Biogas analyses were conducted on a Shimadzu GC-17A and a
Shimadzu GC-8A with TCD detectors and a Haysep Q 80/100 column
with UHP helium carrier gas at 30 mL/min. Samples and
standards were manually injected using a 1 mL gas tight syringe.
Two methods adapted from Souza et al. (2011) were used to
determine dissolved methane concentrations. In 2013, the ABR
effluent was collected directly into a 60 mL serum bottle and
immediately sealed with a septum and aluminum cap. The serum
bottlewas shaken and was stored at 4 C until the next day, when it
was brought to room temperature. In 2014, the ABR effluent was
collected directly into a 250 mL serum bottle to which 1.18 g BESA
had been added, and immediately sealed with a septum and
aluminum cap. The serum bottle was shaken and stored at room
temperature until the following day. In both 2013 and 2014 the
headspace volume of the serum bottle was determined by weight.
After equilibration for 24-h, the headspace of the serum bottle was
analyzed for methane content, and compared to the expected
methane content based upon the original ABR headspace concentration
and Henry's Constant. Data is presented as an average
typically followed by the standard deviation (±SD).