Page 38 - Plant-Based Remediation Processes

2 Protocols for Applying Phytotechnologies in Metal-Contaminated Soils 25

Table 2.1 Micro steps characterizing each phase in a phytotechnology
Sequential period Type of investigation
Ante operam phase Site characterization
Plant and treatment selection
Organization and preparation of site intervention
Sowing
Control of plant growth
In itinere phase Agronomic care and administration of any fertilizer
Administration of the chelating agent if necessary
System monitoring
Plants harvesting
Post operam phase Safety of the site
Waste management
System monitoring

• Ante operam phase (preoperational)
• In itinere phase (during the process)
• Post operam phase (post-operational)
Each of these phases is characterized by micro-steps aimed at providing the
necessary basic information for site characterization. Table 2.1 shows the micro-
steps characterizing each of the three main sequential steps, above. In Fig. 2.1,is
shown the flow chart of the procedure for the evaluation of the applicability of in
situ phytoextraction. The efficiency of phytoextraction is difficult to assess and
depends on the nature of contaminants, additive specifications (if used), plant
characteristics, and the environmental and soil conditions. To better enhance
phytoextraction efficiency, preliminary tests at a laboratory scale and at a green-
house scale are fundamental, but treatment, biomass, and plant performance are
also severely influenced by local environmental conditions. For these reasons, field
tests for phytoremediation applicability should be planned for a more realistic
estimation of its effectiveness at a specific contaminated site. As for other
technologies, treatability could require time and money, but results are fundamental
and can be responsible for the success or failure of the project, and can at the end
reduce costs. A scheme that could be adopted is subdivided in three steps, which is
shown in Fig. 2.2 and briefly indicated below:

First step: characterization of chemical and physical characteristics of the soil
matrix
Second step: selection of plant species and/or treatments to be used in phytoextraction
Third step: evaluation through a field-scale pilot test
The first step should be conducted directly on the specific contaminated site
in order to evaluate the level of contamination, the agronomic characteristics, and
a screening of the indigenous vegetation. The following analyses have to be
carried out: