Ics 2100

Water
sampling and geochemical
measurements were performed before initiating the experiment and subsequently
at time intervals of 30 min to 30 h for up to 200 h. Measurements
of pH and redox potential (Eh) were performed in conjunction with
water sampling. The pH electrode (VWR Symphony) was calibrated to
NIST-traceable 4, 7, and 10 buffer solutions. The electrode performance
was regularly checked, and recalibration was performed as necessary.
The performance of the redox electrode (Accumet) was verified using
ORP calibration solution (Orion). The water samples were collected
in PE syringes, passed through 0.2 μm polyethersulfone (PES)
syringe filter membranes, stored in high-density PE (HDPE) bottles,
and refrigerated until analysis. Inorganic anions (NO₃^–, NO₂^–, and SO₄^2–) were quantified by ion chromatography (ICS2100;
Dionex Corporation) on nonacidified samples. Total Se was quantified
by inductively coupled plasma–optical emission spectroscopy
(SPECTROBLUE SOP, SPECTRO Analytical Instruments GmbH, Germany) on
samples acidified to pH < 2 with trace-metal-grade nitric acid
(Thermo Fisher Scientific). Spectrophotometric (DR2800; HACH Chemical
Co.) determination of total ammonium (NH₄⁺)
concentrations (by the Nessler method) was performed for samples from
B3 and B4, which initially contained NO₃^–.

Samples for sulfide
analysis were diluted in a solution containing 1 mM NaOH and 0.1 mM
zinc acetate for sulfide fixation. Dissolved sulfide was analyzed
using a Hach Lange kit LCK-653 (Hach, Germany) which is based on the
reaction of sulfide with dimethyl-p-phenylenediamine
and ferric chloride. The absorption was measured in a spectrophotometer
DR3900 (Hach, Germany). Sulfate was measured by ion chromatography
on a Dionex ICS 2100 equipped with an IonPac AS19 column (4 ×
2550 mm) (Dionex, USA) eluted at 30 °C with potassium hydroxide
(5 mM, 1 mL·min^–1).
The headspace composition
of the batch bottles was analyzed with gas chromatography (Shimadzu
GC-2010 series) equipped with two columns in parallel, a Porabond
Q (50 m × 0.53 mm) and Molsieve 5A (25 m × 0.53 mm) for
nitrogen, oxygen, and methane. Hydrogen analysis was carried out with
a Hewlett Packard GC-5890 series equipped with a CP-Molsieve 5A column
(30 m × 0.53 mm). Acetate, propionate, butyrate, methanol, and
ethanol were measured with a GC system Agilent 7890B equipped with
an HP-FFAP column (25 m × 0.32 mm). Formate was analyzed with
an HPLC system Ultimate 3000 (Thermo Fisher, USA) equipped with an
Alltech OA-1000 column (300 mm × 6.5 mm) (Hichrom, UK) eluted
at 60 °C with sulfuric acid (1.25 mM, 0.6 mL·min^–1).

The concentration of CO₂ sparged into the reactor was
confirmed using GasLab software and a cozIR wide-range 0–20%
CO₂ sensor (CM-0123, Gas Sensing Solutions Ltd., Glasgow,
UK).
Sulfate concentrations accumulated, from the sparged simulated
flue gases, during the 50 h bioreactor experiment were quantified
using SulfaVer 4 Method 8051 (HACH, Loveland, CO, USA) with a HACH
DR6000 UV–Vis spectrophotometer (see Figures S3 & S4 in
the Supporting Information).
During
the cultured simulated flue gas trials, sulfate, phosphate,
and nitrate concentrations were measured in daily samples of the culture
medium (0.2 μm filtered) using an ion chromatograph (Thermo
Fisher ICS-2100) equipped with a Dionex IonPac AS18 column. Combined
Seven Anion Standard II (Dionex, Sunnyvale, CA) was used to calibrate
the instrument.