January Exam Flashcards
What is the first stage of drinking water?
Preliminary
What is the second stage of drinking water?
Sedimentation
What is the third stage of drinking water?
Aerobic digestion
What is the fourth stage of drinking water?
Anaerobic digestion
What happens in the first stage of drinking water?
Screening is done to remove large bits like bags, twigs and grit from the sewage
What happens in the third stage of drinking water?
REMOVED
Effluent is removed and mixed with bacteria in the presence of lots of oxygen, the bacteria aerobically digest organic matter in the effluent including other microbes.
What happens in the second stage of drinking water?
During sedimentation heavier sewage sinks know as sludge, lighter sewage floats known as effluent
What happens in the fourth stage of drinking water?
broken down
Sludge is broken down by bacteria in a different process called anaerobic digestion
What does anaerobic digestion produce?
Lots of methane gas which can be used as an energy source to power the plant or neighbouring homes.
What is ozone disinfection?
involves pumping an electrical current through the water that causes oxygen molecules to disassociate and combine with a free oxygen molecule forming O3(also known as ozone)
What happens on UV disinfection?
the bacteria in the water aren’t killed rather there sterilised making them harmless.
How does chlorine disinfect water?
Through chemical disinfection. It is added to the effluent to kill off any bacteria and organisms still living in the water. It is then removed before it can be discharged as to not kill off anything in the discharge location
How long does the process of waste water treatment take?
Average 24 - 36 hours
Where is the effluent released?
Stream or lake or other water source.
Discharged into another treatment plant directly.
What are bar screens?
large vertical bars that stand at the inlet of nearly every waste water treatment plant
What are grit chambers?
sift
As the sewage flows into the grit chamber the velocity of the sewage is adjusted to allow for particles of sand and rock to settle out.
What are the three grit chambers?
Horizontal grit chambers
Aerated grit chambers
Vortex grit chambers
What is settling velocity?
speed at which a particle settles
What is scalar?
Quantities have magnitude only
What is vector?
Quantities have magnitude and an associated direction
What is speed?
How fast an object is travelling
What is velocity?
Speed with direction
What is acceleration?
The rate of change of velocity
Distance
Scalar
Displacement
Vector