PSC Inspections of Sewage Systems
PSC inspectors may check:
- Proper operation of sewage treatment plant (STP) by crew
- Crew knowledge of regulations
- Sewage discharge valve closed/sealed in port
- Condition of STP internal chamber
- Safety management system includes STP maintenance procedures
- Chlorine content of effluent
- Logs of discharge valve operation
- Validity of International Sewage Pollution Prevention Certificate
Sewage Effluent Tests
Key tests conducted onboard:
- Chlorine test (≤5 ppm in chlorine contact compartment)
- Suspended solids
- Biochemical oxygen demand (BOD)
- Coliform count
- Chemical oxygen demand (COD)
Suspended Solids Test
- Collects and weighs solid material in effluent
- Uses asbestos mat filter
- Results in ppm or mg/L
BOD Test
- Incubates 1L sample at 20°C in oxygenated water
- Measures oxygen consumed
- Results in mg/L or ppm
Coliform Count
- Indicates effectiveness of disinfection
- Counts coliforms per 100 mL of effluent
- Incubated for 48 hours at 35°C
Permissible Discharge Limits (MEPC.227(64))
- Suspended solids: 35 mg/L
- BOD: 25 mg/L
- E. coli count: 100/100 mL
- COD: 125 mg/L
These tests and limits help ensure proper sewage treatment before discharge to protect marine environments.
