An argument that is often presented to support the
use of AT processes is a faster specific transformation
rate of organic material at high temperature, which
should mean smaller bioreactors (Kambhu and
Andrews, 1969; Yi et al., 2003). However, experiments
have not always supported this hypothesis. For
example, Couillard and Zhu (1993) reported a higher
maximum specific utilization rate of substrate (slaughterhouse
effluent) at 58 8C whereas LaPara et al.
(2000) found no significant difference between 25 and
65 8C with a synthetic wastewater. With pig manure,
Hissett et al. (1982) made respirometric measurements
using bacterial consortia adapted to temperatures
between 5 and 50 8C. They reported the results as
an Arrhenius plot that showed a typical straight line
with a positive slope between 5 and 40 8C; however,
after that, the slope become negative and an optimum
appears around 45 8C