3.1 Overview
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3.1.2 Influencing Factors of Composting Process
3.1.2.1 Organic Matters
The content of organic matters influences the temperature of windrows and ventilation and oxygen supply. At extremely low content of organic matters, the heat
generated due to decomposition is insufficient to promote and sustain proliferation
of thermophilic bacteria during fermentation. Therefore, the temperature of compost
piles is hard to reach the high-temperature period, which influences the sanitary and
non-hazardous effect of fermentation. Moreover, extremely low content of organic
matters can influence the fertilizer efficiency and utilization value of fermentation
products. However, under an extremely high content of organic matters, it is necessary to provide a great oxygen supply, which practically brings difficulties for oxygen
supply during the turning. It is likely to result in partially anaerobic condition due to
lacking of oxygen supply. The moderate content of organic matters is in the range
of 20–80%.
3.1.2.2 C/N Ratio
C/N ratio is one of important parameters for investigating the composition of compost
mixture. If the C/N ratio is too high, the temperature of compost piles likely fails to
rise; otherwise, the compost probably emits malodorous gas. The initial C/N ratio
of the compost mixture is supposed to be ranged from 25:1 to 40:1, and even 50:1.
However, different materials made of wood fibres show a great difference in density,
particle size and lignin content and therefore the specific range of initial C/N ratio is
hard to define. With the increase of C/N ratio, the fermenting time relatively prolongs.
When the C/N ratio of the raw materials is 20, 30–50, and 78, the corresponding
required fermenting time is about 9–12, 10–19 and 21 days, respectively. However,
when the C/N ratio is larger than 80:1, fermentation is difficult to appear. The C/N
ratio decreases during the composting process and generally maintains at (10–20):1
in the maturation stage. The change of C/N ratio during maturation and fermentation
of materials can be considered as a criterion for maturation of compost products,
bringing favorable fertilizer efficiency during agricultural utilization.
3.1.2.3 Moisture Content
Moisture is crucial for the composting process, which can promote degradation of
substrates by moving active microorganisms and offer a favorable condition for nitrogen fixation. Whether moisture is proper directly influences the fermenting speed and
maturation. A high humidity can block small pores and further restricts the transport
of oxygen, thus forming anaerobic condition to release odorous gas. Therefore, the
65
3.1.2 Influencing Factors of Composting Process
3.1.2.1 Organic Matters
The content of organic matters influences the temperature of windrows and ventilation and oxygen supply. At extremely low content of organic matters, the heat
generated due to decomposition is insufficient to promote and sustain proliferation
of thermophilic bacteria during fermentation. Therefore, the temperature of compost
piles is hard to reach the high-temperature period, which influences the sanitary and
non-hazardous effect of fermentation. Moreover, extremely low content of organic
matters can influence the fertilizer efficiency and utilization value of fermentation
products. However, under an extremely high content of organic matters, it is necessary to provide a great oxygen supply, which practically brings difficulties for oxygen
supply during the turning. It is likely to result in partially anaerobic condition due to
lacking of oxygen supply. The moderate content of organic matters is in the range
of 20–80%.
3.1.2.2 C/N Ratio
C/N ratio is one of important parameters for investigating the composition of compost
mixture. If the C/N ratio is too high, the temperature of compost piles likely fails to
rise; otherwise, the compost probably emits malodorous gas. The initial C/N ratio
of the compost mixture is supposed to be ranged from 25:1 to 40:1, and even 50:1.
However, different materials made of wood fibres show a great difference in density,
particle size and lignin content and therefore the specific range of initial C/N ratio is
hard to define. With the increase of C/N ratio, the fermenting time relatively prolongs.
When the C/N ratio of the raw materials is 20, 30–50, and 78, the corresponding
required fermenting time is about 9–12, 10–19 and 21 days, respectively. However,
when the C/N ratio is larger than 80:1, fermentation is difficult to appear. The C/N
ratio decreases during the composting process and generally maintains at (10–20):1
in the maturation stage. The change of C/N ratio during maturation and fermentation
of materials can be considered as a criterion for maturation of compost products,
bringing favorable fertilizer efficiency during agricultural utilization.
3.1.2.3 Moisture Content
Moisture is crucial for the composting process, which can promote degradation of
substrates by moving active microorganisms and offer a favorable condition for nitrogen fixation. Whether moisture is proper directly influences the fermenting speed and
maturation. A high humidity can block small pores and further restricts the transport
of oxygen, thus forming anaerobic condition to release odorous gas. Therefore, the