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Biodiversity & Environment

Legacy Waste

  • 26 Mar 2020
  • 3 min read

Why in News

Recently, the National Green Tribunal (NGT) has directed a committee to assess the amount of damage caused to the environment due to the dump sites (legacy waste) in Delhi.

Key Points

  • Legacy wastes are the wastes that have been collected and kept for years at some barren land or a place dedicated for Landfill (an area to dump solid waste).
  • This waste can be roughly grouped into four categories:
    • Contained and/or stored waste(contained or stored waste are wastes in tanks, canisters, and stainless steel bins).
    • Buried waste.
    • Contaminated soil and groundwater
    • Contaminated building materials and structures.
  • Biomining method has been proposed by the Central Pollution Control Board (CPCB) for the effective disposal of legacy wastes.
  • Environmental Impact of Legacy Waste
    • Legacy wastes not only occupy large space, but also become a breeding ground for pathogens, flies, malodours and generation of leachate, which may lead to water contamination.
    • They also contribute to generation of greenhouse gases and pose risk of uncontrollable fire.

Biomining

  • Biomining is the process of using microorganisms (microbes) to extract metals of economic interest from rock ores or mine waste.
  • Biomining techniques may also be used to clean up sites that have been polluted with metals.
  • It is usually used for old dumped waste that remains in a partly or fully decomposed state with no segregation in existence between wet and dry waste.
  • In the cost effective method of biomining, treatment is done by dividing the garbage heap at the site into suitable blocks to let the air percolate in the heap.
  • As a result, the leachate which is the water in the heap with suspended solid particles is drained off and microbes are sprayed in the heap to initiate biological decompositions.
  • The waste is turned over several times in order to devoid the waste to leachate as much as possible.
  • This biological decomposition of the waste decreases the volume of the waste by 40%.

Source: TH

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