REMEDIATION OF POLLUTED SOILS

This study investigated the application of magnetic granular activated carbon (MGAC) in soil washing process for the removal of polycyclic aromatic hydrocarbons (PAHs) from real contaminated soil. The magnetic composite was prepared using a facile-modified co-precipitation method. The presence of the synthesized magnetite (Fe₃O₄) nanoparticles on the composite surface was confirmed by the SEM and XRD characterization tests. The surface area and total pore volume of MGAC were determined to be 837.9 m²/g and 0.5 cm³/g, respectively, which were approximately 10% smaller than those for the bare GAC. The Langmuir model fitted the adsorption isotherm data the best; therefore, monolayer adsorption was predominant in the treatment process with MGAC. The maximum PAH adsorption capacity of MGAC was obtained at 153.5 µg/mg for the total PAHs, which was nearly 20% lower than that of bare GAC (190.3 µg/mg). The soil washing parameters were optimized, and the results demonstrated that the total PAH removal reached a maximum of 47.4% at an MGAC dose of 2% (w/w), washing time of 24 h, a liquid-to-soil ratio of 15:1, stirring speed of 100 rpm, pH of 8.3, and a temperature of 25 °C. For low molecular weight (LMW) PAHs, the removal from soil ranged from 34.6% to 57.7%, whereas the removal percentage of high molecular weight (HMW) PAHs was determined to be between 27.9 and 67.1 %. This indicated that the optimized soil washing with MGAC had a better efficiency for some HMW PAHs than the LMW PAHs. According to the thermodynamic studies, the adsorption of PAHs onto MGAC in the soil washing process was non-spontaneous (ΔG° > 0) and endothermic (ΔH° > 0) with increased randomness at the solid/solution interface of MGAC as temperature increases. The obtained results confirmed the efficiency of the magnetized activated carbon as adsorbent in soil washing to remove the hazardous PAH compounds from soil.

Heavy metal pollution is one of the most critical concerns of communities, which challenges health and global sustainability. Non-biodegradable heavy metals such as cadmium, arsenic, lead, mercury, etc., enter the food chain, causing severe health complications. Therefore, it is crucial to constantly check the heavy metal trace in food, water, and the environment and remediate them properly. Although the practical implication of nanomaterials for pollutant remediation is still arguable but, nanotechnology would be a sustainable approach for tackling heavy metals remediation in the future. In this comprehensive review, first of all a brief overview were provided on the conventional heavy metals remediation methods. In the next section after a brief introduction on nanomaterial, critical outlooks were taken on the recent heavy metals nano-remediation approaches including adsorption, filtration, photolysis and so on. Finally, further recommendation on the practical implication of nanotechnology for remediation of heavy metals were provided for the better and sustainable removal of heavy metals in the future.

One of the serious environmental concern around the world is heavy metals contamination. They can enter to the environment through human activities such as mining, farming, and factory activities. Soil contamination by heavy metals can affect crops, enter the food chain and threat human health. Therefore, clearance of the soil from these heavy metals is one of the most important environmental issues. Up to now, different strategies are introduced for heavy metals remediation of soil and some of them were briefly reviewed, here. We were mainly focus on the soil remediation from heavy metals which has the highest percentage of abundance in the contaminated soil, namely arsenic, lead, cadmium, nickel, mercury, iron, copper, and zinc by plants (phytoremediation). On the other hand, different kinds of plants, including trees, flowers, grasses, vegetables, and ferns that can help clean these metals from the soil, are introduced. Growth conditions of these plants, such as light and water, were also studied, and it was found that 48% plants require partial sunlight, and 50% of plants grew in moist soil. They were also classified based on their biological ages, and it was found 68% of plants were perennials and had more than two years of lifespan. Among these plants, some of them are capable of capturing several heavy metals simultaneously, and they are called as Valuable Phytoremediation Plants and they are more useful for soil remediation from heavy metals. It seems that present study can help environmental officials and governments to find a sustainable solution to get rid of heavy metals hazardous on mines ecosystem.

Soil pollution is one of the main environmental issues worldwide. The intensive use of the soil for industrial and agricultural purposes increases the necessity of recovering brownfields and other polluted emplacements. There are many remediation technologies used until now for this aim, with nanoremediation and bioremediation being the most successful ones in terms of effectiveness and cost. On the one hand, zerovalent iron nanoparticles and their derivatives have been described as highly favorable remediation agents, being extensively used in soil and groundwater remediation. On the other hand, bioremediation, compared with nanoremediation that requires more time to reduce the same amount of pollutants, has many biological benefits, including making the soil ready for reuse. Considering the advantages and disadvantages of both technologies, a combined technology known as nanobioremediation has been developed, which acts as an extremely interesting alternative to merge the main advantages of nano- and bioremediation. In this chapter, the main aspects of nanoremediation and bioremediation are reviewed, and some examples of their use on full-scale applications are described. Finally, the application of a combined method, that is, nanobioremediation, is described.

The objective of this current review article is to evaluate the current knowledge of the contaminated soil in the study area based on reports and the results of previous experimental studies in the literature and to discuss the feasibility of phytoremediation with biofuel production using energy crops. The results indicated that the soil contamination was related mainly to the thermal power plant and mining activities in Kütahya, high industrial activity in İzmir, heavy metal and radioactive pollution in Manisa and Muğla. Moreover, the sources of the contamination are geothermal resources and transportation in Aydın and Denizli, respectively. However, soil pollution in Afyonkarahisar and Uşak provinces has not been discussed due to a lack of detailed reports and data in the literature. Besides, energy crops such as Zea mays, Ricinus communis, and Gossypium hirsitum were identified as appropriate candidates for İzmir, Denizli, Manisa, and Aydın due to being resistant to the arid climate. In Muğla province, Eucalyptus grandis and Eucalyptus bicostata can be cultivated because of having adaptation to moderate climatic conditions. Ricinus communis and Helianthus annuus were determined to be very suitable energy crops for the phytoremediation of many heavy metals in Kütahya. The review promotes the development of economic, environmental, and social benefits to regain the contaminated areas through phytoremediation. The findings of the study are important for creating sustainable solutions for remediation of polluted soils in Turkey, as well as for shedding light on the process of establishing appropriate policies to make soils contaminated suitable for agriculture.

With the new soil uses such as land restoration and to protect wilderness, the human health risk assessment (HHRA) and environmental risk assessment (ERA) should be combined. Based on the relationships demonstrated between an indicator of soil quality, the land snail, and human exposure, the aim of this study is to examine the snail and human risk indicators for twenty-nine soils contaminated by metal(loid)s. HHRA was evaluated by both hazard quotient and carcinogenic risk. When the human health indicators were ranked as uncertain, they were weighted by bioaccessibility to refine the risk assessment. The ERA was performed with risk coefficient after ex situ snail exposure. The results showed strong and novel relationships between human health and environmental risk indicators that had never been found before. For 62% of the soils, both indicators revealed either a confirmed risk or an uncertain level of risk. Overall pollutants present greater risk for human than for environment, with 55 vs 28% of the studied soils classified in the proven risk, respectively. An original integrative risk assessment of polluted soils has been proposed, that shall help setting up relevant strategies to manage contaminated soils considering not only human but also environmental indicators of risk.