CONICET | Buscador de Institutos y Recursos Humanos

Bioremediation technologieshave demonstrated significant success on biological quality recovery ofhydrocarbon contaminated soils, employing techniques among which composting andvermiremediation stand out. The aim of this study was to evaluate the efficiencyof these processes to remediate diesel-contaminated soil, employing localorganic materials and earthworms. During the initial composting stage (75 days),the substrate was made up using contaminated soil, lombricompost, rice hullsand wheat stubbles (60:20:15:5% w/w). Diesel concentration in the contaminated substratewas about 5 g kg-1, equivalent to a Total Petroleum Hydrocarbon(TPH) experimental concentration of 3425 ± 50 mg kg-1. During the latervermiremediation stage (60 days), the earthworm species Eisenia fetida and Amynthasmorrisi were evaluated for their hydrocarbon degradation capacity. Physicochemicaland biological assays were measured at different times of each stage andecototoxicity assays were performed at the end of the experiments. TPH concentrationreduced 10.91% after composting and from 45.2 to 60.81% in the differenttreatments after vermiremediation. Compared with TPH degradation in the treatmentwithout earthworms (16.05%), results indicate that earthworms, along withindigenous microorganisms, accelerate the remediation process. Vermiremediationtreatments did not present phytotoxicity and reflected high substrate maturityvalues (> 80% Germination Index) although toxic effects were osberved due toE. fetida and A morrisi exposure to diesel. Vermiremediation was an efficienttechnology for the recovery of substrate biological quality after dieselcontamination in a short period. The addition of organic materials and suitablefood sources aided earthworm subsistence, promoted the decontamination processand improved the substrate quality for future productive applications

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