environmental parameters, enhanced mass transfer, and effective use of inoculants
and surfactants. It is a relatively expensive technique that limits its use in bioremediation program, e.g., slurry reactor and aqueous reactor (Zaidi et al. 2012; Vidali
2001).
8.5.8 Composting
It is a type of ex situ and cost-efficient bioremediation program. It is the process of
the aerobic and thermophilic treatment in which contaminated soil is mixed with a
bulking agent. The development of a rich microbial population and the elevated
temperature are a characteristic of composting (Vidali 2001). The extended treatment time is the limitation of the composting (Zaidi et al. 2012).
8.5.9 Land Farming
It is a simple type of ex situ and cost-efficient bioremediation technique in which
contaminated soil is excavated and spread over a prepared bed and intermittently
plowed until contaminants are degraded (Vidali 2001) or it is a solid-phase treatment
system for contaminated soil or maybe in constructed soil treatment cell. The space
requirement is the limitation of land farming (Zaidi et al. 2012).
8.6 Plant Growth-Promoting Rhizobacteria
Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria living in the
soil in association with plant roots and are known to enhance the plant growth
through a variety of direct and indirect mechanisms (Asad 2017) (Fig. 8.3). Direct
mechanisms include nitrogen fixation, phosphate solubilization, potassium solubilization, phytostimulation, siderophore production which limits the Fe activity
(Bhattacharyya and Jha 2012), heavy mineral uptake by plants (Ma et al. 2011),
etc. while indirect mechanisms include antibiotics production, chitinase and
glucanase activity, induced systemic resistance against plant diseases which is
termed as systemic resistance, exopolysaccharide production, phytoremediation
(Nadeem et al. 2014), etc. The PGPR facilitate plant growth under stressful environmental conditions by producing some key enzymes such as ACC-deaminase,
chitinase, and rhizobitoxine exopolysaccharides.
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M. K. Chitara et al.
and surfactants. It is a relatively expensive technique that limits its use in bioremediation program, e.g., slurry reactor and aqueous reactor (Zaidi et al. 2012; Vidali
2001).
8.5.8 Composting
It is a type of ex situ and cost-efficient bioremediation program. It is the process of
the aerobic and thermophilic treatment in which contaminated soil is mixed with a
bulking agent. The development of a rich microbial population and the elevated
temperature are a characteristic of composting (Vidali 2001). The extended treatment time is the limitation of the composting (Zaidi et al. 2012).
8.5.9 Land Farming
It is a simple type of ex situ and cost-efficient bioremediation technique in which
contaminated soil is excavated and spread over a prepared bed and intermittently
plowed until contaminants are degraded (Vidali 2001) or it is a solid-phase treatment
system for contaminated soil or maybe in constructed soil treatment cell. The space
requirement is the limitation of land farming (Zaidi et al. 2012).
8.6 Plant Growth-Promoting Rhizobacteria
Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria living in the
soil in association with plant roots and are known to enhance the plant growth
through a variety of direct and indirect mechanisms (Asad 2017) (Fig. 8.3). Direct
mechanisms include nitrogen fixation, phosphate solubilization, potassium solubilization, phytostimulation, siderophore production which limits the Fe activity
(Bhattacharyya and Jha 2012), heavy mineral uptake by plants (Ma et al. 2011),
etc. while indirect mechanisms include antibiotics production, chitinase and
glucanase activity, induced systemic resistance against plant diseases which is
termed as systemic resistance, exopolysaccharide production, phytoremediation
(Nadeem et al. 2014), etc. The PGPR facilitate plant growth under stressful environmental conditions by producing some key enzymes such as ACC-deaminase,
chitinase, and rhizobitoxine exopolysaccharides.
210
M. K. Chitara et al.