Implication of particle sizes on bioremediation of crude oil polluted sandy soil in Okolomade part of Niger Delta Basin, southern Nigeria

Abstract

Bioremediation is a cost-effective and environmentally friendly technology that exploits the capabilities of microorganisms to degrade organic pollutants leading to complete mineralization. It has become the most preferred technique for oil spill remediation on soil in Nigeria. The study aims to examine the implication of particle sizes on bioremediation of crude oil polluted sandy soil in Okolomade part of Niger Delta Basin, southern Nigeria. Once a week samples were collected for a total of 28 days and were analyzed for chemical and microbial content in an aerobic setting. The classification of the soil samples was done according to the U.S. Bureau of soil classification system, the soil samples were divided into X and Y, where X represented fine to coarse sand and Y represented very fine to coarse sand. The particle size distribution, total hydrocarbon content (THC), total heterotrophic bacteria count (THBC), total organic carbon, soil pH, and available nitrogen and phosphorus were the parameters investigated throughout the 28-day examination of the soil samples. The results shows that the total heterotrophic bacterial count and soil pH increased in all of the soil samples, with samples A for fine to coarse sand (X) and sample E for very fine to coarse sand showing the most significant increase with values of 120 Cfu × 105/g and 266 Cfu × 105/g, respectively. These samples also had the lowest coefficients of uniformity (Cu). The results further reveal that the total hydrocarbons content, available nitrogen and phosphorus, as well as total organic carbon, all decreased noticeably. In contrast to samples with higher coefficient of uniformity values, samples with lower coefficients of uniformity showed a higher decrease in hydrocarbon content, suggesting that particle size distribution affects bioremediation. 0.0899 and 0.0942 were calculated to be the correlation coefficient of total hydrocarbon content vs coefficient of uniformity for fine to coarse sand (X) and very fine to coarse sand (Y). The contaminated soil samples are treated by combining pig manure, NPK 15:15:15, and the microorganism Pseudomonas aeruginosa, the total hydrocarbon content of sandy soil was reduced.