AWWA AWWA Water Treatment Processes 2

Question 1

What is the maximum contaminant level (MCL) for total trihalomethanes (TTHMs) in US drinking water under the Stage 2 Disinfectants and Disinfection Byproducts Rule?

Accepted Answer

80 µg/L

Answer

The Stage 2 D/DBP Rule sets the MCL for TTHMs at 80 µg/L, enforced using locational running annual averages at distribution system monitoring sites.

Question 2

What treatment process does AWWA recommend for removing taste and odor compounds such as geosmin and MIB from drinking water?

Accepted Answer

Activated carbon adsorption

Answer

Powdered or granular activated carbon (PAC/GAC) is the AWWA-recommended treatment for adsorbing geosmin and 2-methylisoborneol (MIB) taste and odor compounds.

Question 3

In membrane filtration, which process has the smallest pore size and can remove dissolved salts and minerals?

Accepted Answer

Reverse osmosis (RO)

Answer

Reverse osmosis operates at the smallest pore scale (< 0.001 µm) and uses high pressure to remove dissolved salts, minerals, and most contaminants.

Question 4

What is the primary purpose of adding fluoride to drinking water per AWWA and US public health policy?

Accepted Answer

To prevent dental caries (tooth decay)

Answer

Community water fluoridation at 0.7 mg/L (the current USPHS recommendation) is practiced to reduce dental caries prevalence in the population.

Question 5

Which oxidant is commonly used in water treatment to convert soluble iron (Fe²⁺) and manganese (Mn²⁺) to insoluble forms that can be filtered?

Accepted Answer

Potassium permanganate

Answer

Potassium permanganate oxidizes soluble ferrous iron and manganous manganese to their insoluble precipitate forms, enabling removal by filtration.

(AWWA) American Water Works Association Practice Test

(AWWA) American Water Works Association Practice Test

AWWA AWWA Water Treatment Processes 2