Sewage Treatment Plant Flashcards
What are the advantages of having a STP on Board?
To reduce number of ship side openings
To simplify pipe runs
Heads and bathrooms can be lower in ship
Heads and bathrooms can be used in dry dock
The ship can operate in anti-pollution areas
It is easier to close down in CBRN conditions (and heads can still be used)
Briefly explain Aerobic Digestion
Aerobic = Good
The action of digesting the sewage is known as “Aerobic Digestion” (the microorganisms thrive in air). We promote this by pumping air in.
Briefly explain Anaerobic Digestion
Anaerobic = Bad
If the air supply fails the microorganisms will die, giving off a gas, Hydrogen Sulphide H2S, which smells like rotten eggs. This process is called “Anaerobic Digestion”.
How would you detect Anaerobic digestion at low levels?
smells like rotten eggs
What could cause Anaerobic digestion?
Air supplies fails and microorganisms will die, giving off gas
Sewage Plant
What are the health Hazards
Hepatitis
Typhoid
Gastro- enteritis
What is the purpose of the Primary and Secondary Air Lifts?
What is the purpose of the Aeration Diffuser?
Fully explain the Collect, Hold and Transfer system
Collect hold and transfer (CHT) is a fully automated system, whereby the sewage is collected in large tanks with a storage capacity of about 12 days.
The sewage is collected by means of a vacuum
What is the effect of H2S at
0.03ppm
150-400ppm
1000+ppm
0.03ppm is detectable by odour
70 – 150 ppm Kills sense of smell in about 3 – 15 mins, irritates eyes, throat and lungs
700-1000ppm IMMEDIATE THREAT TO LIFE rapidly produces unconsciousness, permanent brain damage is possible
Over 1000 ppm IMMEDIATE UNCONSCIOUSNESS AND DEATH WITHIN SECONDS
What hazards are associated with Raw Sewage?
Typhoid
Hepatitis
Gastro-Enteritis
What hazards are associated with STP’S
Chemicals
Raw Sewage
Gasses (Methane, Chlorine, Hydrogen Sulphide)
