Bioremediation: A Sustainable Approach for Environmental Cleanup 3
as bioaugmentation involves the use of different cultured microorganisms to degrade soil and
water contaminants. Microorganisms must enzymatically attack contaminants and transform them
into harmless compounds for bioremediation to be efficient (Vidali 2001). Since environmental
conditions must be favorable for microbial development for bioremediation to be effective,
environmental parameters are regulated/monitored to accelerate microbial growth and deterioration.
Bioremediation procedures are often less expensive than traditional methods like incineration, and
certain contaminants may be treated on-site, lowering exposure hazards for cleanup workers and
possibly broader exposure due to transportation problems. Bioremediation is more widely accepted
than other approaches since it is based on natural attenuation. Most bioremediation systems are
operated under aerobic circumstances; however, operating one under anaerobic conditions may
allow microbial organisms to degrade compounds that are typically resistant to degradation (Colberg
and Young 1995).
1.4 Types of Bioremediation
The bioremediation process is divided into in-situ and ex-situ based on the origin and removal of
pollutants, as shown in Figure 1.1.
In situ
Ex situ
Figure 1.1. Types of bioremediation techniques (Tyagi and Kumar 2021).
1.4.1 In-situ Bioremediation
In-situ bioremediation is defined as the process of degrading the contaminants in a naturalistic
environment to produce carbon dioxide and water. It is a low-cost, low-maintenance, environmentally
beneficial and long-term solution for contaminated site cleaning (Aggarwal et al. 1990, Jørgensen,
2007, Megharaj et al. 2011, Latha and Reddy 2013). In-situ bioremediation is most commonly
used to degrade pollutants in saturated soils and groundwater. This technique is basically applied
to polluted material on-site. Some of the examples of in-situ bioremediation strategies as shown in
Figure 1.1 are described next.