Abstract

The potential effects of using poultry droppings and mushroom substrate, either alone or in combination, as amendments or nutrient supplements for hydrocarbon biodegradation were investigated in this study. The rates of biodegradation of drill cuttings were studied over remediation periods of 4 and 8 weeks under laboratory conditions. The concentrations of polycyclic aromatic hydrocarbons (PAHs) in untreated drill cuttings, spent mushroom substrate, and poultry manure were 18.464, 13.29, and 19.59 mg kg^-1, respectively. The first-order empirical model was employed to predict changes in hydrocarbon concentrations. Subsequently, Biodegradation Efficiency (BDE), Diagnostic Ratio, and Toxicity Equivalent Factor (TEF) were determined. Analysis of the empirical data revealed a highly statistically significant difference in PAHs at 8 weeks due to the amendment. Notably, spent mushroom substrate (SMS) exhibited better performance on its own compared to animal waste (poultry droppings). However, a combination of poultry droppings and SMS (4:1:1) resulted in higher values of BDE. Diagnostic ratios calculated indicated that PAHs originated from both combustion and anthropogenic sources. TEF demonstrated a reduction in value from 4 to 8 weeks, with the 14 individual PAHs investigated showing a 50% reduction in fluoranthene. Conversely, the biodegradation rate constants obtained were higher with lower half-life times for the various amendments using plant and animal-source organic wastes, either alone or in combinations.

Key words: Toxicity equivalent factor (TEF), biodegradation efficiency (BDE), diagnostic ratio, polycyclic aromatic hydrocarbons (PAHs), drill cuttings, poultry droppings, spent mushroom substrate.