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2 High-Efficient Anaerobic Fermentation Technology of Organic …
production under the condition of hydrothermal hydrolysis of adding 40% of water
and being treated at 150 °C for 60 min. Compared with anaerobic fermentation
of solid and liquid phases of kitchen wastes, mixed and solid phases show higher
potentials for methane production. However, the optimal condition of hydrothermal
hydrolysis for mehtane prodution of solid wastes was to add 60% of water and treat
for 50 min at 80 °C. Under this condition, the required pre-treatment temperature
was lower than that of mixed phase and the required energy consumption was low,
while the obtained methane production was relatively high, so this condition was
more suitable for engineering application. In conclusion, phase separation of anaerobic fermentation of kitchen wastes can markedly improve utilization rate of kitchen
wastes and maximise the differentiated resourceful utilization of wastes.
2.2.2 Pre-treatment Technology of Wastes with High Content
of Lignocellulose
Agricultural activities, fruit and vegetable wholesale markets and flower markets
in villages and towns can produce a lot of organic wastes with high content of
lignocelluloses. Due to the lack of efficient pre-treatment technologies, it is difficult
for microorganisms to utilise these wastes, thereby leading to a low resourceful
utilization rate. Through the pre-treatment technologies with acid, alkali and enzyme,
this study improved bioavailability and energy conversion efficiency of wastes with
high content of lignocellulose by optimizing combinations.
2.2.2.1 Influences of Pre-treatment on Microstructure of Straws
The microstructures of straws before and after pre-treatment were observed by using a
scanning electron microscope (SEM) (Fig. 2.9). The results demonstrated that lignocellulose structures of straws after pre-treatment were damaged in different degrees.
Although the structure was still complete after acid pre-treatment, waxy structure
gradually disappeared and showed bubbles on the surface. After alkali pre-treatment,
the surface presented pores and porous structures and was uneven. Moreover, the surface was deeply corroded, so that internal microfibre was completely exposed. Obviously, acid and alkali pre-treatments significantly damage lignocellulose structure of
materials, which is favorable for microorganisms to utilize the materials.
Cellulase treatment damaged large area of fibre structure, resulting in serious
structural damages. Due to deep corrosion, the structure was decomposed into
fragments. Owing to cellulase can be specifically adsorbed on and thus decompose cellulose structure of materials, such that the contact area of microorganisms
increased, which was beneficial to the interaction of materials and microorganisms
and promoted the resourceful utilization of anaerobic fermentation.
2 High-Efficient Anaerobic Fermentation Technology of Organic …
production under the condition of hydrothermal hydrolysis of adding 40% of water
and being treated at 150 °C for 60 min. Compared with anaerobic fermentation
of solid and liquid phases of kitchen wastes, mixed and solid phases show higher
potentials for methane production. However, the optimal condition of hydrothermal
hydrolysis for mehtane prodution of solid wastes was to add 60% of water and treat
for 50 min at 80 °C. Under this condition, the required pre-treatment temperature
was lower than that of mixed phase and the required energy consumption was low,
while the obtained methane production was relatively high, so this condition was
more suitable for engineering application. In conclusion, phase separation of anaerobic fermentation of kitchen wastes can markedly improve utilization rate of kitchen
wastes and maximise the differentiated resourceful utilization of wastes.
2.2.2 Pre-treatment Technology of Wastes with High Content
of Lignocellulose
Agricultural activities, fruit and vegetable wholesale markets and flower markets
in villages and towns can produce a lot of organic wastes with high content of
lignocelluloses. Due to the lack of efficient pre-treatment technologies, it is difficult
for microorganisms to utilise these wastes, thereby leading to a low resourceful
utilization rate. Through the pre-treatment technologies with acid, alkali and enzyme,
this study improved bioavailability and energy conversion efficiency of wastes with
high content of lignocellulose by optimizing combinations.
2.2.2.1 Influences of Pre-treatment on Microstructure of Straws
The microstructures of straws before and after pre-treatment were observed by using a
scanning electron microscope (SEM) (Fig. 2.9). The results demonstrated that lignocellulose structures of straws after pre-treatment were damaged in different degrees.
Although the structure was still complete after acid pre-treatment, waxy structure
gradually disappeared and showed bubbles on the surface. After alkali pre-treatment,
the surface presented pores and porous structures and was uneven. Moreover, the surface was deeply corroded, so that internal microfibre was completely exposed. Obviously, acid and alkali pre-treatments significantly damage lignocellulose structure of
materials, which is favorable for microorganisms to utilize the materials.
Cellulase treatment damaged large area of fibre structure, resulting in serious
structural damages. Due to deep corrosion, the structure was decomposed into
fragments. Owing to cellulase can be specifically adsorbed on and thus decompose cellulose structure of materials, such that the contact area of microorganisms
increased, which was beneficial to the interaction of materials and microorganisms
and promoted the resourceful utilization of anaerobic fermentation.