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Oil pollution control :Bilge water separator for ships & record keeping of vessel discharges

Bilge water Ė The water that collects in the bilges of a vessel which generally becomes foul and noxious. Bilge water also contains fluids from machinery spaces, internal drainage systems, sludge tanks and various other sources. This mixture is collected in the bilge water holding tank, which generally is maintained at an elevated temperature. Regardless of its source bilge water must be treated to reduce the oil content to levels meeting international regulations for release into the environment.

Note: Cleaning agents, emulsifiers, solvents or surfactants used for cleaning purposes may cause the bilge water to emulsify. Proper measures should be taken to minimize the presence of these substances in the bilges of a ship.

Bilge water legislation Ė Current MARPOL legislation stipulates that separated bilge water containing 15 ppm or below in water can be disposed into international waters. Some national, regional and local authorities have more stringent regulations. In the United States and in the Baltic and North Seas disposal of separated bilge water is only permitted at least 12 nautical miles from shore. In the future, legislation is expected to become even more stringent, requiring levels of oil in water to be reduced further to five ppm for discharge at sea and to zero-discharge in sensitive waters.

Bilges must be kept dry at all times by transferring bilge water to the bilge holding tank. All oil and water leaks must be stopped, or flow reduced to a minimum, as soon as possible, to ensure bilges and bilge water tanks contain minimum amounts of bilge water.

Machinery Space Bilges:
Any discharge into the sea of oil or oily mixtures is prohibited, except when all of the following conditions are satisfied:
  1. the ship is proceeding en route
  2. the oily mixture is discharged through the Oily Water Separator
  3. the oil content does not exceed 15 ppm
  4. the oily mixture does not include cargo pump room bilges or contain cargo residues
  5. if the ship is in a Special Area the OWS must be fitted with an Alarm and Auto Stop.

To ensure that all entries within vesselsí Oil Record Books are clear and accurate, it is vitally important that discharges ashore or to a barge, are accounted for in quantities of specific fluids. (i.e. Sludge / Bilge Water / Slops / etc)
Discharge receipts often provide details of only the total amount of fluids discharged, which does not allow for suitable accountability records to be maintained onboard. Quantities must be accounted for in segregated terms (i.e. total amount of each fluid discharged.)

Oil Record Book entries should be recorded immediately and signed by the officer in charge of the operation. Each completed page should also be signed by the Master.

It is the vesselís responsibility to ensure that all onboard records are maintained accurately, with supporting evidence available as necessary. Vessels should ensure that specific fluid quantities are stated on barge receipts and entered within the Oil Record Book.

Where a quantity of fluids (Sludge / Bilge Water / Slops / etc) is discharged and the discharge receipt does not provide evidence of the different quantities, the vessel must write on the discharge receipt the volumes discharged, after which the receiving facility should countersign the quantities thereby confirming and accepting the vessels figures of discharge.

Should the vesselís quantities not be confirmed or where discharge facilities refuse to countersign the vessels figures (therefore hindering transparency of onboard records), a Note of Protest which includes the specific volumes should be issued. A copy of the Note of Protest is to be retained onboard, again for accountability purposes.

Nonetheless, total amounts of each fluid must be accountable at all times with the vesselís records showing complete accuracy and transparency.


Guideline for bilge water separator

The Chief Engineer shall ensure that the certificate for the equipment and the required signboards are present and readable at all times.

All engineers who are authorized by the Chief Engineer to operate the equipment shall be totally familiar with normal operations, the piping system to and from the separator, and the testing procedures.

The equipment shall be operated in full compliance with MARPOL Annex I, and absolutely NO BYPASSING of the equipment shall be done no matter what. If there is the slightest doubt that the equipment is operating satisfactorily, it shall not be used until a proper investigation and tests have been carried out under supervision of the Chief Engineer.

The bilge water overboard discharge valve shall be kept closed and padlocked. It shall only be opened after permission from the Chief Engineer.




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