Managing Oily Waste Onboard: A Practical Guide for Ship Crews

Poor management of oily waste is one of the main causes of vessel detention under the PSC (Port State Control) regime in the Caribbean. For the chief engineer, maintaining an orderly waste management system is not only a regulatory obligation — it is an operation that requires continuous planning during the voyage to avoid surprises in port.

Oily waste generated on board a conventional propulsion vessel falls into three main groups. Purifier sludge is the residue resulting from the purification of fuel oil and lubricating oil. Depending on daily fuel consumption and purifier efficiency, a mid-size vessel may generate between 0.3 and 1.5 m³ of sludge per day at sea. Bilge water consists of mixtures of water with oils and fuels that accumulate at the bottom of the engine room. Although it can be treated on board with the bilge separator (15 ppm bilge separator) and discharged at sea if the hydrocarbon content is below 15 ppm, best practice is to retain it for port delivery. Used lubricating, hydraulic, and refrigeration oils complete the inventory of typical oily residues.

Onboard storage requires segregated and clearly identified tanks. MARPOL requires that sludge be stored in the sludge tank, whose minimum capacity is regulated according to the vessel's displacement. The onboard incinerator can be an alternative to reduce volume, but its use is regulated by Annex VI (NOx/SOx) and cannot be used in port waters or within 12 nautical miles of the coast in many jurisdictions.

Documentation that must be in order before a port discharge includes: the Oil Record Book Part I with all entries up to date, the valid IOPP (International Oil Pollution Prevention) certificate, and the volume estimate to be delivered divided by waste type. In the Dominican Republic, the chandler or receiving facility will issue a hazardous waste reception manifest in accordance with national Environmental Law 64-00.

To properly plan discharge during a port call, the chief engineer must calculate the accumulated volume of each waste type, verify the capacity of retention tanks, and estimate the generation rate until the next discharge port. If the sludge tank capacity is insufficient to reach the next port, discharge at the current port becomes mandatory, not optional.

A common mistake is assuming that all Caribbean ports have operational reception facilities 24/7. In the Dominican Republic, De Jesús Ship Supply guarantees service availability with a minimum 12-hour advance coordination. The more data provided to the chandler — waste type, estimated volume, vessel availability window — the more efficient the operation and the lower the impact on total port time.