WARNV6Mean CE × OLR = 126.0 exceeds empirical Logan-group envelope (≤25). Mass transport limits CE at high loading; prediction may be optimistic.· Cheng & Logan 2011 — empirical envelope
Reproducing
Kim BH, Chang IS, Gil GC, Park HS, Kim HJ (2003) — Biotechnology Letters
Novel BOD (biochemical oxygen demand) sensor using mediator-less microbial fuel cell
DOI: 10.1023/A:1022891231369
Metric
Reported
Predicted
Δ
Band
Current density
steady-state sensor current density at ~100 mg/L BOD analyte feed (mid-range of the calibration), 30°C, ferricyanide catholyte. The sensor headline number is the LINEAR-RANGE limit, not the peak current; we encode the mid-range current as the most representative single-point comparison.
p. 542, Fig. 1 + Table 1
0.50
A/m²
0.39
A/m²
-21.2%
green
Coulombic efficiency
apparent coulombic efficiency in the sensor configuration; lower than analytical-MFC CE because the sensor is operated FAR from peak power to stay in the linear-response regime
p. 542, §Results
35.0
%
35.0
%
0.0%
green
Sensor K_M
Michaelis-Menten K_M for whole-cell BOD biofilm — analyte concentration at i_max/2. Sets the upper end of the linear dynamic range. Paper reports linear current-vs-BOD across ~0-100 mg/L BOD; the upper limit ≈ K_M for a Hill-saturating sensor (h ≈ 1.2).
p. 542, Fig. 2 + Table 1
100
mg/L BOD
100
mg/L BOD
0.0%
green
Sensor LOD
lower limit of detection — paper notes instrument lower bound at ~3-5 mg/L BOD with the synthetic-wastewater pure-culture-like biofilm (clean baseline, low noise floor). For BOD biosensors operating in low-noise conditions, LOD ≈ baseline microbial current + 3σ per IUPAC.
p. 542, §Results (instrument lower bound)
5.00
mg/L BOD
5.00
mg/L BOD
0.0%
green
Dynamic range
log10(K_M / LOD) = log10(100 / 5) ≈ 1.3 decades. Derived from the paper's linear-range bounds (5 mg/L to 100 mg/L BOD).
p. 542, derived from Fig. 2 endpoints
1.30
decades
1.30
decades
0.0%
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)
Wave 3 (2026-05-22) — LOD vs K_M are now reported as SEPARATE series (substrate_lod_mg_per_L and substrate_k_m_mg_per_L). Previously both were squeezed into one generic `substrate` reportedResult, which made the Tardy-2020 holdout (LOD=20 mg/L) un-comparable to this preset (linear-range upper=100 mg/L) — they are different physical quantities (noise-floor lower bound vs Michaelis-Menten saturation upper bound). The +400% Wave-2 T9 false-failure was a category error, not a real model gap.
BOD vs COD: the paper reports BOD (5-day biological oxygen demand), the harness uses COD (chemical oxygen demand). For typical wastewater, BOD ≈ 0.6-0.7 × COD. We encode the analyte at ~150 mg/L COD to correspond to ~100 mg/L BOD; the conversion factor varies with feed composition.
Sensor response time (~30-60 min) and drift (~5-10% per week) are not yet in the backtest seriesKey set. These are CRITICAL for sensor applications; the next physics extension (Wave 4) should add `response_time_sec` and `drift_per_week_pct` keys.
Ferricyanide catholyte is research-only — toxic and unsustainable for commercial sensors. Modern commercial BOD biosensors use air cathodes with carefully-controlled cathode hydrodynamics; the calibration would be different.
The 2003 paper used artificial wastewater (defined-composition feed). Real-wastewater BOD sensors require frequent re-calibration because the feed composition varies and the current-vs-BOD slope shifts with the BOD-to-COD ratio of the actual stream.
LOD reportedValue=5 mg/L BOD corresponds to the paper's "instrument lower bound" with a clean synthetic-wastewater biofilm. Real-wastewater inoculum has noisier baseline current and ~4× higher LOD (e.g., Tardy 2020 reports 20 mg/L); the biofilmStabilityFactor knob in buildMBESSensorSweep captures this.