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 - Biology


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.



The effluent from the primary treatment is passed to aeration tanks where air is pumped into it. The useful aerobic microbes grow into flocs (masses of bacteria associated with fungal filaments) and consume the major part of the organic matter in the effluent which reduces BOD of the effluent. The effluent is then passed into a settling tank where bacterial flocs are allowed to sediment. This sediment is called activated sludge.

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2014-2015 (March) All India Set 2

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

What is sewage? In which way can sewage be harmful to us?

What is the key difference between primary and secondary sewage treatment?

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?

Find out the role of microbes in the following

Single cell protein (SCP)

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

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

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

Why is this sewage water treatment essential?

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 ______.

Which of the following is/are found in discharge from industrial waste?

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

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

Identify the INCORRECT statement with respect to sewage treatment.

What happens during the course of sewage decomposition?

During tertiary treatment, the bacterial floes sediment in the sedimentation tank, this sediment is called ____________.

Study the following statements regarding tertiary treatment of sewage and choose the correct option.

i. It produces methane gas.

ii. The effluents formed from these plants undergo chlorination.

iii. BOD is significantly increased at this step.

iv. It includes screening and passage of effluent through grit chamber.

Which of the following is TRUE regarding 'Flocs'?

In the process of sewage treatment, the activated sludge is digested by ______

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 do we prefer to call secondary waste water treatment as biological treatment?

Why are flocs important in biological treatment of waste water?

What would happen if a large volume of untreated sewage is discharged into a river?

Biochemical Oxygen Demand (BOD) may not be good index for pollution for water bodies receiving effluents from ______.

Explain the steps involved in preliminary treatment of sewage.


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