Read the following Assertion and Reason and choose the correct option. Assertion: Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment, this sediment is called activated sludge Reason: The major part of activated sludge is pumped into larger tanks called aerobic sludge digestors

Step-by-step solution

Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment, this sediment is called activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into larger tanks called anaerobic sludge digestors