2.2. Reactor operation and experimental design
Two different sized fermenters were operated in this study.
Small scale fermentations used working volume of 0.8 L glass bottles
fitted with an air-lock, and 40 mL mixed culture was added to
the reactors at the start of operation. The reactors were operated as
sequencing batch reactors, magnetically stirred (500 rpm) and
temperature controlled at 35 C with a heated water-jacket.
Weighted certain amount of PPW sample (according to the
experimental design) from the Nampa plant and gelatinized at
100 C for 30 min and cooled down prior to use.
A statistical design of experiments (DOE) approach using central
composite design (CCD)/response surface methodology (RSM)
was employed in this part of the study to further evaluate and
establish potential relationships between LA production (concentration
and yield) and the two influencing factors (SRT and SC).