Waste Water

Question 1

Describe waste water

Answer 1

Contains very large amounts of organic molecules
Eg urine and faeces

Question 2

First stage of waste water treatment

Answer 2

Sewage is screened by passing through a mesh
= removes solids and prices of grit

Question 3

Second stage

Answer 3

Sewage can settle in large sedimentation tanks
= produces liquid effluent and semi solid sludge which sinks
Sludge is taken away and digested by anaerobic bacteria

Question 4

What happens when no oxygen

Answer 4

Bacteria produces biogas
= can be burned for electricity