Remediation strategies for oil spills
Oil spills have enormous adverse effects on different environmental components and result into physical, ecological changes and eco-toxicity. The severity of all consequences depend on the extent, physical and chemical properties of the oil spill, weather conditions and the sensitivity of surrounding living beings. The toxicity due the oil spills exposure may be acute/chronic on the living beings and usually depend on the duration of exposure and concentration (Ndimele et al., 2018). Therefore, it is very urgent to understand the basics, complexities of all remediation techniques for oil spills. The selection of remediation technique for oil spill is based on the type, quality and environmental conditions etc. The remediation techniques for oil spill is mainly divided into four categories: physical, chemical, biological and thermal. All these are briefly explained below:
1. Physical: The physical methods include the use of a barrier for the prevention of oil spill spreading without altering the physical and chemical properties of oil. The usually used barrier are blooms, skimmers and adsorbents to control the spread of oil to the environment (types are shown in Figure 2). The controlling of oil spills is divided into two main steps: containment and recovery. Booms are for both containment and recovery while, skimmer are useful only in recovery in the combination of booms.
2. Chemical: These generally applied in combination with the physical remediation techniques. The chemical applied are capable of altering the physical and chemical properties of oil (Vergetis, 2002). Dispersants and solidifiers are usually used chemical to remediate oil spill.
3. Biological: Biological remediation methods are based on the use of living organisms for the remediation purpose and mainly used living organisms are microorganisms and plants for the removal of petroleum from contaminated water and soil. The mainly used microorganisms (bacteria and fungi) are listed in Table 3.a and phytoremediators in Table 3.b.
4. Thermal: Thermal remediation method consisted of the in-situ burning of oil which is a rapid method and requires minimal specialized equipments. It is applied efficiently for the removal of fresh oil from calm wind environment and widely used since late 1960s (Dave et al., 2011).
Figure 2: Different remediation strategies for the remediation of oil spill
Table 3.a: List of different fungi and bacteria used in bioremediation (Source: Webb, 2005; Capotori et al., 2004)
Table 3.b: List of different potential phytoremediators
Wiltse et al., 1998
White et al., 2006
Alarcon et al., 2008
Cai et al., 2010
Boonsaner et al., 2011
Atagana et al., 2011
Basumatary et al., 2012
Kuo et al. 2013
(Iris dichotoma Pall. and Iris lactea Pall
Cheng et al., 2016
Al-Mansoory et al., 2017
It can be concluded that oil spills have a wide spectrum of consequences on the living organisms and the restoration of petroleum contaminated aquatic and terrestrial ecosystem is quite complex process. Therefore, there is a need of more such remediating technologies which are quick, economic, simpler and easy to conduct in response of quick emergencies like oil well blowout, wide scale accidental leakage during storage and transportation.