Shaalaa.com | Primary Sewage Treatment
- Primary treatment, Secondary treatment or Biological treatment, BOD (biochemical oxygen demand), activated sludge, anaerobic sludge digesters, biogas,Ganga Action Plan
Explain the process of sewage water treatment before it can be discharged into natural water bodies. Why is this treatment essential?
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?
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