Oily water separator (OWS)

An oily water separator processes machinery-space bilge water so the discharge oil content stays at or below 15 ppm, the MARPOL Annex I Reg.14 limit for the open sea. It uses gravity coalescence stages backed by fine coalescers, and a 15 ppm oil-content monitor that triggers a three-way valve to recirculate to the bilge holding tank when the limit is exceeded. The performance and test standard is IMO resolution MEPC.107(49); discharges are logged in Oil Record Book Part I.