52
2 High-Efficient Anaerobic Fermentation Technology of Organic …
archaeal proteins. Eventually, methane was produced due to the effects of methylcoenzyme M reductase. The results revealed that numerous proteins of archaea and
bacteria participated in the production of methane by using the reduction pathway
of CO 2 , mainly including bacteria of Azotobacter and archaea of Methanoculleus,
Methanosarcina, Methanocaldococcus and Methanothermobacter (Jia et al. 2017d).
2.3.4 Dry Anaerobic Fermentation Technology of Livestock
Manure
In recent years, livestock and poultry breeding industries in villages and towns in
China have changed from the traditional courtyard-type free breeding with small
quantities to field centralized-type with large quantities. However, peasant households are still the unit of the main breeding subjects and non-point source pollution
is serious. These livestock and poultry breeding industries are small and highly decentralized, have mixed compositions of excrements of livestock and poultry and significant regional differences. Aiming at this, key manageable techniques and equipment
of low pollution, low cost, and low maintenance requirement for dry anaerobic fermentation of excrements of livestock and poultry were developed. The purpose is to
improve energy-fertilizer integrated utilization of wastes in decentralized breeding.
2.3.4.1 Biogas Production Performance
Dry anaerobic fermentation is an anaerobic fermentation technology in which the
concentration of TS in the fermentation liquid exceeds 20%. Due to too high TS concentration, continuously or semi-continuously feeding is difficult and the bulk feeding
is adopted in most situations (Fig. 2.27). Cow dung was used as research object in
which anaerobic digested sludge was inoculated (Figs. 2.28, 2.29 and 2.30). Based
on this, this study investigated biogas production performances of dry anaerobic fermentation of excrements of livestock and poultry at the fermentation temperature of
35 ± 2 °C when the TS concentration ranged from 25 to 30%. Moreover, the key
technology for energy-saving and dry anaerobic fermentation of excrements of livestock and poultry was developed. The research showed that unit biogas production
in the early stage of dry anaerobic fermentation was low (25 L/d) and then gradually
increased after being performed for 3 d. After 8 d, the biogas production reached
50 L/d, while it stabilized at the yield more than 50 L/d after continuous operation for
43 d and the volumetric biogas production rate reached 1.5–2 m
3 /m
3 . The energysaving and dry anaerobic fermentation technology of excrements of livestock and
poultry shows characteristics of high solid content and small amount of water. In
comparison with the traditional anaerobic fermentation, it significantly reduces the
volume of materials participating in reaction and investment, saves more than 30%
of energy consumption for operation and has no secondary pollution.
2 High-Efficient Anaerobic Fermentation Technology of Organic …
archaeal proteins. Eventually, methane was produced due to the effects of methylcoenzyme M reductase. The results revealed that numerous proteins of archaea and
bacteria participated in the production of methane by using the reduction pathway
of CO 2 , mainly including bacteria of Azotobacter and archaea of Methanoculleus,
Methanosarcina, Methanocaldococcus and Methanothermobacter (Jia et al. 2017d).
2.3.4 Dry Anaerobic Fermentation Technology of Livestock
Manure
In recent years, livestock and poultry breeding industries in villages and towns in
China have changed from the traditional courtyard-type free breeding with small
quantities to field centralized-type with large quantities. However, peasant households are still the unit of the main breeding subjects and non-point source pollution
is serious. These livestock and poultry breeding industries are small and highly decentralized, have mixed compositions of excrements of livestock and poultry and significant regional differences. Aiming at this, key manageable techniques and equipment
of low pollution, low cost, and low maintenance requirement for dry anaerobic fermentation of excrements of livestock and poultry were developed. The purpose is to
improve energy-fertilizer integrated utilization of wastes in decentralized breeding.
2.3.4.1 Biogas Production Performance
Dry anaerobic fermentation is an anaerobic fermentation technology in which the
concentration of TS in the fermentation liquid exceeds 20%. Due to too high TS concentration, continuously or semi-continuously feeding is difficult and the bulk feeding
is adopted in most situations (Fig. 2.27). Cow dung was used as research object in
which anaerobic digested sludge was inoculated (Figs. 2.28, 2.29 and 2.30). Based
on this, this study investigated biogas production performances of dry anaerobic fermentation of excrements of livestock and poultry at the fermentation temperature of
35 ± 2 °C when the TS concentration ranged from 25 to 30%. Moreover, the key
technology for energy-saving and dry anaerobic fermentation of excrements of livestock and poultry was developed. The research showed that unit biogas production
in the early stage of dry anaerobic fermentation was low (25 L/d) and then gradually
increased after being performed for 3 d. After 8 d, the biogas production reached
50 L/d, while it stabilized at the yield more than 50 L/d after continuous operation for
43 d and the volumetric biogas production rate reached 1.5–2 m
3 /m
3 . The energysaving and dry anaerobic fermentation technology of excrements of livestock and
poultry shows characteristics of high solid content and small amount of water. In
comparison with the traditional anaerobic fermentation, it significantly reduces the
volume of materials participating in reaction and investment, saves more than 30%
of energy consumption for operation and has no secondary pollution.