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North Carolina Department of Environmental Quality (NC
DEQ) Exam Questions and Correct Answers (Verified
Answers) Plus Rationales
focused on wastewater operator certification and general environmental regulatory compliance
- What agency is responsible for administering the wastewater operator certification program in North Carolina? A. EPA B. OSHA C. NC Water Pollution Control System Operators Certification Commission (WPCSOCC) D. Department of Energy The WPCSOCC administers wastewater certification in NC under the NC DEQ.
- Which type of wastewater treatment process uses microorganisms to decompose organic matter? A. Physical treatment B. Biological treatment C. Chemical treatment D. Filtration
Biological treatment relies on bacteria to consume and break down organic pollutants.
- What is the purpose of a clarifier in a wastewater treatment plant? A. Add chlorine B. Aerate the water C. Remove suspended solids D. Heat the water Clarifiers allow solids to settle out from wastewater, reducing turbidity.
- What is the required frequency for submitting discharge monitoring reports (DMRs) to NC DEQ? A. Annually B. Monthly C. Weekly D. Quarterly Most NPDES permits require monthly DMR submissions.
- What is the main purpose of an NPDES permit? A. To regulate solid waste disposal B. To control point source discharges to surface waters C. To certify laboratory personnel D. To inspect water tanks NPDES (National Pollutant Discharge Elimination System) regulates wastewater discharge.
- What measurement is used to assess the strength of wastewater based on oxygen demand?
D. 4.5 - 6.
Effluent pH must remain in a neutral range to protect aquatic life and comply with permit conditions. 10.Which of the following is considered a point source of pollution? A. Pipe discharging from a treatment plant B. Urban stormwater C. Agricultural runoff D. Groundwater infiltration Point sources are direct discharges like pipes; others are non-point sources. 11.Which agency sets the national water quality standards? A. NC DEQ B. U.S. Environmental Protection Agency (EPA) C. U.S. Army Corps of Engineers D. NC DHHS The EPA sets federal guidelines that NC DEQ enforces at the state level. 12.Which lab test determines the amount of solid material suspended in wastewater? A. BOD B. Total Suspended Solids (TSS) C. pH D. DO TSS quantifies suspended solids that can cause turbidity and affect water quality.
13.What does the acronym "CMOM" stand for? A. Certified Maintenance Operations Manual B. Clean Maintenance and Operation Management C. Capacity, Management, Operation, and Maintenance D. Chlorine Monitoring and Optimization Manual CMOM is a framework required under EPA guidelines for wastewater utilities. 14.What is a common cause of sanitary sewer overflows (SSOs)? A. pH imbalance B. High chlorine dosage C. Blockages in sewer lines D. Proper flow design Grease, debris, or tree roots often cause sewer line blockages, leading to SSOs. 15.What treatment method involves rotating biological contactors (RBCs)? A. Trickling filters B. Fixed-film biological treatment C. Chemical oxidation D. UV disinfection RBCs are a type of fixed-film biological treatment that rotates discs to expose biofilms to wastewater. 16.Who must sign the DMR before submission in NC? A. Lab technician B. Mayor
20.Which part of the wastewater plant removes grit? A. Grit chamber B. Clarifier C. Chlorine contact tank D. Digester Grit chambers remove heavy inorganic materials like sand before biological treatment. 21.What is the primary source of phosphorus in municipal wastewater? A. Lead pipes B. Bacteria C. Human waste and detergents D. UV exposure Phosphorus mainly comes from excreta and some industrial or household detergents. 22.What process converts ammonia to nitrate? A. Nitrification B. Denitrification C. Chlorination D. Digestion Nitrification is a two-step aerobic process that oxidizes ammonia to nitrite and then nitrate. 23.Denitrification occurs under which condition? A. High pH B. Anoxic (no oxygen) conditions
C. Aerobic conditions D. High chlorine Denitrifying bacteria require anoxic conditions to reduce nitrate to nitrogen gas. 24.A sample collected without prior planning is called: A. Composite sample B. Grab sample C. Random sample D. Scheduled sample A grab sample is a single sample taken at one point in time. 25.What is the result of low dissolved oxygen in an aeration tank? A. Improved treatment B. Poor microbial activity C. Excess chlorine use D. Excess solids Microbes require oxygen; low DO leads to inefficient BOD removal and possible odor. (26–50 continued in next message...) North Carolina NC DEQ Practice Exam (continued: Questions 26–50) Answers in bold; rationales in italic 26.What instrument is used to measure pH in the field? A. Turbidimeter B. pH meter
Filamentous organisms thrive under low DO or nutrient stress, leading to poor settling. 30.In NC, which document outlines how a wastewater system will operate and be maintained? A. Permit Application B. Operation and Maintenance (O&M) Plan C. DMR D. MSDS An O&M Plan is a requirement and serves as a guide for system operations and troubleshooting. 31.What is the purpose of a weir in a clarifier? A. To aerate sludge B. To evenly distribute effluent C. To disinfect water D. To grind solids Weirs maintain uniform flow and prevent short-circuiting in clarifiers. 32.Which process follows secondary treatment in most wastewater plants? A. Grit removal B. Aeration C. Disinfection D. pH adjustment Disinfection (e.g., chlorination or UV) is the final treatment to kill pathogens.
33.What is the maximum holding time for a BOD sample before incubation? A. 12 hours B. 6 hours C. 3 hours D. 1 hour EPA recommends starting BOD testing within 6 hours of sample collection. 34.What is the main objective of secondary treatment? A. Settle out large solids B. Biologically remove organic matter C. Remove metals D. Add chlorine Secondary treatment uses microorganisms to break down dissolved organic material. 35.How often must a certified operator visit a collection system pump station in NC (small system)? A. Once a month B. Once every 6 months C. Daily or as required by permit D. Weekly only Operator visits are required daily unless the permit states otherwise. 36.What does F/M ratio refer to? A. Flow/Minute B. Food-to-Microorganism ratio C. Final Measurement
B. Nitrate C. Ammonia D. Nitrogen gas Ammonia is predominant in raw domestic wastewater from urine and waste. 41.What process removes phosphorus by incorporating it into biomass? A. Denitrification B. Enhanced biological phosphorus removal (EBPR) C. Coagulation D. Chlorination EBPR uses special bacteria to take up excess phosphorus under specific conditions. 42.What component measures flow rate in a treatment plant? A. BOD meter B. Flowmeter C. UV transducer D. Sludge press Flowmeters provide accurate data for monitoring plant performance and reporting. 43.What can cause poor UV disinfection efficiency? A. High pH B. High TSS or turbidity C. High BOD
D. High DO TSS and turbidity block UV light, reducing disinfection effectiveness. 44.What is the best way to avoid permit violations? A. Bypass during rain B. Routine monitoring and maintenance C. Add extra chlorine D. Skip sampling Regular checks, preventive maintenance, and compliance monitoring are key. 45.What condition is most harmful to aerobic bacteria? A. High DO B. High pH C. Lack of oxygen D. High nutrients Aerobic bacteria require oxygen; oxygen deficiency halts their activity. 46.Which of the following must be recorded daily in a wastewater logbook? A. Operator's meals B. Flow measurements and process notes C. TV schedules D. Personal notes Regulations require daily logging of flows, treatment performance, and operator observations. 47.What happens if chlorine is overdosed in wastewater effluent? A. Increased BOD
Accurate compliance data depends on properly calibrated instruments per regulation. 51.What is the most appropriate personal protective equipment (PPE) when handling chlorine gas? A. Safety shoes B. Full-face respirator and chemical-resistant gloves C. Cotton gloves D. Dust mask Chlorine gas is highly toxic; full-face respirators and gloves protect respiratory and skin exposure. 52.When performing a BOD test, the incubation period is: A. 3 days at 20°C B. 5 days at 20°C C. 5 days at 4°C D. 7 days at 10°C The standard EPA BOD test is conducted over 5 days at 20°C. 53.Which process uses gravity to remove large debris at the beginning of treatment? A. Disinfection B. Screening C. Filtration D. Chlorination
Screening removes large items like rags and sticks to protect downstream equipment. 54.Which sampling technique collects samples at predetermined time intervals? A. Composite sampling B. Grab sampling C. Random sampling D. Batch sampling Composite sampling averages fluctuations over time for more accurate representation. 55.What is the main reason for chlorinating effluent? A. Odor control B. Improve clarity C. Kill pathogenic organisms D. Control sludge Chlorination is used primarily for disinfection to reduce microbial risks. 56.What does MLSS stand for? A. Most Likely Sludge Source B. Mixed Liquor Suspended Solids C. Major Load Solids Survey D. Minimal Load Settling Solids MLSS is the total suspended solids concentration in the aeration tank, including biomass.
C. Chlorine D. DO Fecal coliform counts indicate the potential for pathogens in treated water. 61.What is the typical detention time in a primary clarifier? A. 5 minutes B. 1.5 to 2.5 hours C. 6 hours D. 10 hours Primary clarifiers are designed for 1.5–2.5 hours to settle solids efficiently. 62.What is the main risk when working in a confined space at a treatment plant? A. Loud noises B. UV exposure C. Oxygen deficiency or toxic gas buildup D. High pressure Confined spaces may lack oxygen or contain harmful gases like H₂S. 63.What type of pump is most commonly used for sludge transfer? A. Centrifugal B. Diaphragm C. Positive displacement D. Jet Positive displacement pumps handle thick, viscous sludges with minimal clogging.
64.What is used to monitor dissolved oxygen in an aeration basin? A. pH probe B. DO probe or meter C. ORP sensor D. Turbidity tube DO meters are essential for controlling aeration efficiency and microbial health. 65.A sample with a pH of 5.0 is considered: A. Acidic B. Basic C. Neutral D. Alkaline A pH less than 7.0 is acidic; above 7.0 is basic or alkaline. 66.What does a SCADA system do? A. Monitor and control plant operations remotely B. Store chemicals C. Measure BOD D. Treat solids SCADA (Supervisory Control and Data Acquisition) automates and monitors equipment. 67.A digester with no oxygen is called a(n): A. Aerobic digester B. Anaerobic digester C. Oxidation ditch
