California Wastewater Operator Exam, Secondary Treatment (Activated Sludge, Trickling Filters, RBC): all 31 questions

All questions from the Secondary Treatment (Activated Sludge, Trickling Filters, RBC) section for California Wastewater Operator Exam, each with the correct answer.

• 4001In the activated sludge process, the activated sludge is
• 4002The purpose of returning activated sludge (RAS) from the secondary clarifier to the aeration tank is to
• 4003The purpose of wasting activated sludge (WAS) is to
• 4004If the operator wastes more sludge from an activated sludge system, the mean cell residence time (MCRT) will
• 4005Which F/M ratio range is typical for a conventional activated sludge plant?
• 4006A very low F/M ratio in an activated sludge plant tends to produce
• 4007Which sludge condition is typically seen with a high F/M ratio?
• 4008A sludge volume index (SVI) of 80 mL/g indicates
• 4009Filamentous bulking is often related to
• 4010Which microscopic organism is commonly found in a healthy, well-settling activated sludge with moderate sludge age?
• 4011Rotifers in large numbers in the aeration tank suggest
• 4012The best location to measure the settleability of mixed liquor with a 30-minute test is
• 4013Foam that is thick, brown, and greasy on an aeration tank is often caused by
• 4014White, billowy foam on an aeration tank is most often a sign of
• 4015Nitrification is the biological conversion of
• 4016Denitrification occurs when
• 4017Rising sludge or floating clumps in a secondary clarifier on a hot day is often caused by
• 4018A trickling filter is a
• 4019Sloughing in a trickling filter refers to
• 4020Which problem often occurs in trickling filters when the hydraulic loading is too low?
• 4021The purpose of recirculation in a trickling filter plant is to
• 4022A rotating biological contactor (RBC) is a
• 4023The purpose of the secondary clarifier is to
• 4024A sludge blanket that is rising too high in a secondary clarifier should be corrected by
• 4025Which is a sign of toxic shock to an activated sludge system?
• 4026Extended aeration plants typically operate with
• 4027A sequencing batch reactor (SBR) carries out its treatment steps
• 4028When dissolved oxygen in an aeration tank is too low, the most likely result is
• 4029Which of the following is true about return activated sludge concentration compared to mixed liquor?
• 4030Which factor most affects the oxygen transfer in a diffused aeration system?
• 4031Suspended-growth treatment is best described as

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