Heavy metal pollution is a significant environmental concern with detrimental effects on ecosystems and human health, and traditional remediation methods may be costly, energy-intensive, or have limited effectiveness. The current study aims were to investigate the impact of heavy metal toxicity in Eisenia fetida, the growth, reproductive outcomes, and their role in soil remediation. Various concentrations (ranging from 0 to 640 mg per kg of soil) of each heavy metal were incorporated into artificially prepared soil, and vermi-remediation was conducted over a period of 60 days. The study examined the effects of heavy metals on the growth and reproductive capabilities of E. fetida, as well as their impact on the organism through techniques such as FTIR, histology, and comet assay. Atomic absorption spectrometry demonstrated a significant (P Cd > Pb. Histological analysis revealed a consistent decline in the organism's body condition with increasing concentrations of heavy metals. However, comet assay results indicated that the tested levels of heavy metals did not induce DNA damage in E. fetida. FTIR analysis revealed various functional group peaks, including N-H and O-H groups, CH2 asymmetric stretching, amide I and amide II, C-H bend, carboxylate group, C-H stretch, C-O stretching of sulfoxides, carbohydrates/polysaccharides, disulfide groups, and nitro compounds, with minor shifts indicating the binding or accumulation of heavy metals within E. fetida. Despite heavy metal exposure, no significant detrimental effects were observed, highlighting the potential of E. fetida for sustainable soil remediation. Vermi-remediation with E. fetida represents a novel, sustainable, and cutting-edge technology in environmental cleanup. This study found that E. fetida can serve as a natural and sustainable method for remediating heavy metal-contaminated soils, promising a healthier future for soil.

Environmental context Mitigating the environmental fallout of industrial accidents is crucial. In a recent study, researchers conducted tests on model substrates to explore the effectiveness of bioremediation in treating complex refinery contaminants resulting from both accidental and deliberate facility damage. The research reveals that bioremediation can be a promising, eco-friendly solution for cleaning up such pollutants, aligning with broader efforts to combat environmental harm resulting from industrial incidents.Rationale Bioremediation harnesses microorganisms' diverse metabolic abilities to detoxify and eliminate pollutants, particularly hydrocarbon-based ones such as oil. This natural biodegradation process performed by microorganisms is a cost-effective method for environmental cleanup compared to other remediation technologies.Methodology In this study, we examined the fate of heavy metals, cobalt and molybdenum, by the analysis of the basic chemical parameters of other sample components, such as n-hexane extractable substances and total petroleum hydrocarbons. The metal content was determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). Exchangeable (loosely bound to the surface of particles and due to its high mobility and availability is crucial for understanding the potential immediate impact of metal contamination) and more stable fractions of the metal and the metal forms were determined using a sequential extraction method. The phase composition of the samples was determined by X-ray diffraction.Results In our microbiological analysis, we isolated various cultures from a consortium of microorganisms. Basic chemical analysis indicators, such as n-hexane extractable substances, total petroleum hydrocarbons and humic acids, reflected robust microbiological activity. During the study, metals in exchangeable form decreased and those in more stable forms increased.Discussion The sequential extraction of cobalt and molybdenum revealed shifts in various metal fractions within the bioaugmented substrate post-bioremediation, differing from the initial substrate. These alterations in metal fractions are likely attributable to microbial actions, leading to the formation of more stable metal fractions throughout the bioremediation process.