bioremediation were studied in details. Moreover, some case studies that have
considered the bioremediation in different locations were reviewed.
12.2 Oil Spills
12.2.1 Characteristics of Oil Spills
Waste oil, gasoline, diesel, heavier fuels, oily white refuse, and crude oil are the
components of marine oil spills (Dave and Ghaly 2011). After an oil spill, chemical
and physical changes occur in the oil (Annunciado et al. 2005). Different weathering
processes such as spreading, drifting, evaporation, dissolution, biodegradation,
photolysis, and formation of water–oil emulsions that change the oil viscosity,
density and interfacial tensioner processes result from the formation of oil slicks
(Daling and StrØm 1999). All these processes form the chocolate mousse and tar ball
(Daling and StrØm 1999). Also, formation of many other products is a challenge to
oil recovery. Photolysis of oil results in oxygenated products like benzoic acid,
aliphatic, aromatic, naphthanoic acids, alcohols, aliphatic ketones, and phenols
(Hussein et al. 2009). The quantity of oil and its physical and chemical properties
affect transformation and weathering processes. Crude oil includes aliphatic and
aromatic hydrocarbons. According to their types, their degradation by microorganism can be easy or complex. Two complex degradation classes of hydrocarbons are
aliphatic hydrocarbons with long-chain and polycyclic aromatic hydrocarbons,
which are carcinogenic, cytotoxic, and genotoxic (Hasanuzzaman et al. 2007).
12.2.2 Physical Characteristics
The surface tension, color, viscosity, and specific gravity are the physical properties
of oil. These properties change based on the kind of spilled oil in waters. The brown
and black color of oil can become red, green, and yellow (Dave and Ghaly 2011).
The surface tension, viscosity, and specific gravity determine the capacity of oil spill
to spread. The surface tension of oil is affected by temperature and in warmer
watersthe spreading tendency of oil increases. A lower surface tension of oil
means it has a higher and quicker ability to spread even without wind or waves.
Most of the oils have a lower density than that of seawater; therefore, they float on
the water surface and horizontally disperse but the lighter components of oil can
evaporate and increase the oil gravity. This allows the formation of tar balls for
heavier oils, which can interact with sediments and rocks in the bottom of water after
the oils sink. Oils with higher viscosity tend to spread out less, and form a “chocolate
mousse” that is difficult to degrade or treat (Dave and Ghaly 2011). According to the
report of Nordvik et al. (1996) 10–50
C increase in temperature decreases the
density and viscosity of oil from 0.88 to 0.855 kg/dm
3 and 5000 to 200 cSt,
12 Remediation of Pollution by Oil Spills
391
considered the bioremediation in different locations were reviewed.
12.2 Oil Spills
12.2.1 Characteristics of Oil Spills
Waste oil, gasoline, diesel, heavier fuels, oily white refuse, and crude oil are the
components of marine oil spills (Dave and Ghaly 2011). After an oil spill, chemical
and physical changes occur in the oil (Annunciado et al. 2005). Different weathering
processes such as spreading, drifting, evaporation, dissolution, biodegradation,
photolysis, and formation of water–oil emulsions that change the oil viscosity,
density and interfacial tensioner processes result from the formation of oil slicks
(Daling and StrØm 1999). All these processes form the chocolate mousse and tar ball
(Daling and StrØm 1999). Also, formation of many other products is a challenge to
oil recovery. Photolysis of oil results in oxygenated products like benzoic acid,
aliphatic, aromatic, naphthanoic acids, alcohols, aliphatic ketones, and phenols
(Hussein et al. 2009). The quantity of oil and its physical and chemical properties
affect transformation and weathering processes. Crude oil includes aliphatic and
aromatic hydrocarbons. According to their types, their degradation by microorganism can be easy or complex. Two complex degradation classes of hydrocarbons are
aliphatic hydrocarbons with long-chain and polycyclic aromatic hydrocarbons,
which are carcinogenic, cytotoxic, and genotoxic (Hasanuzzaman et al. 2007).
12.2.2 Physical Characteristics
The surface tension, color, viscosity, and specific gravity are the physical properties
of oil. These properties change based on the kind of spilled oil in waters. The brown
and black color of oil can become red, green, and yellow (Dave and Ghaly 2011).
The surface tension, viscosity, and specific gravity determine the capacity of oil spill
to spread. The surface tension of oil is affected by temperature and in warmer
watersthe spreading tendency of oil increases. A lower surface tension of oil
means it has a higher and quicker ability to spread even without wind or waves.
Most of the oils have a lower density than that of seawater; therefore, they float on
the water surface and horizontally disperse but the lighter components of oil can
evaporate and increase the oil gravity. This allows the formation of tar balls for
heavier oils, which can interact with sediments and rocks in the bottom of water after
the oils sink. Oils with higher viscosity tend to spread out less, and form a “chocolate
mousse” that is difficult to degrade or treat (Dave and Ghaly 2011). According to the
report of Nordvik et al. (1996) 10–50
C increase in temperature decreases the
density and viscosity of oil from 0.88 to 0.855 kg/dm
3 and 5000 to 200 cSt,
12 Remediation of Pollution by Oil Spills
391