especially within the following parameters optimizing the conditions: temperature,
moisture content, concentration of oxygen and nutrients in the soil.
Different bioremediation approaches should be considered before the site cleanup. Enhancing the indigenous microflora by different kinds of amendments, referred
to as biostimulation, can improve the effectivity of bioremediation (Ortíz et al. 2013;
Silva et al. 2004). In case of lack of indigenous microflora with biodegradable
potential, the addition of specific bacteria able to decompose the target contaminant,
so-called bioaugmentation, is supposed to be a convenient solution (Salunkhe et al.
2015; Chen et al. 2014).
21.2 Bioremediation of Petroleum Hydrocarbons
Petroleum hydrocarbons represent the main source of energy. Due to its extensive
use in industry, contamination with TPH still poses one of the major environmental
problems to which bioremediation seems to be an effective and cheap solution.
The three different approaches (natural attenuation, landfarming, and
bioaugmentation) were compared with the treatment of TPH-contaminated soil.
The moisture content was 15–20% w/w. The highest TPH removal with 86%
efficiency was achieved in the bioaugmentation variant when compared with
landfarming where the efficiency was 70% in 90 days at 27
C (Guarino et al.
2017). In different studies (Martinéz Álvarez et al. 2017; Wang et al. 2016),
biostimulation was found to be sufficient for effective contaminant removal. While
in some cases biostimulation is more effective than bioaugmentation, in others the
addition of TPH-degrading bacteria is the best solution for petroleum hydrocarbon
removal (Guarino et al. 2017).
To enhance the bioremediation process an extensive range of amendments can be
used. Brown et al. (2017) compared in his study the effect of nutrient addition,
bulking and sorption agents, biosurfactants, earthworm enzymes, and soil neutralization. The results showed that most amendments did not prove more effective than
the fertilizer addition, only the combination of the nutrients, biochar, and
rhamnolipid facilitated the removal of TPH by 23%. The biochar function consisted
of hydrophobicity reduction, water capacity holding, and microbial colonization
(Brown et al. 2017), and rhamnolipids served as surface active compounds that
improved the bioavailability of hydrocarbons (Whang et al. 2008). Nevertheless, the
agriculture fertilizer causing the highest TPH degradation efficiency of 45% was
chosen as the best amendment for Niger Delta soils landfarming clean-up because of
its cost and performance.
In a different study, pea straw addition was evaluated as the best solution for the
bioremediation of diesel-contaminated Libyan soil (Koshlaf et al. 2016). Plant
residues such as the above-mentioned pea straw represent cheap materials that can
promote biodegradation of contaminated soils by providing essential nutrients
leading to effective bioremediation (Zhang et al. 2008).
21 Biotechnologies for Soil Treatment
439
moisture content, concentration of oxygen and nutrients in the soil.
Different bioremediation approaches should be considered before the site cleanup. Enhancing the indigenous microflora by different kinds of amendments, referred
to as biostimulation, can improve the effectivity of bioremediation (Ortíz et al. 2013;
Silva et al. 2004). In case of lack of indigenous microflora with biodegradable
potential, the addition of specific bacteria able to decompose the target contaminant,
so-called bioaugmentation, is supposed to be a convenient solution (Salunkhe et al.
2015; Chen et al. 2014).
21.2 Bioremediation of Petroleum Hydrocarbons
Petroleum hydrocarbons represent the main source of energy. Due to its extensive
use in industry, contamination with TPH still poses one of the major environmental
problems to which bioremediation seems to be an effective and cheap solution.
The three different approaches (natural attenuation, landfarming, and
bioaugmentation) were compared with the treatment of TPH-contaminated soil.
The moisture content was 15–20% w/w. The highest TPH removal with 86%
efficiency was achieved in the bioaugmentation variant when compared with
landfarming where the efficiency was 70% in 90 days at 27
C (Guarino et al.
2017). In different studies (Martinéz Álvarez et al. 2017; Wang et al. 2016),
biostimulation was found to be sufficient for effective contaminant removal. While
in some cases biostimulation is more effective than bioaugmentation, in others the
addition of TPH-degrading bacteria is the best solution for petroleum hydrocarbon
removal (Guarino et al. 2017).
To enhance the bioremediation process an extensive range of amendments can be
used. Brown et al. (2017) compared in his study the effect of nutrient addition,
bulking and sorption agents, biosurfactants, earthworm enzymes, and soil neutralization. The results showed that most amendments did not prove more effective than
the fertilizer addition, only the combination of the nutrients, biochar, and
rhamnolipid facilitated the removal of TPH by 23%. The biochar function consisted
of hydrophobicity reduction, water capacity holding, and microbial colonization
(Brown et al. 2017), and rhamnolipids served as surface active compounds that
improved the bioavailability of hydrocarbons (Whang et al. 2008). Nevertheless, the
agriculture fertilizer causing the highest TPH degradation efficiency of 45% was
chosen as the best amendment for Niger Delta soils landfarming clean-up because of
its cost and performance.
In a different study, pea straw addition was evaluated as the best solution for the
bioremediation of diesel-contaminated Libyan soil (Koshlaf et al. 2016). Plant
residues such as the above-mentioned pea straw represent cheap materials that can
promote biodegradation of contaminated soils by providing essential nutrients
leading to effective bioremediation (Zhang et al. 2008).
21 Biotechnologies for Soil Treatment
439