This document discusses various causes of marine pollution including sewage waste, pesticides and fertilizers, petroleum, and ship accidents. It then focuses on pollution caused by organic wastes from sewage, noting that sewage contains biodegradable waste that increases biochemical oxygen demand in water. Control measures for sewage pollution include sewage treatment plants that use primary and secondary treatments to reduce biochemical oxygen demand before wastewater is discharged into seas. The document also discusses pollution caused by oil from tanker operations and accidents, as well as control measures for oil spills.

1. MARINE
POLLUTION

2. • Introduction of substances -marine
environment- directly or indirectly-
harming humans, marine life and
lowering the sea quality.
• Pipes – discharging wastes-
municipalities near coast
• Pesticides/ fertilizers –rain-rivers-seas
• Petroleum and oil wash offs- roads-
rivers
• Ship accidents-350,000 tones of
capacity

3. POLLUTION DUE TO ORGANIC WASTES
 The greatest amount of waste discharged into
water- sewage
 The wastes- biodegradable- aerobic bacteria –
BOD increases
 The leftover waste is again decomposed-
anaerobic bacteria –HS, Methane and ammonia-
kills- yeast, anaerobic bacteria and fungi- foul
smelling n toxic

4. CONTROL MEASURES
 Introduction of sewage treatment plants- reduce BOD-
when finally discharged into sea water.
 PRIMARY TREATMENT:
 A screen of parallel bars- 2-7 cm apart are placed-
wire mesh- larger wastes – comminuter- grinds- grit
chamber-detention time is given- some lighter
materials settle down- primary settling tank- further
sedimentation happens- chlorinated
 35 % of BOD -60% of suspended solids are removed

5. SECONDARY
TREATMENT
 Removal of BOD
 3 Methods are used
 1. Trickling filter : a rotating distribution arm – sprays
water – pebbles lined with slime- bacteria, fungi and
algae- degrades wastes trickling through the slime-
Reduces BOD
 2. Activated Sludge Process- sewage is pumped large
tank- bacteria rich sludge n air bubbles- water goes to
sedimentation tank- bacteria becomes a part of
sludge- anerobic bacteria breaks this apart- CO2,
Methane, gases- 60% methane- water removed- dried
sludge- manure
 3. Oxidation Ponds- large shallow ponds- sewage n

6. “
⊹ ADVANCED SEWAGE
TREATMENT
⊹ Effluents-Large amount of
nitrates and phosphates-
Eutrophication- remove these-
very expensive- hardly done

7. POLLUTION DUE
TO OIL

8. Tanker operatons
⊹ Crude oil- 3 billion tones transported
⊹ While unloading cargo- sea water ballast –return journey-
water stored in oil stored containers- 800 tones in
200,000 ton tanker
⊹ Ballast water- contaminated
⊹ Load-on-top : oily water retained inside- oil floats on top-
the water below- discharged- new oil is filled inside the
same tank
⊹ Crude oil washing: jets of crude oil used to remove
clingage- unloading
⊹ Segregated ballast- the ballast water – stored separately

9.  Dry Docking: Cleaning up of ships- oil
seeps into the sea
 Bilge and Fuel Oils: Additional ballast –
while being pumped- leak and join the sea
 Tanker accident: major disaster- Exxon
Valdez
 Offshore Oil production: drilling muds –
70-80 % oil-dumped on sea bed- heavy
contamination of sea water

10. “
⊹ CONTROL MEASURES
⊹ Emulsification of oil- accelerated through chgemical
dispersants
⊹ Slick-lickers that suck the dispersed oil
⊹ Rocks, harbor walls- cleaned through high pressure
steam / dispersants
⊹ EFFECTS
⊹ Eutrophication- red tides- phytoplankton blooms-
clogging of gills kills marine life
⊹ Salt marshes, mangroves- trap oil- do not flower or bear
fruit
⊹ Liquid oil- bird’s plumage- traps water n drowns the bird
⊹ When preening- intake- death
⊹ Seabed oilspills- benthic fauna