Wastewater Treatment Plant Operations, Exams of Nursing

Download Wastewater Treatment Plant Operations and more Exams Nursing in PDF only on Docsity! ABC WASTEWATER LEVEL 3 - ACTIVATED SLUDGE EXAM QUESTIONS AND DETAILED CORRECT ANSWERS What treatment process occurring in some activated sludge plants requires the addition of caustic soda and lime to raise alkalinity? A. Clarification B. Aeration C. Nitrification D. Disinfection Correct Answer C. Nitrification Which of the following does NOT result from the addition of caustic soda and lime to the activated sludge process? A. DO levels drop to zero B. Grit removal C. Disinfection D. Increased alkalinity Correct Answer D. Increased alkalinity Primary clarifiers are designed to remove how much of the influent BOD load? A. 10 to 20% B. 30 to 40% C. 50 to 60% D. 70 to 80% Correct Answer B. 30 to 40% Primary clarifiers are designed to remove how much of the influent SS load? A. 10 to 20% B. 30 to 40% C. 50 to 60% D. 70 to 80% Correct Answer C. 50 to 60% The person most responsible for an operator's safety is _______________. A. The local safety agency inspector B. The plant manager C. The operator D. The plant's safety coordinator Correct Answer C. The operator Because of warm wastewater temperatures, ice on walkways, steps, and areas around biological reactors and clarifiers is rarely a problem. A. True B. False Correct Answer B. False Typically, employees require training on procedures and practices for handling hazardous chemicals only when this information is not included on the material safety data sheet. A. True B. False Correct Answer B. False Typically, employees should not eat, drink, or smoke while or after handling potentially hazardous or toxic materials until ______________. D. Discharge location Correct Answer C. Regulatory requirements Devices improvised for manual sample collection at the process tanks include _____________. A. Ball and sprocket samplers B. Containers attached to a rod or chain C. Pestle and morter samplers D. Pipette samplers Correct Answer B. Containers attached to a rod or chain Automatic samplers are most commonly used to collect ______________. A. Final effluent samples B. Mixed liquor samples C. Return activated sludge samples D. Waste activated sludge samples Correct Answer A. Final effluent samples One reason to collect composite samples is that ___________. A. Average data are needed to make process adjustments B. Instantaneous data are needed to make process adjustments C. Maximum data are needed to make process adjustments D. Minimum data are needed to make process adjustments Correct Answer A. Average data are needed to make process adjustments Composite samples are used when testing for most constituents that require immediate analysis. A. True B. False Correct Answer B. False Which of these parameters can be monitored using an online analyzer? A. pH B. Dissolved oxygen C. Chlorine residual D. All of the above Correct Answer D. All of the above Results for the BOD5 test are available after what period of time? A. 5 hours B. 5 weeks C. 5 solids retention times D. 5 days Correct Answer D. 5 days The total BOD test includes both carbonaceous and ___________ components. A. Dissolved B. Nitrogenous C. Particulate D. Soluble Correct Answer B. Nitrogenous COD levels in untreated municipal wastewater typically range from _________________. A. 100 to 250 mg/L B. 200 to 600 mg/L C. 300 to 900 mg/L D. 400 to 1200 mg/L Correct Answer B. 200 to 600 mg/L The ratio of BOD to COD in untreated municipal wastewater is typically _______________. A. 0.5 to 1 B. 1 to 1.5 C. 1.5 to 2 D. 2 to 2.5 Correct Answer A. 0.5 to 1 The _________ test is a way of quickly estimating the suspended solids concentration in the mixed liquor or RAS. A. Buchner funnel B. Centrifuge C. Muffle furnace D. Core sampler Correct Answer B. Centrifuge Microscopic examination of the mixed liquor provides valuable information on the biological characteristics and health of the activated sludge process. A. True B. False Correct Answer A. True The specific oxygen uptake rate is calculated by determining the change in DO per unit time and relating it to ________________. A. COD B. F:M C. MLSS D. MLVSS Correct Answer D. MLVSS D. Remove any excess DO that has collected in the sampling line Correct Answer A. Avoid collecting nonrepresentative samples caused by alteration from chemical A database is a tool that can help organize data from process observations, measurements, and calculations that form the foundation for basic process control decisions. A. True B. False Correct Answer A. True Because each treatment scheme is different, it is important that all plants within an area use the same database format to facilitate the exchange of information. A. True B. False Correct Answer B. False Within a process control database, long-term storage of data should be provided to ______________. A. Assess past operational problems and evaluate corrective solutions B. Have as much data as possible for charts and graphs C. Reduce paper records to be stored D. Track performance of specific analyzers and other equipment Correct Answer A. Assess past operational problems and evaluate corrective solutions A disadvantage to providing long-term storage of data in a database is that data could be used against the plant if permit and other discharge limits are exceeded. A. True B. False Correct Answer B. False In a NITRIFYING activated sludge process, the recommended pH range is _________________. A. 5.5 to 6.5 B. 6.5 to 7.5 C. 6.5 to 8.5 D. 7.0 to 8.0 Correct Answer D. 7.0 to 8.0 For the conventional activated sludge process, the proper pH range is _______________. A. 5.5 to 6.5 B. 7.0 to 8.0 C. 6.5 to 8.5 D. 8.0 to 9.0 Correct Answer C. 6.5 to 8.5 Nutrient deficiencies are more likely to be of concern in plants with ______________. A. High ammonia levels B. Large industrial contributions C. Domestic influent wastewater D. Low DO levels Correct Answer B. Large industrial contributions Which of the following dischargers will produce high- strength (high-BOD) wastewater? A. Metal-finishing plant B. Dry cleaning business C. Fruit juice processor D. All of the above Correct Answer C. Fruit juice processor Bulking sludge is more susceptible to high flow washout than well-settling sludge. A. True B. False Correct Answer A. True Even with the use of online DO analyzers, portable units should still be used for _____________. A. Mixing B. Checking salinity C. Finding possible dead spots D. Monitoring MLSS concentrations Correct Answer C. Finding possible dead spots If you calculate the F:M for your plant and find it to be higher than the target ratio, you should increase the wasting rate from your biological reactor. A. True B. False Correct Answer B. False When BOD loads are fairly constant, mean cell residence time can be used to guide wasting rates and maintain the necessary solids. A. True B. False Correct Answer A. True Which of the following statements regarding solids inventory maintenance is accurate? A. F:M is the best parameter to track when BOD loads are constant A. Bulking solids in clarifiers B. Excessive foam on reactors C. Low BOD in effluent D. Floating solids in clarifiers Correct Answer C. Low BOD in effluent In reactors with mechanical aeration systems, hydraulic surging problems are more likely to be encountered under peak flow conditions. A. True B. False Correct Answer B. False Hydraulic surging of mechanical aerators is caused by which of the following conditions? A. Submergence of impellers being too low B. Obstructions to impellers C. Solids concentration being too high D. Power surges Correct Answer A. Submergence of impellers being too low Stiff white foam may appear on reactors during cold weather because of the effect of lower temperature on the biomass. Under these conditions, ________________. A. Increase the WAS rate and decrease the RAS rate B. Maintain conditions as is unless ice appears on the reactors C. Perform a microbial examination of the mixed liquor to determine biological activity and troubleshoot the situation D. Increase the RAS rate and decrease the WAS rate Correct Answer D. Increase the RAS rate and decrease the WAS rate Which of the following is NOT a possible cause of high F:M in the activated sludge process? A. Excess microorganism buildup B. Toxic influent C. High or low pH D. Excessive hydraulic or "shock" loads Correct Answer A. Excess microorganism buildup Thick, dark tan, greasy foam is typically caused by ___________. A. High F:M B. Nocardia C. Septic conditions D. All of the above Correct Answer B. Nocardia In secondary clarifiers, poor settling sludge could indicate all of the following EXCEPT _________. A. Hydraulic loading is too high B. Solids loading is too high C. Plant influent flow is too low D. Excessive amounts of filamentous bacteria are present Correct Answer C. Plant influent flow is too low Uneven flow distribution can result in hydraulic overload of a component of an activated sludge process. A. True B. False Correct Answer A. True What is the first step that should be taken when troubleshooting hydraulic overload problems in clarifiers? A. Bypass any excess flows straight to the receiving stream B. Adjust gates and weirs if necessary to ensure that all clarifiers have equal flow C. Track down industries that use the most water D. Throttle back plant influent during wet weather events Correct Answer B. Adjust gates and weirs if necessary to ensure that all clarifiers have equal flow The presence of straggler floc in the clarifiers is typically characteristic of decreasing __________. A. Temperature B. Plant influent flow C. MCRT D. Return activated sludge concentration Correct Answer C. MCRT When F:M is increasing or greater than required, the best course of action is to increase wasting rates. A. True B. False Correct Answer B. False A pH lower than 6.5 in reactor influent can lead to the predominance of ______________. A. Rotifers B. Flagellates C. Fungi D. Amoebas Correct Answer C. Fungi Chlorination of RAS is useful for destroying filamentous microorganisms that are contained within the floc. B. Inability to maintain a healthy biomass C. Damage to process equipment D. Increased cost because of chemical addition Correct Answer A. Power consumption Because of industrial flows and the nitrification process, pH imbalances may become a concern for activated sludge processes if sufficient __________ is not present. A. TSS B. Alkalinity C. Ammonia D. BOD Correct Answer B. Alkalinity Which of the following is NOT a phase of a typical sequencing batch reactor treatment cycle? A. Filter B. Fill C. Decant D. Settle Correct Answer A. Filter Because multiple steps occur in a single reactor, the sequencing batch reactor process provides little control over effluent quality. A. True B. False Correct Answer B. False Which of the following terms is used to describe biological reactors arranged in a parallel configuration? A. Parallel processors B. Parallel-lined systems C. Multiple process trains D. Reactor chains Correct Answer C. Multiple process trains Using portable DO meters can be more economical than using permanently installed, continuous-read units. A. True B. False Correct Answer A. True What equipment can be used with surface aerators to aid mixing in deep reactors? A. Draft tubes B. Rotor extensions C. Turbo injectors D. Extended impellers Correct Answer A. Draft tubes What type of problem can the splashing of surface aerators cause in or around a reactor? A. Poor oxygen transfer B. Inadequate mixing C. Excessive heat gain D. Biohazards Correct Answer D. Biohazards Accelerated respiration rates in high-purity oxygen systems require increased detention times for sufficient treatment of wastewater. A. True B. False Correct Answer B. False Which of the following is NOT used to generate high-purity oxygen for activated sludge processes? A. Liquid oxygen B. Electrolysis of water C. Cryogenic generation D. Pressure-swing adsorption Correct Answer B. Electrolysis of water Rectangular clarifiers can be classified into three general categories: cocurrent flow, countercurrent flow, and which of the following? A. Tangential flow B. Folded flow C. Cross-sectional flow D. Rapid flow Correct Answer B. Folded flow In clarifiers, inlet distribution devices are used to INCREASE influent flow velocity. A. True B. False Correct Answer B. False What function do traveling bridges and continuous flights perform in rectangular clarifiers in addition to sludge removal? A. Sludge settling B. Scum removal C. Aeration D. Mixing Correct Answer B. Scum removal Sludge blanket depth is an unimportant process control parameter. A. True B. False Correct Answer B. False