly forcing the country to import water.

Desalination:
Desalination the process that extracts minerals from saline water. Sea water is desalinated to produce water suitable for human consumption. Approx 1% of world population is dependent on desalination water to meet daily needs, but United Nations expects that 14% of worlds population will encounter water scarcity by 2025 hence desalination assumes importance.

Efficiency and affordability:-
The use of expensive energy intensive methods like multi stage flash desalination, to evaporate water like multi stage flash distillation , to evaporate water by heat or the reverse osmosis, process which is less energy intensive but still require a great deal of energy to pump water through filtration membranes make it less efficient and less affordable.
But now with new researches like Graphene Oxides (GO) membranes in which salts in seawater are strongly attracted to water molecule which increases its diameter and hence it is unable to pass through membrane used.
Also technology indigenously developed by National Institute of Ocean Science and Earth System Science Organisation (ESSO) has been developed.

Potential:-
India has a long coastline of 7500 km which is a huge amount of Sea water.
Mostly with the advancements in technology the cost of disalination will come down eventually.
With desalination production of salt also increases – India is already 3rd largest salt producer after China and US.
India is a water hungry nation and with 57% area drought prone it is wise to utilise the abundant resource.
Most island nations have adopted it and Israel is the leader in Sea water utilisation – Technology transfer.
Producing potable water through desalination may become more efficient and less energy-intensive if use graphene oxide (GO) membranes to filter common salts in seawater on a commercial scale.

Limitations
Technology development is yet to reduce cost of desalination even more (61 Paise is still High considering the quanity of water needed – It is feasible for small islands).
The high energy cost to evacuate disalinised water is a hurdle – India with large geographical area and population is still struggling to become energy surplus.
Environment issues.. (1) loss of aquatic life at the intake of sea water to RO plant (2) continuous discharge of the rejected concentrated salt solution, called brine into the sea impacts marine life and (3) greenhouse gas emissions (GHG) from power plant.

Technology which meant to help solve the world’s growing water shortage is now producing a salty environmental dilemma for the world. At such point of time, there is a need for improved brine management strategies to meet a fast-growing challenge, noting predictions of a dramatic rise in the number of desalination plants, and hence the volume of brine, worldwide. Also, there is a need to translate and convert an environmental problem into an economic opportunity and it is particularly important in countries producing large volumes of brine with relatively low efficiencies.