WTO Source Water Characteristics 3

Question 1

What term describes the phenomenon where warm and cold water layers fail to mix in a lake or reservoir?

Accepted Answer

Thermal stratification

Answer

Thermal stratification occurs when temperature-driven density differences prevent mixing between the warm epilimnion and cold hypolimnion layers.

Question 2

Which characteristic of source water most directly affects the required coagulant dose in a conventional treatment plant?

Accepted Answer

Turbidity and NOM concentration

Answer

Turbidity (suspended particles) and natural organic matter (NOM) are the primary factors that determine how much coagulant is needed to form settleable floc.

Question 3

A source water with very low alkalinity (less than 30 mg/L as CaCO3) presents what challenge during coagulation?

Accepted Answer

Insufficient buffering to maintain optimal coagulation pH

Answer

Low alkalinity water lacks the buffering capacity needed to maintain the optimal pH range for coagulation, often requiring alkali addition.

Question 4

What does the term 'specific conductance' measure in source water?

Accepted Answer

The ability of water to conduct electrical current, indicating dissolved ion content

Answer

Specific conductance measures the capacity of water to conduct electricity, which correlates directly with the total concentration of dissolved ions.

Question 5

Which naturally occurring compound in source water is most commonly responsible for a rotten egg odor?

Accepted Answer

Hydrogen sulfide

Answer

Hydrogen sulfide gas, produced by sulfate-reducing bacteria in anaerobic conditions, is responsible for the characteristic rotten egg odor in some source waters.

(WTO) Water Treatment Operator Certification Practice Test

(WTO) Water Treatment Operator Certification Practice Test

WTO Source Water Characteristics 3