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Apart from rainwater harvesting, water recycling is one of the key strategies to conserve water. Water reuse or water recycling is reusing the treated wastewater for beneficial purposes like agriculture and irrigation, industrial processes, potable water suppliesflushing in toilets, environmental restoration and groundwater recharge.
 
Water recycling provides alternatives to the existing water supplies, which enhance water security and sustainability. Sources of water that can be recycled includes:
  • Municipal wastewater
  • Agricultural runoff
  • Industry process and Cooling water
  • Water that is produced from natural resource extraction activities.
Wastewater Recycling Stages:
Wastewater treatment consists of physical, chemical and biological processes that remove the wastewater's solids, organic matter and nutrients.
 
There are \(3\) main stages of wastewater treatment that includes:
  • Primary treatment
  • Secondary treatment
  • Tertiary treatment
In some applications, a more advanced treatment called quaternary water treatment is required. Each stage involves removing different pollutants, with water becoming cleaner as it moves through the successive stages. The different treatment stages are used depending on the quality of water and the required final use.
 
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Steps in a wastewater treatment process
Primary Treatment:
During the primary treatment, wastewater is held temporarily in a settling tank. The heavier solids settle at the bottom of the tank, while lighter solids like oil and grease float over the surface.
 
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Settling tank
 
Once the lighter materials are settled, the floating materials are removed. At the same time, the remaining liquid is moved to the secondary phase of wastewater treatment. Primary treatment removes the material that floats or settles readily due to gravity. It includes the physical processes involving screening, comminution, grit removal, and sedimentation.
 
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Bar screens are used to remove large objects
  
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Sedimentation tank
Reference:
https://commons.wikimedia.org/wiki/File:Steps_in_a_typical_wastewater_treatment_process.png
https://commons.wikimedia.org/wiki/File:Secondary_sedimentation_tank_1_w.JPG
https://www.yaclass.in/p/science-cbse/class-7/wastewater-story-3661/re-18e72798-bc68-489a-8c05-62ab267a59b1