Abstract—Petroleum exploration, production, transportation and application can adversely affect the environment. Leakages from pipelines, oil wells, underground storage tanks, improper disposal of petroleum wastes and soil spills are the major sources of surface and groundwater contamination. These hydrocarbons have to be removed from the soil for environmental and health reasons as well as avoiding further contamination of surface and groundwater. Various methods are available to achieve soil habilitation. The performance of these methods depends on several factors such as amount of oil spill, oil penetration depth into the soil, soil type and as well as age and level of contamination. This study reviews various oil contaminated remediation methods such as extraction with organic solvents, extraction with aqueous solution, subcritical fluid extraction and bioremediation with bacteria. Keywords—Contamination, environment, extraction, habilitation, petroleum. I. INTRODUCTION IL production and shipping operations result in accidental contamination of soil with petroleum hydrocarbons. Petroleum refining also results in the generation of large quantities of oil sludge consisting of hydrophobic substances and substances resistant to biodegradation. Soil oil contamination also result from fuel storage tank leakages, crude oil spill sand refinery waste disposal. The soil near railroad junctions usually becomes oil contaminated because the railroad industry uses diesel oil for fuel, lubricating oil for machinery, and waste-lubricating oil on the railroad. Such sites often contain organic contaminants including benzene, toluene, ethylbenzene, and petroleum hydrocarbons (PHCs) [1]. Contamination of soils by these PHCs poses a major environmental problem, especially to the soil environment, and has caused serious health problems [2]. PHCs are highly toxic and carcinogenic substances, often produced by incomplete combustion of carbon compounds [3]. Their solubility in pure water is low [4], and they are strongly adsorbed in soils, especially onto terrestrial colloids. Also, Motshumi Joseph Diphare is with the Department of Chemical Engineering, Faculty of Engineering and the Built Environment, University of Johannesburg, Doornfontein, Johannesburg 2028, (email: [email protected]). Edison. Muzenda is a full Professor of Chemical Engineering, is with the Department of Chemical Engineering, Faculty of Engineering and the Built Environment, University of Johannesburg, Doornfontein, Johannesburg 2028, South Africa, Tel: +27115596817, Fax: +27115596430, (Email: [email protected]). small amounts of heteroatom like nitrogen and sulphur, as well as trace amounts of metals like vanadium and nickel are found in oil contaminated soil [5]. Meanwhile, the world demand for fuel has led to the exploration and production of an increasing number of petroleum hydrocarbon reserves. Therefore it is very important to recover these scarce and valuable hydrocarbons while protecting the environment. There is also an increasing demand for development of soil remediation technologies that are cost effective and sustainable [6]. It is essential to regenerate the soil to support animal and plant life, and also guard against long-term health threats to humans and other species. References [7]-[11] studied various cost effective and sustainable soil remediation technologies to regenerate oil contaminated land. These methods include surfactant solubilisation, solvent extraction, supercritical fluid extraction, hot water extraction, and various other leaching remediation techniques. Onsite incineration has been mostly used as the cheapest process for remediating contaminated soil, but negative public opinion and perception towards incineration has led to the consideration of other treatment options. Remediating oil contaminated sites could provide more land for housing development which is a challenge for developing countries due to population growth and diminishing residential land [12]. This can also make land available for agricultural activities increasing food. Solvent extraction complemented with bioremediation is an attractive approach as bioremediation has the ability to inexpensively treat a wide range of organics in all environmental media, generating little or no residues with a low carbon footprint, and causing minimal, if any, ecological effects [13]. The objective of this study is to highlight the importance of oil contaminated soil remediation, review the various treatment options paying attention on their application and limitations. II. REVIEW OF VARIOUS REMEDIATION TECHNOLOGIES A. Soil Washing with Organic Solvents Solvent extraction can be utilized to efficiently remove hydrophobic organic contaminants from soils [14]. References [15, 16] reported solvent extraction efficiencies between 75 and 99%. Reference [7] studied the extraction of pentachlorophenol from soils contaminated with wood treating Remediation of Oil Contaminated Soils: A Review Motshumi Diphare and Edison Muzenda O Intl' Conf. on Chemical, Integrated Waste Management & Environmental Engineering (ICCIWEE'2014) April 15-16, 2014 Johannesburg 180
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Remediation of Oil Contaminated Soils: A Reviewpsrcentre.org/images/extraimages/34 414042.pdfFig. 7 Subcritical water extraction apparatus [30] Fig. 8 Effect of temperature on the
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Abstract—Petroleum exploration, production, transportation and application can adversely affect the environment. Leakages from
pipelines, oil wells, underground storage tanks, improper disposal of petroleum wastes and soil spills are the major sources of surface and groundwater contamination. These hydrocarbons have to be removed from the soil for environmental and health reasons as well as avoiding further contamination of surface and groundwater. Various methods are available to achieve soil habilitation. The performance of these methods depends on several factors such as amount of oil spill, oil penetration depth into the soil, soil type and as well as age and
level of contamination. This study reviews various oil contaminated remediation methods such as extraction with organic solvents, extraction with aqueous solution, subcritical fluid extraction and bioremediation with bacteria.