Abstract

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Quite a minute number of plants have been investigated for rhizoremediation of crude oil contaminated rainforest soils in the Niger Delta in relation to the overwhelmingly large number of plants. S. officinarum, one of the world’s most propagated grasses was investigated by contaminating soils with oil at 3480 and 7050 mg/kg respectively and subjecting it to the following treatments: soil + oil [SO], soil + oil + fertilizer (NPK)[SOF], soil + oil + fertilizer + hydrocarbon utilizing bacteria and fungi [SOFM], Soil +oil + fertilizer + hydrocarbon utilizing bacteria and fungi + solarisation [SOFMS] (in triplicates). All contaminated soils were planted with S. officinarum (P) and monitored for 120 days to determine: population dynamics of culturable aerobic-mesophilic heterotrophic and hydrocarbon utilizing bacteria and fungi, and residual soil total petroleum hydrocarbon (TPH). Results indicated that while bacterial and fungal populations increased, residual TPH decreased with time in the rhizosphere of the plant at both concentrations. Degradation efficiency for the applied treatments was in order: PSOFM ˃ PSOFMS ˃ PSOF ˃ PSO. Although, the highest attainable rates of degradation for PSOFM were 75.6 and 71.2 % within the study period, the cumulative TPH loss from soil were 2630 and 5020 mg/kg from the initial contamination levels of 3480 and 7050 mg/kg respectively. The occurrence of substantial remediation in the rhizosphere of S. officinarum indicates the plant holds enormous promise in the remediation of crude oil contaminated rainforest soils in the Niger Delta.

Keywords: Contamination; Crude oil; Rainforest soil; Rhizoremediation; Treatment; Saccharum officinarum.