Reuse of composted food waste from rural China as vermicomposting substrate: effects on earthworms, associated microorganisms, and economic benefits

• Published in: Environmental technology 2024-06, Vol.45 (14), p.2685-2697
• Main Authors: Zheng, Huabao, Wang, Min, Fan, Yueqin, Yang, Jian, Zhao, Zhuoqun, Chen, Hengyuan, Ye, Zhenwei, Zheng, Zhanwang, Yu, Kefei
• Format: Article
• Language: English
• Subjects: adults; Aerobic microorganisms; Cattle manure; Chemical properties; Community structure; Composting; Coprinopsis; Cost analysis; cow manure; Dominant species; Dung; earthworms; environmental technology; Financial analysis; Food; Food waste; Fulvic acids; fungi; gene function; Humification; humin; juveniles; lignocellulases; microbial communities; microbial community structure; Microbiomes; Microflora; Microorganisms; Oligochaeta; Organic matter; reproduction; Saccharopolyspora rectivirgula; salt content; Substrates; Vermicomposting; Vibrio cholerae; Worms
• ISSN: 0959-3330; 1479-487X; 1479-487X
• DOI: 10.1080/09593330.2023.2184728

Aerobic composting of food waste (FW) from rural China using a composting device results in a substantial financial burden on the government. This study aimed to assess the feasibility of mitigating this cost using vermicomposting of composted FW. The specific aims were to elucidate the effects of composted FW on earthworm growth and reproduction, reveal the changes in the physical and chemical properties of earthworm casts during vermicomposting, identify the microbial community structure associated with vermicomposting, and perform a financial analysis based on the yield of earthworms and earthworm casts. Mixing composted FW and mature cow dung in an equal ratio achieved the highest earthworm reproduction rate, where 100 adult earthworms produced 567 juvenile earthworms and 252 cocoons in 40 d. Earthworms reduce salt content of vermicomposting substrates by assimilating Na + and promoting humification by transforming humin into humic and fulvic acid, thus producing earthworm casts with a high generation index > 80%. When composted FW was added to a vermicomposting substrate, a distinctive microbial community structure with alkaliphilic, halophilic, and lignocellulolytic microorganisms dominated the microflora. The dominant bacterial species was Saccharopolyspora rectivirgula, and the dominant fungal species changed from Kernia nitida to Coprinopsis scobicola. Furthermore, microbial genes for refractory organic matter and fat degradation were observed in Vibrio cholerae, Kernia nitida, and Coprinopsis scobicola. Financial analysis showed that vermicomposting has the potential to reduce the cost associated with FW disposal from $ 57 to $ 18/t.