EAS can promote the growth of earthworms and specific bacterial species, thus
improving the decomposition efficiency, and could improve the nutritional content
of the final products as fertilizer (Li et al. 2020). Moreover, the EAS consists of
microorganisms with large population and diversity, for example, various nitrogenfixing bacteria and the phosphate-accumulating bacteria, which can enhance the
microbial activity and the decomposition process of FVW, thus accelerating the
nitrification and mineralization process and leading to higher content of nitrogen and
phosphorus in the final product (Li et al. 2020). This novel idea has been proven to
be a more feasible and sustainable method for treating FVW and EAS at the
same time.
9.3 Effects of Excess Activated Sludge on Vermicomposting
of Fruit and Vegetable Waste
To clarify the effects of EAS on vermicomposting of FVW, comparative experiment
was conducted by Li et al. (2020). A novel vermireactor consisting of substrate and
bed compartment was used for treating five types of FVW (banana peels, cabbage,
lettuce, carrot, and potato) with and without the addition of EAS. The operation
condition could be found in Table 9.3, and the vermireactor conditions are displayed
in Table 9.4.
The addition of EAS obviously increased the total nitrogen, total phosphorus,
copy numbers of 16S rDNA, and the dehydrogenase activity of substrates (FVW)
before starting the vermicomposting, as could be seen in Table 9.5. It is well-known
that the content of nitrogen and phosphorus in the initial substrate strongly affects the
nutrient value of the final product as fertilizer (Huang et al. 2012; Li et al. 2020).
Furthermore, the great number and high activity of bacteria in the initial substrate
inoculated through the addition of EAS could enhance the vermicomposting since
the complex microbial communities are reported to play a key role during
vermicomposting (Chen et al. 2018a, b). On the other hand, Zhao et al. (2018)
reported that the healthy growth status of earthworms directly reflects a successful
vermicomposting since the earthworms are considered as crucial drivers of the
process. Body weight changes of the earthworms were monitored over
vermicomposting, as displayed in Fig. 9.1. In general, earthworms in the treatment
of FVW with the addition of EAS showed a better capability of weight gain
compared to the treatment of FVW alone. Moreover, Li et al. (2020) also reported
that the cocoon production of earthworms was also promoted by adding EAS.
The total carbon in the substrate compartment of the treatment with addition of
EAS was lower than that of the treatment for FVW alone (except for cabbage), as
could be seen in Fig. 9.2. The possible reasons of lower total carbon are explained as
the better growth of earthworms and higher microbial activity caused by the addition
of EAS. However, no significant changes in the total carbon were demonstrated in
bed compartments (except for cabbage). The mass reduction rate of substrate in each
9 Vermicomposting Treatment of Fruit and Vegetable Waste and the Effect of the. . .
147
improving the decomposition efficiency, and could improve the nutritional content
of the final products as fertilizer (Li et al. 2020). Moreover, the EAS consists of
microorganisms with large population and diversity, for example, various nitrogenfixing bacteria and the phosphate-accumulating bacteria, which can enhance the
microbial activity and the decomposition process of FVW, thus accelerating the
nitrification and mineralization process and leading to higher content of nitrogen and
phosphorus in the final product (Li et al. 2020). This novel idea has been proven to
be a more feasible and sustainable method for treating FVW and EAS at the
same time.
9.3 Effects of Excess Activated Sludge on Vermicomposting
of Fruit and Vegetable Waste
To clarify the effects of EAS on vermicomposting of FVW, comparative experiment
was conducted by Li et al. (2020). A novel vermireactor consisting of substrate and
bed compartment was used for treating five types of FVW (banana peels, cabbage,
lettuce, carrot, and potato) with and without the addition of EAS. The operation
condition could be found in Table 9.3, and the vermireactor conditions are displayed
in Table 9.4.
The addition of EAS obviously increased the total nitrogen, total phosphorus,
copy numbers of 16S rDNA, and the dehydrogenase activity of substrates (FVW)
before starting the vermicomposting, as could be seen in Table 9.5. It is well-known
that the content of nitrogen and phosphorus in the initial substrate strongly affects the
nutrient value of the final product as fertilizer (Huang et al. 2012; Li et al. 2020).
Furthermore, the great number and high activity of bacteria in the initial substrate
inoculated through the addition of EAS could enhance the vermicomposting since
the complex microbial communities are reported to play a key role during
vermicomposting (Chen et al. 2018a, b). On the other hand, Zhao et al. (2018)
reported that the healthy growth status of earthworms directly reflects a successful
vermicomposting since the earthworms are considered as crucial drivers of the
process. Body weight changes of the earthworms were monitored over
vermicomposting, as displayed in Fig. 9.1. In general, earthworms in the treatment
of FVW with the addition of EAS showed a better capability of weight gain
compared to the treatment of FVW alone. Moreover, Li et al. (2020) also reported
that the cocoon production of earthworms was also promoted by adding EAS.
The total carbon in the substrate compartment of the treatment with addition of
EAS was lower than that of the treatment for FVW alone (except for cabbage), as
could be seen in Fig. 9.2. The possible reasons of lower total carbon are explained as
the better growth of earthworms and higher microbial activity caused by the addition
of EAS. However, no significant changes in the total carbon were demonstrated in
bed compartments (except for cabbage). The mass reduction rate of substrate in each
9 Vermicomposting Treatment of Fruit and Vegetable Waste and the Effect of the. . .
147