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Current Affairs

Role of man-made wetlands in treating waste water

Date: 27 December 2020 Tags: Miscellaneous

Issue

To reduce some load of untreated sewage that flows into the Yamuna, authorities in Delhi are planning a method to naturally treat the waste water.

 

Background

These constructed wetland systems will use boulders and a variety of plants to naturally treat sewage from 25 drains.

 

Details

  • The method involves a three-step process, which does not require electricity. At the mouth of the drain, a team of scientists have made a one-acre wide wetland from boulders and plants.

  • The drain opens into an oxidation pond, which is the first step of the treatment process. Here the solid material in the waste is removed from a wire mesh and atmospheric oxygen dissolves in the water.

  • The water then travels further and passes through channels and small ridges made from boulders, which creates turbulence and causes aeration.

  • Aeration brings water and air in close contact, introducing small bubbles of air which rise through the water and remove dissolved gases in it.

  • The final step in the treatment process happens when water passes through 25 species of plants such as typha, phragmites, ipomoea and cyprus which are effective in the treatment of heavy metals, including arsenic.

  • The team will check the quality of water being released into the river through this constructed wetland.

  • The same process has increased the concentration of dissolved oxygen (DO) at Neela Hauz biodiversity park lake, which used to receive untreated sewage through drains from nearby areas.

Wetlands

  • A wetland is a distinct ecosystem that is flooded by water, either permanently or seasonally, where oxygen-free processes prevail.

  • The primary factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil.

  • Wetlands play a number of functions, including water purification, water storage, processing of carbon and other nutrients, stabilization of shorelines, and support of plants and animals.

  • Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life. 

  • The main wetland types are swampmarshbog, and fen; sub-types include mangrove forestcarr, pocosin, floodplainsmirevernal poolsink, and many others.