environmental factors that may influence the microbial activity, like temperature,
oxygen concentration, pH, water content, C/N ratio, and particle size, need to be
adjusted by a pretreatment process before composting (An Ceustermans et al. 2009).
Besides these two methods, some other sustainable treatment methods are being
developed (e.g., fermentation, microbial fuel cell). Table 9.2 summarizes some
published investigations on the treatment of FVW by using different methods.
Vermicomposting is attracting researchers’ attention in recent years owing to the
reason that it can degrade organic wastes like FVW and can recycle and convert the
valuable nutrients into organic fertilizer (Li et al. 2020). Compared to composting,
vermicomposting has more effective functions of biodegradation and stabilization of
the organic wastes through the joint action of earthworms and microorganisms
(Domínguez 2004). In general, there are two operation systems that are widely
used for vermicomposting, namely, mixed system and separated system. The substrate and bed material are mixed together in the mixed system, while the substrate
and bed material are simply separated into two layers or separated by using a mesh
with holes in the separated system (Li et al. 2020). Many researchers investigated the
vermicomposting of FVW with different operation systems and conditions which are
summarized in Table 9.3. It is worth to note that these previous studies used dry
FVW or the addition of other bulking materials for earthworms. The pretreatment for
drying the fresh FVW usually takes 7–21 days before vermicomposting process
(Li et al. 2020). This kind of pretreatment not only increases the whole time needed
for vermicomposting but also leads to the loss of significant amounts of nutrients
through leachate (Huang et al. 2012). Moreover, limited literatures related to the
vermicomposting of fresh FVW reported that the earthworms cannot live in the fresh
FVW due to the high water content and high electrical conductivity of the generated
leachate (Gunadi and Edwards 2003; Huang et al. 2012; Li et al. 2020). Therefore, it
is necessary to enhance the efficiency of the treatment of FVW by vermicomposting;
owing to that, the sustainable treatment methods are regarded as one of the key
approaches to achieve the urban sustainability by recycling resources and recovering
energy (Wang et al. 2020).
The excess activated sludge (EAS) is a kind of organic waste generated from
wastewater treatment process and can be treated by vermicomposting. However, it is
reported that the high content of nitrogen in EAS can give rise to a higher ammonia
concentration environment, thus leading to the death of earthworms (Fu et al. 2015;
Li et al. 2020). To solve this problem, a pretreatment is required to adjust the C/N
ratio by mixing some bulking materials with rich carbon content, such as paper
mulch (Ndegwa et al. 2000), straw (Contreras-Ramos et al. 2005), and sawdust
(Zhao et al. 2018). Adding these kinds of bulking materials can not only improve the
living environment for earthworms by increasing the C/N ratio but also cause a
longer decomposition process (non-degradable substrate) and lower utilization value
(lower nitrogen content) of final product as fertilizer (Li et al. 2020). Moreover, other
pretreatment methods like air drying, airing, creating pellet, and pre-composting
could also increase the whole period of vermicomposting. On the other hand, Li et al.
(2020) suggested that the high content of nitrogen in EAS not only has negative
effects but also has some positive effects if co-vermicomposted with the FVW. The
9 Vermicomposting Treatment of Fruit and Vegetable Waste and the Effect of the. . .
145
oxygen concentration, pH, water content, C/N ratio, and particle size, need to be
adjusted by a pretreatment process before composting (An Ceustermans et al. 2009).
Besides these two methods, some other sustainable treatment methods are being
developed (e.g., fermentation, microbial fuel cell). Table 9.2 summarizes some
published investigations on the treatment of FVW by using different methods.
Vermicomposting is attracting researchers’ attention in recent years owing to the
reason that it can degrade organic wastes like FVW and can recycle and convert the
valuable nutrients into organic fertilizer (Li et al. 2020). Compared to composting,
vermicomposting has more effective functions of biodegradation and stabilization of
the organic wastes through the joint action of earthworms and microorganisms
(Domínguez 2004). In general, there are two operation systems that are widely
used for vermicomposting, namely, mixed system and separated system. The substrate and bed material are mixed together in the mixed system, while the substrate
and bed material are simply separated into two layers or separated by using a mesh
with holes in the separated system (Li et al. 2020). Many researchers investigated the
vermicomposting of FVW with different operation systems and conditions which are
summarized in Table 9.3. It is worth to note that these previous studies used dry
FVW or the addition of other bulking materials for earthworms. The pretreatment for
drying the fresh FVW usually takes 7–21 days before vermicomposting process
(Li et al. 2020). This kind of pretreatment not only increases the whole time needed
for vermicomposting but also leads to the loss of significant amounts of nutrients
through leachate (Huang et al. 2012). Moreover, limited literatures related to the
vermicomposting of fresh FVW reported that the earthworms cannot live in the fresh
FVW due to the high water content and high electrical conductivity of the generated
leachate (Gunadi and Edwards 2003; Huang et al. 2012; Li et al. 2020). Therefore, it
is necessary to enhance the efficiency of the treatment of FVW by vermicomposting;
owing to that, the sustainable treatment methods are regarded as one of the key
approaches to achieve the urban sustainability by recycling resources and recovering
energy (Wang et al. 2020).
The excess activated sludge (EAS) is a kind of organic waste generated from
wastewater treatment process and can be treated by vermicomposting. However, it is
reported that the high content of nitrogen in EAS can give rise to a higher ammonia
concentration environment, thus leading to the death of earthworms (Fu et al. 2015;
Li et al. 2020). To solve this problem, a pretreatment is required to adjust the C/N
ratio by mixing some bulking materials with rich carbon content, such as paper
mulch (Ndegwa et al. 2000), straw (Contreras-Ramos et al. 2005), and sawdust
(Zhao et al. 2018). Adding these kinds of bulking materials can not only improve the
living environment for earthworms by increasing the C/N ratio but also cause a
longer decomposition process (non-degradable substrate) and lower utilization value
(lower nitrogen content) of final product as fertilizer (Li et al. 2020). Moreover, other
pretreatment methods like air drying, airing, creating pellet, and pre-composting
could also increase the whole period of vermicomposting. On the other hand, Li et al.
(2020) suggested that the high content of nitrogen in EAS not only has negative
effects but also has some positive effects if co-vermicomposted with the FVW. The
9 Vermicomposting Treatment of Fruit and Vegetable Waste and the Effect of the. . .
145