(10-25 C), mesophilic (30-40 C), and thermophilic
(50-60 C) temperatures, and can occur under
hydraulic flow regimes being BR (batch reactor), SBR
(sequencing batch reactor) or CFR (continuous flow
reactors). Continuous flow bioreactors are operated as
a PER (plug flow reactor) or as CSTR (completely
stirred tank reactor). Both CFR types are operated at
constant volume, which means that as substrate is fed
into the bioreactor an equivalent volume of bioreactor
content is removed at the same flow rate. Continuous
flow operation requires more sophisticated equipment
and is more prone to biomass washout and bioreactor
failure than sequencing batch reactors [2]. In anaerobic
biological processes, proper C/N (carbon to nitrogen)
ratio is important for efficient digestion. The optimal
C/N ratio for the microbes is 15 to 30 according to
Haug [5], who claims that a decreased ratio is no
problem for the composting process but leads to losses
of excess nitrogen via ammonia volatilization. Others
claim the optimal range for bacterial decomposition to
be C/N ratio 20 to 40. A balance nutrient availability
for the microorganisms is important for a high
decomposition rate. Literature review reported that the
proper C/N ratio for anaerobic digestion was 25 to 30
from lignocellulosic materials (C/N ratio 35 to 118)
mixed with waste with high nitrogen carbon combined
with lignocellulosic material with carbon content can
provide a versatile mixture for anaerobic processes that
could be optimized for each organic waste source to
maximize the desired product. As other research
reported biohydrogen production could be enhanced by
co-digestion of food waste and sewage sludge due to
the balanced C/N ratio [6]. However, the desired C/N
ratio for efficient hydrogen fornmation by co-digestion
of Napier Pak Chong I and animal dung has not been
reported in literature.
loading rate [4]. AD can be completed at psychrophilic