Biological Sulfide Oxidation in a Fluidized Bed Reactor

Abstract

Feasibility of a laboratory scale fluidized bed process for biological sulfide oxidation to elemental sulfur and the formation of well-settleable sulfur sludge is demonstrated. Sulfide oxidation strongly depends upon oxygen concentration, sulfide loading rate and upflow velocity. At reactor dissolved oxygen concentrations (DOr) higher than 0.1 mg l(-1), sulfate was the main product of sulfide oxidation Upon increasing the sulfide loading rate, the sulfate production rate decreased as sulfide oxidation to sulfur showed marked increase. Low formation of sulfate could mean that sulfide was inhibitory to sulfate producing bacteria or that conversion of sulfide to sulfur was more favorable than sulfate production. Sulfide conversions higher than 90% were obtained at sulfide loading rates of 0.13-1.6 kgS mr(-3) d(-1). At DOr less than 0.1 mg l(-1), sulfur was the major end product of the sulfide oxidation. Upflow velocity in the range of 16-26 m h(-1) and sulfide loading rate of 0.9-1.6 kgS mr(-3) d(-1) were necessary for generation of biogranules containing 65-76% of elemental sulfur. The elemental sulfur production of 76% was obtained at upflow velocity of 17 m h(-1) with sulfide loading rate up to 1.6 kgS mr(3)d(-1). Morphological examination of the biogranules showed elemental sulfur deposition in the sludge granule and outside the bacterial cells.

The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester

“…In P3 through P6, 26.94%, 32.70%, 37.24% and 42.39% of the sulfur dosed was transformed into elemental sulfur, respectively, while in P7 a 30.07% reduction was achieved. The possible reason could be that excess oxygen was supplied, leading to part of sulphide being oxidized to thiosulfate or sulphate [46].…”

Simultaneous nitrate and phosphate removal from wastewater lacking organic matter through microbial oxidation of pyrrhotite coupled to nitrate reduction

“…(5).Reduced sulfur can be oxidized with O 2 by autotrophic denitrifiers(Annachhatre and Suktrakoolvait, 2001), therefore, pyrrhotite can be aerobically oxidized by autotrophic denitrifiers using dissolved oxygen in the influent wastewater, expressed by Eq. (8): 3À eP levels in B2 and B3 effluent decreased continuously until stabilizing in Day 38.…”

Investigation on laboratory and pilot-scale airlift sulfide oxidation reactor under varying sulfide loading rate

“…An acid requirement is necessary to maintain pH at 7.5 that is the optimal value of biological sulfide oxidation. [10,25] The actual acid consumption was higher than the theory as illustrated in Figure 8. Since sulfur was more preferred to form at the top part of a riser than a downcomer, some recovered sulfur was probably oxidized to sulfate in the downcomer where oxygen was sparged.…”

“…Annachhatre and Suktrakoolvait [25] obtained the recovered sulfur at 0.6 kgS/m 3 -day of sulfide loading rate with a fluidized bed bioreactor. The higher shear force in airlift bioreactor was a cause for smaller size of sulfur sludge than in the fluidized bed bioreactor, allowing the penetration of oxygen through the biomass which favored the conversion of sulfide to sulfate.…”