Waste Water Operator Lv 1 Exam Prep: Questions & Answers: Updated A+ Guide

In the activated sludge process, some of the activated sludge must be wasted to... A. Prevent excessive solid buildup B. Prevent clogging of the sludge return line C. Prevent overloading of sludge return pumps D. Increase digester gas production (Ans - A. Prevent excessive solid buildup The best operating strategy for feeding primary sludge to an anaerobic digester is to feed... A. Several time a day B. Large quantities once or twice a day C. Once a day D. When the volatile solids drop below 60% (Ans - A. Several time a day Why is scum skimmed from the liquid surface of a primary settling tank? A. To reduce load on the digester B. To eliminate interference with sludge removal C. To allow aeration of the tank contents D. To reduce odor and insect nuisance (Ans - B. To eliminate interference with sludge removal Which of the following test would give the fastest indication of toxicity in an activated sludge process? A. Oxygen Uptake Rate (OUR) B. Settle meter C. MLSS D. Microscopic Observation (Ans - A. Oxygen Uptake Rate (OUR) Filamentous bulking of activated sludge may be controlled temporarily by... A. Adding sodium chloride to the aeration tank B. Spraying water on the aeration tank surface C. Carefully chlorinating the return sludge and mixed liquor D. Aerating the final settling tank (Ans - C. Carefully chlorinating the return sludge and mixed liquor Since reaction rates are lower during the winter, the operator of an activated sludge plant will usually... A. Increase dissolved oxygen levels B. Decrease MCRT C. Decrease wasting D. Increase MCRT (Ans - D. Increase MCRT In a healthy activated sludge process which of the following organisms will most likely be found in the greatest numbers? A. Stalked Ciliates B. Amoebas C. Free swimming ciliates D. Nymphs