Response and Recovery of Sulfate-Reducing Biochemical Reactors From Aerobic Stress Events

Abstract

Abstract. Microbially-mediated treatment of mining-influenced water (MIW) through the implementation of sulfate-reducing biochemical reactors (BCRs) is an attractive option for passive, in situ remediation with low operating costs and reduced maintenance requirements. However, BCRs can be unpredictable in terms of how they recover from environmental stresses such as oxygen exposure. Previous studies have demonstrated that the inoculum can impact performance positively, suggesting that engineered control of the microbial community structure could improve the resilience of BCRs to stress. The purpose of this study was to determine the effect of bioaugmentation and biostimulation on performance and recovery from oxygen stress. Twelve columns (six conditions in duplicate) were packed with a complex organic substrate (wood chips, etc.), inoculated with dairy manure, and fed simulated acid mine drainage containing Fe, Cd, and Zn at pH 5.5. The conditions tested were: 1.) bioaugmentation with cellulose degraders (CD); 2.) bioaugmentation with sulfate reducers (SRB); 3.) biostimulation with ethanol (EtOH); 4.) biostimulation with carboxymethyl cellulose (CMC); 5.) dairy manure only control (DM); 6.) un-inoculated control (CR). Once the columns reached steady state anaerobic performance, they were exposed to oxygen, allowed to reach steady state again, and then oxygen-exposed for a second, longer time. The results indicate that all columns performed well in terms of pH neutralization and removal of sulfate and heavy metals. However, the cellulose and ethanol biostimulated columns appeared to be the most resilient to oxygen exposure and performed best by the end of the experiment (171 days), while the bioaugmented columns performed similarly to the controls. The microbial communities were evaluated at each steady state using a suite of biomolecular tools, including active community profiling (ACP) and quantitative realtime PCR (Q-PCR) targeting key functional groups of sulfate-reducers, cellulosedegraders, fermenters, and methanogens. It was found that the active microbial community structure was distinct among the six column conditions and that bioaugmentation significantly impacted the kinds and diversity of bacteria present following stress events. Functional gene analysis supported these observations, but provided finer resolution regarding the response of each functional group to stress. Additional

Diversity and predictive metabolic pathways of the prokaryotic microbial community along a groundwater salinity gradient of the Pearl River Delta, China

“…The functional gene mcrA of the methanogens was amplified by PCR using the forward primer ME1-F (5′- GCMATGCARATHGGWATGTC-3′) and the reverse primer ME2-R (5′-TCATKGCRTAGTTDGGRTA-3′) 57 . The functional gene dsrA of the sulfate reducers was amplified by PCR using the forward primer dsrA 290-F (5′-CGGCGTTGCGCATTTYCAYACVVT-3′) and the reverse primer dsrA 660-R (5′-GCCGGACGATGCAGHTCRTCCTGRWA-3′) 58 . PCR reactions were conducted on a BioRad S1000 thermocycler (Bio-Rad Laboratories Inc., Hercules, CA, USA) under the following conditions: 94 °C for 5 min; 30 cycles: 94 °C for 30 s, 52 °C for 30 s and 72 °C for 30 s; and 72 °C for 10 min.…”

Evaluación de bacterias sulfato reductoras presentes en reactores pasivos durante la remediación de drenajes ácidos de minas

“…La cuantificación de BSR mediante la amplificación del gene dsrA, ha permitido el estudio de su dinámica bajo la influencia de diferentes factores que determinan la eficiencia de los reactores sulfato reductores. En previos estudios se ha demostrado mediante la cuantificación por qPCR, cómo la aclimatación a condiciones sulfato reductoras (Pruden et al, 2007), la composición de los sustratos orgánicos (Pereyra et al, 2010;Hiibel et al, 2011;Schmidtova et al, 2011), el efecto de la bioaumentación y bioestimulación (Pereyra et al, 2012) y las condiciones medio ambientales y de operación de los biorreactores (Perrault et al, 2009), pueden estimular las comunidades microbianas, en especial las sulfato reductoras, y por lo tanto el éxito para la remoción de sulfatos y metales.…”