Comparison of Uasb and Fluidized-Bed Reactors for Sulfate Reduction

Abstract

-Reactor hydrodynamics is important for sulfidogenesis because sulfate reduction bacteria (SRB) do not granulate easily. In this work, the sulfate reduction performance of two continuous anaerobic bioreactors was investigated: (i) an upflow anaerobic sludge blanket (UASB) reactor and (ii) a fluidized bed reactor (FBR). Organic loading, sulfate reduction, and COD removal were the main parameters monitored during lactate and glycerol degradation. The UASB reactor with biomass recirculation showed a specific sulfate reduction rate of 0.089±0.014 g.gSSV -1 .d -1 (89% reduction), whereas values twice as high were achieved in the FBR treating either lactate (0.200±0.017 g.gSSV -1 .d -1 ) or glycerol (0.178±0.010 g.gSSV -1 .d -1 ). Sulfate reduction with pure glycerol produced a smaller residual COD (1700 mg.L -1 ) than that produced with lactate (2500 mg.L -1 ) at the same COD.sulfate -1 mass ratio. It was estimated that 50% of glycerol degradation was due to sulfate reduction and 50% to fermentation, which was supported by the presence of butyrate in the FBR effluent. The UASB reactor was unable to produce effluents with sulfate concentrations below 250 mg.L -1 due to poor mixing conditions, whereas the FBR consistently ensured residual sulfate concentrations below such a value.

Recovery of Metals from Waste Lithium Ion Battery Leachates Using Biogenic Hydrogen Sulfide

“…During periods of sulfide production (dissolved sulfide concentrations >100 mg L −1 ), the volumetric sulfate reduction rate varied between 170 and 633 mg L −1 d −1 , with an average of 378 mg L −1 d −1 (Figure 2B) and the sulfate reduction efficiency varied between 21% and 86% with an average of 50% ( Figure 2B). Although with lower sulfate reduction rates, the sulfate reduction efficiencies were similar to those reported for other FBRs [30,35,37,39,47]. This is likely due to the longer HRT used in this study (2 days), when compared to these other studies.…”