**5.4 Bioreactor**

Bioreactor is a vessel in which raw materials are converted to specific product(s) following series of biological reactions. There are different operational modes of bioreactors, which include: batch, fed-batch, sequencing batch, continuous and multistage. Bioreactor provides optimal growth conditions for bioremediation. Bioreactor filled with polluted samples for remediation process. The bioreactor based treatment of polluted soil has several advantages as compared to ex-situ bioremediation procedures. Bioreactor-based bioremediation process having excellent control of pH, temperature, agitation and aeration, substrate and inoculum concentrations efficiently reduces bioremediation time. The ability to control and manipulate process parameters in a bioreactor implies that biological reactions. The flexible nature of bioreactor designs allows maximum biological degradation while minimizing abiotic losses [21].

**227**

**5.5 Bioventing**

*Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations…*

• Biodegradation are greater in a bioreactor system than or in solid-phase

systems because the contaminated environment is more manageable and more

• Not applicable to heavy metal contamination or chlorinated hydrocarbons such

• The contaminant can be stripped from soil via soil washing or physical extrac-

These techniques comprise treating polluted substances at the pollution site. It does not need any excavation and by little or no disturbance in soil construction. Perfectly, these techniques should to be cost effective compared to ex-situ bioremediation techniques. Some in-situ bioremediation techniques like bioventing, biosparging and phytoremediation may be enhanced, while others may be progress without any form of improvement such as intrinsic bioremediation or natural attenuation. In-situ bioremediation techniques have been effectively used to treat chlorinated solvents, heavy metals, dyes, and hydrocarbons polluted sites [22–24].

In-situ bioremediation is two types; these are intrinsic and engineered

technique is less expensive compared to other in-situ techniques.

cal conditions to encourage the growth of microorganisms.

ii.Engineered in-situ bioremediation

Intrinsic bioremediation also known as natural reduction is an in-situ bioremediation technique, which involves passive remediation of polluted sites, without any external force (human intervention). This process deals with stimulation of indigenous or naturally occurring microbial population. The process based on both microbial aerobic and anaerobic processes to biodegrade polluting constituents containing those that are recalcitrant. The absence of external force implies that the

The second approach involves the introduction of certain microorganism to the site of contamination. Genetically Engineered microorganisms used in the in-situ bioremediation accelerate the degradation process by enhancing the physicochemi-

Bioventing techniques involve controlled stimulation of airflow by delivering oxygen to unsaturated (vadose) zone in order to increase activities of indigenous microbes for bioremediation. In bioventing, amendments are made by adding

*DOI: http://dx.doi.org/10.5772/intechopen.90453*

controllable and predictable.

• Non-permeable soil requires additional processing.

tion before being placed in bioreactor.

*5.4.1 In-situ bioremediation techniques*

*5.4.2 Types of in-situ bioremediation*

i.Intrinsic bioremediation

bioremediation.

Disadvantages

as trichloroethylene.

Advantages of ex-situ bioremediation


*Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations… DOI: http://dx.doi.org/10.5772/intechopen.90453*

• Biodegradation are greater in a bioreactor system than or in solid-phase systems because the contaminated environment is more manageable and more controllable and predictable.
