Practice Test Geeks(WTO) Water Treatment Operator Certification Practice Test
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Water Quality & Treatment Principles Flashcards

7 cards from real WTO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Water Quality & Treatment Principles flashcards as text

  1. What is the maximum contaminant level (MCL) for total trihalomethanes (TTHMs) in drinking water under the EPA Stage 2 D/DBP Rule?

    Answer: 0.080 mg/L

    The EPA Stage 2 Disinfectants/Disinfection Byproducts Rule sets the MCL for TTHMs at 0.080 mg/L (80 µg/L).

  2. Which physical property of water is used to measure the amount of suspended particles using light scattering?

    Answer: Turbidity

    Turbidity is the measure of water clarity based on how much light is scattered by suspended particles, expressed in nephelometric turbidity units (NTU).

  3. In water treatment, what process uses gravity to separate floc from water after coagulation?

    Answer: Sedimentation

    Sedimentation (also called clarification or settling) allows gravity to pull floc particles to the bottom of a basin after coagulation and flocculation.

  4. What unit is used to express chlorine residual in a distribution system?

    Answer: Milligrams per Liter (mg/L)

    Chlorine residual is expressed in milligrams per liter (mg/L), which is equivalent to parts per million (ppm) in water treatment.

  5. Which of the following is a primary source of nitrate contamination in drinking water supplies?

    Answer: Agricultural fertilizers and animal waste

    Agricultural fertilizers and animal waste are the primary sources of nitrate contamination, as nitrogen compounds leach from fields into groundwater and surface water.

  6. What is the primary purpose of adding alum (aluminum sulfate) during water treatment?

    Answer: To destabilize and coagulate suspended particles

    Alum is a coagulant that destabilizes the electrical charges on colloidal particles, allowing them to clump together into floc for removal.

  7. The term 'CT value' in disinfection refers to which combination of measurements?

    Answer: Chlorine dose (mg/L) × Contact time (minutes)

    CT value is the product of disinfectant residual concentration (C, in mg/L) multiplied by contact time (T, in minutes), used to measure disinfection effectiveness.