ABSTRACT
Environmental pollution is escalating at an alarming rate due to human activities such as rapid urbanization, technological innovation, improper farming practices, and industrialization. Among all concerns, heavy metal contamination has been identified as one of the most critical environmental risks. Heavy metals contamination in the environment is persistent due to their toxicity, and it causes even risks to human lives. Even though some metals are essential components for plants and animals, high quantities of metals disrupt metabolic activities in organisms. Conventional chemical and physical treatments, typically expensive and ineffectual when metal 100concentrations are low, produce considerable amounts of toxic sludge. As a remedy, bioremediation is an eco-friendly technique that can be employed for cleaning up such polluted areas from heavy metal contamination. It uses bacteria and plants to eliminate pollutants through biological mechanisms to restore the environment. The basic concepts of bioremediation entail modifying pH, redox processes, and adsorption of contaminants from polluted environments. Phytoremediation applies plants and rhizospheric microbes to clear up organic and metal pollutants. This approach is advantageous as it is affordable, sustainable, and effective in restoring polluted areas, especially heavy metals. The effectiveness of phytoremediation is influenced by the amount of metal pollutant content in the soil and the ability of plants to take up metals from the soil actively. The removal of heavy metals from contaminated soils by plants involves several processes. Phytoextraction employs the technique of hyperaccumulation to remove metal contaminants from the soil and transport them into the plants’ above-ground components through the roots. Rhizofiltration (the use of plant roots), blastofiltration (the use of seedlings), and caulofiltration (the use of excised plant shoots) are the three types of phytofiltration. It is the use of plant roots or seedlings from aqueous wastes to clean up polluted areas. Rhizofiltration is the process of removing contaminants from groundwater by filtering them through plant roots. Rhizofiltration uses the plant’s rhizospheric accumulation mechanism. Plants that can absorb and resist high quantities of hazardous metals, such as hyperaccumulators, are ideal for rhizofiltration. Phytostimulation stands for stimulating microbial activity to break down organic pollutants by exudates from plant roots. Soil contaminants are absorbed and stabilized by plant roots in the rhizosphere, inhibiting their spread into the environment. Plants remove soil pollutants via phytovolatilization, converting them into vapor and releasing them into the atmosphere. The metabolic potentials of plants in conjunction with rhizosphere bacteria convert pollutants into volatile forms during phytovolatilization. Phytodegradation is another process of breaking down pollutants by plant enzymes. Rhizospheric microorganisms could also facilitate the breakdown of organic contaminants in soil via the rhizodegradation process. Furthermore, understanding plant pathways for metal detoxification is critical for developing genetically altered plants with phytoremediation potential. Therefore, this chapter explores the environmental consequences of heavy metal pollution and how phytoremediation can effectively repair the damage. Moreover, it also discusses how these organisms remove heavy metals from the environment or how do they perform that function while the detoxification of heavy metals by plants is also taken into consideration.
