Dose-related effect of fly ash on edaphic properties in laterite cropland soil

A comprehensive review on phytoremediation of fly ash and red mud: exploring environmental impacts and biotechnological innovations

Fly ash (FA) and red mud (RM) are industrial byproducts generated by thermal power plants and the aluminum industry, respectively. The huge generation of FA and RM is a significant global issue, and finding a safe and sustainable disposal method remains a challenge. These dumps contain harmful trace elements that have a significant impact on the environment and human health. It contributes to air, water, and soil pollution, disrupting the delicate balance of the ecosystems. It also introduces toxins into the food chain through biomagnification. Utilizing a vegetation cover can assist in addressing environmental health concerns associated with FA and RM dumps. Nevertheless, the presence of alkaline pH, toxic metals, the absence of soil microbes, and the pozzolanic properties of both FA and RM pose challenges to plant growth. Taking a comprehensive approach to the ecological restoration of these dumps through phytoremediation is crucial. This review examines the role of various factors in the ecological restoration of FA and RM dumps, specifically the use of naturally occurring plants. However, the issue of slow plant growth due to a lack of nutrients and microbial activities is being resolved through various advances, such as amendments in conjunction with organic matter, microbial inoculants, and the use of genetically modified plants. Research has demonstrated the benefits of using amendments to stimulate vegetation growth on FA and RM dumps. In this review, we explore various approaches to restoring FA and RM dumps and transforming them into productive sites that enhance the ecosystem services.

Land application of industrial wastes: impacts on soil quality, biota, and human health

Globally, waste disposal options such as landfill, incineration, and discharge to water, are not preferred long-term solutions due to their social, environmental, political, and economic implications. However, there is potential for increasing the sustainability of industrial processes by considering land application of industrial wastes. Applying waste to land can have beneficial outcomes including reducing waste sent to landfill and providing alternative nutrient sources for agriculture and other primary production. However, there are also potential hazards, including environmental contamination. This article reviewed the literature on industrial waste applications to soils and assessed the associated hazards and benefits. The review investigated wastes in relation to soil characteristics, dynamics between soils and waste constituents, and possible impacts on plants, animals, and humans. The current body of literature demonstrates the potential for the application of industrial waste into agricultural soils. The main challenge for applying industrial wastes to land is the presence of contaminants in some wastes and managing these to enhance positive effects and reduce negative outcomes to within acceptable limits. Examination of the literature also revealed several gaps in the research and opportunities for further investigation: specifically, a lack of long-term experiments and mass balance assessments, variable waste composition, and negative public opinion.

Arbuscular mycorrhizal fungi and exogenous glutathione mitigate coal fly ash (CFA)-induced phytotoxicity in CFA-contaminated soil

Coal fly ash (CFA) makes a bulk of the coal combustion wastes generated from coal-fired power plants. There are several environmental mishaps due to coal ash spills around the world and in the United States. Management of CFA-polluted sites has proven inefficient resulting in soil infiltration, leaching, and phytotoxicity. This study assessed the mitigation strategies for CFA-induced phytotoxicity using biological [arbuscular mycorrhizal fungi (AMF)] and chemical [exogenous glutathione (GSH)] agents. Indices of phytotoxicity include seed germination, plant morphometrics, lipid peroxidation and genomic double-stranded DNA (dsDNA) in switchgrass plant (Panicum virgatum). Experiments include laboratory screening (0, 5, 10, 15 and 20% w/w CFA/soil) and greenhouse pot study (0, 7.5 and 15% w/w CFA/soil) culturing switchgrass plant in Armour silt loam soil co-applied with AMF (Rhizophagus clarus) and GSH. Experiments showed that CFA exposure caused a concentration-dependent increase in seed germination. 10% CFA increased seedling growth while 15 and 20% CFA decreased seedling growth and induced leaf chlorosis. Furthermore, CFA (7.5 and 15%) in the 90-d pot study significantly (p < 0.05) impaired plant growth, induced lipid peroxidation and reduced genomic dsDNA. However, the incorporation of AMF or GSH enhanced seed germination, plant growth, and/or genomic dsDNA, reduced lipid peroxidation and prevented leaf chlorosis in CFA-exposed switchgrass plant. This study demonstrates that AMF and GSH have the potential to mitigate CFA-induced phytotoxicity. These biological and chemical strategies could be further harnessed for efficient utilization of switchgrass plant in the phytoremediation of CFA contaminated soil environment while simultaneously limiting CFA-induced phytotoxicity.