Degradation and accumulation rates of fresh human excreta during vermicomposting by Eisenia fetida and Eudrilus eugeniae

Unveiling the earthworm-associated preferential remediation of emerging organic pollutants and heavy metals in MSW-based vermicomposting systems: Insights through the lens of multivariate techniques and novel empirical models

Studies on the efficacies of vermicomposting and composting in countering the toxic impacts of pollutant cocktails in municipal solid waste (MSW) are scarce. Moreover, further research is needed to explore earthworms' remediation preferences for various pollutants in heterogeneous vermicomposting feedstocks, such as MSW. Therefore, removal dynamics of pesticides (chlorpyrifos, cypermethrin, and carbofuran), pharmaceuticals (diclofenac and carbamazepine), and heavy metals (Pb, Zn, Cu, and Mn) in MSW-based vermicomposting (Eisenia fetida and Eudrilus eugeniae) and composting systems were evaluated through multivariate analytical techniques (principal component (PCA) and multi-factor (MFA)) on the R-platform. Both earthworms satisfactorily increased their population and augmented NPK (nitrogen, phosphorous, and potassium) availability, cation exchange, microbial biomass C&N, and their metabolic activity 2-3 folds more than composting, accompanied by a 3-4 folds reduction of organic C, pH, and bulk density. Correspondingly, heavy metals, pesticides, and pharmaceuticals decreased by 8-10-folds via earthworm's significant pollutant removal efficiencies that subsided MSW-driven ecological risks by 60-90%. PCA and MFA revealed that N, P, and K-availability, organic C, and microbial activity were the indicative attributes for heavy metal and emerging organic micropollutant (EOMP)-removal during biocomposting; however, earthworms remove pesticides faster than pharmaceuticals and heavy metals. PCA-based novel empirical models demonstrated that in MSW-only feedstock, earthworm-mediated pollutant detoxification followed the order of pesticides > pharmaceuticals > heavy metals. However, in MSW combined with cow dung (1:1 ratio) feedstock, the detoxification order shifted to pharmaceuticals > heavy metals > pesticides. Therefore, this study provides fresh insights into pollutant-focused feedstock optimization for vermicomposting through model-based approaches, advancing the eco-friendly valorization of toxic MSW.