DEVELOPMENT OF AN ELECTRO-SPRAY BIOREACTOR FOR CRUDE-OIL PROCESSING

Biological removal of organic sulfur from petroleum feedstocks offers an attractive alternative to conventional thermochemical treatment due to the mild operating conditions afforded by the biocatalyst, In orde r for biodesulfurization to realize commercial success, it will be nec essary to design reactors that allow for sufficient liquid/liquid and gas/liquid mass transfer while simultaneously reducing operating costs . In this study, the use of electric field contactors for the biodesul furization of the model compound dibenzothiophene (DBT) as well as act ual crude oil was investigated. The emulsion phase contactor (EPC) cre ates an emulsion of aqueous biocatalyst in the organic phase by concen trating forces at the liquid/liquid interface rather than by imparting energy to the bulk solution as is done in impeller-based reactors. Ch aracterization of emulsion quality and determination of rates of DBT o xidation to 2-hydroxybiphenyl (2-HBP) were performed for both batch st irred reactors (BSR) and the EPC. The EPC was capable of producing aqu eous droplets of about 5 mu m in diameter using 3 W/1 whereas the impe ller-based reactor formed droplets between 100 and 200 mu m with compa rable power consumption, The presence of electric fields was not found to adversely affect biocatalytic activity. Despite the greater surfac e area for reaction afforded by the EPC, rates of DBT oxidation in bot h reactors were similar, demonstrating that the biocatalyst used (Rhod ococcus sp. IGTS8) was not active enough to be mass transport limited, The EPC is expected to have tremendous impact on reactor operating co sts and biocatalyst utilization once advances in biocatalyst developme nt provide systems that are mass transport limited. (C) 1997 Elsevier Science B.V.