A test series of three replicates was carried
out in sealed glass bottles (500 ml) for the crude glycerol
co-digested with digestate, which was the liquid material leftover
from the anaerobic treatment of sewage sludge at the waste water
treatment plant (WWTP), and was compared to a reference series
of digestate alone in three replicates. All bottles were loaded with
a 2:1 VS (w/w) digestate to substrate ratio to a total of 400 g and
placed in a 37 C water bath throughout the experiment. A 3M
NaOH solution was used for scrubbing out all CO2 from the produced
biogas. Once the gas passed through the NaOH scrubbers,
the remaining methane entered a calibrated flow cell which
recorded the gas production in real time by sending data to the
AMPTS software. Prior to the start of the analysis, the system is
flushed with nitrogen. The BMP reactors were operated for 30 days.
From these experiments the methane production from the glycerol
waste and digestate from the WWTP was obtained