Desalination plants

Recently, Maharashtra State Govt announced the setting up of a desalination plant in Mumbai, becoming the fourth state in the country to experiment with the idea.

What are desalination plants?

• A desalination plant turns salt water into water that is fit to drink.
• The most used technology used for the process is reverse osmosis where 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 seawater. 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 litres a day (MLD) each to Chennai.
• The other states that have proposed these plants are Gujarat, which has announced to set up a 100 MLD RO plant at the Jodiya coast in Jamnagar district.
• There are also proposals to set up desalination plants in Dwarka, Kutch, Dahej, Somnath, Bhavnagar and Pipavav, which are all coastal areas in Gujarat. Andhra Pradesh, too, has plans of setting up a plant.