Which of the following is the correct expression of the aeration period in hours?
Explanation: Aeration period = 24V/Q where, V is the volume of the tank and Q is the quantity of sewage. It is measured in hours.
Which of the following activated sludge process has minimum food to microorganism ratio?
Explanation: Extended aeration process has minimum food to microorganism ratio of 0.5 which means it has the maximum BOD removal efficiency.
The maximum aeration period for a conventional activated sludge system is
Explanation: The detention period for a conventional activated sludge system is between 4 to 6 hours.
The organic loading in an activated sludge plant is defined as
Explanation: The organic loading in an activated sludge plant is defined as the mass of BOD to the aeration tank in grams per unit volume of aeration tank in m3.
_________ is defined as a volume in ml occupied by 1gram of solid in the mixed liquor after 30 minutes of settling.
Explanation: Sludge volume index is used to indicate the settling behavior of sludge. It is measured in ml/gm.
The design value of food to microorganism ratio in the tapered aeration sludge process is
Explanation: The design value of food to microorganism ratio is 0.3-0.4 for a tapered aeration sludge process.
Which of the following sludge process has maximum aeration period?
Explanation: Extended process has the maximum aeration period of 12 to 24 hours.
The maximum BOD removal efficiency of the Step aeration process of the activated sludge system is
Explanation: The BOD removal efficiency of the step aeration process of the activated sludge system is between 85% to 92%.
_________ is the time at which sewage is detained in the aeration tank.
Explanation: Aeration period decides the loading rate at which sewage is introduced in the aeration tank.
Which of the following has minimum hydraulic retention time?
Explanation: Modified aeration process has a minimum hydraulic retention time with an aeration period of 1.5 hours.