Project Materials

BIOREMEDIATION OF OIL-CONTAMINATED SOIL USING EMULSIFIER (LIQUID SOAP), NPK FERTILIZER AND MICROBIAL (BACILLUS SP) TREATMENT

Abstract

Two separate sets of soil samples were collected at Kaduna Refining and Petrochemical Company Limited (KRPC), a subsidiary of the Nigerian National Petroleum Corporation (NNPC) Kaduna. The first set of samples, branded (D), were gathered from regions where diesel from the refinery spilt into the environment, whereas the second set, labelled (P), was collected from areas where petrol leaked and spilt into the environment. The soil pH was found to be 5.9 and 6.2 for D and P samples, respectively. Sample P had a higher cation exchange capacity (CEC) than sample D (32.0 and 30.0 mmol/kg soil, respectively). Because of its high CEC, sample P has high cation concentrations (Ca2+, Mg2+, K+, and Na+ with concentration values of 3.6, 1.17, 0.50, and 0.22 mol/kg, respectively), whereas sample D has a lower cation concentration (Ca2+, Mg2+, K+, and Na+ with concentrations of 1.20, 0.27, 0.25, and 0.17 mol/kg, respectively). The oil (contaminant) was extracted in dichloromethane, and a GC-MS analysis was performed to determine the nature (composition) of the oil. The contaminant’s concentration was calculated using the gravimetric method. The results showed that the overall concentration of the pollutant (oil) before treatment was 398 g/kg and 194 g/kg for samples D and P, respectively. The GC-MS results revealed that linear and branched alkanes (n-Tetratetracontane, 3,6-Dimethyldecane, n-Pentadecane, 2-Bromodecane, n-Heptadecane, etc. and n-Tetradecane, 2-Bromododecane, n-Octadecane, 14-Methyl-8-hexadecenal, etc.) were the main contaminants in both samples (D and P). Bioremediation was initiated and tested by applying fertiliser (F), bacteria inoculation (B), and emulsifier (E) to the contaminated soil separately, as well as by combining bacteria inoculation and fertiliser (B and F), fertiliser and emulsifier (F and E), bacteria inoculation and emulsifier (B and E), and a combination of bacteria inoculation, emulsifier, and fertiliser (B,E, and F) on both samples D and P. Throughout the 28-day treatment period, bioremediation was measured using the weight-loss method, and the degradation trend was as follows: (B, E, and F) > B > (B and E) > (B and F) > (E and F) > F. The results showed that treatment with B, E, and F together resulted in the highest percentage of oil degradation (97% and 95% for samples P and D, respectively), followed by B (96% and 81% for samples D and P). This finding indicates that Bacillus sp is a feasible microbial strain for bioremediation of oil-contaminated soil when biostimulated with fertiliser and emulsification (B, E, and F). The proportion of oil degraded in samples P and D is about the same (97 and 95%, respectively), but there is a significant difference (P < 0.05) in the degradation trend for D and P. This could be because, while the samples included oil (contaminant) with almost same content, they differed in the number of carbon chains and other physical parameters such as density and viscosity.

Chapter one

INTRODUCTION

Background of the Study

One of the world’s most serious environmental issues today is hydrocarbon contamination caused by petrochemical industrial activities. Oil pollution concerns in Nigeria have existed from the beginning of oil exploration and petroleum sector expansion (Okoh et al., 2001).

The accidental leakage of petroleum products is a major environmental hazard. Hydrocarbon components are recognised to be carcinogenic and neurotoxic organic contaminants. When considerable levels of pollutants are present, the currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive.

The negative impact of pollutants on the environment has raised awareness and vigilance against pollution in the Niger Delta environment. In recent years, Nigeria has seen a significant growth in population, urbanisation, and industrial activity (Eze and Okpokwasili 2010). Oil spills, which leak crude oil into the environment, are gaining worldwide attention (Millioli et al., 2009).

Bioremediation, defined as the biological response to environmental abuse, has continued to garner study interest around the world (Hammer, 1993). Bioremediation has been defined as the utilisation of live microorganisms to break down environmental pollutants.

In other words, it is a technology for eliminating contaminants from the environment, hence restoring the natural ecosystem (Sasikuma and Papmazath, 2003). The long term aim of bioremediation designs is to propose cost effective solutions which decreases the pollutant to a level referred to as low as reasonable and practicably achievable (ALARP).

To attain this cost-effectiveness, researchers all around the world have begun to focus their attention on using organic waste as a supply of limiting nutrients for effective bioremediation (Ibiene et al., 2011).

Mechanical and chemical approaches for removing hydrocarbons from contaminated locations are inefficient and costly (Das and Chandran, 2011). Bioremediation is a promising approach for treating contaminated sites since it is cost-effective and results in complete mineralisation.

Bioremediation relies primarily on biodegradation, which can refer to the complete mineralisation of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein, or the transformation of complex organic contaminants into simpler organic compounds by biological agents such as microorganisms (Das and Preethy, 2010). Many indigenous microorganisms in water and soil can degrade hydrocarbon pollutants.