The Zero Valent Iron (ZVI) is the material most commonly used for permeable reactive barriers (PRB). For technical and economic reasons, hoter reactive substances usable in alternative to ZVI are investigated. The present study takes into account a vegetable fibers, the cabuya, investigating its capacity to retain heavy metals. The capacity of the cabuya fibers to adsorb heavy metals was verified in laboratory, by batch and column tests. The batch tests were carried out with cabuya and ZVI, using copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb). The results obtained by the cabuya fibers showed a very high adsorption capacity of heavy metals and resulted very similar to those obtained for the broom fibers in a previous study. The high value of the absorption capacity of the cabuya fibers was also confirmed by the analogous comparison made with the results of the batch tests carried out with ZVI. Column tests, using copper, zinc and cadmium, allowed to determine for the cabuya fibers the maximum removal percentage of the heavy metals considered, the corresponding times and the time ranges of the release phase. For each metal considered, for a given length and three different times, the constant of degradation of cabuya fibers was determined, obtaining values very close to those reported for broom fibers. The scalar behavior of heavy metal removal percentage was verified. An electron microscope analysis allowed to compare, by SEM images, the characteristics of the cabuya and broom fibers. Finally, to investigate the chemical structure of cabuya and broom fibers, the FTIR technique was used, obtaining their respective infrared spectra.

A series of experimental batch tests has been carried out with the aim of improving the knowledge of fundamental processes related to the fate and behavior of heavy metals that can be of environmental concern in groundwater. The analysis of contaminants (i.e., Cu, Zn, Cd and Pb) dynamics in different environmental compartments is specifically addressed by comparing the removal efficiencies of different types of reactive materials, three natural (i.e., vegetal fibers, natural limestone and natural zeolite) and one synthetic (i.e., synthetic zeolite). Results stemming from these reactive media has been compared with the outcomes related to the same test performed using zero valent iron which is the reactant usually employed for heavy metals remediation. All tested reactants exhibited important removal percentages, even larger than 90% in most cases, achieved in a contact time ranging between about 12 h and slightly longer than a day (i.e., 30 h). Maximum adsorption percentages are observed for pH ranging between 4 and 8 for all tested materials and contaminants. Our findings provided relevant evidence, to both researchers and technicians, on the competitiveness of the explored alternative mediums with respect to the classical reactants usually employed for heavy metals remediation.

A filtering analysis of hydraulic head data deduced from slug tests injected in a confined aquifer with different porous media is proposed. Experimental laboratory tests were conducted in a large-scale physical model developed at the University of Calabria. The hydraulic head data were deduced from the records of a pressure sensor arranged in the injection well and subjected to a processing operation to filter the high-frequency noise. The involved smoothing techniques are the Fourier transform and two types of wavelet transform. The performances of the filtered hydraulic heads were examined for different slug volumes and four model layouts in terms of optimal fitting of the Cooper’s analytical solution. The hydraulic head variations in the confined aquifer were analyzed using wavelet transform in order to discover their energy contributions and frequency oscillations. Finally, the raw and smoothed hydraulic heads were adopted to calculate the hydraulic conductivity of the aquifer.

The growing contamination of groundwater requires increasingly remediation. Among the different reclamation techniques of contaminated aquifers, recourse is frequently made to permeable reactive barriers (PRB). To build such barriers Zero Valent Iron (ZVI) is commonly used, which shows a good reactivity towards the most part of the heavy metals. However, owing to economic reasons, and to some problems that this substance produces, reactive substances usable in alternative to zero valent iron are constantly being researched. The present study takes into account the fibers of a vegetable substance, the cabuya, investigating its capacity to retain heavy metals. Specifically, among these, Copper (Cu), Zinc (Zn), Lead (Pb) and Cadmium (Cd) were considered. The capacity of the fibers of cabuya to absorb heavy metals was verified in the laboratory, at first by batch tests and later by appropriate column tests. The same tests were carried out using also Zero Valent Iron. The results obtained for the cabuya vegetable fibers, showed a very high adsorption capacity of heavy metals and resulted very comparable to that of ZVI, without, however, showing the negative aspects of the latter. Some comparisons were also carried out with broom fibers, investigated in a previous study.