A Study of the Effect of Time on the Separation of Tank Bottom Sludge (TBS) for Difference Volume of Extraction Solvent (XYLENE) Used

The crude oil Tank Bottom Sludge (TBS) is made up of fine oil coated particles that occur in crude water mixture and settles at the bottom of the crude storage tank. This sludge contains an appreciable volume of crude; hence their indiscriminate disposal will present not only an economic loss but also a serious environmental pollution problem. This study therefore, is an investigation of the best method of disposal of TBS such that the effect on the environment is reduced. The method of study was to examine the different solvents as extraction solvent for the separation of TBS. It was found that out of the four solvents stated -ethyl acetate, hexane, benzene and xylene, only xylene proved effective in the separation of aqueous layer. With the chosen extraction solvent (xylene), the effect of operating conditions such as time and volume of surfactant are examined to obtain the best results of separation. For each volume of xylene used, percentage volume of the aqueous layer was found to be 20%. The aqueous layer was in the form of water-sand mixture. No matter how long centrifuging was carried out, there was no separation between the water and muddy phase, but separation did occur with greater amount of the aqueous phase. The maximum volume of aqueous layer was 10 mL, which was obtained after 45 min of separation. Further increase in xylene from (5-25 mL) and separation time did not increase the aqueous layer. The volume of xylene required, 5 mL represents 10% of the volume of TBS treated. The optimum combination of TBS, xylene and surfactant, was obtained at centrifuging time of fifteen minutes which give an aqueous layer of 10 mL. Further centrifuging resulted in the separation of each 10 mL aqueous phase into 3.5 and 6.5 mL of mud.