Wastewater

Which substance is used in a sewage treatment system to kill harmful bacteria?

• ammonia

• chlorine

• sand

• soap

What gas must be maintained at precise levels in the aeration tank?

• CO₂
• O₂
• H₂
• CO

What is the first step of preliminary wastewater treatment, which removes large items such as plastic wrappers and sticks?

• screening - employs the use of a "bar screen"

• sedimentation

• aeration

• disinfection

Where does the solid materials removed from the wastewater in the Primary treatment step end up?

• Landfills

• Farms

• The ocean

• Drinking water

After being pressed into "cakes" the sewage sludge can be used where?

• To fertilize non food crops

• To fertilize any crops

• To cover landfills

• To send to home gardens