Marshall CW, Ross DE, Fichot EB, Norman RS, May HD (2013) — Environmental Science & Technology
Long-term operation of microbial electrosynthesis systems improves acetate production by autotrophic microbiomes
DOI: 10.1021/es400341b
Metric
Reported
Predicted
Δ
Band
Coulombic efficiency
mean Faradaic efficiency to acetate across long-term steady-state operation, mixed autotrophic community, cathode poised at -590 mV vs SHE
p. 6025, §Results
84.0
%
84.0
%
0.0%
green
Current density
steady-state cathodic current density at -590 mV vs SHE, mixed autotrophic biocathode; ~10× higher than the Nevin 2010 pure-culture baseline due to higher cathode biofilm coverage
p. 6025, Fig. 1 + text
0.50
A/m²
0.00
A/m²
-99.2%
red
Δ-bands per Logan & Regan 2006 lab-to-lab reproducibility envelope: green ≤±25%, amber ±25–50%, red >±50%. Predictions from Butler-Volmer + Ohmic + Tafel closure calibrated against the Logan corpus (regression-tested in butler-volmer-calibration.test.ts).
What we don't know about this paper (5 items)
BV MODEL CALIBRATION IS MFC-ONLY — same caveat as the Nevin 2010 preset. The backtest harness will produce red bands here because MES kinetics are not yet wired into `buildSweep`. Honest signal, not a regression.
Acetate productivity (~17 mmol/L/day, the canonical headline number) is not in the standard backtest seriesKey set; we report Faradaic efficiency (`coulombic`) and current density (`current_areal`) which ARE in the schema. Extending the seriesKey set to include `acetate_productivity_mmol_L_day` is tracked as a future enhancement.
Reported current density (~0.5 A/m²) is derived from the paper's steady-state current (~4-5 mA over ~90 cm² nominal cathode geometric area). The paper sometimes reports per-unit-mass rather than per-area; we use the geometric-area convention to align with the MFC presets.
Mixed-community MES generally shows lower Faradaic efficiency than pure-culture S. ovata due to methanogen contamination; the 84% FE_acetate here is the paper's headline long-term-stable value AFTER initial methanogen washout. Short-term FE values are lower.
Several biofilm and seeding details are paper-specific (brewery-pretreatment of the seed inoculum, multi-month enrichment) and cannot be portably reproduced in a fresh MES setup. Treat the headline numbers as the OPTIMIZED steady-state outcome, not the startup baseline.