Agriculture Reference
In-Depth Information
Fig. 3.1
Example show-
ing effect on temperature
when compost is inoculated
during the cool-down phase.
White-rot fungus was added
to the compost only in the
case represented by unfilled
circles. The unfilled squares,
lower in the figure, represent
the ambient air temperature.
(Data replotted from Hachi-
cha et al.
2012
)
present naturally in the environment, and due to rapid rates of reproduction under
suitable conditions, it is not always clear whether significant benefits can be achieved
by inoculation (Hubbe et al.
2010
). Thus it is notable that several recent studies
have shown significant increases in the rate of changes within compost files follow-
ing inoculation (Kausar et al.
2010
; Amira et al.
2011
; Parveen and Padmaja
2011
;
Wang et al.
2011
; Yang et al.
2011
; Hachicha et al.
2012
; Saha et al.
2012
). Saha
et al. (
2012
) demonstrated an innovative strategy in which straw biomass was pre-
composted with addition of white-rot fungus, followed by combination with poultry
droppings in a second stage of composting. Superior overall results were obtained.
Some interesting evidence, supporting the ability of inoculation to promote met-
abolic activity as well as self-heating during composting (Hachicha et al.
2012
)
(Fig.
3.1
). Olive mill wastewater sludge was mixed with spent coffee grounds and
poultry manure. Two matching piles were prepared. On day 106 of composting
one of the two piles was treated with white-rot fungus. As shown, the inoculation
resulted in significantly higher temperatures following treatment. Such an increase
in temperature can be tentatively attributed to increased metabolism due to the en-
zymatic processes.
3.2.1.5
Enzyme Addition
Enzymes can be regarded as being the tools by which bacteria and fungi bring about
chemical changes during composting, changes that can account for the improve-
ments noted in the previous section. It follows that, as a possible alternative to in-
oculating a compostable mixture with bacteria or fungi, it is possible to just add
enzymes directly. Thus, Feng et al. (
2011
) showed that addition of ligninolytic en-
zymes hastened the degradation of lignin, in comparison to hemicellulose. The enzy-
matic treatment not only decreased the time required for composting, but it also gave
rise to higher temperatures during composting and enhanced the populations of biota
taking part in the decomposition processes. Innovative work by Zhao et al. (
2012
)
