Assessing Hydrocarbon Degradation using Pleurotus ostreatus

Abstract

Hydrocarbon-contaminated drilling waste disposal areas remain difficult to remediate because of complex petroleum hydrocarbon mixtures, limited soil structure, and variable contaminant distribution. This study evaluated the potential of Pleurotus ostreatus for hydrocarbon degradation in drilling waste collected from a hydrocarbon-impacted wellsite in Alberta, Canada. A greenhouse microcosm experiment was established using 54 experimental units arranged across 18 treatment groups, including fungal inoculation rates of 5% and 20% w/v, calcium nitrate amendments targeting carbon-to-nitrogen ratios of 60:1 and 30:1, and a 2% w/w surfactant amendment. Total extractable hydrocarbons (TEH) and petroleum hydrocarbon fractions were monitored to assess treatment performance. The baseline TEH concentration was 3,440 mg/kg, with PHC fractions F2 and F3 exceeding applicable Alberta Tier 1 guideline values. The strongest TEH reduction was observed in Treatment 10, which combined 5% w/v P. ostreatus, a 30:1 nitrate amendment, and 2% w/w surfactant, resulting in a 65% reduction relative to the baseline. Treatments 4, 6, 8, 9, and 10 showed significant reductions in final TEH concentrations relative to the control. However, all treatments remained above the F3 regulatory criterion, and baseline heterogeneity likely influenced treatment comparisons. The results indicate that fungal inoculation alone was insufficient, while nutrient amendment, with or without surfactant addition, improved hydrocarbon reduction under controlled microcosm conditions.