• Subject:


  • Chapter:


List the events that reduce the Biological Oxygen Demand (BOD) of a primary effluent during sewage treatment.                                                                                                                         (2)


   Primary effluent is passed into large aeration tanks 


   Constantly agitated mechanically and air is pumped into it 


   This allows vigorous growth of useful aerobic microbes into flocs 


    While growing these microbes consume major part of the organic matter  in the effluent 


   This reduces BOD of the effluent significantly.                                                                     (2)