Objective Question & Answer

Statement A is correct: In a trickling filter (an attached-growth process), microorganisms grow as a fixed biofilm on stationary filter media

(such as gravel, rocks, or plastic). If organic or hydraulic loads are unbalanced, this stationary layer can grow too thick and clog the

media voids over time.

Statement B is correct: In the activated sludge process (a suspended-growth process), the bacterial mass is not attached to any fixed 

structure. Instead, the fine suspended particles and microbes group together to form dynamic sludge flocs. These active, free-moving

biological films are kept continuously moving and suspended in the wastewater by artificial constant agitation or aeration