Wastewater Treatment Operator Certification Test #2

Wastewater Treatment Operator Certification Test #2 What is the typical BOD removal efficiency in a primary clarifier? A) 10 to 15% B) 40 to 60% C) 20 to 50% D) 95 to 99% Ans- C) 20 to 50% (v.1 pg 129) What does the "F" in F/M ratio represent? A) The microorganism population in the aeration tank B) The amount of filamentous bacteria in the activated sludge process C) The MLVSS in the aeration tank D) The food for the microorganisms flowing into the aeration tank, in lbs/day Ans- D) The food for the microorganisms flowing into the aeration tank, in lbs/day (v.2 pg 58) Which of the following describes the appearance of healthy activated sludge? A) Thick, greasy, dark tan foam B) Brown with a moderate amount of crisp, white foam C) Clear liquid with clear foam D) Gray liquid with no foam Ans- B) Brown with a moderate amount of crisp, white foam What is used to control filamentous organisms? A) Polymer B) Sulfur Dioxide C) Coagulant D) Chlorine Ans- D) Chlorine (v.1 pg 399) What are commonly used to control chlorine feed rate for disinfection? A) BOD and MLVSS B) pH and temperature C) Flow and chlorine residual D) DO and TSS Ans- C) Flow and chlorine residual (v.1 pg 356) Which toxic gas is commonly found in septic wastewater and smells like rotten eggs? A) Hydrogen Sulfide B) Carbon monoxide C) Hydrogen D) Carbon Dioxide Ans- A) Hydrogen Sulfide (v.2 pg 299) What is the permissible exposure limit for chlorine gas vapor during a normal 8 hour workday and a 40 hour work week? A) 0.1 ppm B) 0.5 ppm C) 1 ppm D) 15 ppm Ans- B) 0.5 ppm (v.2 pg 268) What is a vulnerability assessment? A) Assesses the impact of hydrogen sulfide to a concrete structure B) Analyzes the impact of flow and infiltration problem to the plant hydraulics C) Estimates the vulnerability of aquatic wildlife to excessive algae growth D) Contingency planning to determine the vulnerability of the utility during various types of emergencies and identify corrective actions to reduce the risks Ans- D) Contingency planning to determine the vulnerability of the utility during various types of emergencies and identify corrective actions to reduce the risks (v.2 pg 722) What is the difference between the settling rate of activated sludge and raw sludge? A) Activated sludge settles slightly faster than raw sludge B) Activated sludge settles at the same rate as raw sludge C) Activated sludge settles slower than raw sludge D) Activated sludge settles much faster than raw sludge Ans- C) Activated sludge settles slower than raw sludge (v.1 pg 109) What should be mostly found in healthy activated sludge? A) Tiny flagellates B) Amoeboids C) Short Filaments D) Free swimmers and stalked ciliates Ans- D) Free swimmers and stalked ciliates (v.2 pg 120,124) One to two percent of the digester gas in an anaerobic consists of A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases B) Methane C) Carbon Dioxide D) CH_4 Ans- A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg 158) What is true during the colder winter months? A) Modify operations to decrease solids under aeration to provide less microorganisms to treat the BOD B) Modify operations to increase solids under aeration to provide more microorganisms to treat the BOD C) Biological activity will increase, which results in more overall sludge production D) Microorganisms become more active Ans- B) Modify operations to increase solids under aeration to provide more microorganisms to treat the BOD (v.2 pg 71) What type of sludge would you expect in an aeration tank if the content is dark and has low DO? A) Sludge that is heavy B) Chlorinated Sludge C) Septic Sludge D) Healthy Sludge Ans- C) Septic Sludge (v.2 pg 75) What could have happen if the volatile acid/alkalinity ratio starts to increase, and corrective action is not taken immediately? A) Carbon dioxide content in the digester gas will decrease B) Carbon monoxide content in the digester gas will fluctuate C) pH of the digester sludge will increase D) Carbon dioxide content in the digester gas will increase Ans- D) Carbon dioxide content in the digester gas will increase (v.2 pg 191) What are screenings? A) Colloids B) TDS C) Pieces of wood, roots, rags, and other large debris D) COD Ans- C) Pieces of wood, roots, rags, and other large debris (v.1 pg 41) What happens when there is more food in the influent to the aeration tank? A) Less oxygen is required in t