Articles

Costus afer, a known medicinal plant used in the removal of total monocyclic aromatic hydrocarbon (TMAH) in crude oil-contaminated soil add to the list of plant that has the potential to restore the soil quality. This study investigated the potential of <i>Costus</i><i> </i><i>afer</i> plant at various ages (7, 14, 21, 28, 35, and 42 days old) to biodegrade crude oil-contaminated soil. The group-balanced block design (GBBD) was used in establishing the experiment. TMAH was quantified by the standard method, according to USEPA method using gas chromatography-mass spectrometry (GC-MS). The contamination of 48kg of sandy loam soil was simulated by mixing 0.5, 1.0, and 1.5L of Bonny-Light crude oil with the soil in three separate vessels to achieve conditions of low (C<SUB>1</SUB>), medium(C<SUB>2</SUB>), and high(C<SUB>3</SUB>) contamination, respectively. An additional vessel with medium-level contaminated soil but no treatment (C<SUB>4</SUB>) served as the control. The <i>Costus</i><i> </i><i>afer</i> plants were nursed and transplanted at the stated ages to each vessel except the control. Controlled irrigation was applied, and the setups were housed to shield them from rainfall. After 90 days of treatment, results showed that the 7 days old <i>Costus</i><i> </i><i>afer</i> plants produced the highest amount of TMAH reduction of 96.5, 39.8, and 32.1%, for C<SUB>1</SUB>, C<SUB>2</SUB> and C<SUB>3</SUB>, respectively, while the control (C<SUB>4</SUB>) was 9.45%. Furthermore, the sequence of TMAH reduction by the plants was 7 days old, 14 days old, 21 days old, 28 days old, 35 days old, and 42 days old. Thus, in addition to its medicinal value, <i>Costus</i><i> </i><i>afer</i> plant also has the potential to biodegrade TMAH in crude oil-contaminated sandy loam soil.