Why is this sewage water treatment essential? - Biology

Short Note

Why is this sewage water treatment essential?



Importance of sewage water treatment:

  1. The sewage water contains pathogenic microorganisms like bacteria, viruses, protozoa, and parasitic worms, which can spread a variety of diseases.
  2. Also, it contains harmful chemicals that may cause toxicity if mixed with the natural resources of water. Therefore, sewage water treatment is essential before it can be discharged into natural bodies.
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Chapter 11: Enhancement of Food Production - Exercises [Page 271]


Balbharati Biology 12th Standard HSC for Maharashtra State Board
Chapter 11 Enhancement of Food Production
Exercises | Q 4.1 | Page 271

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Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) it.

Distinguish between the roles of flocs and anaerobic sludge digesters in sewage treatments.

Explain the process of sewage water treatment before it can be discharged into natural water bodies.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Describe how do 'flocs' and 'activated sludge' help in Sewage Treatment.

What is primary treatment of sewage?

Answer the following question.
What are ‘flocs’, formed during secondary treatment of sewage?

Removal of large pieces of floating debris, oily substances, etc. during sewage treatment is called _______________.

One of the free-living anaerobic nitrogen-fixer is _________.

Name the chamber in which the suspended objects are filtered and removed during sewage treatment?

Name the tank to which the sewage water is passed after the preliminary treatment?

What are flocs with respect to sewage treatment?

Small part of activated sludge is passed back into primary sedimentation tank.

If the above statement is correct then rewrite as it is and in case it is incorrect then reframe it.

Rearrange the names of tanks used in sewage treatment as per the flow of procedure.

  1. settling tank
  2. Grit Chamber
  3. aeration tanks 
  4. primary sedimentation tank.

The purpose of biological treatment of waste water is to ______.

In which of the following microbial digestion of organic wastes of sewage takes place?

Due to which of the following reason/s sewage water cannot be discharged directly into river?

Which of the following is TRUE about primary treatment?

Small part of activated sludge is passed back into ______ and major part is pumped into large tanks called ______.

Into which of the following the sewage water is pumped after preliminary treatment?

Identify the type of microorganisms involved in floe formation during sewage treatment.

After which of the following treatment BOD of the effluent is significantly reduced?

Which of the following process is a part of preliminary treatment of sewage?

Which of the following is TRUE regarding 'Flocs'?

Nitrogen fixation by organisms requires conditions that are:

During sewage, treatment biogas is produced wits which include:

Which of the following is put into Anaerobic sludge disaster for further sewage treatment?

Methanogenic bacteria are not found in ______.

In a sewage treatment plant, all of the following processes belong to secondary treatment except: 

In which of the following step large and small particles are removed from sewage through sequential filtration and sedimentation?

Activated sludge should have the ability to settle quickly so that it can ______.

Why are flocs important in biological treatment of waste water?

Discuss about the major programs that the Ministry of Environment and Forests, Government of India, has initiated for saving major Indian rivers from pollution.

Study the given diagram of the Sewage Treatment  Plant (S.T.P.) and answer the question that follows:

  1. Which one of the two 'S.T.P.' (A) or (B) will be more effective in treating the human excreta in municipal waste?
  2. Write the steps followed in carrying the treatment of the sewage in step (Z), once the BOD of sewage is reduced significantly till it is passed on to the "anaerobic sludge digesters".

Which one is wrongly matched?

The aeration tank of a sewage treatment plant is not functioning properly. Explain in detail the impact of this on the treatment of sewage and BOD of the effluent.

Explain the steps involved in preliminary treatment of sewage.


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