A review of the vermicomposting process of organic and inorganic waste in soils: Additives effects, bioconversion process, and recommendations

Soil nutrient recovery has emerged as a critical issue to maintain the soil fertility. However, the use of some organic and inorganic chemicals in agricultural and industrial systems gives rise to soil contamination. Advances in biological engineering have empowered for developing vermicomposting technology to decompose desired organic and inorganic wastes in soils. Three clusters of earthworms have been applied including epigeic, anecic, and endogeic to break down organic and inorganic wastes in soils, even though epigeic cluster, for instance Eisenia fetida, has been frequently employed for vermicomposting since it can be found readily in soil surfaces and can survive in any environment conditions. This review is designed to cover three potential earthworm clusters for vermicomposting process, earthworm decompose mechanism of organic and inorganic waste, chelation process in earthworm intracellular digestive system to decompose inorganic waste during vermicomposting process, the effect of the presence of materials, microorganism, and treatments during vermicomposting process, and the potential of bio-conversion product. The discovery of complex behaviors of earthworm system for decomposing inorganic waste including heavy metals is also enclosed to contribute a comprehensive overview of the advancements made and forthcoming directions.