ETC Water Quality & Treatment

Question 1

Which federal law establishes Maximum Contaminant Levels (MCLs) for drinking water contaminants and is enforced by the EPA?

Accepted Answer

Safe Drinking Water Act (SDWA)

Answer

The Safe Drinking Water Act (SDWA) authorizes the EPA to set and enforce MCLs and treatment technique requirements for public water systems to protect public health.

Question 2

In wastewater treatment, what is Biochemical Oxygen Demand (BOD) a measure of?

Accepted Answer

The amount of oxygen consumed by microorganisms when decomposing organic matter in water

Answer

BOD measures the oxygen consumed by microorganisms as they biologically degrade organic matter in water over a standard 5-day incubation period (BOD5) at 20°C.

Question 3

What is the primary treatment objective of coagulation and flocculation in a drinking water treatment plant?

Accepted Answer

To aggregate suspended particles and colloids into larger settleable masses

Answer

Coagulation (chemical destabilization) and flocculation (gentle mixing to form larger aggregates called floc) are the first treatment steps that convert fine suspended particles into settleable masses for removal by sedimentation.

Question 4

Which water quality parameter, measured in mg/L as CaCO3, indicates the water's ability to resist changes in pH?

Accepted Answer

Alkalinity

Answer

Alkalinity measures the water's buffering capacity — primarily due to bicarbonate, carbonate, and hydroxide ions — expressed as mg/L CaCO3 equivalent, which resists acidification.

Question 5

What is the purpose of the National Pollutant Discharge Elimination System (NPDES) permit program under the Clean Water Act?

Accepted Answer

To control point source discharges of pollutants into navigable waters of the United States

Answer

The NPDES program requires permits for any point source discharge (pipes, outfalls, ditches) of pollutants into waters of the US, setting specific effluent limits and monitoring requirements.

ETC - Environmental Technician Certification Practice Test

ETC - Environmental Technician Certification Practice Test

ETC Water Quality & Treatment