Disinfection Kinetics Quiz

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Questions and Answers

What is the purpose of disinfection or sterilization in water treatment?

  • To increase the pH level of water
  • To soften the water
  • To kill harmful disease-producing bacteria (correct)
  • To remove suspended particles from water

Which law describes the reduction in microorganisms when exposed to a disinfectant?

  • Newton's Law
  • Boyle's Law
  • Brewster's Law
  • Chick's Law (correct)

What effect does excess lime have on bacteria in water treatment?

  • It makes the water more acidic, which is beneficial for bacteria growth
  • It helps bacteria multiply
  • It has no effect on bacteria
  • It makes the water excessively alkaline, which is detrimental to bacteria survival (correct)

Why is boiling water not a practical method for disinfection of large amounts of water?

<p>Boiling large amounts of water takes a long time and is impractical (A)</p> Signup and view all the answers

What happens to ozone in water treatment?

<p>It breaks down into normal oxygen and releases nascent oxygen (B)</p> Signup and view all the answers

Why is lime removed from water after disinfection before supplying it for public use?

<p>To prevent excessive alkalinity that can harm bacteria (D)</p> Signup and view all the answers

What is the reference level used for head loss computations in the treatment plant?

<p>Water surface at the influent of the first treatment unit (A)</p> Signup and view all the answers

When can flow by gravity not be achieved in a treatment plant?

<p>If total available head is less than the headloss through the plant (B)</p> Signup and view all the answers

What does the head loss through the treatment plant comprise?

<p>Head losses in treatment units and connecting piping (B)</p> Signup and view all the answers

Which of the following is NOT included in the head losses through the treatment unit?

<p>Head losses due to bends and fittings (D)</p> Signup and view all the answers

What contributes to the total loss through connecting pipings, channels, and appurtenances?

<p>Head loss due to contraction, friction, and free-fall surface allowance (A)</p> Signup and view all the answers

When should hydraulic profiles be prepared in a treatment plant?

<p>At peak and average design flows, at minimum initial flow, and for all main paths of flow through the plant (D)</p> Signup and view all the answers

What is the role of nascent oxygen in water treatment?

<p>It removes organic matter and bacteria (A)</p> Signup and view all the answers

According to the Enzymatic hypothesis, how does chlorine act as a germicide on bacteria?

<p>It kills the enzymes essential for metabolic processes (A)</p> Signup and view all the answers

What forms the free chlorine residual in water treatment?

<p>Hypochlorous acid and hypochlorite ion (B)</p> Signup and view all the answers

What is the consequence of excess free chlorine after all ammonia nitrogen has converted to monochloramine?

<p>Oxidation through breakpoint reactions (B)</p> Signup and view all the answers

What is the stoichiometry when hypochlorous acid reacts with ammonia in water treatment?

<p>$1/10C5H7O2N + HOCl \rightarrow 4/10CO2 + 1/10HCO3- + 1/10NH4++ H+ + Cl- + 1/10H2O$ (C)</p> Signup and view all the answers

How are chloramines removed in water treatment?

<p>Breakpoint reactions with excess free chlorine (A)</p> Signup and view all the answers

In water treatment, what reaction can increase the chlorine demand by reacting with reduced iron at corrosion sites?

<p>$1/10C5H7O2N + OCl- \rightarrow 4/10CO2 + 1/10HCO3- + 1/10NH4++ Cl- + 1/10H2O$ (A)</p> Signup and view all the answers

"Plant layout" in water treatment refers to:

<p>The arrangement of designed treatment units on the site (C)</p> Signup and view all the answers

"Siting" in water treatment involves:

<p>&quot;Character, topography, and shoreline selection&quot; of a site (A)</p> Signup and view all the answers

"Site development" for a treatment plant should aim to:

<p>&quot;Take advantage of existing site topography&quot; (B)</p> Signup and view all the answers

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