## 1 Introduction
In particular, the use of natural sorbents is emphasized, both for their low cost and the removal efficiency demonstrated in several studies. In the manuscript of [PERSON] et al. [4], peat, diatomic, vermiculite, and their mixtures were applied to remove one metalloid and five metals (As, Cd, Cr(III), Cr(VI), Cu, Pb). The best result for the removal efficiency was achieved with granular peat-diatomic, followed by large-fraction vermiculite, medium-fraction vermiculite, non-granular peat-diatomic, and diatomic. Unfortunately, one drawback was evidenced: the removal efficiency decreased with time. [PERSON] et al. [5] studied the metal adsorption by biochar in mining areas to remediate these heavily polluted soils. They investigated the Cd concentration and bioavailability in pots with loamy soil, monitoring the growth of oak seedlings in the presence of rice husk biochar. The results demonstrated that at the highest tested biochar addition (5% by weight), the bioavailability was always lower than in pots without biochar and also when the Cd concentration reached 50 mg kg\({}^{-1}\). The uptake of one metalloid and some heavy metals (As, Cd, Ce, Co, Cr, Cu, Fe, La, Mn, Ni, Pb, V, Zn) by edible plants in urban soils is the main topic of the manuscript presented by [PERSON] et al. [6]. They studied metal uptake in two common vegetables, namely, _Lactuca sativa_ and _Brassica oleracea_, grown in contaminated soils, with and without soil amendment deriving from biodegradable wastes. Specifically, the authors analyzed the aerial parts and roots of these vegetables. Then, the results were compared with the ones observed in uncontaminated soil. It was shown that the plants grown in contaminated soils absorbed the toxic elements. When soil amendment was used, the toxic element accumulation was found mainly in the roots, with a limited amount of pollutants reaching the aerial parts (i.e., the edible parts). As the last manuscript, but of no minor relevance, [PERSON] et al. [7] present the study carried out on the flow polluted with copper through a permeable membrane in the filters for contaminant removal, as occurs in Korean landfills. The experimental runs were performed in hydrophobic-coated capillary tubes to simulate the landfill in which similar flow conditions can be present. The results showed that in the center of the tube, the flow rate was always higher than near the surface, where the hydrophobic condition slowed down the hydrophilic contaminant. This also occurred when the pH was changed, namely when it increased from 4 to 10. The experimental data were modeled by computational fluid dynamics (CFD). From the applicative point of view, this means an effect by the pH condition, in terms of slowing down the flow rate by the hydrophobic surface, giving the opportunity of selective remediation. Altogether, the Special Issue collected data and results coming from different features of the same environmental issue, namely the remediation of soils polluted with heavy metals. All the studies evidenced the need to further investigate such features. Moreover, all the manuscripts highlighted the crucial point to transfer the current data to a larger scale, to obtain robust data and information for a real-scale application. In other terms, tighter cooperation between research and the industrial world is required. The Authors have given the same contribution to all the steps during the preparation of this manuscript. They have read and agreed to its published version. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Acknowledgments:** The Guest Editors would like to thank both the authors for their contribution to the Special Issue and the reviewers for their time spent to enhance the quality of the manuscripts and journal. A special thank to [PERSON] and the Editorial Office for their support. **Conflicts of Interest:** The authors declare no conflict of interest.