TEST YOURSELF

Both temporary and permanent hardness of water can be removed by

• boiling

• distillation

• filtration

• decantation

Coliform bacteria in water is an indication of the presence of

• radioactive wastes

• excess fertilizer

• decaying animals and plants

• human feces

The activated sludge process is sometime referred as

• fluid bed biological oxidation system

• fixed bed biological oxidation system

• turning bed biological oxidation system

• none of the above

BOD stands for

• biochemical oxygen demand

• british oxygen demand

• british oxygen depletion

• biological oxygen depletion

When temporary hard water is boiled, one of the substances formed is

• calcium bicarbonate

• calcium sulfate

• hydrogen chloride

• carbon dioxide

The methods used for biological treatment are

• lagoon

• activated sludge process

• oxidation ditches

• all of these

The purest form of naturally occurring water is

• Rain water

• River water

• Pond water

• Well water

The activated sludge process consists of returning a portion of the clarifier

• effluent water entering the reactor

• influent water coming out of the reactor

• influent water entering the reactor

• effluent water coming out of the reactor

Lagoons may be characterized as

• anaerobic

• facultative

• aerated

• all of these

Which of the following substances are commonly used in a filter?

• Charcoal

• Sand

• Both (1) and (2)

• Aluminum chloride