Basic Biological Processes
Fats
Proteins
Carbohydrates
1
_JoG~
l .
Ketoac1ds
Long-chain
'
fatty acids
.._.. Pyruvic
~
~~acid ~
acticacitz
~ Aldehydes
.0.
Butyric aci d~
·ro· n·acl,
Alcohols
Acetic acid
Formic acid
Fig 3.18 The acid step, anaerobic processes, in a simplified representation /27/.
External produclion (from acid step)
Fig 3.19 Methane step, anaerobic processes, in a simplified representation /27/.
3.7.1 Reactions, anaerobic processes
Compared with methane production, acid production is a quick process. As an example
of the complicated removals, the result of a combined propionic acid fermentation and
a mixed acid fermentation is given in Expression (3.39). These processes are carried out
by a larger collective group of bacteria and the result is as follows:
5 glucose --+ 2 lactic acid + 4 propionic acid +
3 acetic acid + ethanol + 4 carbon dioxide+ 2 hydrogen+ water
(3.39)
or
101