– Marpol Annex I – Is there a better way? A challenge and a questionnaire for marine managers. By Mark Parsons –
Did you know that in 2007 the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection estimated that annually 189, 000 tonnes of oil and sludge are discharged legally from ships? This is the 15 parts per million component discharged through oily water separators. That’s roughly equivalent to the result of the Amoco Cadiz casualty or twice the Torrey Canyon or four times the Exxon Valdez spill, entering the oceans every year. All that is legal, so how much extra is being discharged through accidental or illegal discharges? One can only guess.
As the Marpol convention came into effect in the 1970s, the part that deals with discharging the waste oily water that accumulates in ships, engine rooms (Annex I) seems to have evolved around the equipment that was available at the time i.e. the conventional oily water separator using gravity and filtration to clean the water before discharge at sea.
As the oil discharge limit has tightened to 15 ppm the technology appears to have struggled to keep up. Most ships’ engineers have tales of woe regarding the use of oily water separators and there is evidence that many units are simply unreliable, with low efficiency and cumbersome operation and maintenance procedures key factors. Over the years several ‘new technologies’ have come into this field but still concentrate on disposal over the side. A lot of these newer systems seem to have problems of their own that don’t make them any more reliable than the conventional units.
Often the result of this unreliability is the infamous ‘magic pipe’ scenario and resultant high profile prosecutions and large fines sought by the US Department of Justice.
Did you know that in 2008, a former chief warrant officer in the US Coast Guard and main propulsion assistant for the Coast Guard Cutter Rush, was sentenced in the US District Court in Hawaii for making a false statement to federal agents investigating allegations of discharge of oil-contaminated waste into Honolulu Harbour? He was fined $5, 000, told to carry out 200 hours of community service and put on probation for two years.
It was said that 2, 000 gallons of bilge waste was pumped overboard, bypassing the oily water separator.
This case in particular reinforces the idea that all may not be well with the current system.
So what can we do about it? Well, how about a different method of disposal altogether, where the water content is evaporated and collected as pure water (effectively distillation), so that there is no overboard discharge at all. Whatever remains is either burnt on board in the ship’s boiler or incinerator, or retained and discharged ashore when the opportunity arises.
If you’re thinking – that’s a large volume of water to boil off, you’d be correct. Typically it takes about 2.5kW to boil a gallon of water, so an electric heat source would be very expensive, although smaller electric units for work boats are already available from companies such as Skimoil in the US. Another source of heat can be found in the exhausts of main engines, boilers and auxiliaries. It’s been common practice for many years to take advantage of this ‘free’ source of energy so maybe it can be used for this different application. In the ideal system the heat from the burnt waste itself could be put back in the system and the recovered fresh water used elsewhere on the vessel.
Obviously there would be a lot of work to investigate if such a system would be technically and commercially viable, and to design and test a system itself would be no small task. It may be decided it is not viable, a complete waste of time, and we would be back to square one. To this end, I have set up a simple online questionnaire to see what the world’s shipping industry thinks and what companies’ experiences actually are. The questions are aimed at superintendents and marine managers who deal with the day-to-day issues of operating the ships and port state control inspections of the equipment. If anyone in this category is interested in the topic or have any comments or experiences they would like to share, the questionnaire can be found via the link:
Mark Parsons is technical manager for Serco Marine Services, Portsmouth. He was one of the first dual cadets with Shell Tankers in 1985, and after leaving Shell in 1996 he worked as chief mate and chief engineer on passenger ships, with a brief spell as production manager in a precision engineering company. He came ashore as a ship manager in 2006.