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Coal-mine-drainage treatment solids secondary resource

Heterogeneous solids accumulated during treatment of drainage from coal mines, including metal-rich precipitates and coatings in passive remediation systems. Their processing origin distinguishes this secondary resource from untreated mine water, natural ore, coal combustion ash and an individual oxide mineral. The curated experiment used material from five Pennsylvania passive systems containing different proportions of manganese, iron, aluminium and rare-earth elements. Neither a universal composition nor a constituent's criticality designation is assigned to the resource. Laboratory culture-associated metal mobilization is documented; a purified recovered product, economic recovery yield and industrial deployment are not established.

Microbial & Biochemical Mechanisms (1)

Acidogenic-culture-associated rare-earth mobilization from treatment solids

bioleaching Microbial

Associated Organisms: Bacillus mycoides (NCBITaxon:1405), Bacillus pseudomycoides (NCBITaxon:64104)

Separately inoculated living cultures reported as Bacillus mycoides JR07 and Bacillus pseudomycoides KB7 were associated with increased total rare-earth concentrations in decanted supernatants from several prepared coal-mine-drainage treatment solids. Effects depended on the feed and isolate; JR07 did not exceed the sterile control for Wingfield Pines. Acid production, biofilm assays and surface association make acidogenesis plausible but do not demonstrate a unique lactate pathway, gene requirement or phase-specific rare-earth dissolution mechanism.

Experimental Context & Analytical Limits:
Methods 2.3 used solids from Glasgow, Scootac, Kentucky Hollow, Sterrett and Wingfield Pines passive remediation systems. Coatings were washed from limestone rocks with sterile water, dried at 60 degrees C for approximately 24-48 h, ground and autoclaved at 121 degrees C for 30 min. Prepared solids at 1% w/v were incubated with individual isolates for three days at 30 degrees C in modified manganese-reduction medium (3 g peptone, 2.5 g glucose and 0.010 g FePO4 per litre; recipe pH 7.6 adjusted with NaOH). Corresponding sterile-medium/solid samples appear in Figure 3 and Table S1. ICP-MS/ICP-OES analyzed decanted supernatant; filtration and digestion of this metal-assay fraction, working volume, inoculum dose and replicate number are not specified for this experiment. Its final pH and oxygen conditions are not reported. The stationary, unaerated 10% solid-loading Mn(II) assay in Methods 2.2 and the 10% inoculum/2 mL SEM preparation in Methods 2.5 are separate assays. Species IDs map the authors' species names, not independently verified JR07 or KB7 genome accessions. These laboratory tests do not demonstrate metal recovery in the field systems that supplied the feed.
Curated Evidence Points:
Table S1 TREE column reports JR07, KB7 and sterile sample concentrations, respectively, of 92.29, 36.37 and 7.27 ppb for Glasgow (GJ/GK/GS); 260.42, 136.58 and 3.36 ppb for Scootac (SJ/SK/SS); 466.11, 400.80 and 228.08 ppb for Kentucky Hollow (KJ/KK/KS); and 317.65, 302.82 and 3.97 ppb for Sterrett (StJ/StK/StS). These are source-reported supernatant totals, not isolated-product yields or independently estimated effect sizes. The high Kentucky Hollow sterile value is retained; the main article's approximately 40-fold comparison is to other isolates, not this sterile control, and varies with the chosen comparator.
Table S1 Wingfield Pines TREE values are 0.82 ppb for JR07 (WJ), 4.30 ppb for KB7 (WK) and 1.59 ppb for sterile WS. Several individual analytes are BDL; they are not treated as zeros. AV20 and AV21 Kentucky Hollow totals are below the sterile total. AV22 and AV24 rows are absent for Kentucky Hollow, Sterrett and Wingfield Pines, so no complete six-isolate-by-five-feed design or unreported negative result is inferred. No uncertainty is given for the TREE values. Table S1 names promethium in its TREE definition but has no Pm column; the totals are retained as reported without inventing a promethium measurement or assigning a censoring convention to the sum.
Methods 2.4 and Figures 4-6 associate JR07/KB7 with lactate production, annotated fermentation genes, crystal-violet staining and contact with Glasgow solids. Neither matched-pH abiotic acid controls nor interventions establish that lactate, a particular gene or biofilm is necessary for REE release. The approximately pH 4 statement refers to prior Mn experiments; it is not a measured pH trajectory for every REE treatment. SEM-EDS elemental association does not uniquely identify MnO2 or a REE host phase. Figure 3 uses column-normalized heat-map values, not directly comparable concentrations across elements. Discussion's less-than-1% statement lacks an explicit mass-balance calculation and is not adopted as a verified extraction yield; the 1% w/v loading, Figure 2 feed values and Table S1 solution units require reconciliation. No recovered solid REE product or independently demonstrated process economics is reported.

Sources & References

  1. vietmeier2026: Vietmeier, Beebe, Flett, Trun and Gulliver (2026). Bioleaching Rare Earth Elements from Abandoned Coal Mine Drainage as an Unconventional Feedstock for Biomining. Minerals 16(9):930, published 11 September 2026. DOI 10.3390/min16090930; Methods 2.1-2.5, Results 3.1-3.6, Figures 1-7 and Discussion. Real treatment solids, laboratory assays and qualified physiological interpretations.
    https://doi.org/10.3390/min16090930 (accessed 2026-10-11)
  2. vietmeier2026supp: Supplementary Materials for Vietmeier et al. (2026), Minerals 16(9):930. Publisher ZIP contains minerals-4280163-supplementary.pdf, four pages: Figures S1-S2 and Tables S1-S2. Table S1 provides 29 sample rows in ppb, including sterile controls and censored individual analytes; this is the same experiment as the main article, not independent replication.
    https://mdpi-res.com/d_attachment/minerals/minerals-16-00930/article_deploy/minerals-16-00930-s001.zip (accessed 2026-10-11)
  3. ncbi_mycoides: NCBI Taxonomy, Bacillus mycoides, species Taxonomy ID 1405; not a JR07 strain identifier.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1405&mode=info (accessed 2026-10-11)
  4. ncbi_pseudomycoides: NCBI Taxonomy, Bacillus pseudomycoides, species Taxonomy ID 64104; not a KB7 strain identifier.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=64104&lin=f&lvl=3&mode=Info (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T14:19:40Z codex (GPT-6; codex) CREATE Created a treatment-origin secondary-resource record from the complete primary article and supplement; retained sterile-control and feed-dependent counterevidence, analytical and mass-balance limits, and species-versus-strain identity distinctions without assigning criticality or industrial recovery.

Record source: data/records/coal-mine-drainage-treatment-solids.yaml