Population Dynamics of a Single-Stage Sulfidogenic Bioreactor Treating Synthetic Zinc-Containing Waste Streams

Abstract

Waste streams from industrial processes such as metal smelting or mining contain high concentrations of sulfate and metals with low pH. Dissimilatory sulfate reduction carried out by sulfate-reducing bacteria (SRB) at low pH can combine sulfate reduction with metal-sulfide precipitation and thus open possibilities for selective metal recovery. This study investigates the microbial diversity and population changes of a single-stage sulfidogenic gas-lift bioreactor treating synthetic zinc-rich waste water at pH 5.5 by denaturing gradient gel electrophoresis of 16S rRNA gene fragments and quantitative polymerase chain reaction. The results indicate the presence of a diverse range of phylogenetic groups with the predominant microbial populations belonging to the Desulfovibrionaceae from delta-Proteobacteria. Desulfovibrio desulfuricans-like populations were the most abundant among the SRB during the three stable phases of varying sulfide and zinc concentrations and increased from 13% to 54% of the total bacterial populations over time. The second largest group was Desulfovibrio marrakechensis-like SRB that increased from 1% to about 10% with decreasing sulfide concentrations. Desulfovibrio aminophilus-like populations were the only SRB to decrease in numbers with decreasing sulfide concentrations. However, their population was <1% of the total bacterial population in the reactor at all analyzed time points. The number of dissimilatory sulfate reductase (DsrA) gene copies per number of SRB cells decreased from 3.5 to 2 DsrA copies when the sulfide concentration was reduced, suggesting that the cells' sulfate-reducing capacity was also lowered. This study has identified the species present in a single-stage sulfidogenic bioreactor treating zinc-rich wastewater at low pH and provides insights into the microbial ecology of this biotechnological process.

Characterization of the Bacterial and Sulphate Reducing Community in the Alkaline and Constantly Cold Water of the Closed Kotalahti Mine

“…In Ollinkuilu, the SRB contributed with 0.2% of the total microbial community at −70 and −100 m depth. These values are significantly lower than in recent studies, which have typically shown the clear dominance of sulphate reducers in the reactors treating sulphate and metal rich waters [35], also in in situ reactors [36] and at low temperatures (9 °C) [37]. However, it is plausible that the most effective sulphate reduction is taking place at the bottom of the pit at 800 m depth to where the organic substrates and sulphate reducers have sedimentated.…”

Structure and function of the microbial community in an in situ reactor to treat an acidic mine pit lake

“…Recent studies have shown that anoxic reactors for the treatment of sulfate and metal‐rich waters are typically dominated by microbial sulfate reduction and that the phylogenetic diversity of the microbial communities is comparably small (Auvinen et al ., 2009; Bijmans et al ., 2009; Dar et al ., 2009). In contrast, the microbial community in our reactor was rather diverse, with the majority of the identified phylotypes belonging to SRB, homoacetogens and methanogens.…”

Effect of Sulfate Loading Rate and Organic Loading Rate on Anaerobic Baffled Reactors Used for Treatment of Sanitary Landfill Leachates

“…Based on this scenario, the acetate degradation rate is affected by sulfate reduction, provoking its inhibition at low COD/SO 4 2-ratio (Omil et al 1998;Barber and Stuckey, 2000). At high COD/SO 4 2-ratio, acetogenesis is not inhibited by sulfate reduction, while the overall reactor performance is improved by molecular hydrogen removal (JWH et al, 1994;Kalyuzhnyi et al, 1998;Dar et al, 2009;Zhao et al, 2010). If SO 4 2-is present, SRB consumes molecular hydrogen at higher rates compared with methanogenic archeas because of its superior scavenging capability (Kristjansson et al, 1982).…”

“…Sulfate-reducing bacteria (SRB) can remove molecular hydrogen, allowing optimal performance of methanogenic microorganisms (JWH et al, 1994;Kalyuzhnyi et al, 1998;Dar et al, 2009;Zhao et al, 2010). Under anaerobic conditions, SRB, alone or in consortia, use sulfate as the main electron acceptor, consuming hydrogen and VFAs.…”

“…High anaerobic reaction rates can be achieved if hydrogen is depleted by oxidation with a suitable electron acceptor. Sulfate can accomplish this role in a cost-effective way with a low environmental impact (JWH et al, 1994, Kalyuzhnyi et al, 1998Dar et al, 2009;Zhao et al, 2010).…”