78
3 Bio-augmented Composting of Organic Wastes in Villages and Towns
relative proportions of bacteria generating key enzymes. Thus, it avoids inhibition
on the acidification in the early stage of composting of kitchen wastes.
In the composting process, propionic acid mainly stemmed from succinic acid
generated from the TCA cycle. Afterwards, propionic acid was transformed into
succinic acid through 2-methyl-citrate to be subjected to TCA cycle and then utilised
(Fig. 3.9). In the research, two key enzymes A and B were mainly detected in which
enzyme A refers to acetyl-coenzyme A synthetase, which was produced by Bacillus
spp., Yersinia spp. and Bradyrhizobium spp. in the inoculated group. However, no
enzyme A was found in the alkalified and CK groups. Enzyme B refers to aconitate hydratase, which was generated by Staphylococcus spp., Legionella spp., Pseudomonas spp., Deinococcus spp., Streptococcus spp. and Rickettsia spp. in the inoculated group. Moreover, enzyme B was generated by Legionella spp., Pseudomonas
spp., Escherichia spp., Corynebacterium spp., Rickettsia spp. and Mycobacterium
spp. in the alkalified group while it only came from Pseudomonas spp. in the CK
group. The biochemical reactions under the catalytic effect of enzymes A and B both
appeared at the propionic degradation direction. Compared with the control group,
the diversity of microorganisms generating enzyme A in the inoculated group A
greatly rose while that in the alkalified group insignificantly changed. The diversities of microorganisms producing enzyme B all significantly increased. Inoculating
acidification-resistant complex microbial inoculants can greatly improve the diversity of strains generating the two key enzymes in metabolic pathways of propionic
acid.
The proportion (2.21%) of enzyme A in the inoculated group was significantly
larger than those in the other two groups. In terms of proportion of enzyme B,
the three composting treatments were displayed in a descending order as alkalified group (7.69%), inoculated group (5.52%) and CK group (1.89%). Inoculating
acidification-resistant complex microbial inoculants and adding chemical buffers
both can increase the proportion of enzymes which can catalyse the biochemical
reaction at the propionic acid degradation direction.
3.3.3 Composting Technology for Humification of Mixed
Materials
3.3.3.1 Experimental Design and Implementation
For the urgent demand for resourceful utilization of agricultural wastes, the composting technology for oriented humification of mixed materials of biogas residue
and excrements of livestocks (pig manure and chicken manure) was explored (Table
3.4). On this basis, the technical control of mixed composts with different proportions, characteristics of DOM spectroscopy and evolutionary change law of diversity
of microorganisms were separately analyzed. In this way, the optimal technological
parameters of composting for oriented humification of agricultural mixed materials
3 Bio-augmented Composting of Organic Wastes in Villages and Towns
relative proportions of bacteria generating key enzymes. Thus, it avoids inhibition
on the acidification in the early stage of composting of kitchen wastes.
In the composting process, propionic acid mainly stemmed from succinic acid
generated from the TCA cycle. Afterwards, propionic acid was transformed into
succinic acid through 2-methyl-citrate to be subjected to TCA cycle and then utilised
(Fig. 3.9). In the research, two key enzymes A and B were mainly detected in which
enzyme A refers to acetyl-coenzyme A synthetase, which was produced by Bacillus
spp., Yersinia spp. and Bradyrhizobium spp. in the inoculated group. However, no
enzyme A was found in the alkalified and CK groups. Enzyme B refers to aconitate hydratase, which was generated by Staphylococcus spp., Legionella spp., Pseudomonas spp., Deinococcus spp., Streptococcus spp. and Rickettsia spp. in the inoculated group. Moreover, enzyme B was generated by Legionella spp., Pseudomonas
spp., Escherichia spp., Corynebacterium spp., Rickettsia spp. and Mycobacterium
spp. in the alkalified group while it only came from Pseudomonas spp. in the CK
group. The biochemical reactions under the catalytic effect of enzymes A and B both
appeared at the propionic degradation direction. Compared with the control group,
the diversity of microorganisms generating enzyme A in the inoculated group A
greatly rose while that in the alkalified group insignificantly changed. The diversities of microorganisms producing enzyme B all significantly increased. Inoculating
acidification-resistant complex microbial inoculants can greatly improve the diversity of strains generating the two key enzymes in metabolic pathways of propionic
acid.
The proportion (2.21%) of enzyme A in the inoculated group was significantly
larger than those in the other two groups. In terms of proportion of enzyme B,
the three composting treatments were displayed in a descending order as alkalified group (7.69%), inoculated group (5.52%) and CK group (1.89%). Inoculating
acidification-resistant complex microbial inoculants and adding chemical buffers
both can increase the proportion of enzymes which can catalyse the biochemical
reaction at the propionic acid degradation direction.
3.3.3 Composting Technology for Humification of Mixed
Materials
3.3.3.1 Experimental Design and Implementation
For the urgent demand for resourceful utilization of agricultural wastes, the composting technology for oriented humification of mixed materials of biogas residue
and excrements of livestocks (pig manure and chicken manure) was explored (Table
3.4). On this basis, the technical control of mixed composts with different proportions, characteristics of DOM spectroscopy and evolutionary change law of diversity
of microorganisms were separately analyzed. In this way, the optimal technological
parameters of composting for oriented humification of agricultural mixed materials