Cleaning oil-contaminated vessels with .alpha.-emulsans

A process for cleaning and recovering hydrocarbonaceous residues, including residual petroleum, from oil-contaminated tankers, barges, storage tanks, tank cars and trucks, pipelines and other containers used to transport or store crude oil or various petroleum fractions, which comprises (A) washing oil-contaminated surfaces of such containers with an emulsifying agent comprising an aqueous solution in sea water or fresh water containing (1) from about 10 mcg/ml to about 20 mg/ml of extracellular microbial protein-associated lipopolysaccharides (herein collectively called ".alpha.-emulsans") produced by Acinetobacter Sp. ATCC 31012 and its mutants, in which the lipopolysaccharide components (herein collectively called "apo-.alpha.-emulsans") are N- and O-lipoacylated heteropolysaccharides made up of major amounts of D-galactosamine and an aminouronic acid, such apo-.alpha.-emulsans containing at least 7 percent by weight of fatty acid esters in which the fatty acids contain from about 10 to about 18 carbon atoms and are characterized by an average equivalent weight from about 200 to about 230, from about 50 to about 70 percent by weight of such fatty acids being composed of 2-hydroxydodecanoic acid and 3-hydroxydodecanoic acid;

• and (2) from about 1 to about 100 mM of at least one divalent cation, thereby forming an oil-in-water emulsion of such hydrocarbonaceous residues;
• (B) removing such oil-in-water emulsions from the cleaned container;
• and (C) recovering the hydrocarbonaceous residues from such oil-in-water emulsion.