water film on the surface of substrate changes with different reaction
unit, which lead to different water environment to microorganism.
For example, a rice particle has a high content of starch
and lack of protein, but a pork particle may have a high content
of protein and fat and lack of starch. Accordingly, the composition
of the chemical and physical properties of water film on the surface
of rice particle and pork particle has a great difference. In TSC, the
only driving force for organic matters ‘trading’ between two kinds
of food waste particles is diffusion. So the rate of organic matter
exchange is very slow. As a result, the static environment has a
low buffering capacity, which may lead to emergence of extreme
environment inhabiting microbial activity. However, the extreme
environment can’t appear in DHAF due to water exchange brought
by collision and friction between different food waste bits. The
water exchange can mix two or more different water films with
the fastest speed to avoid the emergence of unbalanced distribution
of organic matters. The strong buffering capacity brought by
water exchange can sustain a moderate water environment for
microorganisms to survival in DHAF.
In conclusion, the relationships between microbial activity and
aeration, friction, collision can be summarized for three aspects:
(1) strong oxygen transfer capacity, (2) great reaction surface area,
(3) strong buffering capacity. With these advantages, food waste
can be rapidly degraded in DHAF process.