Ca Grade 2 Wastewater Treatment Operator Practice Exam 1

Ca Grade 2 Wastewater Treatment Operator Practice Exam 1 What is the methane content in a properly operating anaerobic digester? Ans- 65 to 70% by volume What will the addition of chlorine gas do to the pH of wastewater? Ans- decrease the pH What is the purpose of a Parshall Flume? Ans- Measure the flow rate What is the typical removal efficency of settleable solids in a primary clarifier? Ans- 95 to 99% Which of the follwing is true about pumoing scum from a primary clarifier? Ans- scum causes more piping problems than other substances pumped at a wastewater treatment plant What might cause thick billows of white sudsy foam in the aeration tank? Ans- MLSS is too low What does the M in F/M ratio represent? Ans- The mixed liquor volatile suspended solids in the aeration tank In general, how will warmer temp affect the settling rate of solids in a clarifer? Ans- Increase the settling rate What could happen if the digester gas is mixed with air(85 to 95% by volume)? Ans- Cause an explosion How will algae impact the chlorine demand in the pond effluent? Ans- increase the chlorine demand Which of the following is true about a positive displacement pump? Ans- it must never be started with the discharge valve closed What is true about the F/M ratio? Ans- the volume of the secondary clarifier is not needed to determine the f/m ratio Which of the following is one of the basic rules of lab work? Ans- never pipet hazardous material with your mouth, even if the pipet has been sterialized What is the recirculation ratio for a trickling filter? Ans- Qr/Q Which of the following is true about COD and BOD? Ans- they are indirect measurements of the organic content in the influent What is the purpose of the grit channel? Ans- remove heavy inorganic waste Which of the following is true about the extended aeration process? Ans- it does not produce as much waste sludge as other processes What is the correct formula for solids in raw wastewater? Ans- Non settleable solids + settleable solids = total suspended solids What is freeboard in a waste stabilization pond? Ans- the vertical distance from normal water surface to the top of the levee What is one of the requirements for a BOD test? Ans- The BOD bottle should be completely filled to the top What should be scheduled every 3 months for a flamer arrester in an anaerobic digester? Ansmaintenance What is common practice in an activated sludge process? Ans- recirculate activated sludge Prior to entering a permit-required confined space, what should you verify? Ans- a standby person should be located outside the entrance to the confined space, while another person should be within sight or call of the standby person What is a common way to determine the organic strength of wastes in the influent? Ans- test for the biochemical oxygen demand What should you do if you are mildly exposed to chlorine gas? Ans- immediately evacuate the contaminated area, remian calm, keep warm. breath lightly, avoid coughing What are the main sources of domestic sewage in the collection system? Ans- household and commercial establishments Why is it important to maintain a horizontal weir in a clarifier? Ans- to prevent short circuiting What are mostly removed in the grit channel? Ans- sand, eggshells, cinders, and heavier particulate matter How often should an anaerobic digester be fed? Ans- several times a day What is the health effect of carbon dioxide? Ans- could lead to asphyxiation Which of the following enters the headworks of a treatment plant? Ans- influent Which gas diminishes your sense of smell? Ans- hydrogen sulfide What type of microorganism can use nitrate as a source of oxygen? Ans- facultative bacteria What is the equivalent of 1 mg/l? Ans- 1 ppm Select the most accurate statement about extended aeration? Ans- an oxidation ditch is usually operated in extended aeration mode, and is used for small flows What is equivalent to organic solids? Ans- volatile solids What should be done if a large amount of organic matter is found in the grit channel? Ans- increase the velocity of the wastewater Which flow rate should you use to calculate the hydraulic loading to a trickling filter? Ans- plant inflow plus recirculated flow What is the differnce between the sludge from a primary clarifier and a secondary clarifier? Ans- primary sludge is denser than secondary Which process includes a blower? Ans- activated sludge How does an activated sludge system remove watse from wastewater? Ans- biological treatment Which of the following best describes pre-chlorination? Ans- addition of chlorine to wastewater at the entrance to the plant used for odor control, BOD reduction, grease removal, and aid sedimentation When would you expect reduced algae population and less oxygen released into a pond? Ans- fall and winter, when the weather is cool and sunlight is reduced What is the first step of the lockout/tagout procedure? Ans- notify all affected employees that a lockout/tagout system is going to be used and the reas