Vessels produce a voluminous waste stream of a high-water content/oil mixture typically comprising 60-70 % water and the balance of oil. The first operation is to separate oil and water: it is the dewatering phase. Then the water is treated by physic chemical or bio treatment. Through expert treatment procedures, the oily streams can be recovered to become suitable for reuse. Marine Care Association believes that by avoiding the need to produce an equivalent amount of virgin replacement fuel it can save a 15-40 % carbon reduction by reusing a material that has already been manufactured but not fully used. Currently the world’s commercial shipping fleet demands around 260m tpa of a heavy mineral oil fuel that requires pre-treatment before its use in large diesel engines. It is estimated that some 2% oil fraction of the originally loaded fuel quantity in this way becomes waste. Thanks to the high technology used by MARPOL service companies, this represents a significant solution, as are the alternative solutions currently being developed.