Bioremediation and human health risk assessment of iron in crude oil-polluted soil treated with combinations of cocoa pod husk, potato peels and fluted pumpkin husk

Abstract

This study evaluated the potential of cocoa pod husk (CPH), potato peels (PP) and fluted pumpkin husk (FPH) in the bioremediation of iron (Fe) contamination in petroleum-polluted soil collected from Gokana Local Government Area of Rivers State, Nigeria. Two kilograms (2 kg) of the polluted soil were weighed into 36 transparent plastic buckets in triplicates of 4 groups and 3 treatment concentrations of 250, 500 and 1000 mg/kg. The soil was amended with CPH + PP, CPH + FPH, PP + FPH and CPH + PP + FPH combinations of the three different concentrations and monitored for 150 days. Results revealed that the baseline polluted soil had Fe concentration of 91.174 mg/kg, while the baseline unpolluted soil had Fe concentration of 2.115 mg/kg. The best remediation performance was observed in the soil treated with CPH + PP + FPH combination which had the highest decrease in Fe level at each treatment concentration and time. The Fe reduction increased with treatment duration and dosage, ranging from 48.55% (Day 150, 250 mg/kg) to 58.73% (Day 150, 1000 mg/kg). The Average Daily Dose (ADD) of Fe via ingestion, inhalation and dermal exposure decreased significantly especially in children compared to adults. The Target Hazard Quotient (THQ) for Fe through ingestion for adults and children decreased at 1000 mg/kg substrate concentration to 1.79E-04 and 1.67E-03 respectively in the triple amendment on day 150. The findings indicate that combinations of CPH, PP and FPH are more effective in the reduction of Fe contamination and its environmental health risks associated with petroleum-polluted soils, promoting a sustainable and eco-friendly remediation strategy.