Detoxification of chromium-rich tannery industry sludge by Eudrillus eugeniae: Insight on compost quality fortification and microbial enrichment

Chromium-rich tannery sludge (TS) is a hazardous industrial waste. Although vermicomposting can be an effective remediation pathway; but, the unique waste degrading efficiency of Eudrillus eugeniae is least explored. The present work showcases an efficient earthworm-mediated protocol for TS sanitization deploying E. eugeniae. Changes in pH, TOC (%), nutrients (NPK), metals (Cr, Cd etc.) and microbial diversity were monitored in various E. eugeniae mediated TS based vermibed. Total N, P, and K availability increased by 2-5 folds upon vermicomposting with 3-4 folds reduction in C/N ratio. Moreover, substantial removal of Cr (89%), Cd (88%), and Zn (79%) was recorded in the substrate. Bioaccumulation of these metals in the gut significantly reduced the pollution load in the finished products. The corresponding augmentation of microbial density and low respiratory CO2 release from the vermibeds substantiated the environmental proficiency of vermitechnology.