Removal of hydrogen sulfide, benzene and toluene by a fluidized bed bioreactor

Hydrogen sulfide removal by bacteria from upflow anaerobic sludge blanket

This study investigated the biological removal of hydrogen sulfide (H2S) from biogas by anaerobic wastewater treatment processes. Heterotrophic and autotrophic bacteria were isolated from upflow anaerobic sludge blanket (UASB)-mixed liquor of fruit processing factory using nutrient broth and thiosulfate mineral salt medium, respectively. Hydrogen sulfide-removal activities were investigated using sterile UASB-mixed liquor and hydrogen sulfide as growth substrates. It was found that the growth rate of autotrophic bacteria (319 mg VSS l−1 day−1) was higher than that of the heterotrophic bacteria (267 mg VSS l−1 day−1). Hydrogen sulfide(g) was totally removed by absorption into liquid phase: 78·24% removal of aqueous sulfide (S2−(aq)) was achieved by autotrophs and 68·03% by heterotrophs. Molecular identification by polymerase chain reaction-denaturing gradient gel electrophoresis technique and DNA sequencing showed that heterotrophic consortium consisted of Pseudomonas fluorescens Pf0-1, P. aeruginosa PAO1, P. putida KT2440, Bacillus megaterium DSM319 and B. cereus ATCC14579. Autotrophic consortium consisted of Thiobacillus thioparus NZ, T. denitrificans ATCC25259 and Halothiobacillus neapolitanus c2.