Practice Test Geeks(WTO) Water Treatment Operator Certification Practice Test
← All WTO Flashcard Decks

Disinfection Processes 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 Disinfection Processes flashcards as text

  1. What is the primary advantage of using chloramines over free chlorine for disinfection?

    Answer: Chloramines produce fewer disinfection byproducts

    Chloramines form fewer trihalomethanes and haloacetic acids compared to free chlorine, making them preferred in systems with high organic precursors.

  2. Which parameter most directly affects the disinfection efficiency of chlorine in water treatment?

    Answer: pH

    pH determines the ratio of hypochlorous acid (HOCl) to hypochlorite ion (OCl⁻); HOCl is the more effective disinfectant and dominates at lower pH.

  3. A water system switches from free chlorine to chloramine disinfection. What operational concern must be addressed?

    Answer: Nitrification in the distribution system

    Chloramine systems are susceptible to nitrification, where ammonia-oxidizing bacteria convert ammonia to nitrite, depleting the disinfectant residual.

  4. What does CT value represent in disinfection calculations?

    Answer: Chlorine concentration multiplied by contact time

    CT is the product of disinfectant concentration (C, in mg/L) and contact time (T, in minutes), used to evaluate pathogen inactivation credit.

  5. Why is ultraviolet (UV) disinfection considered ineffective against Cryptosporidium in terms of CT-based comparison?

    Answer: CT tables do not apply to UV; UV efficacy is measured in mJ/cm²

    UV disinfection efficacy is measured by UV dose (mJ/cm²), not CT; Cryptosporidium is actually highly susceptible to UV at standard doses.

  6. Which disinfectant is most effective for inactivating Cryptosporidium oocysts?

    Answer: Ozone or UV

    Cryptosporidium oocysts are highly resistant to chlorine and chloramines but are effectively inactivated by ozone and UV at practical doses.

  7. A operator measures a chlorine residual of 0.0 mg/L in the distribution system. What is the immediate regulatory concern?

    Answer: Potential violation of the Total Coliform Rule and surface water treatment requirements

    Loss of detectable disinfectant residual in the distribution system can trigger coliform sampling requirements and may indicate a treatment technique violation.