Digestion of other materials in the food waste did not produce sig-
nificant amounts of gas. For maximum digestion of food waste to
produce a digest with minimal environmental impact a long incu-
bation time of about 25 days is needed but for ethanol production a
short incubation time is desirable. A two stage process seems fea-
sible: distillation after a 7 day incubation to recover ethanol as a
saleable product followed by a longer step to further biologically
degrade the distillery waste (stillage) as much as possible before
composting (Blonskaja et al., 2003). The second stage could involve
methanogen digestion or digestion using physiologically versatile
rhodopseudomonads (Mekjinda and Ritchie, 2014).