22 Questions
What is the purpose of disinfection or sterilization in water treatment?
To kill harmful disease-producing bacteria
Which law describes the reduction in microorganisms when exposed to a disinfectant?
Chick's Law
What effect does excess lime have on bacteria in water treatment?
It makes the water excessively alkaline, which is detrimental to bacteria survival
Why is boiling water not a practical method for disinfection of large amounts of water?
Boiling large amounts of water takes a long time and is impractical
What happens to ozone in water treatment?
It breaks down into normal oxygen and releases nascent oxygen
Why is lime removed from water after disinfection before supplying it for public use?
To prevent excessive alkalinity that can harm bacteria
What is the reference level used for head loss computations in the treatment plant?
Water surface at the influent of the first treatment unit
When can flow by gravity not be achieved in a treatment plant?
If total available head is less than the headloss through the plant
What does the head loss through the treatment plant comprise?
Head losses in treatment units and connecting piping
Which of the following is NOT included in the head losses through the treatment unit?
Head losses due to bends and fittings
What contributes to the total loss through connecting pipings, channels, and appurtenances?
Head loss due to contraction, friction, and free-fall surface allowance
When should hydraulic profiles be prepared in a treatment plant?
At peak and average design flows, at minimum initial flow, and for all main paths of flow through the plant
What is the role of nascent oxygen in water treatment?
It removes organic matter and bacteria
According to the Enzymatic hypothesis, how does chlorine act as a germicide on bacteria?
It kills the enzymes essential for metabolic processes
What forms the free chlorine residual in water treatment?
Hypochlorous acid and hypochlorite ion
What is the consequence of excess free chlorine after all ammonia nitrogen has converted to monochloramine?
Oxidation through breakpoint reactions
What is the stoichiometry when hypochlorous acid reacts with ammonia in water treatment?
$1/10C5H7O2N + HOCl \rightarrow 4/10CO2 + 1/10HCO3- + 1/10NH4++ H+ + Cl- + 1/10H2O$
How are chloramines removed in water treatment?
Breakpoint reactions with excess free chlorine
In water treatment, what reaction can increase the chlorine demand by reacting with reduced iron at corrosion sites?
$1/10C5H7O2N + OCl- \rightarrow 4/10CO2 + 1/10HCO3- + 1/10NH4++ Cl- + 1/10H2O$
"Plant layout" in water treatment refers to:
The arrangement of designed treatment units on the site
"Siting" in water treatment involves:
"Character, topography, and shoreline selection" of a site
"Site development" for a treatment plant should aim to:
"Take advantage of existing site topography"
Test your knowledge on disinfection kinetics with this quiz. Learn about Chick's Law and the process of disinfecting water to make it safe for drinking.
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