Heavy metal toxicity, sources, and remediation techniques for contaminated water and soil

Arsenic is a highly toxic metalloid that is extensively distributed in soils and water bodies, resulting in a variety of toxicity mechanisms and harmful effects on humans and environmental health. This paper comprehensively reviews the technological development in arsenic (As) removal from wastewater and contaminated soil, and provides insights into the challenges in effective arsenic removal from the environmental compartments. The arsenic removal efficiency of the available technologies is also discussed in terms of their principle of operation, efficiency, advantages, and shortcomings. Many of the existing technologies are not found economically feasible for the regions of interest or are not applicable at the community level. Some of the techniques are often responsible for producing toxic by-products. Overall, the adsorption technique demonstrated high efficiency of almost 100% and a maximum of 95% in removing arsenic from water and soil, respectively. Novel methods such as the application of nanotechnology and polymeric ligand exchangers have also been gaining traction but also seem to possess limitations similar to conventional and non-conventional techniques.