WARNV5Coulombic mass-balance is open on 9/12 sweep points (>5% closure error). Check substrate consumption + Q_measured.· Logan-group hygiene check; mass balance fundamentals
WARNV6Mean CE × OLR = 58.5 exceeds empirical Logan-group envelope (≤25). Mass transport limits CE at high loading; prediction may be optimistic.· Cheng & Logan 2011 — empirical envelope
Reproducing
ter Heijne A, Liu F, Weijden R, Weijma J, Buisman CJN, Hamelers HVM (2010) — Environmental Science & Technology
Copper recovery combined with electricity production in a microbial fuel cell
DOI: 10.1021/es100526g
Metric
Reported
Predicted
Δ
Band
COD removal
Cu²⁺ removal from catholyte (electrodeposited as metallic Cu on the cathode) over a single batch cycle starting from ~6.4 mM Cu²⁺. Maps to the `substrate` series as a proxy for metal-recovery percentage since the schema does not yet have a `metal_recovery_pct` seriesKey.
p. 4379, Table 2
84.0
%
85.0
%
+1.2%
green
Power density
peak power density during the simultaneous Cu²⁺ reduction + electricity generation cycle, ~6.4 mM initial Cu²⁺ catholyte, acetate-fed anode
p. 4379, Table 2 / §Results
430
mW/m²
492
mW/m²
+14.3%
green
Current density
steady-state cathodic current density during active copper electrodeposition phase
p. 4378, Fig. 3
1.60
A/m²
1.40
A/m²
-12.6%
green
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 (6 items)
BV MODEL CALIBRATION IS MFC-ONLY; the metal-electrowinning kinetics + deposit-morphology penalties live in `predictors/mmrc.ts` but the backtest harness does not yet route to that predictor. Expect amber/red bands on `substrate` (metal-recovery proxy).
The `substrate` seriesKey is being used as a proxy for Cu²⁺ recovery percentage. This is INCOMMENSURABLE with the COD-removal meaning of `substrate` elsewhere; extending the schema with a `metal_recovery_pct` key is the right fix.
The paper ran multiple initial-Cu²⁺ conditions (1.6, 3.2, 6.4 mM); we encode the 6.4 mM run as the canonical preset. At higher initial Cu²⁺, electrolysis-driven H₂ evolution starts competing with Cu²⁺ reduction below pH ~3, lowering Faradaic efficiency to Cu.
Catholyte pH ~3-4 is necessary to keep Cu²⁺ soluble; this acidity is incompatible with a biocathode (would kill biofilm) so the architecture requires the membrane to isolate the anode biofilm at near-neutral pH. The membrane is a critical component.
Cu²⁺ is a relatively easy metal to recover electrochemically (E° = +0.34 V vs SHE); harder targets like Ni²⁺ (E° = -0.25 V), Cd²⁺ (-0.40 V), or Cr(VI)→Cr(III) require additional applied potential and have much lower spontaneous recovery in an MFC configuration. The Cu case is the headline; the architecture does not generalize trivially to other metals.
The 84% removal figure is for a single batch cycle; the deposition-rate vs concentration relationship is sub-linear (mass-transport limitation as [Cu²⁺] depletes), so the LAST few percent take disproportionately long.