80
3 Bio-augmented Composting of Organic Wastes in Villages and Towns
0
50
100
150
200
250
300
350
25
30
35
40
45
50
55
60
65
70
t/h
T1
T2
T3
T4
Fig. 3.10 Changes of temperature during composting
The pH values of different experimental groups all rose at first, then declined
and finally increased. The pH value steadily varied and fluctuated at around 8.0, and
finally reached the alkalescent standard of mature compost. At the high-temperature
period of composting, organics were rapidly decomposed to further generate micromolecular organic acids, which led to the reduction of pH value. At the end of
composting, micromolecular organic acids were consumed out and the remained
macromolecular humic substances caused the slight growth of pH value, so that the
system appeared as alkalescence (Fig. 3.11).
Some scholars suggested that a high content of NH 4
+ -N represents instability of
compost and put forward that the NH 4
+ -N content of compost products of municipal
wastes should be lower than 0.04%. After composting for 30 days, in terms of NH 4
+ -
N content, the composting treatments were displayed in an ascending order as T3,
T2, T1 and T4, in which the NH 4
+ -N contents of T3, T2 and T1 were 0.25 mg/g,
0.34 mg/g and 0.35 mg/g, respectively, satisfying the standard of maturation of
compost. By contrast, T4 failed to reach the maturation standard in terms of NH 4
+ -N
content (Fig. 3.12).
3.3.3.2 Evolutionary Change Law of Bacterial Communities During
the Composting of Mixed Materials
The biodiversity index is an important indicator for effectively characterizing richness and distribution uniformity of species in ecological environment. By counting the number of bands in DGGE atlas and calculating Shannon-Weaver index,
the bacterial diversity during composting was analyzed (Fig. 3.13). The number of
3 Bio-augmented Composting of Organic Wastes in Villages and Towns
0
50
100
150
200
250
300
350
25
30
35
40
45
50
55
60
65
70
t/h
T1
T2
T3
T4
Fig. 3.10 Changes of temperature during composting
The pH values of different experimental groups all rose at first, then declined
and finally increased. The pH value steadily varied and fluctuated at around 8.0, and
finally reached the alkalescent standard of mature compost. At the high-temperature
period of composting, organics were rapidly decomposed to further generate micromolecular organic acids, which led to the reduction of pH value. At the end of
composting, micromolecular organic acids were consumed out and the remained
macromolecular humic substances caused the slight growth of pH value, so that the
system appeared as alkalescence (Fig. 3.11).
Some scholars suggested that a high content of NH 4
+ -N represents instability of
compost and put forward that the NH 4
+ -N content of compost products of municipal
wastes should be lower than 0.04%. After composting for 30 days, in terms of NH 4
+ -
N content, the composting treatments were displayed in an ascending order as T3,
T2, T1 and T4, in which the NH 4
+ -N contents of T3, T2 and T1 were 0.25 mg/g,
0.34 mg/g and 0.35 mg/g, respectively, satisfying the standard of maturation of
compost. By contrast, T4 failed to reach the maturation standard in terms of NH 4
+ -N
content (Fig. 3.12).
3.3.3.2 Evolutionary Change Law of Bacterial Communities During
the Composting of Mixed Materials
The biodiversity index is an important indicator for effectively characterizing richness and distribution uniformity of species in ecological environment. By counting the number of bands in DGGE atlas and calculating Shannon-Weaver index,
the bacterial diversity during composting was analyzed (Fig. 3.13). The number of