Primary & Secondary Sewage Treatment

What is activated sludge?

• Distilled bacteria

• Fermented bacteria

• Sediment bacterial flocs

• Fungi

What is the most suitable for dry waste?

• Aerobic composting

• Anaerobic composting

• Closed vessel

• Anaerobic digestion

Which of the following is a characteristic of anaerobic digestion?

• Low degradation rate

• Low odor emission

• Narrow suitability of waste

• Gas Phase

What is the role of microorganisms in secondary wastewater treatment?

• to consume waste

• to dissolve gases in permanent hard water

• to biologically remove contaminants from wastewater

• to remove hardness of water

Coliform bacteria in water is an indication of the presence of:

• Radioactive waste

• excess fertilizer

• decaying animals and plants

• Human feces

In ____ during sewage treatment , ammonia is oxidized to

• Nitrification , nitrate

• Ammonification, nitrite

• Ammonification, nitride

• Nirtrification, nitrite

How much percent of organic matter is removed during secondary treatment?

• 86%

• 82%

• 85%

• 80%

What reduces the sludge and produce methane gas from it?

• Fungi

• Algae

• Aerobic bacteria

• Anaerobic bacteria

Why is wastewater treated with bacteria?

• to reduce the amount of organic matter

• to reduce the Biological Oxygen Demand or BOD

• cleanse the liquid of contaminants

• All of these

What is the major advantage of anaerobic fermentation over aerobic composting ?

• Human control

• Production of methane

• High water content

• Less water contents