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Explain how sludge is treated. - Science

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प्रश्न

Explain how sludge is treated.

थोडक्यात उत्तर
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उत्तर

  • In the clarifier (or sedimentation tank), sludge settles at the bottom and is collected using a scraper. It is then moved to a separate tank known as the digester, where it is digested by anaerobic microorganisms.
  • The biogas created during the process can be utilized for fuel or to generate electricity. The clarified water from the sedimentation tank is pumped into the aeration tank. In the aeration tank, suspended microorganisms sink to the bottom as activated sludge.
  • The activated sludge is approximately 97% water. Water is removed using sand-drying beds or machinery. Dried sludge is utilized as manure, reintroducing organic matter and nutrients into the soil.
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Wastewater Treatment Plant (WWTP)
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पाठ 18: Wastewater Story - Exercises [पृष्ठ २२८]

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एनसीईआरटी Science [English] Class 7
पाठ 18 Wastewater Story
Exercises | Q 5. (ii) | पृष्ठ २२८

संबंधित प्रश्‍न

Drains get blocked by ______ and ______.


Describe the steps involved in getting clarified water from wastewater.


Sewage is mainly a


The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as


State whether the following statement is True or False. In case a statement is false, write the correct statement.

Used water is wastewater


State whether the following statement is True or False. In case a statement is false, write the correct statement.

Wastewater could be reused


State whether the following statement is True or False. In case a statement is false, write the correct statement.

Where underground sewerage systems and refuse disposal systems are not available, the high cost on-site sanitation system can be adopted


Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence.

  1. Sludge is scraped out and skimmer removes the floating grease. 
  2. Water is made to settle in a large tank with a slope in the middle.
  3. Large objects like plastic bags are removed by passing wastewater through bar screens.
  4. Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
  5. Wastewater enters a grit and sand removal tank.

Three statements are provided here which define the terms –

  1. sludge
  2. sewage and
  3. wastewater.

Pick out the correct definition for each of these terms.

  1. The settled solids are removed in wastewater treatment with a scraper.
  2. Water from the kitchen is used for washing dishes.
  3. Wastewater is released from homes, industries, hospitals and other public buildings.

Describe various steps of cleaning wastewater in a wastewater treatment plant.


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