2025 Texas Wastewater Class A
Exam | Full Versions A & B with
Certified Solutions – Already Graded
A Comprehensive Study Guide for Texas Wastewater Class A
Certification August 26, 2025
,Contents
1 Introduction 5
2 Wastewater Treatment Processes 5
2.1 What is the primary purpose of primary treatment in a wastewater
treatment plant? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 What is the purpose of recirculation in a trickling filter? . . . . . . . . 5
2.3 What is the typical solids content in sludge from a primary clarifier? . 5
2.4 What is eutrophication in a pond system? . . . . . . . . . . . . . . . . 5
2.5 Which activated sludge process typically requires primary clarifiers? 6
2.6 What is a ”Racetrack” in the context of activated sludge treatment? . 6
2.7 What is the primary function of dissolved air flotation in wastewater
treatment? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.8 What is the purpose of adding lime to sludge? . . . . . . . . . . . . . . 6
2.9 What is the primary function of an Imhoff tank? . . . . . . . . . . . . . 6
2.10 What is the purpose of biomonitoring a plant’s effluent? . . . . . . . . 6
2.11 What is the optimal temperature range for trickling filter operation? 7
2.12 What is the purpose of aeration in activated sludge processes? . . . . 7
2.13 What is the typical detention time for an extended aeration basin? . 7
2.14 What is the role of a secondary clarifier in wastewater treatment? . . 7
2.15 Why is seeding necessary for BOD samples? . . . . . . . . . . . . . . . 7
2.16 What is the typical appearance of biomass on a functioning rotating
biological contactor (RBC)? . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.17 What does a high Sludge Volume Index (SVI) indicate in an activated
sludge process? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.18 What is the purpose of a cyclone grit separator? . . . . . . . . . . . . 8
2.19 When is blue-green algae most dominant in a pond system? . . . . . 8
2.20 What is the primary purpose of a grit chamber? . . . . . . . . . . . . . 8
2.21 What is the main advantage of using an anaerobic digester? . . . . . 8
2.22 What is the ideal gas composition in an anaerobic digester? . . . . . 9
2.23 What is the minimum temperature for an anaerobic digester? . . . . 9
2.24 What is the purpose of a bar screen in wastewater treatment? . . . . 9
2.25 What type of pump is most commonly used in wastewater collection
systems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.26 What is the function of a comminutor in wastewater treatment? . . . 9
2.27 What is the purpose of a sequencing batch reactor (SBR)? . . . . . . . 9
2.28 What is the main benefit of a membrane bioreactor (MBR)? . . . . . . 10
2.29 What is the role of a denitrification process in wastewater treatment? 10
1
, 2.30 What is the purpose of a wastewater stabilization pond? . . . . . . . . 10
3 Safety and Regulations 10
3.1 What type of fire extinguisher is used on a de-energized electrical
control panel? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 What is the minimum pressure rating for wastewater pressure mains
per 30 TAC Chapter 317? . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 When must TCEQ be notified about treatment facility expansions? . . 11
3.4 What are the symptoms of carbon monoxide (CO) poisoning? . . . . 11
3.5 What dangerous gases in a confined space may not be detected by
senses? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6 What dangerous gases might a collection system worker encounter? 11
3.7 How should trench shoring be removed? . . . . . . . . . . . . . . . . . 11
3.8 What is the minimum clearance for equipment booms from over-
head electric lines? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.9 How should trench shoring be installed? . . . . . . . . . . . . . . . . . 12
3.10 What is the major cause of wastewater line stoppages? . . . . . . . . 12
3.11 What is the minimum velocity of flow in a wastewater line? . . . . . . 12
3.12 When can a manhole be installed within 9 feet of a waterline per
Chapter 317? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.13 What tests are required for land-applied effluent used for irrigation? 12
3.14 What is the maximum allowable coliform level in wastewater effluent? 12
3.15 How often must a facility conduct a TCLP on sludge if disposal ex-
ceeds 15,000 metric tons annually? . . . . . . . . . . . . . . . . . . . . 13
3.16 What is the minimum inside diameter of a manhole? . . . . . . . . . . 13
3.17 What is the goal of a sanitary wastewater physical survey? . . . . . . 13
3.18 When should drop manholes be utilized? . . . . . . . . . . . . . . . . . 13
3.19 What is the first step in designing a wastewater rehabilitation pro-
gram? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.20 What type of valve is typically used for isolation in wastewater sys-
tems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Operational Calculations 14
4.1 A 30-inch wastewater interceptor flows half-full at 2 fps. What is the
flow rate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 A sludge pump with a 10-inch bore and 5-inch stroke pumps at 50
cycles/min. How long to pump 5,000 gallons? . . . . . . . . . . . . . . 14
4.3 A clarifier is 80 ft in diameter, 12 ft deep, with a 2.5 MGD flow. What
is the detention time? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2
Exam | Full Versions A & B with
Certified Solutions – Already Graded
A Comprehensive Study Guide for Texas Wastewater Class A
Certification August 26, 2025
,Contents
1 Introduction 5
2 Wastewater Treatment Processes 5
2.1 What is the primary purpose of primary treatment in a wastewater
treatment plant? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 What is the purpose of recirculation in a trickling filter? . . . . . . . . 5
2.3 What is the typical solids content in sludge from a primary clarifier? . 5
2.4 What is eutrophication in a pond system? . . . . . . . . . . . . . . . . 5
2.5 Which activated sludge process typically requires primary clarifiers? 6
2.6 What is a ”Racetrack” in the context of activated sludge treatment? . 6
2.7 What is the primary function of dissolved air flotation in wastewater
treatment? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.8 What is the purpose of adding lime to sludge? . . . . . . . . . . . . . . 6
2.9 What is the primary function of an Imhoff tank? . . . . . . . . . . . . . 6
2.10 What is the purpose of biomonitoring a plant’s effluent? . . . . . . . . 6
2.11 What is the optimal temperature range for trickling filter operation? 7
2.12 What is the purpose of aeration in activated sludge processes? . . . . 7
2.13 What is the typical detention time for an extended aeration basin? . 7
2.14 What is the role of a secondary clarifier in wastewater treatment? . . 7
2.15 Why is seeding necessary for BOD samples? . . . . . . . . . . . . . . . 7
2.16 What is the typical appearance of biomass on a functioning rotating
biological contactor (RBC)? . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.17 What does a high Sludge Volume Index (SVI) indicate in an activated
sludge process? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.18 What is the purpose of a cyclone grit separator? . . . . . . . . . . . . 8
2.19 When is blue-green algae most dominant in a pond system? . . . . . 8
2.20 What is the primary purpose of a grit chamber? . . . . . . . . . . . . . 8
2.21 What is the main advantage of using an anaerobic digester? . . . . . 8
2.22 What is the ideal gas composition in an anaerobic digester? . . . . . 9
2.23 What is the minimum temperature for an anaerobic digester? . . . . 9
2.24 What is the purpose of a bar screen in wastewater treatment? . . . . 9
2.25 What type of pump is most commonly used in wastewater collection
systems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.26 What is the function of a comminutor in wastewater treatment? . . . 9
2.27 What is the purpose of a sequencing batch reactor (SBR)? . . . . . . . 9
2.28 What is the main benefit of a membrane bioreactor (MBR)? . . . . . . 10
2.29 What is the role of a denitrification process in wastewater treatment? 10
1
, 2.30 What is the purpose of a wastewater stabilization pond? . . . . . . . . 10
3 Safety and Regulations 10
3.1 What type of fire extinguisher is used on a de-energized electrical
control panel? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 What is the minimum pressure rating for wastewater pressure mains
per 30 TAC Chapter 317? . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 When must TCEQ be notified about treatment facility expansions? . . 11
3.4 What are the symptoms of carbon monoxide (CO) poisoning? . . . . 11
3.5 What dangerous gases in a confined space may not be detected by
senses? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6 What dangerous gases might a collection system worker encounter? 11
3.7 How should trench shoring be removed? . . . . . . . . . . . . . . . . . 11
3.8 What is the minimum clearance for equipment booms from over-
head electric lines? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.9 How should trench shoring be installed? . . . . . . . . . . . . . . . . . 12
3.10 What is the major cause of wastewater line stoppages? . . . . . . . . 12
3.11 What is the minimum velocity of flow in a wastewater line? . . . . . . 12
3.12 When can a manhole be installed within 9 feet of a waterline per
Chapter 317? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.13 What tests are required for land-applied effluent used for irrigation? 12
3.14 What is the maximum allowable coliform level in wastewater effluent? 12
3.15 How often must a facility conduct a TCLP on sludge if disposal ex-
ceeds 15,000 metric tons annually? . . . . . . . . . . . . . . . . . . . . 13
3.16 What is the minimum inside diameter of a manhole? . . . . . . . . . . 13
3.17 What is the goal of a sanitary wastewater physical survey? . . . . . . 13
3.18 When should drop manholes be utilized? . . . . . . . . . . . . . . . . . 13
3.19 What is the first step in designing a wastewater rehabilitation pro-
gram? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.20 What type of valve is typically used for isolation in wastewater sys-
tems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Operational Calculations 14
4.1 A 30-inch wastewater interceptor flows half-full at 2 fps. What is the
flow rate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 A sludge pump with a 10-inch bore and 5-inch stroke pumps at 50
cycles/min. How long to pump 5,000 gallons? . . . . . . . . . . . . . . 14
4.3 A clarifier is 80 ft in diameter, 12 ft deep, with a 2.5 MGD flow. What
is the detention time? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2
