Effects of particle sizes on bioremediation of crude oil polluted sandy soils

Thesis Abstract

Bioremediation has been proven to be the most effective method of cleaning up oil contaminated soils through the application of nutrients and microorganism to contaminated soils. Hence, this research was aimed at investigating the effects of particle sizes on bioremediation of crude oil polluted sandy soils. Six different soil samples were sieved using the B.S sieve sizes. The sieve sizes were classified into X and Y such that X is fine to coarse sand while Y is very fine to coarse sand according to U.S Bureau and PRA (Public Roads Administration) soil classification system. The soil samples were polluted with escravous sweet crude oil at a uniform rate of concentration under aerobic condition. Treatment commenced after four days using nutrients and microorganism. Soil samples were examined for physiochemical and microbial characteristics   for a period of 42days. The parameters examined were moisture content, particle size distribution, total hydrocarbon content, soil pH, available nitrogen, available phosphorus, total heterotrophic bacteria and fungi count. The analysis of the soil characteristics throughout the remediation period showed that total heterotrophic bacteria and fungi counts increased in all the soil samples. THBC was highest in sample G for both fine to coarse sand(X) and very fine to coarse sand (Y ) with values of 250cfux105/g and 298 cfux105/g at least values of Cu and D50 respectively. There was a decrease in nitrogen, phosphorus, organic carbon content, moisture content, pH and total hydrocarbon content. The result of the study revealed that, the rate of hydrocarbon loss was higher in samples with less Cu and D50 values compared to samples of higher values, an indication that particle size distribution parameters could be one of the factors affecting bioremediation. The correlation coefficient(r) of THC versus Cu for fine to coarse sand(X) is 0.867 while for very fine to coarse sand is 0.923.