Suitability of vermicomposting for different varieties of organic waste: a systematic literature review (2012-2021)

The aim of this study was to assess the suitability of vermicomposting for various types of organic waste based on earthworm growth and reproduction as well as nutrient content in final vermicompost. The study was also focused on the kinds of earthworms employed in the research, the countries where vermicomposting research was done, and fundamental operating conditions. To fulfill these aims, we developed research questions and used two reputable databases, namely, SCOPUS and Science Direct. We developed inclusion and exclusion criteria and the papers were taken from the years between 2012 and 2021. This study identified the majority of vermicomposting research related to waste management was conducted in Asian countries (55%) where India has the highest number of paper publications (35%). Research in the field of vermicomposting grew continuously from 2017. Furthermore, Eisenia fetida is a commonly used species for vermicomposting. The majority of vermicomposting experiments were conducted on animal waste, followed by sewage and industrial sludge. According to existing literature, almost all organic wastes can be used for vermicomposting. However, before being used as earthworm feed, these wastes should be pre-composted and should mix with secondary waste in proper proportions. Eighty percent of the papers suggested the importance of pre-composting or treatment before the actual vermicomposting starts.