Evaluating the effectiveness of various remediation therapies on the engineering properties of oil-contaminated soils

Abstract

This study was embarked upon to ascertain the effectiveness of using physical and biological remediation procedures to amend the impact of oil pollution on soil engineering properties. Soil contaminated with crude oil at a mix ratio of 20:1 (percentage by weight), was remediated with charcoal (C2), charcoal + seaweed extract + groundnut plant (C3), and charcoal + wood ash + groundnut plant (C4). During the procedure, the soil’s total petroleum hydrocarbon (TPH) level was determined through American Public Health Association (APHA) approved procedures; while the geotechnical (maximum dry density “MDD”, optimal moisture content “OMC, and California bearing ratio “CBR”) and electrical properties (electrical conductivity “EC”, dielectric constant “ɛʹ, and electrical resistivity “ρ”) were measured in accordance with American Society for Testing and Materials (ASTM) and Institute of Electrical and Electronics Engineers (IEEE) approved procedures. The results depicted that the TPH, ɛʹ and ρ-values of the contaminated soil samples declined by 56.71%, 82.01% and 72.80%; 31.65%, 36.85% and 19.92%; and 56.32%, 62.03% and 60.27%, respectively in the C2, C3 and C4 samples after the remediation program; while the soil EC increased by 103.45%, 145.68% and 135.34% in the C2, C3 and C4 samples, respectively. Likewise, the C2, C3 and C4 samples CBR, MDD and OMC values increased by 29.49%, 34.75% and 50.30%; 7.87%, 11.02% and 4.72; and 12.02%, 28.01% and 40.38%, respectively at the end of the experimental period. These findings portrayed that hybridized remediation therapies are better remediating techniques in remediating contaminated soils; hence sustaining the integrity of the soils’ geotechnical and electrical properties.