Diagnosing Contaminants in Oily Bilge Water
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Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC.1/Circular.677 – Guide to Diagnosing Contaminants in Oily Bilge Water to Maintain, Operate and Troubleshoot Bilge Water Treatment Systems – (22 July 2009) - Annex – A Guide to Diagnosing Contaminants in Oily Bilge Water to Maintain, Operate and Troubleshoot Bilge Water Treatment Systems - Diagnosing Contaminants in Oily Bilge Water

Diagnosing Contaminants in Oily Bilge Water

 Figure 1 is provided for illustrative purposes. It is an example of a flow diagram of several (of many potential) sources of bilge water treatment system failures due to contamination. Contaminants include but are not limited to: waste oils, solvents, detergents, iron oxide particles (rust or “rouge”), engine-room soot, and “biological” contaminants. Biological contaminants are products of bacterial and microbial decomposition such as sewage and growth of life forms in the bilge and piping. In a typical vessel, the main sources of contamination in bilge water and bilge holding tanks include:

  • .1 Diesel engine aftercoolers (clean water);

  • .2 Sludge from decanting/bottom draining storage and sludge tanks. Lube oil and fuel oil purification (oily water);

  • .3 Fuel oil storage and settling tanks (oily water);

  • .4 Lube oil and fuel oil filtration (oil);

  • .5 Machinery leakages;

  • .6 Condensate from air compressors and compressed air systems;

  • .7 Diesel engine piston stuffing box leakages and piston underside blow-down (slow-speed diesels only);

  • .8 Boiler water/condensate drains (different than piston cooling water because these include other types of chemicals (e.g., solvents), causing different concerns);

  • .9 Equipment and engine-room washing;

  • .10 Economizer water washing;

  • .11 Seawater/freshwater cooling (a potential source of biological contaminants);

  • .12 Fire-fighting foam;

  • .13 Water treatment chemicals;

  • .14 Engine coolant;

  • .15 Grey water drains;

  • .16 Sanitary system leaks and overflows; and

  • .17 Air conditioning and refrigeration condensate.

 Some or all of these contaminants can be present in the bilge at any time. Solvents, detergents, and soot are often found after equipment cleaning in machinery spaces. Iron oxide particles and biologicals are common in older ships (leaking pipes, rusting equipment and hull) or when bilge treatment systems have not been operated regularly.

To prevent problems with the operation of bilge water treatment systems or when problems arise, it is important to establish the source of a potential or actual system failure. It is highly recommended that shipowners, port engineers/company superintendents, and chief engineers develop a similar flow diagram for the source(s) of bilge water contaminants for each ship in the company fleet. Simple diagnostic techniques are provided for these purposes in Appendix II.

Parent topic: Annex – A Guide to Diagnosing Contaminants in Oily Bilge Water to Maintain, Operate and Troubleshoot Bilge Water Treatment Systems
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