WTO Water Quality & Treatment Principles 2

Question 1

What is the maximum contaminant level (MCL) for total trihalomethanes (TTHMs) in drinking water under the EPA Stage 2 D/DBP Rule?

Accepted Answer

0.080 mg/L

Answer

The EPA Stage 2 Disinfectants/Disinfection Byproducts Rule sets the MCL for TTHMs at 0.080 mg/L (80 µg/L).

Question 2

Which physical property of water is used to measure the amount of suspended particles using light scattering?

Accepted Answer

Turbidity

Answer

Turbidity is the measure of water clarity based on how much light is scattered by suspended particles, expressed in nephelometric turbidity units (NTU).

Question 3

In water treatment, what process uses gravity to separate floc from water after coagulation?

Accepted Answer

Sedimentation

Answer

Sedimentation (also called clarification or settling) allows gravity to pull floc particles to the bottom of a basin after coagulation and flocculation.

Question 4

What unit is used to express chlorine residual in a distribution system?

Accepted Answer

Milligrams per Liter (mg/L)

Answer

Chlorine residual is expressed in milligrams per liter (mg/L), which is equivalent to parts per million (ppm) in water treatment.

Question 5

Which of the following is a primary source of nitrate contamination in drinking water supplies?

Accepted Answer

Agricultural fertilizers and animal waste

Answer

Agricultural fertilizers and animal waste are the primary sources of nitrate contamination, as nitrogen compounds leach from fields into groundwater and surface water.

(WTO) Water Treatment Operator Certification Practice Test

(WTO) Water Treatment Operator Certification Practice Test

WTO Water Quality & Treatment Principles 2