Download Texas Wastewater Class D | Questions with 100% Correct Answers | Verified | Latest Updat and more Exams Water and Wastewater Engineering in PDF only on Docsity!
Texas Wastewater Class D | Questions with
100% Correct Answers | Verified | Latest
Update 2025
1. What is the primary purpose of wastewater treatment? A. To generate electricity B. To provide drinking water C. To remove contaminants from water before discharge D. To increase water temperature Correct answer: C. Wastewater treatment aims to remove physical, chemical, and biological contaminants to protect public health and the environment. 2. What is the most common type of wastewater treatment plant in Texas? A. Tertiary treatment plant B. Activated sludge plant C. Trickling filter plant D. Membrane bioreactor plant Correct answer: B. Activated sludge systems are widely used due to their efficiency and flexibility.
3. Which of the following is a secondary treatment process? A. Screening B. Grit removal C. Aeration D. Chlorination Correct answer: C. Aeration is part of secondary (biological) treatment where microorganisms break down organic matter. 4. What is the typical pH range for treated wastewater discharge? A. 3.0–5. B. 6.0–7. C. 6.0–9. D. 10.0–12. Correct answer: C. Most permits require the pH of effluent to be between 6. and 9.0. 5. What does BOD stand for? A. Biological Odor Detection B. Biochemical Oxide Demand C. Biochemical Oxygen Demand D. Basic Oxygen Dispersion Correct answer: C. BOD measures the amount of oxygen microorganisms need to decompose organic matter.
9. Why is it important to control the flow rate in a treatment plant? A. To increase chemical use B. To avoid overloading the system C. To raise sludge temperature D. To decrease BOD Correct answer: B. Flow control prevents hydraulic or organic overloads that can upset the treatment process. 10. What is sludge? A. Clean drinking water B. Solid waste material removed from wastewater C. Oxygen-rich water D. Disinfected effluent Correct answer: B. Sludge is the semi-solid waste collected during treatment. 11. What is the purpose of disinfection in wastewater treatment? A. Remove sludge B. Adjust pH C. Remove solids D. Kill disease-causing organisms Correct answer: D. Disinfection destroys pathogens before effluent is released to the environment.
12. Which chemical is most commonly used for disinfection in Texas wastewater treatment? A. Lime B. Chlorine C. Ammonia D. Alum Correct answer: B. Chlorine is widely used to disinfect treated wastewater. 13. What is the main purpose of a flow meter? A. Increase water temperature B. Measure the volume of water C. Adjust chlorine dosage D. Test pH Correct answer: B. Flow meters measure how much wastewater enters or exits the plant. 14. What equipment is used to add oxygen to wastewater? A. Clarifier B. Aerator C. Grit chamber D. UV light Correct answer: B. Aerators mix air into the wastewater, supporting biological treatment.
18. What is the function of a lift station? A. Remove chlorine B. Pump wastewater to a higher elevation C. Aerate the water D. Separate grease Correct answer: B. Lift stations move wastewater from low areas to treatment facilities. 19. What is effluent? A. Solid waste B. Raw sewage C. Treated wastewater discharged from the plant D. Sludge cake Correct answer: C. Effluent is the final, treated water leaving the plant. 20. What should operators do first in an emergency spill event? A. Ignore it B. Notify the supervisor or emergency contact immediately C. Leave the plant D. Add lime to the spill Correct answer: B. Immediate reporting ensures proper containment and safety measures.
21. What does DO stand for in wastewater treatment? A. Daily Overflow B. Discharge Output C. Dissolved Oxygen D. Dynamic Oxidation Correct answer: C. DO is crucial for biological processes in secondary treatment. 22. What is a common sign of poor aeration in a treatment tank? A. Clear water B. No odor C. Foul odor and dark color D. High chlorine levels Correct answer: C. Poor aeration leads to anaerobic conditions, causing bad smells and sludge buildup. 23. What instrument is used to measure pH? A. Flow meter B. DO probe C. pH meter D. Chlorine tester Correct answer: C. A pH meter measures the acidity or alkalinity of water. 24. What is the minimum retention time for chlorine disinfection in Texas? A. 10 minutes
C. 35–50°C
D. 50–80°C
Correct answer: B. Biological processes function best within this temperature range.
28. What must be done before performing confined space entry? A. Bring a flashlight B. Turn on a pump C. Test atmosphere and follow entry permit procedures D. Pour chlorine Correct answer: C. Safety protocols must be strictly followed for confined space work. 29. Who issues Class D Wastewater Licenses in Texas? A. EPA B. OSHA C. Texas Commission on Environmental Quality (TCEQ) D. Texas Department of Health Correct answer: C. TCEQ oversees licensing and certification of wastewater operators. 30. What is the main cause of foaming in aeration tanks? A. Low pH B. Cold water
C. Filamentous bacteria D. High chlorine Correct answer: C. Excessive growth of filamentous organisms can cause foam.
31. What do you do if sludge is bulking in the clarifier? A. Add chlorine to the effluent B. Adjust return activated sludge (RAS) rates and monitor solids C. Raise DO too high D. Bypass the clarifier Correct answer: B. Operational changes can help control sludge settling issues. 32. What is the purpose of the return activated sludge (RAS)? A. Increase effluent flow B. Recycle good microorganisms back to aeration C. Remove chlorine D. Pump out grit Correct answer: B. RAS keeps the biological population alive and effective. 33. What is a grab sample? A. Large sludge volume B. Single sample collected at one time C. Weekly average sample D. Sludge mixed with effluent Correct answer: B. Grab samples give a snapshot of current conditions.
37. What causes high ammonia levels in effluent? A. Excessive chlorination B. Incomplete nitrification C. Low BOD D. High pH only Correct answer: B. Nitrification failure leads to poor ammonia removal. 38. What is supernatant? A. Bottom sludge B. Influent C. Liquid above settled solids D. Sludge blanket Correct answer: C. Supernatant is the clearer liquid layer above solids. 39. What tool is used to measure sludge blanket depth? A. Flow meter B. Sludge judge or sampler C. DO meter D. Grit rake Correct answer: B. A sludge judge helps assess solids levels in clarifiers. 40. What is the purpose of dechlorination? A. Reduce BOD B. Remove excess chlorine before discharge
C. Lower pH D. Control foaming Correct answer: B. Dechlorination protects aquatic life from chlorine toxicity.
41. Which of the following is part of primary treatment? A. UV disinfection B. Sedimentation C. Aeration D. Nitrification Correct answer: B. Sedimentation removes settleable solids early in treatment. 42. What is a digester used for? A. Filtering effluent B. Stabilizing sludge C. Mixing chlorine D. Removing grit Correct answer: B. Digesters break down organic matter in sludge. 43. What safety hazard is common in digesters? A. UV exposure B. Loud noise C. Toxic gases like methane and hydrogen sulfide D. Alkalinity Correct answer: C. Gases from anaerobic digestion can be hazardous.
47. Which is a typical cause of low DO in an aeration basin? A. High alkalinity B. Overloaded organic load C. High pH D. Chlorine overdose Correct answer: B. Too much organic material can reduce oxygen availability. 48. What is the purpose of a weir in a clarifier? A. Remove sludge B. Aerate water C. Control the outflow evenly D. Dose chemicals Correct answer: C. A weir ensures uniform effluent flow. 49. What is the main purpose of secondary clarifiers? A. Remove grit B. Add chlorine C. Settle out biological solids D. Mix chemicals Correct answer: C. Secondary clarifiers remove solids from the biological treatment stage. 50. What should you do if a pump alarm is activated? A. Ignore it
B. Investigate immediately C. Increase flow D. Shut off electricity Correct answer: B. Operators must respond quickly to alarms to prevent damage or backups.
51. What is the main purpose of a manhole in a collection system? A. Remove FOG B. Provide access for inspection and cleaning C. Aerate wastewater D. Store chemicals Correct answer: B. Manholes allow access for maintenance of sewer lines. 52. What does SCADA stand for? A. Sludge Control and Drain Analysis B. Supervisory Control and Data Acquisition C. Sewer Cleaning and Drain Assessment D. Sample Control and Discharge Automation Correct answer: B. SCADA systems monitor and control treatment processes remotely. 53. What is a cause of inflow and infiltration (I&I) in collection systems? A. Chlorine overdose B. Cracked pipes and illegal connections
D. Near electrical panels Correct answer: B. Proper storage prevents spills, reactions, and contamination.
57. What is the typical appearance of healthy activated sludge? A. Clear water with little color B. Thick black sludge C. Brown and flocculent with little odor D. Green with algae Correct answer: C. Properly aerated sludge has a brown, fluffy texture. 58. What causes rising sludge in clarifiers? A. Chlorine deficiency B. Denitrification (gas production) C. Aeration failure D. High DO Correct answer: B. Gas bubbles from denitrification lift solids to the surface. 59. How is chlorine dosage usually measured? A. Milligrams per liter (mg/L) B. Cubic feet C. Pounds per day D. Gallons per hour Correct answer: C. Chlorine feed is often calculated in pounds per day.
60. What is the best action if chlorine levels are too high in effluent? A. Add more chlorine B. Reduce chlorine feed rate C. Increase aeration D. Adjust sludge return Correct answer: B. Lowering dosage helps stay within permit limits. 61. What must operators always do before entering a confined space? A. Add lime B. Vent the space C. Follow entry permit procedures and test air D. Turn off SCADA Correct answer: C. Testing air quality and following entry procedures ensures safety. 62. What is the minimum age to apply for a Texas Class D Wastewater License? A. 21 B. 18 C. 16 D. No age requirement Correct answer: B. Applicants must be at least 18 years old.
