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प्रश्न
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 20 mg/L, 8 mg/L and 400 mg/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?
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उत्तर
Biological oxygen demand (BOD) is the method of determining the amount of oxygen required by micro-organisms to decompose the waste present in the water supply. If the quantity of organic waste in the water supply is high, then the number of decomposing bacteria present in the water will also be high. As a result, the BOD value will increase.
Therefore, it can be concluded that if the water supply is more polluted, then it will have a higher BOD value. Out of the above three samples, sample C is the most polluted since it has the maximum BOD value of 400 mg/L. After untreated sewage water, secondary effluent discharge from a sewage treatment plant is most polluted. Thus, sample A is secondary effluent discharge from a sewage treatment plant and has the BOD value of 20 mg/L, while sample B is river water and has the BOD value of 8 mg/L.
Hence, the correct label for each sample is:
| Label | BOD value | Sample |
| A | 20 mg/L | Secondary effluent discharge from a sewage treatment plant |
| B | 8 mg/L | River water |
| C | 400 mg/L | Untreated sewage water |
APPEARS IN
संबंधित प्रश्न
Explain the role of microbes in sewage treatment.
Explain the different steps involved during primary treatment phase of sewage.
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.
Answer the following question.
Secondary treatment of the sewage is also called Biological treatment. Justify this statement and explain the process.
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 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 the procedure.
- Settling tank
- Grit Chamber
- Aeration tanks
- 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?
Which of the following is TRUE about primary treatment?
After which of the following process effluents from anaerobic sludge digesters are released in natural water bodies?
Into which of the following the sewage water is pumped after preliminary treatment?
What happens during the course of sewage decomposition?
After which of the following treatment BOD of the effluent is significantly reduced?
Which of the following is TRUE regarding 'Flocs'?
In which of the following step large and small particles are removed from sewage through sequential filtration and sedimentation?
Wastewater treatment generates a large quantity of sludge, which can be treated by ______.
Activated sludge should have the ability to settle quickly so that it can ______.
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:
- Which one of the two 'S.T.P.' (A) or (B) will be more effective in treating the human excreta in municipal waste?
- 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".
Given below is the flowchart of sewage treatment. Identify A, B, C, D and E and select the correct option.
Biochemical Oxygen Demand (BOD) may not be good index for pollution for water bodies receiving effluents from ______.
Removal of suspended, floating, coarse and solid particles in sewage treatment is called ______.
What is the major component of municipal wastewater (sewage)?
During primary sewage treatment, floating debris is separated by which physical process?
