Biotreatment of refinery spent-sulfidic caustic using an enrichment culture immobilized in a novel support matrix.
Sodium hydroxide solutions are used in petroleum refining to remove hydrogen sulfide (H2S) and mercaptans from various hydrocarbon streams. The resulting sulfide-laden waste stream is called spent-sulfidic caustic. An aerobic enrichment culture was previously developed using a gas mixture of H2S and methyl-mercaptan (MeSH) as the sole energy source. This culture has now been immobilized in a novel support matrix, DuPont BIO-SEP beads, and is used to bio-treat a refinery spent-sulfidic caustic containing both inorganic sulfide and mercaptans in a continuous flow, fluidized-bed column bioreactor. Complete oxidation of both inorganic and organic sulfur to sulfate was observed with no breakthrough of H2S and < 2 ppmv of MeSH produced in the bioreactor outlet gas. Excessive buildup of sulfate (> 12 g/L) in the bioreactor medium resulted in an upset condition evidenced by excessive MeSH breakthrough. Therefore, bioreactor performance was limited by the steady-state sulfate concentration. Further improvement in volumetric productivity of a bioreactor system based on this enrichment culture will be dependent on maintenance of sulfate concentrations below inhibitory levels.
Conner
J A
JA
Department of Chemical Engineering, University of Arkansas, Fayetteville 72701, USA.
Beitle
R R
RR
Duncan
K
K
Kolhatkar
R
R
Sublette
K L
KL
D001709:Biotechnology / Q000295:instrumentation / Q000379:methods; D018914:Cells, Immobilized; D006838:Hydrocarbons; D006862:Hydrogen Sulfide; D007220:Industrial Waste; D010578:Petroleum; D012972:Sodium Hydroxide; D013438:Sulfhydryl Compounds; D013440:Sulfides; D013855:Thiobacillus
D006838:Hydrocarbons; D007220:Industrial Waste; D010578:Petroleum; D013438:Sulfhydryl Compounds; D013440:Sulfides; D012972:Sodium Hydroxide; D006862:Hydrogen Sulfide