BIOREMEDIATION OF TOTAL MONOCYCLIC AROMATIC HYDROCARBONS IN OIL-BASED DRILL CUTTINGS USING POWDERED

Eichhornia Crassipes

Abstract

Oil-based drill cuttings (OBDCs) contain high concentrations of toxic total monocyclic aromatic hydrocarbons (TMAHs), making them among the most hazardous wastes produced during petroleum exploration. This study evaluated the potential of powdered Eichhornia crassipes as a natural organic amendment for enhancing the bioremediation of TMAHs in OBDCs. A completely randomized design (CRD) with five treatment levels was adopted, consisting of a control (0 g) and four amendment levels (30 g, 50 g, 70 g, and 90 g) of dried water hyacinth powder mixed with 1000 g of loamy soil and 500 g of contaminated drill cuttings. Total heterotrophic bacteria (THB), soil pH, and TMAH concentrations were monitored throughout a 50-day aerobic remediation period. Results showed a significant increase in microbial activity in the amended treatments, with THB counts of (3.95 × 10³ cfu/g) reaching their peak on Day 30. The highest reduction in TMAH concentration (96.36%) occurred in the 90 g treatment, while the control recorded only 30.48% reduction. The amendment also helped maintain a favourable soil pH for microbial activity. Statistical analysis indicated that amendment dosage and remediation period significantly affected remediation efficiency (p < 0.05). These findings demonstrate that Eichhornia crassipes can serve as a cost-effective and environmentally sustainable amendment for remediating hydrocarbon-contaminated soils.