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Bioremediation for Sustainable Environmental Cleanup

2.2 Overview of Contamination and Remediation

2.2.1 Soil and Groundwater Contamination

Metal and metalloid (metal(loid)s) contamination is prevalent in soil, sediment, groundwater and

surface water. Contaminant release (from a point source or continuous) can be from a variety of

industrial operations. The fate and transport of contamination depends largely on the metal(loid)

present and the transport mechanisms. The characteristics of the metal(loid), i.e., speciation,

solubility, vapor pressure and partitioning coefficients dictate the fate of the pollutant in media,

while transport can be evaluated by advection, convection, diffusion or dispersion mechanisms.

The fate and transport of metal(loid) contamination can influence the area of impact and the

concentration. This can affect its impact on humans, animals and ecosystems. Figure 2.1 shows

the likely human exposure to metal(loid) contamination and the resulting consequences on bodily

systems. This highlights the potentially severe impacts contaminant release can have on humans,

but also ecosystems in general.

Figure 2.1. Human exposure to metal(loid) contamination including contact type, exposure pathways, exposure routes, and

impacted organs (Adapted from Kuppusamy et al. 2020).

2.2.2 Clean-up Strategies for Soil and Groundwater Contamination

Soil and groundwater contamination can be mitigated with various clean-up strategies.

Decontamination strategies aim to mitigate pollution via metal(loid) transformation (to a less toxic

and/or less mobile form), immobilization, or removal. Table 2.1 lists numerous soil, groundwater and

sediment clean-up strategies identifying the principal process and the overall goal of the treatment

option. Often, multiple types of remediation strategies can be applied simultaneously or in series to

achieve high efficacies of reclamation outlined by environmental and/or regulatory standards.

At present, biological remediation strategies are a topic of intensive research. These treatment

methods often provide green and sustainable solutions that adhere to environmental concerns

compared to other treatment methods (i.e., physical, thermal and chemical). Comparatively, they

emit relatively low greenhouse gas emissions and are low water and energy consuming processes.

Bioremediation strategies are typically of low cost with moderate to minimal maintenance. Due

to their biological nature, they gain public acceptance more readily and therefore, are more easily

implemented at a site.