IntroductionThe spent Merox caustic waste (SMC) in question is a byproduct of desulfurization of light hydrocarbon fractions and products in petroleum refinery operations. Removal of sulfur is necessary because of environmentally driven product specifications for protecting life and safety of living organisms. The term of industrial ecology is used by answering simple questions, like a) are all of the resources, mass and energy flows in the system rational and harmonized? b) was the production planned and operated without adverse effect on our environment, resources and cannot interfere with food chains [1]. Light hydrocarbon fractions and products can be desulfurized by extraction or by chemical conversion. In extractive treatment a solvent that can be regenerated transfers sulfur compounds into polar phase. This phase does not mix with the apolar hydrocarbon phase and can easily be separated by settling. NaOH is a convenient agent for this. Low molecular weight acids are also separated into the water phase. The action of converting the sulfur compound reveals that the mechanism is a reactive extraction: