Landfilling and composting efficiency to reduce genotoxic effect of petroleum sludge

Abstract

The main aim of the study was the investigation of the petroleum sludge genotoxic aspect by cost-effective way. Indeed, the work was done by assessing the micronuclei frequency (MN) and mitotic index (MI) using Vicia faba roots assay, after direct exposure in solid matrix. The petroleum sludge was highly cytotoxic as its MI was much less than the one of the positive control. The petroleum sludge exhibits a high genotoxic aspect in terms of MN (12.6 ‰ ) and MI (4.3%). Secondly, petroleum sludge was subjected to landfilling and composting treatments. These treatments have led to the organic matter biotransformation, as demonstrated by physicochemical analyses. This biotransformation was more noteworthy in the case of composting by the high decrease of the total petroleum hydrocarbons (TPH) concentration. The TPH removal rate was 60.6 and 93.7% for landfilling and composting treatments, respectively. The genotoxicity test confirmed more the biodegradation of toxic compound in the petroleum sludge by composting and landfilling treatments. This positive effect was assessed by the increase of the MI by 42.9% and 62.5% for landfilling and composting, respectively. On the other side, the MN decreased by 69.8% and 85.7% for landfilling and composting, respectively. However, the Vicia faba test revealed that the genotoxicity was not only due to the TPH concentration, but the specific TPH characteristics can play a significant role. Somehow, the Vicia faba assay is a short, low-cost, and effective test to assess the TPH genotoxic biodegradation. • TPH were biodegraded more by composting than landfilling. • V. Faba test revealed a high genotoxic effect of the petroleum sludge. • Aromatic hydrocarbons accounted for the most genotoxic effect. • Composting was more efficient than landfilling in genotoxicity removal.