An Investigation of Presumptive Synergism of Oil Palm Bunch Ash and Sawdust Amendments in Remediation of crude oil Spiked Soil

Presumed synergistic effect of combined amendment of crude oil spiked soil with oil palm bunch ash and sawdust was carried out in a laboratory experiment. Two kilogram (2 kg) of sandy soil was placed in each of five plastic vessels labeled TA, TB, TC, TD and TE. TA was left in its natural state while the others were each polluted with 6.7% v/w of crude oil. TB was not given any remediation amendment. TC and TD were each amended with 13.3% of oil palm bunch ash and sawdust respectively while TE was amended with 13.3% each of oil palm bunch ash and sawdust. The setups were replicated five times and watered twice weekly. Results showed that soil pH increased from 8.7±0.04 to 10.5±0.06, 5.3±0.01 to 8.5±0.04 and 5.6±0.18 to 11.5±0.15 for TC, TD and TE respectively. Percentage total petroleum hydrocarbon contents reduced by 65% for TC, TD and 52% for TE. Total organic carbon increased from 7.6±0.7 to 8.5±0.5%%, reduced from 4.0±0.1% to 3.7±0.3% and from 4.1±0.1% to 2.2±1.0% TC, TD and TE respectively. Total nitrogen increased from 0.66±0.1 to 0.69±0.0% for TC, remained nearly the same for TD and reduced from 0.4±0.0 to 0.2±0.0% for TE while average phosphorus increased from 0.4±0.0 to 23.0±4.2 mg/kg, 0.3±0.0 to 1.8±0.4 mg/kg and from 0.2±1.0 mg/kg to 52.6±4.6 mg/kg for TC, TD and TE respectively. Conclusively, combined amendment with oil palm bunch ash and sawdust did not induce synergism in soil total petroleum hydrocarbon content reduction. © JASEM http://dx.doi. org/10.4314/jasem.v20i1. 9 INTRODUCTION The activities of the oil and gas industry in Nigeria’s Niger Delta has brought about widespread environmental pollution in the area. The pollutant of concern affecting the environment of the area is crude oil. Some prominent negative effects of petroleum hydrocarbon on the environment is the alteration of soil properties (Kayode et al., 2009; Barua et al., 2011). Studies have shown that soil petroleum hydrocarbon contamination decreases soil moisture content, bulk density, water porosity, water holding capacity, increases soil acidity and decreases phosphorous contents but increases soil total nitrogen content and total organic carbon (Kayode et al., 2009; Barua et al., 2011; Marinescu et al., 2011; Abosede, (2013). Field assessments of crude oil polluted ecosystems by Okoro et al. (2011), Okop and Ekpo (2012) and Oyem and Oyem (2013) reported elevated levels of soil total petroleum hydrocarbon content and total hydrocarbon contents. Studies on the effects of petroleum hydrocarbon on soil or its alteration of soil chemical properties reported negative effects on plants and animals. The problem of petroleum hydrocarbon environmental pollution in Nigeria’s Niger Delta cannot stop now because the oil and gas mining activities still continues. Studies on amendment of petroleum hydrocarbon polluted soil with oil palm bunch material and sawdust reported significant reduction of soil total hydrocarbon content (Amajuoyi and Wemedo, 2015; Tanee and Albert, 2011; Godoy-Faundez et al., 2008). However, there is dearth of report study on combined use of the materials for application in remediation petroleum hydrocarbon polluted soil. Hence, this present work was undertaken to investigate presumed synergism in combined use of the materials for remediation of petroleum hydrocarbon impacted soil. The findings from this study could widen our knowledge on the environmentally beneficial use of the materials for remediation and mitigation of petroleum hydrocarbon polluted soil. This knowledge could be useful for application by the local people for cleanup of small scale and not very severe cases of petroleum hydrocarbon spill especially as the materials are locally available. MATERIALS AND METHODS This experiment was carried out at Centre for Ecological Studies, University of Port Harcourt. Top An Investigation of Presumptive Synergism of Oil Palm Bunch Ash 74 * 1 ALBERT, EJIKEME; ANYANWU, DI soil (sandy soil) was collected within 5 cm depth from a fallow land within the university premises. The soil was air-dried and sieved with 2 mm mesh. Bonny Light Crude Oil was obtained from Shell Petroleum Development Company of Nigeria while oil palm bunches and sawdust were collected from artisanal palm oil mill and wood sawmill. The oil palm bunches were burnt in a furnace to derive its ash i.e. oil palm bunch ash (OPBA). The chemical analysis of sample oil palm ash was carried out and its profile is as shown in Table 1. Table 1: Chemical Profile of Oil Palm Fruit Bunch Ash used in this Study