Oily water separator is use to separate the oil from the water before discharge over board.

Criterion for use of an oily water separator

As per Annex 1 of MARPOL under regulation 4 specified under paragraphs 2, 3, and 6, any direct discharge of oil or oily water mixture into the sea shall be prohibited. The regulation further explains how an oily water mixture can be treated onboard and can be discharged out at sea:

1. As per the MEPC 107(49), the bilge alarm or an Oil Content Monitors, which provides for internal recording of alarm conditions, must be certified by an authorized organization
2. The OCM provided with the oily water separator must be tamper-proof
3. The OCM must activate and sound an alarm whenever freshwater is used for cleaning or zeroing purposes
4. Separator capable of achieving 15 ppm on type C emulsion