Changes in Polyaromatic Hydrocarbon Content of a Waste Engine Oil Polluted Soil Exposed to pH Adjustments

Abstract

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.