In depth: What’s a desalination plant planned in Mumbai
Recently, Maharashtra announced the setting up of a desalination plant in Mumbai. Chennai already has two such plants while Gujarat and Andhra Pradesh too are planning. So what is a desalination plant and how does it work?
The proposed project will be set up on 25-30 acres of land at Manori, Mumbai. It is expected to process 200 million litres of water daily (MLD). The project is expected to be completed by the year 2025, and would cost around Rs1,600 crore. The construction cost is expected to be 3-4 paise per litre. The process for this project will be through the Swiss Challenge Method.
What’s a desalination plant?
A desalination plant turns salt water into water that is fit to drink. Desalination is the process of removing salts from water to produce water that meets the quality (salinity) requirements of different human uses. Most commonly used technology for the process is reverse osmosis.
An external pressure is applied to push solvents from an area of high-solute concentration to an area of low-solute concentration through a semi-permeable 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. The saline water which undergoes this process is monitored and tested in the same way as water from a filtration plant.
Elsewhere in the world
At present, desalination accounts for 1% of the world’s drinking water and is prevalent in countries located in the Middle East and North Africa region. It is also an important source of water for small island nations and developing countries. The disposal of the byproduct (highly concentrated brine) in desalination technology is a major problem. In many places, the brine is pumped back into the sea but it severely damages the local ecology around the plant.