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Abstract
Vermicomposting utilizes the synergistic effect of earthworms with microorganisms to accelerate the stabilization of organic matter in biowastes. Nevertheless, the exact mechanism behind the maturity of vermicompost and the growth of earthworms exposed to biochar of varying particle sizes remains unclear. This study presents an investigation of the effect of biochar particle size on earthworm (Eisenia fetida) survival, microbial diversity, and the quality of vermicompost products. To address these issues, pelletized dewatered sludge samples from a municipal sewage treatment plant were amended with pine-based biochar with particle sizes of 1–2 mm, 25–75 μm, 200 nm, and 60 nm as the substrate for vermicomposting. This study revealed that the addition of millimeter-scale biochar and micron-scale biochar significantly promoted the degradation of organic matter since the organic matter in the treatment with 1–2 mm biochar at the end of the vermicomposting experiment decreased by 12.6%, which was equivalent to a 1.9-fold increase compared with that of the control. Excessive nanopowdering of nanobiochar significantly affected the survival of earthworms and led to 24.4–33.3% cumulative mortality, while millimeter-scale (mm) biochar and micron-scale (μm) biochar achieved zero mortality. The findings of this study could be used for evaluating the potential impact of nanoscale biochar to earthworms and guiding biochar-augmented vermicomposting.Graphical
Highlights
As a cost-effective and eco-friendly biotechnology, vermicomposting was first proposed by researchers in 1983 for sludge treatment (Frank et al 1983) and has received increasing attention in recent years as a way to support the circular economy and UN sustainable development goals (Boruszko 2023; Vavouraki and Kornaros 2023).During vermicomposting, earthworms, which thrive solely in aerobic environments, assume the dual responsibility of aerating and maintaining the material, eliminating the requirement for costly turning equipment for conventional composting (Ndegwa and Thompson2001)
A previous study found that the synergy between earthworms, microorganisms, and biochar enhances the production of highly active enzymes, thereby accelerating organic matter degradation in vermicomposting
Biochar at the millimeter and micron scales can promote the degradation of organic matter in the process of vermicomposting sludge
Summary
As a cost-effective and eco-friendly biotechnology, vermicomposting was first proposed by researchers in 1983 for sludge treatment (Frank et al 1983) and has received increasing attention in recent years as a way to support the circular economy and UN sustainable development goals (Boruszko 2023; Vavouraki and Kornaros 2023).During vermicomposting, earthworms, which thrive solely in aerobic environments, assume the dual responsibility of aerating and maintaining the material, eliminating the requirement for costly turning equipment for conventional composting (Ndegwa and Thompson2001). Earthworms, which thrive solely in aerobic environments, assume the dual responsibility of aerating and maintaining the material, eliminating the requirement for costly turning equipment for conventional composting The addition of biochar can enhance the physicochemical properties of compost mixtures, stimulate microbial activities (Khan et al 2020) and expedite the humification and biostabilization of sludge, leading to a shorter vermicomposting process (Xie et al 2023; Zhang et al 2014). Biochar and earthworms have synergistic effects on the enhancement of soil structure and increase microbial population and activity (Zhang et al 2021). It is hypothesized that the addition of biochar is a promising solution for accelerating (2024) 6:73 vermicomposting and achieving biologically stable compost products in a shorter duration
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