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Florida Wastewater Practice Test Revision
Exam with Actual Answers 202 5
- What is the main purpose of a bar screen at a wastewater treatment plant? A. Remove nutrients B. Remove large debris C. Remove grit D. Remove bacteria
Bar screens are the first line of defense to remove large debris
such as rags and plastics to protect downstream equipment.
- What does BOD stand for in wastewater treatment? A. Biological Oxidation Demand B. Biochemical Oxygen Demand C. Biological Organic Debris D. Bacterial Oxygen Depletion
BOD measures the amount of oxygen microorganisms need to
decompose organic matter.
- What type of bacteria thrives in oxygen-rich environments? A. Anaerobic B. Aerobic C. Facultative
D. Nitrifying
Aerobic bacteria require oxygen to survive and are essential for
aerobic treatment processes.
- What is the acceptable range of pH for most biological wastewater treatment processes? A. 2.0–4. B. 6.5–8. C. 9.0–11. D. 4.0–6.
Biological treatment processes operate best in a near-neutral pH
range of 6.5 to 8.5.
- What is the main purpose of an aeration tank? A. Remove grit B. Promote microbial digestion C. Disinfect the water D. Settle solids
Aeration tanks add oxygen to support aerobic bacteria that break
down organic matter.
- Which organism indicates a healthy activated sludge system? A. Amoebas B. Free-swimming ciliates C. Nematodes D. Filamentous bacteria
10.Which chemical is commonly used for disinfection? A. Alum B. Ferric chloride C. Chlorine D. Lime
Chlorine is widely used to kill pathogenic organisms before
effluent discharge.
11.What is the purpose of a flow equalization basin? A. Remove solids B. Aerate water C. Even out flow rates D. Add chlorine
It helps prevent shock loading by equalizing flow and pollutant
concentrations.
12.What is a common indicator organism used to test for pathogens in treated wastewater? A. Giardia B. E. coli C. Salmonella D. Cryptosporidium
E. coli is used as an indicator for fecal contamination.
13.What is a digester used for? A. Screening B. Filtration
C. Stabilizing sludge D. Disinfection
Digesters break down sludge biologically, reducing volume and
odors.
14.What type of pump is commonly used in lift stations? A. Diaphragm B. Submersible centrifugal C. Gear D. Piston
Submersible centrifugal pumps are durable and ideal for moving
sewage.
15.What does FOG stand for? A. Flocculants, Organics, and Grit B. Fats, Oils, and Grease C. Fermentable Organic Gases D. Filtration Over Gravity
FOG clogs pipes and causes maintenance issues.
16.What is a permit issued under the Clean Water Act called? A. EPA Water License B. NPDES permit C. Discharge Rights Agreement D. Waste Release License
B. Nitrification C. Chemical precipitation D. Flotation
Alum or ferric salts precipitate phosphorus into a removable solid.
21.Which treatment stage removes grit and sand? A. Primary treatment B. Preliminary treatment C. Tertiary treatment D. Disinfection
Preliminary treatment removes large and abrasive materials to
protect equipment.
22.What is the most common cause of filamentous bacteria problems? A. Low alkalinity B. Low DO or nutrient imbalance C. High chlorine D. High pH
Filamentous bacteria thrive in low-oxygen or unbalanced
conditions.
23.What does SCADA stand for? A. Sewage Control and Data Application B. Supervisory Control and Data Acquisition C. System Control and Digital Automation D. Sewage Cleaning and Dumping Act
SCADA systems monitor and control remote processes.
24.What is the recommended temperature range for mesophilic digestion? A. 90–100°F B. 50–60°F C. 95–98°F D. 120–130°F
Mesophilic bacteria thrive at 95–98°F in anaerobic digesters.
25.What is the purpose of a manhole in a wastewater collection system? A. Filter solids B. Provide maintenance access C. Measure pH D. Remove gas
Manholes allow entry for inspection, cleaning, and repairs.
26.What causes hydrogen sulfide (H2S) in wastewater? A. Aeration B. Anaerobic decomposition C. Chlorination D. Flocculation
H2S is a gas produced when organic matter breaks down without
oxygen.
27.What does a weir in a clarifier do? A. Introduce chemicals B. Remove sludge C. Control flow rate out of the clarifier
31.What happens if sludge is not removed regularly from a clarifier? A. Increased oxygen levels B. Improved settling C. Sludge blanket buildup and carryover D. Higher chlorine demand
Excess sludge will rise and wash out with the effluent, affecting
treatment quality.
32.What is a typical detention time for primary clarifiers? A. 30 minutes B. 1.5 to 2 hours C. 6 hours D. 12 hours
1.5 to 2 hours allows sufficient time for solids to settle.
33.Which test determines the efficiency of organic removal in secondary treatment? A. TSS B. BOD C. COD D. Alkalinity
BOD5 reflects the amount of biodegradable organic matter
removed.
34.Which of the following is NOT a stage of wastewater treatment? A. Preliminary B. Primary
C. Tertiary D. Septic
Septic systems are separate from municipal wastewater treatment
stages.
35.What are biosolids? A. Toxic by-products B. Treated sewage sludge suitable for disposal or reuse C. Grease from pipes D. Industrial waste
Biosolids are processed, stabilized sludge safe for land application.
36.What is commonly used to dechlorinate effluent before discharge? A. Alum B. Sulfur dioxide C. Hydrogen peroxide D. Sodium bicarbonate
Sulfur dioxide neutralizes chlorine to protect aquatic life.
37.Why are composite samples preferred over grab samples in many tests? A. They are faster B. They represent average conditions C. They are less accurate D. They need fewer tools
Composite samples account for variations in flow and quality over
time.
C. When water flows too quickly, bypassing treatment D. Backflow
Short-circuiting reduces detention time and treatment
effectiveness.
42.What is the primary concern with high ammonia levels in effluent? A. Alkalinity boost B. Sludge thickening C. Toxicity to aquatic life D. Increased temperature
Ammonia is harmful to fish and aquatic organisms in receiving
waters.
43.What is a blower used for in wastewater plants? A. Dry sludge B. Supply air to aeration basins C. Pump effluent D. Remove grit
Blowers provide oxygen for aerobic bacteria in the aeration
process.
44.What is the purpose of RAS (Return Activated Sludge)? A. Discharge solids B. Maintain microbial population in the aeration basin C. Backwash filters
D. Remove grit
RAS returns settled microbes to keep the treatment process active.
45.What condition causes septicity in sewers? A. High flow B. Lack of oxygen C. Chlorination D. High pH
Septic conditions occur in stagnant or low-oxygen environments,
producing odors.
46.What is one symptom of filamentous bulking? A. Clear effluent B. Rapid settling C. Poor sludge settling D. Low pH
Filamentous organisms prevent sludge from compacting, leading
to carryover.
47.What happens if the MLSS is too high in an aeration basin? A. Increased DO B. Poor oxygen transfer and bulking C. Faster treatment D. No change
High MLSS can overload the system, leading to oxygen depletion
and poor settling.
