RESUMEN
The comparative study of poultry wastes- and HBB5 biosurfactant-mediated polyaromatic hydrocarbon biodegradation in sediment polluted with crude oil were investigated. The experiments were carried out for a period of 28 days by monitoring pH, nitrate, phosphate, polycyclic aromatic hydrocarbon and microbiological parameters using standard procedures. The pH values obtained ranged between 6.21 and 6.93 in days 1 and 28 for the most effective treatment recipes. Generally, there was depletion in the concentrations of nitrate and phosphate for all set ups, but the most effective recipe witnessed highest reduction. For the polycyclic aromatic hydrocarbons, the recipe with highest limiting nutrients depletion also recorded the most hydrocarbon loss, and yet highest increase in density of hydrocarbonoclastic bacteria and fungi. The sample containing polluted sediment + poultry wastes + HBB5 biosurfactant recorded PAH values of 1932.6472ppm on day 1 and 481.2272ppm on day 28. Total hydrocarbon-utilizing bacterial counts ranged from 1.48×104 cfu/g to 9.70×106 cfu/g, while hydrocarbon-utilizing fungal counts ranged between 2.30×103 cfu/g and 3.90×105 cfu/g. From the results obtained, poultry wastes combined with HBB5 biosurfactant recorded the highest efficiency in the biodegradation of polycyclic aromatic hydrocarbons in sediments, and HBB5 biosurfactant in isolation recorded higher degradation efficiency for polyaromatic hydrocarbons than the degradation effect mediated by poultry wastes alone. It is therefore recommended that a combination of surface-active agent, nutrient amendment source and viable microbial biomass be adopted and employed as potent recipe for the degradation of polyaromatic hydrocarbons in crude oil-contaminated sediments.
RESUMEN
The present study investigated the role of pH adjustments in the remediation of polyaromatic hydrocarbon (PAH) contents of waste engine oil-polluted soil. Sun-dried top soil (0-10cm) was measured into buckets. Waste engine oil (WEO) was added to soil and mixed thoroughly to obtain similar concentrations of 2.5% w/w oil in soil. The polluted soil was thereafter amended with NPK (15:15:15) fertilizer to enhance microbial activity. The buckets were transferred into a well ventilated screen house with inherent constant room temperature. The entire setup was divided into 5 sets. Each set was irrigated daily with 200ml of different pH solutions (pH 3, 5, 7, and 11) for a period of 3 months. There were reductions in total PAH concentrations. Total polyaromatic hydrocarbon (PAH) of soil was lowest when soil was modified with solutions of pH 5 (78.1 mg/kg) followed by that at pH 9 (90.6 mg/kg), pH 3 (213.5 mg/kg) and pH 11(315.1 mg/kg). Obviously, successful remediation of PAH is pH dependent. Fluorene was totally remediated at pH value from acidity to neutrality; whereas at alkalinity, fluorene content was 0.237 mg/kg and 0.139 mg/kg at pH 7 and 11 respectively.