Land Use

and

and

and

and

Figure 2.3. Selection process for clean-up strategy incorporating site assessment, land use requirements, feasibility and

implementation (Adapted from Wilcox et al. 2022).

32

Bioremediation for Sustainable Environmental Cleanup

An overview of reactor designs for ex-situ bioprecipitation is described in Table 2.5. In addition

to the design itself, a reactor can operate under different modes or various stages. The operation

mode refers to how the influent is added to the reactor, i.e., batch, continuous or semi-continuous

application. The stages refer to the sequence of operations. In a one-stage process bioprecipitation

occurs in one reactor, while a two-stage process will separate mechanisms (i.e., oxidative-reductive

processes and precipitation) to occur in different reactors (Sánchez-Andrea et al. 2014).

2.3.3 Strategy Implementation

The implementation of a remediation strategy is developed based on the robust site assessment data.

Samples of polluted soil, sediment and/or water are collected from the affected site to analyze the

contaminant(s) and its potential hazard after release. Site characteristics (i.e., location, geology,

weather, topography, etc.) are all documented or measured to evaluate the extent of potential

contamination over time and brainstorm viable remediation options. The land use requirements

are considered to establish project objects and outline environmental and regulatory standards.

The desired future land use post contamination is evaluated and predicted to best suit the needs

of nearby communities. A contaminated site should always be left in a state equal to or better than

it was before contamination. Remediation strategies that adhere to the project objectives and site

assessment are discussed, addressing the operation efficacy for each scenario, public acceptance

and its green and sustainable nature. An optimal strategy is selected based on feasibility (i.e., cost,

operation and maintenance and time to execute). If a solution is deemed unfeasible, alternative

remediation solutions are established. After iterations of the process, a remediation strategy is

selected and implemented at the site. Figure 2.3 outlines the process and various components that

engineers take into consideration.

Laboratory testing is essential to the performance of a selected biological remediation strategy.

Testing is required to ensure the microorganism mixture or species, energy source and design all

functions to achieve high rates of immobilization, biotransformation or removal of the metal(loid)

2–

2–

contaminant. During testing, the C/N, COD/SO4

and DOC/SO4

ratios can be measured and

documented as indicators for performance. Further, laboratory testing can evaluate different modes

of operation scenarios (i.e., feed mode, hydraulic load rate, HRT, etc.) to establish an optimal

efficacy. Laboratory testing at initial stages of brainstorming can have beneficial impacts to the

design, impacting its timeframe and cost. This can therefore affect the sustainability of a selected

strategy.