Towards modeling and design of vermicomposting systems: Mechanisms of composting/vermicomposting and their implications

Abstract

Several studies have been reported, and are continued to be done by scientists especially in Asia, in which earthworms are added to one or other substrate undergoing composting. The concerned authors call it ‘vermicomposting’. Other authors use the term ‘vermicomposting’ to denote processes in which earthworms are made to feed upon one or other substrate, to generate a useful product (vermicast). Present review has embarked on a series of efforts aimed at clearly defining the mechanism of vermicomposting process and to model it. This, in turn, is envisaged to be made the basis for developing rational criteria with which vermireactors are to be designed and operated in a manner that maximizes the process efficiency and minimizes the production cost. During the course of these efforts, authors have conducted a detailed analysis of the steps associated with composting and vermicomposting. Based on an analysis of the experiments done earlier by authors, as also on the work published by others, it is now reported that composting and vermicomposting are essentially different types of processes involving different bioagents, process conditions, reactor operation strategies, and process control parameters. Hence, to achieve optimal results, the two processes should be run in isolation, composting should always precede vermicomposting, and never in combination. It is also suggested that the term ‘vermicomposting’ should be used only to denote the process in which reactor systems are used to transform biodegradable substrates into vermicasts.