Water desalination plants harm environment: UN

Headline : Water desalination plants harm environment: UN

Details :

The News

  • According to a study backed by UN, though desalinization is a necessity to manage water scarcity globally, it is fraught with ecological challenges mainly due to discharge of Brine.

Background

Desalination

  • Globally around 1.5 to 2 billion people live in areas of physical water scarcity.
  • To tackle the problem of global water scarcity, desalinization plants are on the rise with about 15,906 operational plants in 177 countries.
  • Almost half of the global desalination capacity is located in the Middle East and North Africa region which lack renewable water resources.
  • However the main issue with desalinization plants is that for every litre of freshwater it produces, desalination plants also produce about 1.5 litres of brine.
  • The brine so produced has severe ecological effects on the marine environment according to a study by UN University Institute for Water, Environment and Health.

Brine and Desalinization plants

  • Brine refers to all concentrate discharged from desalination plants.
  • It is highly concentrated salt water ‘hyper-salty water’, comprising of about 5% salt compared to 3.5% salt in global sea water.
  • As shown above for every litre of freshwater it produces, desalination plants also produce about 1.5 litres of brine.
  • The anti-scalants and anti-foulants in the desalination process use toxic chemicals like copper and chlorine which are of major concern.
  • Globally about 80% of brine is produced within 10 km of a coastline.

Harmful Effects of Brine

  • As 80% of brine is produced within 10 km of a coastline, desalination plants near the ocean most often discharge untreated waste brine directly back into the marine environment.
  • This greatly raises the salinity of the receiving seawater.
  • Further the oceans are polluted with toxic chemicals used as anti-scalants and anti-foulants in the desalination process including copper and chlorine.
  • This depletes dissolved oxygen in the receiving waters
  • High salinity and depleted dissolved oxygen levels severely impact benthic organisms including shellfish, crabs and other creatures throughout the food chain.

 

Way Forward

  • Alternative sources of water such as fog harvesting to aquifers below the seabed should be explored to deal with water scarcity
  • Further brine discharged into sea water can be alternately used in aquaculture with increases in fish biomass of 300%.
  • Brine can also be used to irrigate salt tolerant species such as Spirulina.
  • Brine can also be used to generate electricity.
  • Further large amount of salts and metals contained in brine can be mined.

About UNU-INWEH

  • The Canada-based UN University Institute for Water, Environment and Health is a member of the United Nations University family of organisations.
  • It is the UN think tank on water, created by the UNU Governing Council in 1996.
  • Its mission is to help resolve pressing water challenges of concern to the UN through knowledge-based research to generate scalable solutions.

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