Desalination is seen as one possible answer to the problem of water scarcity. Recently, Maharashtra government has announced setting up of desalination plant in Mumbai, becoming fourth state to do. So, what is desalination process and what is its feasibility ?
What are desalination plant ?
A desalination plant convert salt water generally seawater into drinking water. The most common used technology used for the process is reverse osmosis where an external pressure is applied to push solvents from an area of high-solute concentration to an area of low-solute concentration through a membrane. The microscopic pores in the membranes allow water molecules through but leave salt and most other impurities behind, releasing clean water from the other side. These plants are mostly set up in areas that have access to sea water.
How widely is this technology used in India?
Desalination has largely been limited to affluent countries in the Middle East and has recently started making inroads in parts of the United States and Australia. In India, Tamil Nadu has been the pioneer in using this technology, setting up two desalination plants near Chennai in 2010 and then 2013. The two plants supply 100 million liters a day (MLD) each to Chennai. Two more plants are expected to be set up in Chennai. The other states that have proposed these plants are Gujarat, Andhra Pradesh
What is the need to set up a desalination plant in Mumbai?
According to the BMC’s projection, the population of Mumbai is anticipated to touch 1.72 crore by 2041. In 2007, a state government-appointed high-level committee had suggested setting up desalination plants in Mumbai, however, over the years the authorities have avoided building the project claiming that the cost is enormous. However, with the city’s water problems on the rise owing to burgeoning population, Maharashtra Chief Minister Uddhav Thackeray Monday has given the BMC the go ahead for project. It will take about two and a half to three years to complete.
Is it ecologically safe?
The high cost of setting up and running a desalination plant is one reason why the Maharashtra government has over the last decade been hesitant in building such a plant. Desalination is an expensive way of generating drinking water as it requires a high amount of energy. The other problem is the disposal of the byproduct highly concentrated brine ( very high concentration of salt water) of the desalination process. While in most places brine is pumped back into the sea, there have been rising complaints that it ends up severely damaging the local ecology around the plant