Exam Question
(i) How does sewage discharge from the ship affect the environment? (5)
(ii) Sketch and describe aerobic sewage treatment system. (10)
(iii) Name the special areas under Marpol Annex IV? What is 'Black water' and 'Grey water'? (5)
Class 4 (4th Engineer)
SSEP
📅 Oct 2023
Reference Answer
### (i) Effects of Sewage Discharge on the Marine Environment
Sewage discharged from ships introduces a variety of pollutants into the marine environment, including nutrients (nitrates and phosphates), pathogenic microorganisms, toxins, and metals. The primary adverse effects are:
1. **Oxygen Depletion (Hypoxia/Anoxia)**:
* Sewage is rich in organic matter and nutrients. Aerobic bacteria decompose this waste, a process that consumes large amounts of dissolved oxygen (DO) from the water.
Sewage discharged from ships introduces a variety of pollutants into the marine environment, including nutrients (nitrates and phosphates), pathogenic microorganisms, toxins, and metals. The primary adverse effects are:
1. **Oxygen Depletion (Hypoxia/Anoxia)**:
* Sewage is rich in organic matter and nutrients. Aerobic bacteria decompose this waste, a process that consumes large amounts of dissolved oxygen (DO) from the water.
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