L1 /
4
CH3041
SEWAGE TREATMENT II
• In a small city
such as Cairns where water
does not
need to
be re-used
only 1o & 2o
treatment are
carried out.
does not
need to
be re-used
only 1o & 2o
treatment are
carried out.
• 1o treatment
involves the
removal of grit (sediment/filter) and grease.
involves the
removal of grit (sediment/filter) and grease.
• 2o treatment
involves the microorganism
mediated digestion of the organic matter,
followed by settling to remove solids.
mediated digestion of the organic matter,
followed by settling to remove solids.
1o
30% of BOD
60% solids
30% of BOD
60% solids
2o
60% of BOD
30% of solids
60% of BOD
30% of solids
Polishing
ponds
9.9% of BOD
ponds
9.9% of BOD
dried
fertiliser
fertiliser
99% H2O
