desalination-plants-and-their-feasibility-summary

Context: Considering Mumbai’s water problems on the rise owing to the burgeoning population, the Maharashtra government has recently given the go-ahead for desalination project.

About the project:

  • Location and capacity: It is proposed to be set up on 25 to 30 acres of land at Manori and will have a capacity of 200 MLD. 
  • Duration: It will take about two and a half to three years to complete and is expected to cost around Rs 1,600 crore. The BMC will be floating tenders for building the project.

Background:

  • Rising water demand: 
    • According to the BMC’s projection, the population of Mumbai is anticipated to touch 1.72 crores by 2041. Accordingly, the projected water demand would also be 6424 MLD by then. 
    • Currently, BMC supplies 3850 MLD as against the requirement of 4200 MLD each day. 
  • Recommendations by a high-level committee: 
    • 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 prohibitive

Desalination plants

  • It turns salt water into water that is fit to drink
  • Working Mechanism: 
    • The most commonly used techniques 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. 
  • Desalination plants are mostly set up in areas that have access to seawater.

Utilisation of desalination technology 

  • Worldwide: 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.
  • Scenario in India
    • State of 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 already supply 100 million litres a day (MLD) each to Chennai. 
      • Two more plants are expected to be set up in Chennai. 
    • The other states that have proposed desalination 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. 
    • State of Andhra Pradesh also has plans of setting up a plant.

Few problems associated with desalination plants

  • Expensive mechanism: The huge 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 technology is an expensive way of generating drinking water as it requires a high amount of energy. 
  • Ecological dimensions: The other problem associated is the disposal of the byproduct, a highly concentrated brine of the desalination process. 
  • While in many 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.

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