ABC Technical Proficiency and Best Practices 2

Question 1

When calibrating a dissolved oxygen meter, which action ensures the most accurate reading before field use?

Accepted Answer

Allow the probe to air-equilibrate at ambient temperature and pressure

Answer

Submerge the probe in saturated salt solution

Answer

Zero the meter using deionized water

Answer

Calibrate only at the lab regardless of field conditions

Question 2

A wastewater plant operator notices the return activated sludge (RAS) rate is too high. What is the most likely operational consequence?

Accepted Answer

Washout of mixed liquor suspended solids from the secondary clarifier

Answer

Improved BOD removal efficiency

Answer

Increased sludge age in the aeration basin

Answer

Excessive sludge blanket buildup in the aeration basin

Question 3

In a water distribution system, the purpose of a pressure-reducing valve (PRV) is to:

Accepted Answer

Protect downstream piping from excess upstream pressure

Answer

Increase pressure in low-pressure zones

Answer

Prevent backflow from service connections

Answer

Regulate chlorine residual in the distribution system

Question 4

Which safety practice is most critical when entering a confined space at a water treatment facility?

Accepted Answer

Testing the atmosphere for oxygen, flammable gases, and toxic vapors before entry

Answer

Wearing a hard hat and steel-toed boots only

Answer

Having a coworker watch from outside the entrance

Answer

Ensuring the space was last entered within 24 hours without incident

Question 5

What does a high turbidity reading in treated drinking water most directly indicate?

Accepted Answer

Possible passage of pathogens through filtration

Answer

Excessive chlorine demand

Answer

High total dissolved solids concentration

Answer

Inadequate corrosion control treatment

Question 6

An operator observes a sudden drop in filter run time. Which of the following is the MOST likely cause?

Accepted Answer

Coagulation or flocculation process upset

Answer

Increased backwash frequency

Answer

Reduction in source water temperature

Answer

Decreased influent flow rate

Question 7

When collecting a bacteriological sample for compliance monitoring, the operator must:

Accepted Answer

Use a sterile container with sodium thiosulfate for dechlorination

Answer

Flush the tap for at least 10 minutes before collection

Answer

Collect the sample at a location with the highest chlorine residual

Answer

Refrigerate the sample for at least 2 hours before analysis