Agriculture Reference
In-Depth Information
Fig. 1.1
Daily peaks of Temperature and Methane produced during the active phase of a turning
windrow on-farm composting process
1.3.3
Keys for Successful Composting Processes
Controlling the composting process consists of two main operations: turning and
wetting, which could be combined, too. The goal of the turning and wetting pro-
cesses is not only to control the temperature of the composting process but also
the biomass hygienization. The aerobic process takes place in the core of the pile
while at the bottom of the heap the anaerobic process may start quickly after each
turning with an area around the core part, like a cylinder inside the pile, that is cold
and considered a buffer area. The turing operation exchanges cold air with the hot
core area in a way that the cold area is actively involved in the process while the
microbial activity in the core area, that is relatively cooler, slows down. During the
turning process a tyndallization-like process (Gould
2006
) may occur, which can
destroy pathogens, spores, and weeds' seeds without affecting composting micro-
bial communities. Hygienization during composting is not done only through high
temperature but also through the chemical compounds that are capable of pathogen
inactivation. However, hygienization might not be evenly effective throughout the
compost pile, the outer zones is usually cooler and dried than the center of the pile
preventing it from reaching the high temperature required for hygienization. The
turning process is seriously important as it turns the outer parts into inner ones; mix-
ing the outer zones with the hygiene materials favors beneficial microorganisms to
outcompete the harmful ones (Fuchs
2010
).
The composting temperature trend is also an indication of the process itself be-
side chemical and biological changes, as a matter of fact, the succession of microbi-
al communities is affected by composting temperature. Furthermore, the maximum
activity recorded for some enzymes such as cellulase, xylanase and protease were
manifested mainly during the active phase of the composting process (Goyal et al.
2005
).
