SEWERAGE AND SEWAGE TREATMENT. THIS SUMS UP AN OVERVIEW ON SEWERAGE AND SEWAGE TREATMENT. DISCOVERY CHANNELS' VIDEO ON SEWERAGE INSPECTION AND ANOTHER VIDEO ON SEWAGE TREATMENT. CLASS QUIZ

1. EHS 415
PUBLIC UTILITIES AND
ENVIRONMENTAL HEALTH
ISSUES
LECTURER: MS. OLULEGAN

2. SEWERAGE AND SEWAGE AND
TREATMENT
TODAY’S TOPIC:

3. Sewerage refers to
the infrastructure
that
conveys sewage.

5. It encompasses components
such as receiving
drains, manholes, pumping
stations, storm overflows, and
screening chambers of
the combined
sewer or sanitary sewer.

6. Sewerage ends at the
entry to a sewage
treatment plant or at the
point of discharge into
the environment.

7. DO YOU KNOW?

8. In many European
countries, citizens are
obliged to connect their
home sanitation to the
national sewerage
system where possible.

9. This has resulted in
large percentages of
the population being
connected to a
sewerage system

10. For example,
the Netherlands have 99%
of the population
connected to the sewerage
system, and 1% has an
individual sewage
disposal system, e.g., septic
tank.

11. Others have slightly
lower (though still
substantial)
percentages; e.g., 96%
for Germany and 86%
for Belgium

14. SEWAGE TREATMENT

15. Sewage is a
mixture of
domestic and
industrial wastes.

16. It is more than 99% water,
but the remainder contains
some ions, suspended
solids and harmful bacteria
that must be removed
before the water is
released into the sea.

17. The treatment of
wastewater is divided
into three phases:
PRETREATMENT,
PRIMARY TREATMENT
AND SECONDARY
TREATMENT.

19. PRETREATMENT
Large solids (i.e. those with
a diameter of more than
2cm) and grit (heavy solids)
are removed by screening.
These are disposed off in
landfills.

20. PRIMARY TREATMENT
The water is left to stand so that
solids can sink to the bottom and
oil and grease can rise to the
surface. The solids are scraped
off the bottom and the scum is
washed off with water jets.
These two substances are
combined to form sludge.

21. SECONDARY TREATMENT
The sludge is further
treated in 'sludge
digesters': large heated
tanks in which its chemical
decomposition is catalysed
by microorganisms.

22. The sludge is largely
converted to ‘biogas', a
mixture of CH4 and CO2,
which is used to
generate electricity for
the plant.

23. The liquid is treated
by bacteria which
break down the
organic matter
remaining in solution.

24. It is then sent to
oxidation ponds where
heterotrophic bacteria
continue the breakdown
of the organics and
solar UV light destroys
the harmful bacteria.

25. PAST QUESTIONS REVIEWS
QUIZ

26. BJWSA WASTEWATER
TREATMENTS
DURATION: 05:59

27. SEWER INSPECTION:
DISCOVERY CHANNEL
DURATION: 04:44