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 CERTIFICATION EXAM QUESTIONBANK ACTUAL EXAM QUESTIONS AND DETAILED CORRECT ANSWERS| LATEST 2025 One opening has become available which would be an advancement to any one of three qualified eager employees. How should this situation be handled? A. hire an outsider to fill the position B. pick one and notify all personnel of the change C. split the work between the three and leave the position open D. talk to the three as a group, explain the situation and make your selection, then notify all personnel of the change Correct Answer D. talk to the three as a group, explain the situation and make your selection, then notify all personnel of the change One of the employees in your crew complains about having to do a hard job. The proper thing to do is A. explain that all employees must do their fair share of the hard work as well B. give the easier tasks C. ignore the complaint D. promise that the next assignments will be easier ones E. tell the employee to shut up and work or quit and go home Correct Answer A. explain that all employees must do their fair share of the hard work as well Occasionally some of the people on a work crew will indulge in active horseplay. This should be A. discouraged because some of the workers might not like it B. encourage because it promotes good fellowship C. permitted as it is a form of relaxation D. stopped immediately because it is likely to cause an accident Correct Answer D. stopped immediately because it is likely to cause an accident The temperature versus DO relationship for wastewater is such that the A. higher the temperature, the higher the DO saturation level B. higher the temperature, the lower the DO saturation level C. lower the temperature, the lower the DO saturation level D. none of the above Correct Answer B. higher the temperature, the lower the DO saturation level The gas most commonly associated with fresh wastewater is A. carbon dioxide B. carbon monoxide C. hydrogen sulfide D. oxygen Correct Answer D. oxygen D. 250 VAC Correct Answer D. 250 VAC A chlorine gas mask should be provided A. just outside the chlorine room door B. just inside the chlorine room door C. in the plant superintendent's office D. in a locked tamper-proof container Correct Answer A. just outside the chlorine room door Chlorine cylinders should be stored A. below ground level B. in a clean, dry location C. on their side D. with the protective caps off Correct Answer B. in a clean, dry location At a pumping station equipped with centrifugal pumps, what caused the discharge pressure to suddenly increase and the discharge quantity to suddenly decrease? A. a discharge valve was closed B. a suction valve was closed C. the pump amperage was decreased D. the voltage was suddenly increased Correct Answer A. a discharge valve was closed To sample for pH, you should collect a A. composite sample B. continuous sample C. grab sample D. regulated sample Correct Answer C. grab sample You have been directed to examine and review the plans and specifications for a new wastewater pump station prior to the advertising for construction bids. Which of the following is of least significance to your review? A. the clearance around and above pumps, motors, valves and control switch gear B. the provisions for ingress and egress for both wet well and dry well C. the size and geometry of the wet well D. the specific colors for all piping Correct Answer D. the specific colors for all piping Which one(s) of the following items should be inspected when responding to a lift station alarm at night? A. dry well B. motor control center and power panel C. operation of ventilation equipment D. all of the above Correct Answer D. all of the above How many pounds of chlorine gas can be drawn from a 150 pound cylinder in a 24-hour period at ordinary room temperature? A. 20 B. 40 C. 60 D. 65 Correct Answer B. 40 When litmus paper is immersed in an acid solution, the paper turns A. blue B. red C. violet D. yellow Correct Answer B. red What is the greatest distance at which manholes should be installed for an 8-inch sewer line? A. 100 feet B. 200 feet C. 300 feet D. 400 feet Correct Answer C. 300 feet Disaster planning is A. having manuals ready so they can be read if a disaster occurs B. something that, if properly done, will not need to be revised C. useful in reducing confusion in the event of a disaster D. none of the above Correct Answer C. useful in reducing confusion in the event of a disaster The best discipline is A. authoritarian B. general supervisory C. self-discipline D. theocratic Correct Answer C. self-discipline Staffing a new system should be viewed primarily as the function of A. every operator B. personnel department C. the employee B. polaroid system C. tape recorder D. work order system Correct Answer D. work order system The most important function of record-keeping is A. they record how much money was budgeted and how much we spent B. they record the past and provide a sound basis on which to plan the future C. they record what was done and when it was done D. they record where we've been and how we got where we are today Correct Answer B. they record the past and provide a sound basis on which to plan the future The ash content is the same as the A. difference in raw sludge and the sludge after air drying B. inorganic solids C. organic solids D. volatile solids Correct Answer C. organic solids The most abundant pollutant entering natural water bodies (rivers, lakes) is A. domestic waste B. food processing waste C. hospitals D. non-point Correct Answer D. non-point The weight of a chemical compound is 1/8 of the total weight of a chemical solution. The percent, by weight, of the chemical in solution is A. 6.4 B. 8.3 C. 10.5 D. 12.5 Correct Answer D. 12.5 All of the following are types of starters for electrical motors except A. actuator B. autotransformer C. reduced voltage D. resistors Correct Answer A. actuator Instrumentation friction discs or clutch surfaces should be A. frequently brushed briskly with a solution of water and soda. B. kept free of oil C. oiled frequently D. roughened with emery cloth as necessary Correct Answer B. kept free of oil If a generator will not start, check for A. loose terminal connections B. shaft binding or sticking C. tripped circuit breakers D. all of the above Correct Answer D. all of the above Given the data below, what is the most likely cause of the problem? DATA: Wet well inlet increased flow because of rain Wet well unchanged at excessively high level Lead pump running Follow pump running Lead pump check valve lifting arm up Follow pump check valve lifting arm down Force main pressure remains at normal range for one pump Low-level pressure switch normal High-level pressure switch normal Electrical controls automatic A. lead pump clogged B. force main pressure too high C. follow pump clogged D. both pumps clogged Correct Answer C. follow pump clogged Given the data below, what is the most likely cause of the lift station problem? DATA: Wet well inlet has normal dry weather flow Wet well empty with flow going directly to pump suction Lead pump is running Follow pump is running Lead and follow pump check valve lifting arms are slightly above closed position Forced main pressure low and erratic Lead air compressor running Low-level pressure switch is closed Electrical controls automatic mode A. malfunctioning level control is causing pressure switches to open too soon B. malfunctioning level control is causing pumps to run out of phase D. seal water flow to the vacuum pump Correct Answer B. drum speed What problems are created when the sludge build-up on the bottom of the sedimentation basin become too great? A. degradation of process efficiency will result B. localized high flow velocities will be produced C. sludge scouring will occur D. all of the above Correct Answer D. all of the above Jar tests may be used to determine the optimum dosage of A. alum B. BD C. oil and grease D. volatile acids Correct Answer A. alum Given the following data, what is the most likely cause of the primary sedimentation tank problem? DATA: Flow through inlet gates normal Tank level at correct height Sludge collectors (flights) operating normally Scum skimming mechanisms operating normally Sludge collector drive motor controllers in automatic Gas bubbles evident at sides of the tank A. effluent channel restriction B. flow pattern through tank C. sludge accumulation D. sludge collector drive motor load Correct Answer C. sludge accumulation Given the data below, what is the most likely cause of the aeration tankproblem? DATA: Inlet flow and loading to aeration tank constant Aeration tank level at set-point Aeration blower (auto-manual selector) in automatic mode Aeration blower running below maximum output Aeration blower discharge (pressure controller) in automatic mode Dissolved oxygen (probe selector) set on control probe Dissolved oxygen (control probe) below set-point Dissolved oxygen controller calling for increase blower output Air flow controller calling for increased blower output A. dissolved oxygen probe malfunctioning causing false indication B. dissolved oxygen probe selector set on wrong probe C. malfunctioning air flow controller overriding blower automanual selector D. malfunctioning discharge pressure controller causing blower to limit output Correct Answer D. malfunctioning discharge pressure controller causing blower to limit output Given the following data, what is the most likely cause of the chlorinator problem? DATA: All five of the one ton cylinders received from supplier in acceptable condition All five cylinders hooked up to manifold in acceptable manner Manifold header pressure is normal Chlorinator vacuum is normal Chlorine residual after post-treatment chlorination is normal Five cylinders normally last for 10 days, but chlorine flow is dropping after 8 days Chlorine controllers are in the automatic mode Alarm system functioning normally -- no leaks A. Cross-connection bleeding chlorine to water supply B. icing of the immersion heater in the evaporator C. tank leak D. tank valve cap gasket stuck over valve outlet Correct Answer D. tank valve cap gasket stuck over valve outlet Given the following data, what is the most likely cause of the tertiary filter problem? DATA: All filters operating Rate of filter flow is 20 % Effluent valve is 60% open Influent valve open Filter level is normal A. effluent valve open too much B. needs backwashing C. rate of flow too low D. too many filters on-line Correct Answer B. needs backwashing What could be the cause of excessive carbon fines in the effluent from activated carbon column reactors? A. carbon is being produced in the reactor due to poor combustion B. carbon is flowing out in the effluent due to a hole in one of the screens B. delegating authority to one's superiors instead of one's subordinates C. delegating power for decisions to lower levels D. retracting authority which has been previously delegated, and probably changing functions and duties Correct Answer C. delegating power for decisions to lower levels What term means that the employee reports to one specific supervisor, and that the delegation of authority comes from one particular supervisor to the employee? A. unity of command B. span of supervision C. organizational chart D. formal organization Correct Answer D. formal organization It is generally accepted by psychologists that human behavior is goal-oriented and A. selfish B. random C. other-centered D. motivated Correct Answer D. motivated Steel tanks may be protected from rusting by A. alternately wetting and drying walls B. maintaining humidity in tank C. protective coatings D. washing tank walls Correct Answer C. protective coatings What should be the most important concern of an operator after a bypass? A. aquatic life B. clean-up procedures C. health-related effects D. odors Correct Answer C. health-related effects A supervisor could be responsible for an accident, in part or completely, by A. disregarding an unsafe work environment B. haste in requiring work performed C. overlooking a potential hazard D. all of the above Correct Answer D. all of the above Control is A. backward looking B. concentrating on the present C. forward looking D. not connected to the other managerial functions Correct Answer B. concentrating on the present Increased funds for the year are limited. However, 2 or 3 outstanding newly employed individuals are grossly underpaid for their services. How should this situation be handled? A. call a staff meeting, explain the situation and then raise their salaries B. don't give anyone a raise C. pass the word that there will be no raises but change their titles, not their duties, and raise their pay D. Say nothing and do nothing because it is none of the employee's business Correct Answer A. call a staff meeting, explain the situation and then raise their salaries When purchased materials are received by the utility, they should not be A. counted and checked against P.O.'s B. inspected C. placed on shelves where they will be used first D. recorded Correct Answer C. placed on shelves where they will be used first Disaster plans should be developed in case of A. broken sewers B. floods C. power outages D. pump stoppages Correct Answer B. floods Preparing for a public open house, what following in-plant arrangements must be made? A. a printed handout is available and up-to-date B. adequate coffee cups and ash trays are available C. all pump casings are repainted D. visitor safety is ensured Correct Answer D. visitor safety is ensured Public relations are important because we A. want to finish our work in a hurry B. need lots of training C. must deal with the public Given the data below, what is the most likely cause of the problem? DATA: Wet well inlet is normal for dry weather flow. Wet well alternating excessively high and excessively low levels Lead pump starts at right level, level continues to rise, pump stops at right level Follow pump starts at right level, level drops, pump stops at right level Lead pump check valve lifting arm remains stationary in lowered position when pump starts and stops Follow pump check valve lifting arm rises when follow pump starts, goes to lowered position when it stops Force main pressure remains same when lead pump starts, increases when follow pump starts, drops to previous level when follow pump stops Low-level pressure switch normal High-level pressure switch normal Electrical controls automatic A. lead pump clogged B. force main pressure too high C. follow pump clogged D. both pumps clogged Correct Answer A. lead pump clogged Given the data below, what is the most likely cause of the problem? DATA: Wet well inlet has increased flow because of rain Wet well drops normally from weather conditions, rises much more rapidly than normal Lead pump cycles on and off at right levels faster than normal Follow pump cycles on and off at right levels faster than normal Follow pump motor shaft turns backwards when off with lead pump running Follow pump check valve lifting arm stays in raised position Force main pressure high with both pumps on, too low when lead pump is on alone Air bubbler system normal Electrical controls on automatic A. check valve in follow pump clogged B. follow pump check valve stuck closed C. follow pump electrical system wired backwards D. lead pump check valve clogged Correct Answer A. check valve in follow pump clogged Turbidity in wastewater is caused by A. color B. dissolved calcium C. hardness D. finely divided suspended material Correct Answer D. finely divided suspended material The gas most commonly associated with septic wastewater is A. carbon dioxide B. carbon monoxide C. hydrogen sulfide D. methane Correct Answer C. hydrogen sulfide How many cubic meters per second in 10 MGD? A. 0.44 B. 1.44 C. 4.73 D. 24.62 Correct Answer A. 0.44 Mechanical ventilation of a lift station is required to A. lower temperatures to reduce proportion of hydrogen sulfide B. reduce chlorine demand C. reduce corrosion D. increase DO in raw wastewater Correct Answer C. reduce corrosion A wet well probe is usually used for ________ determination(s) of level. A. approximate B. dual point C. continuous D. single point Correct Answer D. single point A pump is delivering at less than the expected rate of discharge. Which of the causes listed below is incorrect? A. speed of motor too low B. pump not primed C. impeller clogged D. discharge head too low Correct Answer D. discharge head too low Metal pipes often fail because of A. back siphonage What is the impact of increased viscosity on the effectiveness of mixed media filters? Mixed media filters are A. affected only if temperature also changes B. less effective C. more effective D. not affected Correct Answer B. less effective The precipitate in coagulation with alum is aluminum A. bicarbonate B. carbonate C. hydroxide D. sulfate Correct Answer C. hydroxide Given the following data, what is the most likely cause of the mechanically cleaned bar screen problem? DATA: Above normal water differential across bar screen Drive motor shaft turning Drive sprocket, chain, rake not moving Less than normal flow on bar screen downstream side Bar screen mode selector in automatic position Normal seasonal flow (influent) coming into bar screen Alarm systems operating normally A. low influent (incoming) level B. raw wastewater pumping units out of service C. sheared pin or disengaged clutch D. none of the above Correct Answer C. sheared pin or disengaged clutch The least amount of chemical used to remove turbidity is known as the A. coagulation range B. combination dosage C. efficiency range D. dosage Correct Answer D. dosage The method of sludge handling resulting in a supernatant with the highest BOD is A. aerobic digestion B. anaerobic digestion C. centrifugation D. vacuum filtration Correct Answer C. centrifugation Sodium chloride is used in the low pressure wet oxidation unit's A. water softener B. steam generator C. deaerator D. chemical feed tank Correct Answer A. water softener The quantity of volatile solids in the content of the sludge is an indirect measure of the A. amount of the sample that will evaporate upon standing B. "food" available for the bacteria in the digester C. number of bacteria in the digester D. primary effluent suspended solids Correct Answer B. "food" available for the bacteria in the digester Which solids cannot be removed by vacuum filtration? A. dissolved solids B. setteable solids C. suspended solids D. total solids Correct Answer A. dissolved solids Belt filter press are operated as a __________ process. A. batch B. continuous C. either one, depending on circumstances Correct Answer B. continuous Given the data below, what is the most likely cause of the activated sludge diffused aeration system problem? DATA: Blower air rate output high Organic load normal Hydraulic load normal Borderline low dissolved oxygen Low turbulence throughout aeration tank A. aeration system piping leaking B. excessive air bubble shearing by diffusers C. return sludge rate too high D. underaeration because of low blower speed Correct Answer A. aeration system piping leaking Given the data below, what is the most likely cause of the extended aeration facility problem? DATA: Blower normal Flow normal for dry weather DO level normal Drop pipe air control valves half open Dead spot on surface around one drop pipe Dead spot remains when drop pipe air control valve fully open A. air header pipe clogged D. internal morale factors Correct Answer A. a good organization Generally, as an individual progresses upward in management, reliance on personal technical skill A. changes to the more complex B. decreases C. increases D. remains the same Correct Answer B. decreases What equipment should be calibrated in a treatment plant? A. chemical feeders B. continuous recording chlorine residual analyzer C. continuous recording pressure gauges D. all of the above Correct Answer D. all of the above Special parts that should be carried by the maintenance worker are usually listed in the A. machine blue print B. machine history record C. machine manufacturer's manual D. work order Correct Answer C. machine manufacturer's manual To protect a wastewater facility against vandalism, you should not use A. combination padlocks on the gates B. fencing around the entire facility C. metal doors D. windows that have plastic panes instead of glass Correct Answer A. combination padlocks on the gates How can the supervisor be certain that scheduled maintenance is completed? A. ask the workers B. hire someone to inspect completed work C. use a form that compares work assigned with work completed D. wait and see if there are any failures Correct Answer C. use a form that compares work assigned with work completed Word has just come down from the top that operating funds are being cut. How should this be handled? A. cut the supplies and repairs in order to balance the budget B. fire some of the less-productive old employees C. keep it quiet and do what you have to do--"The less said the better" D. let the other personnel know what the situation is and ask for their help Correct Answer D. let the other personnel know what the situation is and ask for their help Velocity may be sensed A. electrically B. hydraulically C. mechanically D. all of the above Correct Answer D. all of the above Using water on a gas chlorine leak will A. form sodium hypochlorite which can be salvaged for future use B. make the leak worse C. neutralize the chlorine D. stop the leak Correct Answer B. make the leak worse Saprophytic microorganisms are also called A. acid formers B. methane fermenters C. alcohol fermenters D. facultative fermenters Correct Answer A. acid formers Microorganisms that are methane fermenters will only produce in the pH range of A. 5.8 to 6.5 B. 6.1 to 7.0 C. 6.6 to 7.6 D. 6.8 to 8.3 Correct Answer C. 6.6 to 7.6 Digestion is working properly if the volatile solids content of the raw sludge has been reduced by A. 40 to 60% B. 50 to 60% C. 55 to 65% D. 60 to 75% Correct Answer B. 50 to 60% An anaerobic sludge digester should be operated such that A. acid formation is greater than methane formation B. acid formation is equal to methane formation C. acid formation is less than methane formation D. acid formation is less than alkaline formation Correct Answer B. acid formation is equal to methane formation How often should the thermal valves be dismantled for service? A. every 3 months B. every 6 months C. once/year D. every 2 years Correct Answer C. once/year Typically, how often should sediment and drip traps be drained in cold weather? A. twice a day B. daily C. once/week D. once/month Correct Answer A. twice a day Draft tube propeller mixers are subject to corrosion from A. nitric acid B. phosphoric acid C. sulfuric acid D. hydrogen sulfide Correct Answer B. phosphoric acid What do corbels provide in an anaerobic digester? A. stability and proper cover buoyancy B. they prevent the cover from scraping the sidewall C. support for the floating cover when it is at its lowest point D. they prevent foaming in the annular space Correct Answer C. support for the floating cover when it is at its lowest point What do roller guides provide in an anaerobic digester? A. stability and proper cover buoyancy B. they prevent the cover from scraping the sidewall C. support for the floating cover when it is at its lowest point D. they prevent foaming in the annular space Correct Answer B. they prevent the cover from scraping the sidewall What do ballast block provide in an anaerobic digester? A. stability and proper cover buoyancy B. they prevent the cover from scraping the sidewall C. support for the floating cover when it is at its lowest point D. they prevent foaming in the annular space Correct Answer A. stability and proper cover buoyancy What do skirts provide in anaerobic digesters? A. stability and proper cover buoyancy B. they prevent the cover from scraping the sidewall C. support for the floating cover when it is at its lowest point D. they prevent foaming in the annular space Correct Answer D. they prevent foaming in the annular space The floating cover on anaerobic digester should be inspected A. daily B. weekly C. bimonthly D. monthly Correct Answer A. daily Bacteria in an anaerobic digester will effectively utilize A. hair B. mineral oils C. petroleum products D. fats Correct Answer D. fats What would happen if too much sludge was added to an anaerobic digester? A. methane fermenters would predominate and pH would increase B. methane fermenters would predominate and pH would decrease C. acid fermenters would predominate and pH would increase D. acid fermenters would predominate and pH would decrease Correct Answer D. acid fermenters would predominate and pH would decrease The best operation performance for an anaerobic digester is when it is fed A. several times a day B. twice per day C. once per day D. once every other day Correct Answer A. several times a day The least desirable control method for an anaerobic digester is the use of digester A. pH B. CO₂ C. volatile-acid-to-alkalinity ratio D. last aerobic digester tank Correct Answer A. primary clarifier What should the initial depth of sludge from a digester be when it is placed in a sludge drying bed? A. 6 to 12 in. B. 12 to 18 in. C. 18 to 24 in. D. 24 to 30 in. Correct Answer B. 12 to 18 in. Operators should use special precautions when placing anaerobically digested sludge on a drying bed because sludge contains A. H₂S B. carbon monoxide C. methane D. a high concentration of pathogens Correct Answer C. methane What does the wastewater industry call sludge that is only partially digested? A. gray B. yellow C. green D. brown Correct Answer C. green Hydrogen sulfide will exist in a system depending on the presence or absence of A. iron bacteria B. oxygen C. organic acids D. inorganic sulfides Correct Answer B. oxygen To what pH should wastewater be raised to halt sulfide production and inhibit sludge growth and biological slimes? A. above 8.5 B. above 8.8 C. above 9.0 D. above 9.5 Correct Answer C. above 9.0 If the headworks in a wastewater treatment plant had an H₂S odor, what would be the most likely solution? A. airstream treatment B. correct faulty plant operation C. add treatment chemicals D. remove sludge from grit channel Correct Answer C. add treatment chemicals If the primary sedimentation unit to a wastewater treatment plant had an H₂S odor, what would be the most likely solution? A. improve housekeeping B. reduce turbulence C. increase mixing D. remove sludge faster Correct Answer D. remove sludge faster If the sludge drying beds had a decaying organic odor, what would be the most likely solution? A. increase air in aeration system B. improve operations before digester C. improve housekeeping around drying beds D. chemical addition with counter masking or masking agents Correct Answer D. chemical addition with counter masking or masking agents If the ponds or lagoons had an ammonia odor, what would be the most likely solution? A. improve housekeeping around ponds and lagoons B. remove sludge along sides of ponds or lagoons C. add chemical treatment D. add air or check diffusers in ponds or lagoons for proper function Correct Answer C. add chemical treatment In the activated sludge system for the process control of effluent suspended solids, what is the primary controlling variable for the desired microbial population? A. the sludge volume index (SVI) and sludge density index (SDI) B. the settled sludge blanket C. the concentration of MLSS D. the concentration of MLVSS Correct Answer C. the concentration of MLSS The process that uses heat to selectively destroy undesirable organisms is called A. ultraviolet radiation B. thermal-pulse C. autoclaving D. pasteurization Correct Answer D. pasteurization D. solids loading Correct Answer D. solids loading What is the most probable cause for excessive algae in the effluent of a wastewater pond? A. pond has too much nitrogen B. pond has too much nitrate and not enough surface mixing C. detention time is excessive D. temperature favoring the growth of a particular species of algae Correct Answer D. temperature favoring the growth of a particular species of algae If a secondary clarifier has floatable debris in the effluent, what is the most likely cause? A. solids detention time is excessive B. the clarifier is hydraulically overloaded C. outlet baffle is not in the proper position D. denitrification is occurring in the bottom of the clarifier Correct Answer B. the clarifier is hydraulically overloaded Because water samples sometimes require repeat or backup tests, the amount of sample that should be collected for samples are preserved and transported for any particular analyses should be at least ________ times the amount required for those analyses. A. two B. three C. four D. five Correct Answer A. two Which one of the following parameters can be preserved for later laboratory analysis? A. nitrate B. pH C. temperature D. dissolved oxygen Correct Answer A. nitrate Which one of the following is not a major solids treatment method? A. thickening B. concentration C. dewatering D. stabilization Correct Answer B. concentration A solids treatment thickening process method would be A. gravity B. filter presses C. composting D. chemical oxidation Correct Answer A. gravity One solids treatment thickening process would be A. heat treatment B. flotation C. composting D. belt press Correct Answer B. flotation Another solids treatment thickening process would be A. sand drying beds B. vacuum filters C. solids concentrators D. composting Correct Answer C. solids concentrators A solids treatment stabilization process method would be A. flotation B. gravity C. vacuum filters D. incineration Correct Answer D. incineration A solids treatment dewatering process method would be A. gravity B. incineration C. composting D. flotation Correct Answer B. incineration Which one of the following solids treatment methods can be classified as both stabilization and dewatering? A. incineration B. wet air oxidation C. lime stabilization D. chemical oxidation Correct Answer A. incineration This solids treatment method has a solids buildup that forms a blanket on the bottom that forces the water out due to compression: A. solids concentrator B. vacuum filter C. gravity thickening D. centrifuge Correct Answer C. gravity thickening This solids treatment method aerates the recycled water from the unit under pressure: A. flotation thickening C. centrifuge D. solids concentrators Correct Answer C. centrifuge This solids treatment method maximizes the reduction of moisture and solids: A. incineration B. centrifuge C. thermal treatment D. vacuum filter Correct Answer A. incineration Which solids treatment method removes 100% of the pathogens, water, and organics? A. centrifuge B. chlorine oxidation C. thermal treatment D. incineration Correct Answer D. incineration In general, secondary sludges A. contain 20 to 25% nonvolatile inorganic matter B. are more fibrous C. have less flocculant than primary sludges D. have a density significantly greater than water Correct Answer A. contain 20 to 25% nonvolatile inorganic matter Which type of centrifuge uses a knife or plow insertion to scrape off the cake from its walls? A. scroll centrifuge B. basket centrifuge C. pressure-cone centrifuge D. disc-nozzle centrifuge Correct Answer B. basket centrifuge Which type of centrifuge uses an outer screw conveyor to move the solids to the discharge point? A. scroll centrifuge B. basket centrifuge C. pressure-cone centrifuge D. disc-nozzle centrifuge Correct Answer A. scroll centrifuge What is the ideal temperature range for methane-forming bacteria in anaerobic digesters? A. 90 to 98° B. 92 to 102° C. 94 to 97° D. 95 to 101° Correct Answer C. 94 to 97° What type of wastewater solids would most likely be sent to a rendering reclamation? A. screening B. grit C. secondary sludge D. scum Correct Answer D. scum Which one of the following wastewater solids would most likely never end up on a dedicated land disposal (DLD) site? A. incinerated material B. screenings C. grit D. compost Correct Answer D. compost If a sludge cake consists of 60% solids, where did it most likely originate? A. drying lagoon B. vacuum filter C. filter press D. centrifuge Correct Answer A. drying lagoon What type of protozoan is typically associated with a poor treatment process and a young biosolids age? A. sporozoans B. ciliates C. flagellates D. the Sarcondina Correct Answer C. flagellates The most common pathogen identified in waterborne disease outbreaks in the United States is A. Cryptosporidium B. Giardia C. Entamoeba D. Cyclospora Correct Answer B. Giardia The major gas produced by aerobic decomposition is A. nitrogen B. hydrogen sulfide C. carbon dioxide D. methane Correct Answer C. carbon dioxide If an induction motor is rated at 40 amps for a full-load current, what will be the most probable starting sequences amps required? A. 60 to 80 amps D. soda-acid Correct Answer C. carbon dioxide Which one of the following provides a profile of hazardous substances or mixtures? A. Occupational Safety and Health Administration (OSHA) B. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) C. Code of Federal Regulations (CFR) D. material safety data sheet (MSDS) Correct Answer D. material safety data sheet (MSDS) An atmosphere is defined as oxygen deficient if it contains less than what percent oxygen by volume? A. 16.5% B. 18.5% C. 19.5% D. 19.8% Correct Answer C. 19.5% What class of fire involves sodium and magnesium? A. Class A B. Class B C. Class C D. Class D Correct Answer D. Class D What is the proper emergency chlorine kit for a 1-ton chlorine cylinder? A. emergency kit A B. emergency kit B C. emergency kit C D. emergency kit T Correct Answer B. emergency kit B The specific gravity standard for gases is A. water vapor at 100°C B. air C. oxygen D. nitrogen Correct Answer B. air The standard for gases has a density of A. 1.00 g/L B. 1.13 g/L C. 1.23 g/L D. 1.29 g/L Correct Answer D. 1.29 g/L How many steps are there in coagulation? A. three steps B. four steps C. five steps D. six steps Correct Answer A. three steps Low-temperature water can be compensated for when using alum by A. increasing the pH B. decreasing the pH C. increasing the alum dosage D. decreasing the alum dosage Correct Answer C. increasing the alum dosage When an electrolyte is dissolved in water to form an ion, the ion is said to be A. dissociated B. ionized C. hydrated D. hydrolyzed Correct Answer A. dissociated Which one of the following species is ozone? A. O₂⁺³ B. NO₂ C. O₃ D. N₂O Correct Answer C. O₃ Which laboratory glassware can be used to heat liquids in an open flame? A. flasks B. graduated cylinders C. volumetric flasks D. burettes Correct Answer A. flasks When inserting glass tubing into rubber hose or stoppers, never use _______ for lubrication. A. oil B. flame polishing C. water D. lubricating jelly Correct Answer A. oil Electrical units operating in areas exposed to flammable vapors should A. be removed and reinstalled in a separate room B. be housed in a tightly sealed container C. be double-insulated D. be explosion-proof Correct Answer D. be explosion- proof