Salinity
In estuarine sediments, there is a positive relation between polycyclic aromatic
hydrocarbons mineralization rate and salinity (Kerr and Capone 1988). Some studies
have reported that the evaporation of salt ponds shows that the rate of hydrocarbon
metabolism is highly reduced with increased salinity range of 3.3–28.4% because of
a general decline in the rate of microbial metabolism (Al-Hawash et al. 2018).
Salinity has an important effect on biodegradation and bioremediation processes; it
affects the diversity and growth of microbes and has a harmful effect on the activity
of some principal enzymes in the degradation of hydrocarbons (Qin et al. 2012;
Ebadi et al. 2017).
pH
The pH must be considered to improve biological treatment methods. Catalytic
reaction balance, cell membrane transport, and activities of enzyme are influenced
by the environmental pH (Bonomo et al. 2001). Many of the heterotrophic bacteria
grow in a neutral to alkaline pH compared to the pH of many aquatic ecosystems
(Jain et al. 2011). The acidity of soil can widely vary between pH 2.5 and 11 in
alkaline deserts. Generally, bacteria and fungi prefer almost neutral pH; however,
fungi can bear the acidic pH. The microbial mineralization of octadecane and
naphthalene occurs at pH of 6.5 (Al-Hawash et al. 2018). It has been reported that
the highest level of crude oilbiodegradation in water by Pseudomonas aeruginosa is
at pH ¼ 8.0. Moreover, the highest rate of biodegradation in an oil sludge sample is
at pH 7.8 (Al-Hawash et al. 2018).
Activity of Water
In terrestrial ecosystems, the treatment of hydrocarbons can be limited due to the
available water for metabolism and growth of microbes. In oil sludge, the optimal
biodegradation is in 30–90% water saturation (Al-Hawash et al. 2018). The growth
and movement of microorganism are directly influenced by availability of water.
Microbial Community
The main factor that contributes to biodegradation is availability of yeast, bacteria,
fungi, and some algae that catabolize pollutants. Hydrocarbons in crude oil are the
source of food for microorganisms that may be available in high levels near the sites
contaminated by oils like crude oil: ports, oil fields, shipping lanes, gas stations,
seeps, and other facilities.
12 Remediation of Pollution by Oil Spills
479
In estuarine sediments, there is a positive relation between polycyclic aromatic
hydrocarbons mineralization rate and salinity (Kerr and Capone 1988). Some studies
have reported that the evaporation of salt ponds shows that the rate of hydrocarbon
metabolism is highly reduced with increased salinity range of 3.3–28.4% because of
a general decline in the rate of microbial metabolism (Al-Hawash et al. 2018).
Salinity has an important effect on biodegradation and bioremediation processes; it
affects the diversity and growth of microbes and has a harmful effect on the activity
of some principal enzymes in the degradation of hydrocarbons (Qin et al. 2012;
Ebadi et al. 2017).
pH
The pH must be considered to improve biological treatment methods. Catalytic
reaction balance, cell membrane transport, and activities of enzyme are influenced
by the environmental pH (Bonomo et al. 2001). Many of the heterotrophic bacteria
grow in a neutral to alkaline pH compared to the pH of many aquatic ecosystems
(Jain et al. 2011). The acidity of soil can widely vary between pH 2.5 and 11 in
alkaline deserts. Generally, bacteria and fungi prefer almost neutral pH; however,
fungi can bear the acidic pH. The microbial mineralization of octadecane and
naphthalene occurs at pH of 6.5 (Al-Hawash et al. 2018). It has been reported that
the highest level of crude oilbiodegradation in water by Pseudomonas aeruginosa is
at pH ¼ 8.0. Moreover, the highest rate of biodegradation in an oil sludge sample is
at pH 7.8 (Al-Hawash et al. 2018).
Activity of Water
In terrestrial ecosystems, the treatment of hydrocarbons can be limited due to the
available water for metabolism and growth of microbes. In oil sludge, the optimal
biodegradation is in 30–90% water saturation (Al-Hawash et al. 2018). The growth
and movement of microorganism are directly influenced by availability of water.
Microbial Community
The main factor that contributes to biodegradation is availability of yeast, bacteria,
fungi, and some algae that catabolize pollutants. Hydrocarbons in crude oil are the
source of food for microorganisms that may be available in high levels near the sites
contaminated by oils like crude oil: ports, oil fields, shipping lanes, gas stations,
seeps, and other facilities.
12 Remediation of Pollution by Oil Spills
479