INNOVATIONS
IN DESALINATION AT BARC
Dr.
P.K. Tewari*
India receives abundant
rains. The average annual precipitation is estimated to be 4000
billion cubic metres. But only 1000 billion cubic metres per year
is available as usable surface water and ground water at present.
The annual water consumption in India is now about 750 billion
cubic metres per year for all applications including agricultural,
industrial, domestic and commercial usage. Assuming a conservative
figure of per capita water consumption of 1000 cubic metres per
year, the water availability in the country is likely to get fully
stretched by the year 2010 unless replenishment is planned right
now.
The consumption norm
of 1000 cubic metres per year is only 10-20 per cent of the per
capita consumption in industrialized countries. Moreover, the
geographical distribution and seasonal variation of rainfall are
not uniform. There are pockets like Saurashtra and Kutch in Gujarat,
the coastal areas of Tamilnadu and the land-locked areas of western
Rajasthan and Marathwada in Maharashtra with scanty rainfall and
perennial water scarcity. In addition, a large number of villages
in various parts of the country are known to be suffering from
excess salinity, fluoride, nitrate, iron, arsenic and microbial
contaminations of ground water. These invariably lead to widespread
water-borne diseases and cause enormous hardships to the inhabitants.
A holistic approach is therefore called for to cope with the fresh
water needs of the country in the coming decades.
The Government of
India and the concerned State governments have launched a number
of water supply schemes. They invariably require huge capital
expenditure and take long periods for completion. Desalination
technology is a proven option to increase the water resources
in the scarcity areas. The Bhabha Atomic Research Centre (BARC)
has been engaged in R&D on desalination to develop indigenous
technologies for providing fresh water from seawater in the water-scarce
coastal areas and safe drinking water in salinity-affected inland
areas.
BARC has been engaged
in R&D activities on desalination since the 1970s. The development
activities in the field of desalination was initially based on
thermal processes. Later, the programme for development of membrane
processes was also included in the 1980s when it showed signs
of commercial viability. Over a period of time, BARC has successfully
developed desalination technologies based on multi-stage flash
(MSF) evaporation, reverse osmosis (RO) and low temperature evaporation
(LTE). In the field of thermal desalination, efforts are directed
towards utilizing the low-grade heat and the waste heat as energy
input for desalination. In membrane desalination, work is being
carried out on newer pre-treatment methods such as the use of
ultrafiltration, energy reduction and higher membrane life.
Based on these technologies,
a number of desalination plants have been successfully demonstrated
during the last few years. These include desalination plants for
conversion of sea water into fresh potable water, providing safe
drinking water in brackishness-affected areas and for process
applications.
Based on decades
of operational experience of MSF and RO plants at Trombay, BARC
has initiated the Nuclear Desalination Demonstration Project (NDDP)
at Kalpakkam in Tamilnadu.The NDDP consists of a hybrid MSF-RO
desalination plant of 6300 cubic metres a day capacity. The requirements
of seawater, steam and electrical power for the desalination plants
are met from the Madras Atomic Power Station (MAPS) I & II.
The already commissioned
plant operates at relatively lower pressure to save energy, employs
lesser pre-treatment because of relatively clean feed water from
MAPS outflow and aims at longer membrane life resulting in lower
water cost. The MSF plant which is in an advanced stage of completion
is designed for higher top brine temperature with gain to output
ratio (GOR) of 9:1 and utilizes less pumping power.
The desalination
plant can meet the fresh water needs of around 45,000 persons.
There is a provision of increasing the water capacity by employing
appropriate technology to serve larger numbers of people. The
overall water production cost for this plant is estimated to be
5 paise per litre. For large size plants it is likely to come
down to about 4 paise per litre.
The desalination
industry in India is witnessing numerous technological innovations
so that these are available to the people in the water-scarce
areas. A project called "Desalination Technology Studies
and Development" has been prepared to undertake some of these
innovative features during the ongoing Tenth Plan. These activities
are planned to be taken up in a mission mode to supplement the
efforts on desalination already carried out in the past. On its
successful completion the project would solve the fresh water
needs in the coastal as well as inland areas of the country.(PIB
Features)
*Head,
Desalination Division, BARC, Mumbai
