A probability is determined, including by obtaining a set of probability ratios, wherein each probability ratio in the set is a ratio of a first probability to a second probability. For example, at least a portion of an endless belt defining a channel is movable up an incline relative to horizontal. These sulphoxides and sulphones, whilst being still present in the liquid hydrocarbon streams, are subsequently extracted thereby producing a low sulphur hydrocarbon stream and optionally following further treatment of the sulphoxides andor sulphones, produce a low sulphur aromatic hydrocarbon stream and an aqueous stream of sodium sulphite or sulphuric acid.