ADEQ Wastewater Treatment 1 Practice Test

These questions are part of the practice quiz. Start practicing

• Which of the following is MOST important to ensure confidence in analytical testing results?
• If the effluent from a primary clarifier becomes dark and foul-smelling, what is the most likely cause?
• During routine weir maintenance, which item should be checked?
• In an activated sludge plant, what is the typical operating principle related to mass balance?
• Which chemical is beneficial in correcting the problem that causes a facultative pond to change from deep bright green to dull gray?
• What is the typical detention time for a primary clarifier, and what is its main function?
• What is the surface overflow rate value for the 60 ft diameter clarifier at 2,000 gpm?
• Which parameters are commonly included in routine wastewater effluent monitoring?
• Which of the following characteristics describe chlorine gas?
• Most likely cause of short-circuiting in a tank?
• How much larvicide should be spread over the lagoon surface if the weight of the larvicide is 8.5 lbs/gal, the lagoon surface area is 5 acres & 3 ft deep, and the recommended dose is 1 lb/10,000 ft²?
• If a secondary clarifier becomes septic, what should be checked FIRST?
• What is the purpose of a bar screen in headworks?
• In pump design, what does 'head' refer to, and what is 'friction head'?
• Why is it essential to ventilate a confined space before entry?
• What is the proper way to mix water and acid?
• How does a solids retention time (SRT) control affect sludge production and effluent quality?
• Which statement best describes an effective safety program?
• What are the two main products of anaerobic digestion of sludge?
• Which substance is toxic, corrosive, and explosive?
• Why is Returned Activated Sludge (RAS) returned to the aeration basin?
• SVI is defined as the settled sludge volume per unit MLSS after how many minutes?
• What color was the lagoon described as in that sample?
• Primary objective of the industrial pretreatment program?
• If settled solids volume increases while MLSS remains constant, what happens to SVI?
• What is the difference between COD and BOD and when is COD measured?
• Which statement best describes the primary clarifier's function?
• Which attribute describes the consistency of test results when the same sample is analyzed multiple times under identical conditions?
• Floating surface aerators are secured using a:
• Grit cannot be broken down in biological treatment processes because it is primarily:
• Which term describes a condition in centrifugal pumps when internal pressure is too low due to high flow?
• Which of the following is a chemical used for dechlorination?
• The rate of electrical current is measured in what unit?
• Which document would typically record the amount of chemicals dosed at the plant?
• Which type of valve is typically the first on the discharge side of a pump?
• A primary clarifier (60 ft in diameter) treats a flow of 2,000 gpm. What is the surface overflow rate?
• Define infiltration and inflow, and describe their impact on plant performance.
• What is Sludge Volume Index (SVI) and what does a high SVI indicate?
• After collection and preservation, a BOD sample can be stored for up to:
• What is the most common cause of motor failure?
• Which form of solids is MOST difficult to remove in a gravity treatment process?
• Activated sludge process is turbid. A microscopic exam shows 60% rotifers (old sludge), 30% nematodes (old sludge), 10% stalked colonizers. What action should be taken?
• Increased pump vacuum and increased run time for one of two pump stations' centrifugal pumps is MOST likely caused by:
• Which of the following chemicals are used for disinfection?
• Which trace contaminants may be present in biogas produced by anaerobic digestion?
• Which gas has a rotten egg odor?
• What was used to initially clean a polymer spill before rinsing with water and household bleach?
• How does increasing the F/M ratio influence sludge age?
• Which sign near chlorine gas piping is most indicative of a leak?
• Which is the MOST important precaution while working on rotating equipment?
• A facultative lagoon must be started up in the winter. To what depth should the lagoon be filled?
• A dry chemical feeder delivers 2.65 pounds in 5 minutes. What is the approximate pounds per day?
• Define Food-to-Microorganism (F/M) ratio and explain how it influences reactor performance.
• What hazard is created by a polymer spill?
• An operator is MOST likely to be exposed to which of the following hazardous gases in a plant operation?
• In a chemical feed system, which pump type is most appropriate?
• Chlorine gas concentrations above 1,000 ppm are associated with which outcome?
• In an activated sludge plant, what elements must be balanced to maintain steady-state concentrations?
• Circular clarifier flow is 1.2 MGD, diameter 55 ft, and depth 8 ft. What is the detention time?
• When there is a sudden surge in influent flow to the plant, what is an appropriate action?
• Grit removal specifically targets which type of solids?
• Which material is described as extremely viscous and slippery?
• What is sludge digestion, and what are the two main products of anaerobic digestion?
• Chlorine is particularly corrosive when dissolved in which substance?
• Which statement best describes SRT?
• Why is it important to maintain adequate return sludge flow to the aeration basin?
• What is the purpose of a secondary clarifier in the activated sludge process?
• What are the two common disinfection methods used in wastewater treatment plants and a basic principle of each?
• Which statement best summarizes the regulatory distinction between industrial and domestic pretreatment?
• Nitrification efficiency in an activated sludge system is most efficient at which pH range?
• Flexible coupling connects air lines to the blower to:
• What is the purpose of grit removal?
• Most odors from ponds are caused by:
• Two tanks have different shapes but the same water height, with pressure gauges at their bottoms. Which statement is true?
• What is the main functional difference between a step screen and a bar screen in wastewater facilities?
• When there is an imbalance of current between the hot and neutral conductors of a circuit, the GFCI:
• Explain how nitrification affects alkalinity, and what is the typical impact per unit of NH4+-N oxidized?
• What is the mechanism by which UV disinfection in wastewater treatment inactivates microorganisms?
• In building electrical wiring systems, the ground wire is normally:
• Which statement about BOD and BOD5 is true?
• Which gas is the primary component of biogas produced during anaerobic digestion?
• What causes foaming in aeration basins, and how can it be mitigated?
• MOST commonly used to determine stabilization of solids in an aerobic digester?
• After cleaning a polymer spill with rags and kitty litter, any remaining polymer can be removed with water and:
• Closing the discharge valve on a centrifugal pump will:
• Which information must always be included on a sample label?
• Which of the following is associated with low internal pressure or excessively high flow rates that are structurally detrimental to centrifugal pumps?
• Name two common flow measurement devices used at wastewater plants.
• The results of a 30-minute settleable solids test is 410 mL/L. What is the SVI if the MLSS concentration is 2,000 mg/L?
• At a flow of 2.0 MGD, what is the weir overflow rate of a 60 ft diameter primary clarifier?
• What is the difference between grab sampling and 24-hour flow-proportional composite sampling?
• Changing oil every 1000 hours is what type of maintenance?
• What is the purpose of an emergency response plan in a wastewater treatment plant?
• In a stream with zero DO, what is the expected predominant microbial activity?
• Which statement is true about the lagoon sample collected at 2:15 PM?
• Grit cannot be broken down in biological treatment processes because it:
• Which parameter is used to evaluate the settleability of sludge?
• Which practice best ensures preventative maintenance is completed?
• What time was the sample collected from the lagoon?
• Chlorine is very corrosive when combined with which substance?
• What flow rate does the 60 ft diameter clarifier treat in the example?
• For an area of 8 acres, using a dose of 1 lb per 10,000 ft² and larvicide density 8.5 lbs/gal, how many gallons are required?
• What is the diameter of the secondary clarifier described in the case?
• Direct connection of municipal water supply to the packing gland of a centrifugal wastewater pump would most likely be:
• If disinfection is used, which parameter is commonly monitored in the effluent?
• Why are check valves important in sewer and pump station design?
• In an aeration basin, the typical DO setpoint range for stable biological treatment is approximately what?
• Which procedure is used to determine MLSS in a sludge sample?
• Which safety procedure is essential when servicing rotating equipment?
• Which device is an open-channel flow measurement device?
• A pond has turned dull grey or colorless and DO & pH have dropped. This condition is most likely caused by?
• What is a common reason to use prechlorination at a wastewater treatment facility?
• Which of the following will lower the pH of water?
• To raise the pH of acidic wastewater to neutral, which chemical is commonly added?
• What is the purpose of lockout/tagout in maintenance activities?
• Which term refers to groundwater entering through leaks in pipes and joints?
• What is the diameter of the primary clarifier used in the example?
• Failure to frequently remove solids from a manually cleaned bar screen is most likely to cause an increase in:
• Which instrument is used to diagnose bearing conditions on a rotating machine?
• Which statement about HRT units is true?
• Chemical storage containment should be located so that if one ruptures, the chemicals are:
• Which of the following is a common cause of bulking in activated sludge basins?
• Which device is used to prevent backflow in piping systems?
• During chlorine-based disinfection of wastewater, what is the purpose of maintaining a residual chlorine, and how does contact time affect disinfection?
• An operator notices a strong smell of gasoline around a manhole. Which of the following actions should be taken FIRST?
• A gravity grit removal system operates best with wastewater velocity of:
• Excessive wear on a coupling between pump and motor flange is most likely caused by:
• If the skin or eyes are exposed to a chemical coagulant, which of the following is most likely to occur?
• How does a diffuser-type aeration system improve oxygen transfer in a wastewater treatment basin?
• To minimize downtime when a pump requires frequent maintenance, which action is most appropriate?
• In a well-designed and operated primary clarification or sedimentation system, the expected TSS removal efficiency is:
• Hazard communication is a key element of basic plant safety programs. Which statement best describes its purpose?
• A sample from an aerated lagoon at 2:15 PM on a sunny July day shows DO 20 mg/L, pH 8.8, lagoon bright green, and aerators not running. What is the MOST appropriate action?
• What is biogas, and what major components does it typically contain?
• Who is responsible for rules to be followed throughout the plant?
• If a three-phase motor runs backward after repair, which action should be taken?
• The primary reason mechanical seals are used in rotating equipment is to reduce what?
• When checking the accuracy of a flow meter using a V-notch weir, the head should be measured at:
• Which initial and final dissolved oxygen readings are valid for calculating BOD?
• What are typical indicators of poor settleability in a clarifier?
• What is the purpose of maintaining a consistent alkalinity in wastewater treatment?
• Which pair of initial DO and final DO would yield the valid BOD example?
• What is the primary purpose of a manually cleaned bar screen?
• In a disinfection context, what factors determine the actual CT value?
• Concentrations of chlorine gas in excess of 1,000 ppm are:
• If a GFCI detects an imbalance, what action does it take?
• Which information is essential on a sample label to identify the sampling event?
• In the secondary clarifier scenario, what is the MLSS concentration used?
• Which wastewater characteristics affect grease and scum removal efficiency?
• If a pump will not start, which item should be checked FIRST?
• The electrical current draw rate is measured in which unit?
• What unit is used for surface overflow rate?
• The surface area in square feet of a lagoon that is 5 acres is:
• TSS removal performance in a primary clarifier or sedimentation basin has been declining over the course of several days. The effluent is getting increasingly dark, almost black, and foul-smelling over the same period. What is the MOST likely cause of these issues?
• In the same lagoon sample, what was the measured pH value?
• For a pH test using an electrode, which practice is recommended?
• Which factors are used to calculate the loading rate in lbs/day/ft² for a secondary clarifier?
• Which statement about BOD5 is true?
• What is the typical role of a mixing mechanism in an aeration basin?
• Sampling during which of the following sequence batch reactor (SBR) cycles will provide the MOST accurate MLSS concentration results?
• If a pump requires frequent maintenance, which of the following is the best action to take?
• If the pH of wastewater flowing into a treatment facility is too low, which of the following can be added to adjust the pH to a neutral value?
• Which factor is least likely to mitigate foaming in aeration basins?
• Which statement about pH meters is true?
• Under normal conditions, which seal generally offers the longest service life?
• When starting up a new pump, which action should be performed first?
• To reduce coliform levels in a facultative pond discharging to surface water (flow and temperature constant), which action is appropriate?
• A plant used sixty 55-gallon drums of sodium hypochlorite during 1 year of operation. The average withdrawal from each drum was 50 gallons. What was the total amount used during the year?
• Aerobic digesters typically reduce volatile solids (VS) by:
• What is the difference between industrial pretreatment and domestic pretreatment in terms of regulatory requirements?
• Why is a weir and overflow system critical in a clarifier?
• When starting up a new activated sludge plant, what action will achieve building up MLSS to the desired concentration quickly?
• What tool is used to check bearings on an electric motor?
• Which statement best describes denitrification in wastewater treatment?
• What is the depth of the secondary clarifier described in the case?
• In a stream where the DO content is zero, an operator should expect to find:
• What is hydraulic retention time (HRT), and how is it calculated?
• The time required to fill a tank at a given flow is measured by which term?
• How does temperature affect dissolved oxygen solubility in water?
• What is the primary purpose of a grit chamber in a municipal wastewater treatment plant?
• What is the purpose of sludge thickening before digestion?
• Oxygen may be connected to a lift station by:
• What is the PRIMARY reason to use a mechanical seal?
• Which gas has a rotten egg odor?
• What does SRT stand for in wastewater treatment?
• What is the total energy required to lift wastewater from one level to another?
• Which of the following ensures preventative maintenance is completed?
• If a gravity grit removal system is operated at a velocity significantly lower than the recommended value, what problem is most likely?
• The most commonly used device to measure large wastewater flow is?
• Raw wastewater CBOD concentration of 450 ppm is most likely due to:
• Routine weir maintenance should include checking the:
• What should an operator do before using a pH meter to obtain a reliable result?
• What is used to remove residual chlorine from a sample?
• Which of the following is a common open-channel flow measuring device for wastewater?
• Why is proper calibration of instrumentation essential in wastewater operation?
• The difference in the amount of chlorine applied to a flow and the residual chlorine remaining after a given contact time is called?
• A greasy scummy layer of deep tan or dark brown foam on an aerator tank is most likely due to:
• In a chemical feed system, which of the following pumps is most likely to be used?
• Differentiate nitrification from denitrification and indicate the conditions that favor each process.
• All piping connections in a chlorine gas system should be checked for leaks by which method?
• The MOST important function of the primary clarifier is to remove:
• If a secondary clarifier becomes septic, which operational parameter is typically checked first to diagnose the issue?
• Which of the following describes common indicators of bulking and a typical cause?
• What type of records and reporting are typically required by wastewater plant operators?
• What is a proper action during an influent surge, when permitted by permit?
• What is the purpose of mixing in an aeration basin?
• What is the main function of the secondary clarifier, and what happens to the settled solids?
• What is the minimum DO level test time on a facultative lagoon?
• What is the primary purpose of a spill containment dike in a chemical storage area?
• When operating a plant, an operator notices the secondary clarifier sludge blanket is higher than normal, and the effluent appears turbid. The operator should:
• What is floc formation and why is it important for settling?
• What factor most accurately determines the actual loading to a wastewater facility?
• What happens when closing the discharge valve on a centrifugal pump?
• Septic wastewater MOST likely has a DO range of:
• Which protection equipment should be selected when responding to a chlorine gas leak?
• Which statement correctly describes chlorination and UV disinfection as common plant disinfection methods?
• Which device is commonly used to measure large wastewater flows?
• In a clarifier, increasing the influent flow rate generally results in a higher
• What is the area of the secondary clarifier with a diameter of 45 feet?
• Improper use or lack of backflow preventers may create which issue?
• Distinguish return activated sludge (RAS) from waste activated sludge (WAS) and explain their roles in process control.
• The simplest device used to measure flow in an open channel is which of the following?
• What is the primary purpose of personal protective equipment (PPE) in wastewater plant safety?
• Frost and ice on gas feed lines between chlorinators MOST likely indicates:
• Before turning on a positive displacement pump, suction and discharge valves should be in which positions?
• A secondary clarifier is 45 ft in diameter and 12 ft deep. If the influent flow is 1.5 MGD and the MLSS is 2,415 mg/L, what is the loading rate in lbs/day/ft²?
• When the aeration is turned off, the clear water that forms on top of an aerobic digester is called?
• The most important factor in determining the actual loading to a facility is?
• In an antifriction-type bearing, a rise in temperature is most likely caused by which condition?
• Which statement best describes nitrification in wastewater treatment?
• Which action would correctly address a three-phase motor that runs backward after rewiring?
• Explain how disinfection CT (concentration x time) governs the design of a disinfection system.
• Which statement best describes the rationale for ventilating lift stations?
• In the lagoon sample collected at 2:15 PM, what was the measured dissolved oxygen level?
• In disinfection practice, which term describes the difference between the amount of chlorine added and the residual chlorine after exposure?
• Prechlorination at a wastewater facility helps suppress the growth of what type of organisms?