TRIALS OF RECOVERY AND CLEANUP TECHNIQUES ON BITUMEN DERIVED FROM ORIMULSION

Abstract

ABSTRACT Orimulsion is the trade name for a fine, bitumen-in-water emulsion produced in Venezuela by Bitor S.A. However, when it is spilled in seawater, its dispersibility does not always prevent bitumen from resurfacing as films or patches. The physical properties of the material that resurfaces (i.e., viscosity and cohesiveness) are a function of those of the natural bitumen from which Orimulsion is prepared and represent a serious challenge for oil spill response. To address manufacturers’ and operators’ concerns about dealing effectively with such a spill, trials were organized by Cedre at its test facilities on behalf of Bitor Europe Limited and SK Power and National Power and with the participation of OSRL. The aim was to test recovery and cleaning processes to cope with bitumen originating from a spill of Orimulsion. The trials recreated a bitumen pollution incident on a Cedre lagoon and artificial beach and evaluated various recovery and cleanup equipment. The tests showed that there is no one collecting or cleaning device that can be recommended to the exclusion of all others. Instead, different options have been highlighted, depending on the various forms that bitumen can take (films, patches, tar balls, “tea leaves “), its state (fresh or weathered), and the shoreline substrates. On water, skimming and pumping a slick of bitumen is generally difficult because of the cohesive nature and the high viscosity of the product. On the other hand, a trawl net managed to collect bitumen lumps floating on the lagoon and accumulated them into a disposable sock. On the shore, mechanical screening proved successful in recovering weathered bitumen on the artificial sand beach. Manual collection is also efficient when bitumen forms cohesive slicks. Pressure cleaners removed bitumen from hard surfaces when accumulations were first scraped off and a cleaning product was applied. Coated pebbles could be cleaned by mixing them with solvent in a cement mixer; recommended cleaning agents were petroleum cuts with low aromatic content. Contaminated sand could also be washed using a scrubbing machine. Overall, these trials proved that solutions exist to cope with a spillage of Orimulsion bitumen. Operational conclusions were drawn that incorporated bitumen fate, shoreline types, and logistic considerations.