The technology of phytoremediation is cost effective and ecologically friendly in which plant utilizes its natural abilities to restore environment. In nature there are a number of plants existing with innate mechanisms for removing heavy metals from soil, air and water as a survival strategy. Among several subsets of phytoremediation, the widely studied strategies are (a) phytoextraction (b) phytofiltration (c) PHYTOVOLATILIZATION and (d) phytostabilization. Application of organic / inorganic chelants in soil directly affects the solubility of heavy metals and consequently increases their accumulation in plants that enhances phytoextraction. In the present review current knowledge about the phytoremediation and its techniques are discussed.

Background: From the global point of view, the soil is considered as the third major component of the environment, and its pollution is currently one of the most important challenges for environmental organizations worldwide, as well as the most significant environmental problems for countries. Therefore, the present study aims to comprehensively investigate the mechanisms of phytoremediation as an effective and sustainable tool for the purification of various pollutants from the soil. Materials and Methods: This study was a descriptive review conducted in 2024 to report the process of search, documentation, and screening of the PRISMA checklist for systematic reviews. The search method included articles from 2000 to 2023 using the English keywords Phytoremediation, bioremediation, soil contamination, Heavy metals in soil, and their corresponding Persian equivalents on reputable websites such as PubMed, Scopus, Web of Science, Google Scholar, Magiran, and SID. Results: After searching with relevant keywords, a total of 1021 studies were found, and based on the criteria of input and output, 50 articles were used. According to the results, the main pollutants in soil are heavy metals, BTEX pollutants, and petroleum substances, which can be effectively remediated through various phytoremediation mechanisms, including hydraulic control, phytodegradation, phytoextraction, phytostabilization, PHYTOVOLATILIZATION, rhizosphere degradation, and rhizofiltration, as a novel technology for addressing these contaminations. Conclusion: The high costs of physical and chemical methods of soil remediation have led to the utilization of phytoremediation as a more cost-effective and simple approach for soil purification. The main advantage of this method over others is its affordability and simplicity, while its disadvantages include the potential accumulation of metals in bioaccumulating plants and the consumption of contaminated plant biomass by animals, limited climatic conditions, incomplete understanding of this technology, and its lengthy duration.

Introduction: The oil industry is an important, job-creating, and feeder industry whose products are used as raw materials for other industries. One of the important environmental problems related to this industry is that oil can leak into the environment during extraction, transfer, refining, and processing. Environmental oil pollution poses a major threat to the ecosystem and human health. Therefore, the elimination of oil contaminants entering the environment, especially soil, is essential for environmental health. The current study aims to provide general information about phytoremediation and review the latest research on the use of different plants to remove oil pollutants from the environment. Additionally, several plant species with the ability to remove oil pollutants have been introduced. Materials and Methods: To conduct this study, the electronic libraries of Elsevier, Springer, and Science Information Center (SID) were searched using the keywords Phytoremediation, Oil Contamination, Plant Remediation, Oil Pollution, and Oil Pollutant. The sources were analyzed after extraction and subject classification. Results: By exploring the sources of scientific information, 10 review articles were extracted as the core and a total of 99 references were extracted and analyzed. Based on the findings, the use of plants to remove all kinds of pollutants has been introduced as one of the cost-effective and environmentally friendly methods. Among the advantages of phytoremediation, the following were mentioned: The need for small financial investment, the possibility of removing pollutants on site, proper aesthetics, preventing soil erosion, preventing the release of toxic substances, and the possibility of using this method in areas with low pollutant concentrations. According to studies, plants utilize various mechanisms, including phytoextraction, PHYTOVOLATILIZATION, phytostabilization, phytodegradation, rhizodegradation, or rhizofiltration to remove pollutants from environments. In this study, 12 plants effective in removing heavy metals and 30 plants capable of phytoremediation of oil and related toxic compounds, i. e. polycyclic aromatic hydrocarbons, were introduced. Discussion: Phytoremediation is an environmentally friendly method that is based on solar energy. It is economically reasonable and its commercialization is possible. Currently, phytoremediation technology is in its early stages and there are many technical problems to be overcome for its development. Among plants, herbaceous plants because of their high root surface area are efficient in the removal of polycyclic aromatic hydrocarbons. Currently, especially in our country, there is an urgent need to discover new plant species with the ability to tolerate and remove environmental pollutants such as oil pollution. It is also necessary to carry out research to optimize plant treatment processes, understand plant–, environment interactions, and microbial interactions and finding appropriate equipment to do it. In addition, the use of molecular techniques and the development of transgenic plants to increase the efficiency of the plant to remove toxic materials are expanding. Therefore, genetic engineering is expected to play an important role in increasing the application of plant breeding technologies. Studies on these strategies will be very useful in developing simpler and cost-effective tools for phytoremediation.