Precipitation of valuable metals from bioleaching solution by biogenic sulfides

Comparison of Uasb and Fluidized-Bed Reactors for Sulfate Reduction

“…In this regard, the present study has demonstrated that sulfate reduction in the presence of glycerol as an organic substrate produced a smaller residual COD (1700 mg.L ) when ethanol (utilized in industrial scale sulfate-reducing plants) was applied as a carbon and electron source (Nagpal et al, 2000). The sulfide produced can be separated from acetate by either precipitation with transition metals (Fe, Cu, Ni) (Cao et al, 2009) or stripping by an inert gas (N 2 or CO 2 ), as proposed by Marre et al (2004), or even by oxidizing to elemental sulfur (by Fe 3+ or NO 3 -), as already utilized in industrial processes (Johnson et al, 2006). After H 2 S removal, acetate can be degraded either aerobically or anaerobically, depending on the process configurations and feed water quality.…”

“…Furthermore, in the case of UASB reactors, the residence time must be larger than the generation time to avoid microorganism washout (during sulfidogenesis) (Kaksonen et al, 2004). Overall, the performance of anaerobic reactors treating high sulfate loading rates (SLR) is defined by: (i) substrate type (Liamleam and Annachhatre, 2007); (ii) COD.sulfate -1 ratio (Shayegan et al, 2005;Velasco et al, 2008); (iii) inoculum source and enrichment procedure (Mohan, 2005); (iv) pH values (Cao et al, 2009); competition among different groups of microorganisms (Dar et al, 2008;Zhao et al, 2008), and reactor configuration (Sahinkaya et al, 2007;Sheoran et al, 2010). Moreover, competition between sulfate-reducing bacteria (SRB) and methane-producing microorganisms (MPM) in anaerobic reactors is well documented (Bhattacharya et al, 1996;Harada et al, 1994;Omil et al, 1998), but the fermentative metabolism, which can also degrade low molecular weight carbon sources (Dinkel et al, 2010;Ren et al, 2007;Zhao et al, 2008), is less discussed in the context of continuous sulfate reduction.…”

Formation of Fe-sulfides in cultures of sulfate-reducing bacteria

“…Biogenic sulfide formation through bacterial sulfate reduction has application in bioremediation of metal containing waste streams such as acid mine waters [2][3][4][5][6]. Sulfide precipitation of metals from hydrometallurgical solutions is also of considerable interest as it may confer selectivity in metal separation [7,8]. Several studies have addressed process optimization, organic carbon (electron donor) consumption coupled with sulfate reduction, and the efficiency of metal precipitation in the biological treatment with biogenic sulfide [4][5][6][7]9].…”

Metal Removal and Recovery from Mining Wastewater and E-Waste Leachate

“…Lewis and van Hille (2006) observed that in a fluidized bed reactor with Ni and Co, the metal:sulfide ratio of 1:1 can stabilize metal sulfide precipitates, while a ratio more than 1:1.2 can redissolve both metals and form polysulfide complexes, especially for Ni. The remaining sulfide concentration in the IFBs, which is lower than the MINTEQ predicted values, may thus be due to the generation of polysulfides (Bekmezci et al, 2011;Cao et al, 2009).…”