Wastewater Treatment Operator Certification Test Study Guide, Exams of Water and Wastewater Engineering

Download Wastewater Treatment Operator Certification Test Study Guide and more Exams Water and Wastewater Engineering in PDF only on Docsity! Wastewater Treatment Operator Certification Test 1 (80 Questions) With All Correct Answers What is the methane content in a properly operation anaerobic digester? A) 30 to 35% by volume B) 1 to 2% by volume C) 65 to 70% by volume D) 15 to 20% by volume - C) 65 to 70% by volume (v.2 pg 158) What will the addition of chlorine gas do to the pH of wastewater? A) Moderately increase pH B) pH will not be affected C) Significantly increase the pH D) Decrease the pH - D) Decrease the pH (v.1 pg 349-350) What is the purpose of a Parshall flume? A) measure turbidity B) measure flowrate C) measure settling rate D) measure solids content - B) measure flowrate (v.1 pg 43) What is the typical removal efficiency of settable solids in a primary clarifier? A) 95 to 99% B) 40 to 60% C) 20 to 50% D) 10 to 15% - A) 95 to 99% (v.1 pg 129) Which of the following is true about pumping scum from a primary clarifier? A) Pumping scum is less problematic during colder weather. B) Scum rarely leads to plugged pipelines due to its viscous nature. C) Scum causes more piping problems than other substances pumped at a wastewater treatment plant. D) Scum causes the least amount of piping problems among all the substances pumped at a wastewater treatment plant. - C) Scum causes more piping problems than other substances pumped at a wastewater treatment plant. (v.2 pg 449) What might cause thick billows of white sudsy foam in the aeration tank? A) MLSS is too high B) Temperature in the aeration tank is too low C) Old sludge D) MLSS is too low - D) MLSS is too low (v.2 pg 53,75) What does the "M" in F/M ratio represent? A) MLSS in aeration tank B) The influent BOD loading rate into the aeration tank C) The mixed liquor volatile suspended solids in the aeration tank D) The mass of inorganic solids in the aeration tank - C) The mixed liquor volatile suspended solids in the aeration tank (v.2 pg 16) In general, how will warmer temperature affect the settling rate of solids in a clarifier? A) Decrease settling rate B) Increase the settling rate C) Temperature will not affect the settling rate D) Worsen the settling rate - B) Increase the settling rate (v.1 pg 134) What could happen if the digester gas is mixed with air (85 to 95% by volume)? A) Cause an explosion B) Improve efficiency of digestion C) The bacteria will become aerobic and increase VSR D) The digester becomes safer to operate due to less toxic gas in the system - A) Cause an explosion (v.2 pg 158) How will algae impact the chlorine demand in the pond effluent? A) Slightly decreases chlorine demand B) Does not affect chlorine demand C) Significantly decreases chlorine demand D) Increases chlorine demand - D) Increases chlorine demand Which of the following is true about positive displacement pumps? A) It is a type of centrifugal pump B) Suction valve should be closed when the pump is started C) It must never be started with the discharge valve closed D) Adds head to liquid using several impellers - C) It must never be started with the discharge valve closed (v.2 pg 435) What is true about the F/M ratio? A) MLVSS data in not required to determine the F/M ration B) Volume of the secondary clarifier is not needed to determine the F/M ratio should be located outside the entrance to the confined space, while another person should be within sight or call of the standby person. (v.2 pg 270) What is a common way to determine the organic strength of wastes in the influent? A) Test for the biochemical oxygen demand B) Test for the biological oxygen demand C) Test for the volatile solids reduction D) Test for the carbon and hydrogen concentrations - A) Test for the biochemical oxygen demand (v.1 pg 505) What should you do if you are mildly exposed to chlorine gas? A) Breathe heavily to inhale clean air B) Cough to release chlorine from lungs C) Immediately evacuate the contaminated area, remain calm, keep warm, breathe lightly, and avoid coughing D) Keep your body as cool as possible - C) Immediately evacuate the contaminated area, remain calm, keep warm, breathe lightly, and avoid coughing (v.1 pg 377) What are the main sources of domestic sewage in the collection system? A) Canals B) Surface flow C) Ocean outfall D) Households and commercial establishments - D) Households and commercial establishments (v.1 pg 33) Why is it important to maintain a horizontal weir in a clarifier? A) Prevent sludge bulking B) Prevent short circuiting C) Prevent gasification D) Prevent excessive slime growth - B) Prevent short circuiting (v.1 pg 131) What are mostly removed in the grit channel? A) Biomass B) Organics C) Dissolved solids D) Sand, eggshells, cinders, and heavier particulate matter - D) Sand, eggshells, cinders, and heavier particulate matter (v.1 pg 84) How often should an anaerobic digester be fed? A) Several times a day B) Once a day C) Twice a week D) Five times per week - A) Several times a day (v.2 pg 185) What is the health effect of carbon dioxide? A) Vomiting B) Migraine C) Can lead to asphyxiation D) Rapid heart beat - C) Can lead to asphyxiation (v.2 pg 268) Which of the following enters the headworks of a treatment plant? A) Effluent B) Supernatant C) WAS D) Influent - D) Influent (v.1 pg 33) Which gas diminishes your sense of smell? A) Hydrogen B) Hydrogen Sulfide C) Nitrogen D) Ethane - B) Hydrogen Sulfide (H_2S) (v.2 pg 268) What type of microorganisms can use nitrate as a source of oxygen? A) Aerobic bacteria B) Anaerobic bacteria C) Facultative bacteria D) Zoogleal - C) Facultative bacteria (v.1 pg 254) What is the equivalent of 1 mg/L A) 1 ppb B) 10 ppm C) 10 ppb D) 1 ppm - D) 1 ppm (v.1 pg 468) Select the most accurate statement about extended aeration. A) The bugs are retained in the aeration tank much shorter than the conventional activated sludge system. B) Extended aeration produces the most waste sludge compared to other sludge processes C) An oxidation ditch is usually operated in extended aeration mode, and is used for small flows D) Extended aeration is the least common type of package plant treatment process - C) An oxidation ditch is usually operated in extended aeration mode, and is used for small flows (v.1 pg 269) What is equivalent to organic solids? A) Volatile Solids B) Fixed Solids C) Suspended Solids D) Colloids - A) Volatile Solids (v.1 pg 546) What should be done if a large amount of organic matter is found in the grit channel? A) Decrease the velocity of the wastewater B) Inject sodium hydroxide at the headworks C) Raise the pH D) Increase the velocity of the wastewater - D) Increase the velocity of the wastewater (v.1 pg 87) Which flowrate should you use to calculate the hydraulic loading to a trickling filter? A) Plant inflow B) Plant inflow minus recirculated flow C) Plant inflow plus recirculated flow D) Recirculated flow - C) Plant inflow plus recirculated flow (v.1 pg 199) What is the difference between the sludge from a primary clarifier and secondary clarifier? A) Secondary sludge is denser than primary sludge B) Primary sludge is denser than secondary sludge C) Specific gravity of secondary sludge is larger than that of a primary sludge D) Primary sludge has a smaller specific weight than secondary sludge - B) Primary sludge is denser than secondary sludge (v.1 pg 109) Which process includes a blower? A) Trickling filter B) Waste stabilization pond C) Chlorine contact tank D) Activated sludge - D) Activated sludge (v.2 pg 28) How does an activated sludge system remove waste from wastewater? A) Physical Treatment B) Chemical Treatment C) Biological Treatment What must you do before entering a room with harmful concentration of chlorine gas in the air? A) Read the O&M manual B) Wear self-contained breathing apparatus (SCBA) C) Prepare the fire extinguishers D) Cover your mouth and spray aqueous ammonia in the room. - B) Wear self-contained breathing apparatus (SCBA) (v.1 pg 375) What does black sludge at the bottom of a secondary clarifier located downstream of a trickling filter signify? A) Pumping rate is excessive B) Pumping duration is too long C) Detention time is too short D) Sludge has stayed in the secondary clarifier too long - D) Sludge has stayed in the secondary clarifier too long (v.1 pg 138) If the lab results show that the plant influent sample has a COD of 100 mg/l and the BOD of 300 mg/l, which of the following is most likely true? A) Lab results appear incorrect B) Carbon concentration is very high C) Organic content is unusually high D) COD seems excessive - A) Lab results appear incorrect (v.2 pg 541) If a primary clarifier is placed out of service, then how should a plant with at least two trickling filters operate the system? A) Operate the filters in parallel B) Divert the influent to several trickling filters C) Operate the filters in series D) Maintain existing operation without changing filter arrangement - C) Operate the filters in series (v.1 pg 191) What is the main reason for preventing a direct connection between potable water pipe and a stuffing box (packings) of a wastewater pump? A) Wears out the glands quicker B) Glands should not be wet C) Potable water will rapidly destroy the stuffing box D) Cross Connection - D) Cross Connection (v.2 pg 414) Which of the following is true about algae in a pond? A) During the daytime, the algae will release carbon dioxide B) During the daytime, the algae will release oxygen for the aerobic bacteria C) Algae uses sunlight to produce hydrogen sulfide D) Photosynthesis helps algae create carbon monoxide - B) During the daytime, the algae will release oxygen for the aerobic bacteria (v.1 pg 299) Which of the following is not true about hydrogen sulfide? A) Hydrogen sulfide is flammable B) Hydrogen sulfide is explosive under certain conditions C) Hydrogen sulfide is lighter than air D) Hydrogen sulfide is toxic - C) Hydrogen sulfide is lighter than air (v.2 pg 268,505) What type of treatment if primarily used to thicken sludge instead of dewater the sludge? A) DAF B) Sludge drying bed C) Centrifuge D) Vacuum filters - A) DAF (v.2 pg 219-227) Why should sludge at the bottom of a clarifier be removed in a timely manner? A) To improve the performance of the grit channel B) To maintain a consistent volume of sludge in the drying bed C) To minimize the formation of Chloramines D) To prevent sludge gasification, which causes the sludge to float - D) To prevent sludge gasification, which causes the sludge to float (v.1 pg 130) What is the purpose of sludge digestion? A) Convert primary and secondary sludge to mostly hydrogen sulfide B) Increase efficiency of the DAF C) Reduce the volume of the sludge and stabilize the solids D) increase solids volume - C) Reduce the volume of the sludge and stabilize the solids (v.2 pg 148) Which of the following is true about trickling filters? A) It is mostly an anaerobic process B) The three main parts of a trickling filter are media, distribution system, and underdrain C) In computing BOD loading, it is standard practice to include the BOD of the re-circulated effluent D) Filter ponding is usually due to inadequate organic loading - B) The three main parts of a trickling filter are media, distribution system, and underdrain (v.1 pg 169) Which of the following could cause foaming in an anaerobic digester? A) Temperature is kept constant B) Feeding sludge at a regular, short interval C) Digester is well-mixed D) Organic overload - D) Organic overload (v.2 pg 187,207) Which of the following parameters should be monitored several times a week in a pond? A) TDS B) MLSS C) Dissolved oxygen, temperature, and pH D) MLVSS - C) Dissolved oxygen, temperature, and pH (v.1 pg 315) Which is true about the temperature in an anaerobic digester? A) Temperature in a digester should not be changed by more than 1 degree Fahrenheit per day. B) Temperature must be changed significantly according to the sludge loading rate. C) Temperature at the bottom should be higher than at the top of the digester. D) Mesophilic digestion required a temperature between 105 to 108 degrees Fahrenheit. - A) Temperature in a digester should not be changed by more than 1 degree Fahrenheit per day (v.2 pg 191) The effectiveness of disinfection is determined by: A) The Chlorine residual concentration B) The Chlorine demand C) The Chloramine concentration in the effluent D) The coliform concentration in the effluent - D) The coliform concentration in the effluent (v.1 pg 353) An increase in the acid/alkalinity ratio for an anaerobic digester means A) The digester is in an ideal condition B) The carbon dioxide content is decreasing C) Acid concentration is increasing or alkalinity is decreasing D) pH of the sludge in the digester is increasing - C) Acid concentration is increasing or alkalinity is decreasing (v.2 pg 191) Which of the following will not cause short circuiting in a clarifier? A) Uneven weir settings B) Flow line of launder is low C) Damaged or missing inlet baffles D) Velocity of wastewater is greater in some sections than in others - B) Flow line of launder is low (v.1 pg 125,135)