.png){kind=logo}
Ohio Water Treatment Operator Class A Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2025|2026 Q&A | Instant Download Pdf
- What is the primary purpose of coagulation in water treatment?
- To remove dissolved gases
- To disinfect the water
- To destabilize suspended particles
- To soften the water
Rationale: Coagulation neutralizes particle charges so they can clump
together and settle out during flocculation and sedimentation.
- Which chemical is most commonly used as a coagulant?
- Sodium hypochlorite
- Lime 1 / 3
- Aluminum sulfate (alum)
- Potassium permanganate
Rationale: Aluminum sulfate is the most widely used coagulant for water
treatment due to its effectiveness and low cost.
- What is the typical pH range for optimum coagulation with alum?
A. 3–4
B. 5.5–7.5
C. 7.5–9.0
D. 9.0–11.0
Rationale: Alum works best in slightly acidic to neutral conditions,
generally between pH 5.5 and 7.5.
- Which step follows coagulation in the conventional water treatment
- Filtration
- Disinfection
- Flocculation
- Sedimentation
process?
Rationale: Flocculation follows coagulation and gently mixes water to form
larger flocs that can settle.
5. The term “turbidity” refers to:
- The temperature of the water
- The cloudiness caused by suspended solids
- The concentration of dissolved oxygen 2 / 3
- The hardness level
Rationale: Turbidity measures the light-scattering effect of suspended
particles in water.
6. The unit used to measure turbidity is:
- mg/L
- ppm
- NTU (Nephelometric Turbidity Units)
- mL/L
Rationale: NTU is the standard unit of turbidity measurement using a
nephelometer.
- Which of the following disinfectants leaves a measurable residual in the
- Ozone
- UV light
- Chlorine
- Hydrogen peroxide
water?
Rationale: Chlorine provides a residual disinfectant effect, unlike ozone or
UV.
- What is the minimum chlorine contact time typically required for effective
- 1 second
- 30 seconds
- 5 minutes
- / 3
disinfection?
.png)