Abstract: A method of treating a first batch of oil sludge containing entrapped oil residue comprises the steps comprises the steps of bringing into contact the first batch of oil sludge to a liquid composition of an emulsion with or without a carrier, wherein the emulsion comprises an alkylpolyglucoside surfactant in 2 to 40% by weight of total composition; a co-surfactant in 1 to 30% by weight of total composition selected from the group consisting of C3 to C18 alcohols, C3 to C18 alkyl lactates, lecithins, C3 to C18 fatty acids and any mixtures thereof; an oil phase in 15 to 90% by weight of total composition; and an aqueous phase in 0.5 to 20% by weight of total composition; homogenizing the liquid composition with the first batch of oil sludge; and fluidizing the oil sludge that the oil residues are substantially dissociated from the solid object forming a liquid phase including the liquid composition and the separated oil.