Microbial community activities during establishment, performance, and decline of bench-scale passive treatment systems for mine drainage

Self Cite

Mining-influenced water (MIW) is acidic, metal rich water formed when sulfide minerals react with oxygen and water. There are various options for the treatment of MIW; however, passive biological systems such as biochemical reactors (BCRs) have shown promise because of their low cost and maintenance requirements. The purpose of this study was to explore the effect of organic substrate on microbial communities present in pilot-scale BCRs treating MIW in order to understand how substrate-microbe interactions drive performance. Three organic substrates were evaluated: ethanol (ETOH); and two lignocellulose-based mixtures: hay and wood chips (HYWD), and corn stover and wood chips (CSWD). The microbial community compositions were characterized by cloning of 16S rRNA genes and apsA genes associated with sulfate reduction. Quantitative polymerase chain reaction (Q-PCR) was applied to quantify Desulfovibrio-Desulfomicrobium spp. and methanogens. Results revealed distinct differences in microbial compositions and relative quantities of total and sulfatereducing bacteria (SRB) among the BCRs. In particular, the greatest proportion of SRBs were observed in the ETOH BCRs, but the total number of bacteria was low. The HYWD and CSWD BCRs had highly similar bacterial communities, which were complex in composition in comparison to the ETOH BCRs. Methanogens were found to be present in all BCRs at low levels and were the highest in the lignocellulose-based BCRs. This study demonstrates that substrate influences microbial community composition and diversity, which may play an important role in performance and reliability.

Section: Introductionmentioning

confidence: 99%

Effect of Organic Substrate Composition on Microbial Community Structure of Pilot-Scale Biochemical Reactors Treating Mining Influenced Water

Prieto¹,

Hiibel²,

Pereyra³

et al. 2008

Self Cite

“…They are therefore dependent on other microbes to break down cellulose and ferment it to simple compounds. In typical AMD treatment systems using organic matter, the SRB are a trace to minor component of the bacterial population (Logan et al, 2005;Hiibel et al, 2008). Most of the bacterial population is degrading cellulose and converting complex organics to simple organics that can be used by the SRB (Fig.…”

Section: Organic Materialsmentioning

confidence: 99%

“…Figure 4. Sequence of microbial processes to degrade cellulose into compounds metabolizable by sulfate reducers (Logan et al, 2005) Many types of organic matter have been tested as sulfate-reducing media by many investigators. As concluded by Neculita et al (2007), no clear answer is evident on the best material to use.…”

Section: Organic Materialsmentioning

confidence: 99%

Advances in Passive Treatment of Coal Mine Drainage 1998-2009

Rose¹

2010

Abstract. This report updates the review of passive treatment prepared by the Acid Drainage Technology Initiative (Skousen et al., 1998). Important advances since that report include: 1. Measured and calculated acidities are net acidities that are robust measures of this parameter. 2. Removal rates of Fe at pH>5 can be enhanced by CO 2 degassing, by catalysis by solid Fe phases and by specialized aerators; at pH<5, low pH Fe oxidation by bacteria can be helpful in treating high-Fe acidic discharges. 3. For low-Fe-Al AMD, oxic limestone drains can be effective for treatment, but effectiveness declines over years owing to accumulation of precipitate. 4. For high Fe or Al AMD, limestone beds with timed flushing devices can remove large amounts of metals, though eventual cleaning of the limestone may be needed. 5. Addition of limestone sand or lime to streams can be a cost-effective method of restoring watersheds 6. Vertical flow ponds (VFP's, SAPS) can be sized using a loading factor of 25-35 g of acidity/m 2 /d. 7. Manual flushing of VFP's removes only a few percent of accumulated Al precipitate, but timed flushing can be much more effective. 8. Common problems of VFP's include inadequate size, accumulation of Fe precipitate on compost, deterioration owing to Al coatings, and construction defects. 9. Sulfate reduction in passive systems involves a complex community of microbes, with long-term rates dependent on cellulose degrading microbes. Mixtures of fresh organic matter with high-cellulose material appear to provide good performance in lab tests, but more data on longer-term behavior is needed. 10. Sulfate-reducing bioreactors process Al better than older VFP's. 11. Steel slag and chitin hold promise for effective treatment of AMD. 12. A relation for sizing of limestone beds for Mn removal has been developed. 13. Fe precipitate from sludge is being successfully sold for pigment production, and Mn-rich concentrate has been recovered from limestone beds. 14. A revised flow chart for selection of treatment method has been prepared, and the AMDTreat computer program allows easy costing of passive treatment.

“…The batch experiments were carried out with adaptations to those used for assessment of bench scale treatment systems (Logan et al, 2005). Four of the substrate samples taken from the SRBR cells were chosen for carbon-substrate supplemented, detailed batch studies, while the remaining substrate samples were not supplemented for batch studies.…”

Section: Batch Experimentsmentioning

confidence: 99%

Ethanol-Fed or Solid-Phase Organic Sulfate Reducing Bioreactors for the National Tunnel Drainage, Clear Creek/Central City Superfund Site?

Buccambuso¹,

Ruhs²,

Figueroa³

et al. 2007

Abstract:The Peerless Jenny King treatment system is a series of four sulfate reducing bioreactor cells installed to treat acid mine drainage in the Upper Tenmile Creek Superfund Site located in the Rimini Mining District, near Helena MT. The system consists of a wetland pretreatment followed by the four cells connected in a serpentine manner. The mining impacted water flows from the wetland through each cell before discharge. Sulfate reducing bioreactors mitigate acidity and metal contamination through the microbial production of sulfide. The produced biogenic sulfide precipitates metals, and the microbial process of reducing sulfate to sulfide produces alkalinity.The health of the entire microbial community present in such systems is important for remediation to be effective. Classes of microbes generally present in such systems include fermenters, methanogens and sulfate reducers. The health can be measured in terms of active microbial populations and positive interactions between populations for the support of sulfate reduction. The goal of this research is to measure the activity of each class utilizing analyses that quantify the groups by their function, as opposed to the traditional molecular techniques of identifying bacteria. Gas chromatography, HPLC-DAD, and ICP-AES are used to identify and quantify the end products of metabolism. The microbial activity can then be characterized and changes can be monitored over time. Results from 2005 sampling of Cell 3 within the system indicate that the activity of sulfate reducing bacteria is much higher than the numbers present would indicate. These results combined with those from 2006 sampling indicate that methanogenesis is a minor process within this cell. The calculation of the stoichiometry of carbon utilization by SRB is much higher than what would be predicted from known stoichiometric ratios of carbon used per sulfate reduced.